WO2000014633A1 - Load balancing in a network environment - Google Patents

Load balancing in a network environment Download PDF

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Publication number
WO2000014633A1
WO2000014633A1 PCT/US1999/019875 US9919875W WO0014633A1 WO 2000014633 A1 WO2000014633 A1 WO 2000014633A1 US 9919875 W US9919875 W US 9919875W WO 0014633 A1 WO0014633 A1 WO 0014633A1
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WO
WIPO (PCT)
Prior art keywords
server
status
application
central
instance
Prior art date
Application number
PCT/US1999/019875
Other languages
French (fr)
Inventor
Anita Jindal
Swee Boon Lim
Sanjay Radia
Whei-Ling Chang
Original Assignee
Sun Microsystems, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sun Microsystems, Inc. filed Critical Sun Microsystems, Inc.
Priority to AU61323/99A priority Critical patent/AU6132399A/en
Priority to DE69935920T priority patent/DE69935920T2/en
Priority to EP99948082A priority patent/EP1116112B1/en
Publication of WO2000014633A1 publication Critical patent/WO2000014633A1/en

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Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F9/00Arrangements for program control, e.g. control units
    • G06F9/06Arrangements for program control, e.g. control units using stored programs, i.e. using an internal store of processing equipment to receive or retain programs
    • G06F9/46Multiprogramming arrangements
    • G06F9/50Allocation of resources, e.g. of the central processing unit [CPU]
    • G06F9/5005Allocation of resources, e.g. of the central processing unit [CPU] to service a request
    • G06F9/5027Allocation of resources, e.g. of the central processing unit [CPU] to service a request the resource being a machine, e.g. CPUs, Servers, Terminals
    • G06F9/5055Allocation of resources, e.g. of the central processing unit [CPU] to service a request the resource being a machine, e.g. CPUs, Servers, Terminals considering software capabilities, i.e. software resources associated or available to the machine
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00Network arrangements or protocols for supporting network services or applications
    • H04L67/01Protocols
    • H04L67/10Protocols in which an application is distributed across nodes in the network
    • H04L67/1001Protocols in which an application is distributed across nodes in the network for accessing one among a plurality of replicated servers
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00Network arrangements or protocols for supporting network services or applications
    • H04L67/01Protocols
    • H04L67/10Protocols in which an application is distributed across nodes in the network
    • H04L67/1001Protocols in which an application is distributed across nodes in the network for accessing one among a plurality of replicated servers
    • H04L67/1004Server selection for load balancing
    • H04L67/1008Server selection for load balancing based on parameters of servers, e.g. available memory or workload
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00Network arrangements or protocols for supporting network services or applications
    • H04L67/01Protocols
    • H04L67/10Protocols in which an application is distributed across nodes in the network
    • H04L67/1001Protocols in which an application is distributed across nodes in the network for accessing one among a plurality of replicated servers
    • H04L67/1004Server selection for load balancing
    • H04L67/101Server selection for load balancing based on network conditions
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00Network arrangements or protocols for supporting network services or applications
    • H04L67/01Protocols
    • H04L67/10Protocols in which an application is distributed across nodes in the network
    • H04L67/1001Protocols in which an application is distributed across nodes in the network for accessing one among a plurality of replicated servers
    • H04L67/1036Load balancing of requests to servers for services different from user content provisioning, e.g. load balancing across domain name servers

Definitions

  • This invention relates to the field of computer systems. More particularly, a system and methods are provided for load balancing among application programs or replicated services.
  • clients e.g., computer systems and users
  • servers offering a desired application or service - such as electronic mail or Internet browsing.
  • One computer server may, however, only be capable of efficiently satisfying the needs of a limited number of clients.
  • an organization may employ multiple servers offering the same application or service, in which case the client may be connected to any of the multiple servers in order to satisfy the client's request.
  • a service offered simultaneously on multiple servers is often termed "replicated" in recognition of the fact that each instance of the service operates in substantially the same manner and provides substantially the same functionality as the others.
  • the multiple servers may, however, be situated in various locations and serve different clients.
  • Application programs may also operate simultaneously on multiple servers, with each instance of an application operating independently of, or in concert with, the others.
  • In order to make effective use of an application or replicated service offered by multiple servers e.g., to satisfy clients' requests), there must be a method of distributing clients' requests among the servers and/or among the instances of the application or service. This process is often known as load balancing. Methods of load balancing among instances of a replicated service have been developed, but are unsatisfactory for various reasons.
  • clients' requests are assigned to the servers offering the service on a round-robin basis.
  • client requests are routed to the servers in a rotational order.
  • Each instance of the replicated service may thus receive substantially the same number of requests as the other instances.
  • this scheme can be very inefficient.
  • the servers that offer the replicated service may be geographically distributed, a client's request may be routed to a relatively distant server, thus increasing the transmission time and cost incurred in submitting the request and receiving a response.
  • the processing power of the servers may vary widely.
  • One server may, for example, be capable of handling a larger number of requests or be able to process requests faster than another server.
  • a more powerful server may periodically be idle while a slower server is over-burdened.
  • specialized hardware is employed to store information concerning the servers hosting instances of a replicated service.
  • information is stored on a computer system other than the system that initially receives clients' requests. The stored information helps identify the server having the smallest load (e.g., fewest client requests). Based on that information, a user's request is routed to the least-loaded server.
  • a user's service access request e.g., a connection request to a particular Uniform Resource Locator (URL) or virtual server name
  • DNS Domain Name Services
  • the DNS server queries or passes the request to the specialized hardware. Based on the stored information, the user's request is then forwarded to the least-loaded server offering the requested service.
  • a DNS server This method is also inefficient because it delays and adds a level of complexity to satisfying access requests.
  • one purpose of a DNS server is to quickly resolve a client's request for a particular service to a specific server (e.g., a specific network address) offering an instance of the service. Requiring the DNS server to query or access another server in order to resolve the request is inefficient and delays the satisfaction of the request.
  • client requests are randomly assigned to a server or are assigned to the closest server. Random assignment of client requests suffers the same disadvantages as a round-robin scheme, often causing requests to be routed to geographically distant servers and/or servers that are more burdened than others. This naturally results in unnecessary delay. Simply assigning requests to the closest server may also be inefficient because a faster response may be available from a server that, although further from the client, has less of a load. As mentioned above, present load balancing techniques are also limited in scope.
  • the techniques described above are designed for replicated services only and, in addition, only consider the operational status or characteristics of the servers hosting the replicated service, not the service itself.
  • present techniques do not allow load balancing among instances of an application program or, more generally, the collection or consideration of information concerning the status of individual instances of applications or services executing on multiple servers.
  • a system and methods are provided for balancing client (e.g., user) requests among multiple instances of an application (e.g., application program or replicated service) in accordance with a selected policy.
  • client e.g., user
  • an application e.g., application program or replicated service
  • each instance of the load-balanced application executes on a separate computer server.
  • a load balancing policy is selected for distributing the client requests among the multiple servers and instances of the application and, at periodic intervals, a "preferred" server is identified in accordance with the policy.
  • the selected policy illustratively reflects or specifies one or more application-specific factors or characteristics to be considered in choosing the preferred server.
  • Client requests are routed to the preferred server until such time as a different server is preferred.
  • a selected load balancing policy may be replaced while the application continues operating.
  • Exemplary policies reflect preferences for the least-loaded instance of the application or the instance having the fastest response time.
  • the least-loaded instance is illustratively that which has the fewest connected clients and/or the fewest pending client requests.
  • the preferred server is illustratively the server that can be reached in the fewest network hops or connections.
  • Another illustrative policy favors the server and/or the instance with the greatest throughput (e.g., the highest number of client requests satisfied in a given time period).
  • status objects e.g., agents, modules or other series of executable instructions
  • status objects are configured to collect these various pieces of information from each instance of the application that is being load-balanced (and/or its server).
  • Status objects in one embodiment of the invention thus retrieve application- specific information (e.g., number and/or type of pending client requests) and/or information concerning a server's general status (e.g., its distance from another network entity).
  • application-specific information e.g., number and/or type of pending client requests
  • information concerning a server's general status e.g., its distance from another network entity.
  • Each instance of a load-balanced application is illustratively associated with its own status object(s).
  • multiple status objects having different functions are associated with one instance.
  • Each instance of the application (or, alternatively, each server hosting an instance of the application) is also associated with an individual monitor object or IMO (e.g., another object, module or series of executable instructions).
  • Each IMO invokes and stores information from one or more status object(s) collecting information concerning an instance of the application.
  • each IMO is configured to interact with a single status object; in an alternative embodiment multiple status objects are associated with an IMO.
  • an IMO interfaces directly with its status object(s); in another embodiment each status object stores its application-specific information for retrieval by the IMO.
  • a replicated monitor object (RMO) or module is employed to collect information from the IMOs associated with the various instances of the load-balanced application.
  • the RMO stores this information, which is then analyzed to identify a preferred server in accordance with the selected policy.
  • a specialized updater object updates a lookup table (e.g., a DNS zone file) to identify the preferred server (e.g., by its network address or an alias).
  • the lookup table is illustratively used to resolve a virtual server name (e.g., a virtual identity of the application) to a particular server offering an instance of the application.
  • the central server directs the request to the server indicated in the lookup table (i.e., the preferred server).
  • the specialized object is thus configured to update the lookup table (or other data structure) or otherwise cause the direction or re-direction of load-balanced requests to the preferred server.
  • the status object(s) and an IMO execute on each individual server hosting an instance of the load-balanced application.
  • the RMO and updater objects illustratively operate on a central server.
  • only the status object(s) execute on the individual servers with the application instances.
  • the other objects are illustratively distributed among the central server and other intermediate servers. DESCRIPTION OF THE FIGURES
  • FIG. 1 is a block diagram depicting an illustrative environment in which an embodiment of the present invention may be implemented to load balance client requests among multiple instances of an application.
  • FIG. 2 is a block diagram depicting a method of balancing client requests among application instances in accordance with an embodiment of the present invention.
  • FIG. 3 is a block diagram depicting a method of balancing client requests among geographically dispersed application instances in accordance with an embodiment of the present invention.
  • FIG. 4 is a flow chart demonstrating the generation of objects in a load-balancing framework in accordance with an embodiment of the present invention.
  • FIG. 5 is a flow chart demonstrating the registration of objects within a load balancing framework and their use in monitoring an instance of a load-balanced application in accordance with an embodiment of the present invention.
  • Various embodiments of the invention may therefore involve the use of a central server, such as a Domain Name Services (DNS) server, to resolve an access request for an application into an address of a physical machine such as a computer server.
  • DNS Domain Name Services
  • a central server such as a Domain Name Services (DNS) server
  • DNS Domain Name Services
  • the program environment in which a present embodiment of the invention is executed illustratively incorporates a general-purpose computer or a special purpose device such a hand-held computer. Details of such devices (e.g., processor, memory, data storage and display) are well known and are omitted for the sake of clarity.
  • the techniques of the present invention might be implemented using a variety of technologies.
  • the methods described herein may be implemented in software running on a computer system, or implemented in hardware utilizing either a combination of microprocessors or other specially designed application specific integrated circuits, programmable logic devices, or various combinations thereof.
  • the methods described herein may be implemented by a series of computer-executable instructions residing on a storage medium such as a carrier wave, disk drive, or computer-readable medium.
  • a storage medium such as a carrier wave, disk drive, or computer-readable medium.
  • specific embodiments of the invention are described using object-oriented software programming concepts, the invention is not so limited and is easily adapted to employ other forms of directing the operation of a computer.
  • information concerning instances of an application e.g., an application program or replicated service
  • a preferred server is illustratively the server to which client requests for the application are to be routed for processing.
  • a preferred server is identified on a regular or periodic basis, and may be the same as or different from the server previously identified.
  • client requests are load-balanced between the participating servers. Individual clients may thus be routed to, and their requests (e.g., database access, send electronic mail, browse a web page) satisfied by, any of the multiple servers.
  • the information that may be collected concerning an instance of the program illustratively includes its response time for a client request, its operational status (e.g., whether it is up or down), the number of clients connected to the instance, the number of client requests pending with the instance, its throughput (e.g., number of client requests handled in a period of time), etc.
  • Information concerning the status or performance of the host servers themselves e.g., load, capacity, distance from a central server
  • a central server that distributes client requests for the application among the various instances uses a lookup table or other data structure or means to store an identifier of the current preferred server.
  • the central server is, in one embodiment of the invention, a Domain Name Services (DNS) server.
  • DNS Domain Name Services
  • the application is exposed (e.g., identified) as a virtual server name to which clients connect and which the DNS resolves to an address of one of the multiple servers operating an instance of the application.
  • the specific information that is collected is determined by a load balancing policy that is illustratively selected by a system manager or administrator.
  • the preferred server is then selected by analyzing the collected information.
  • the preferred server is the server offering the application instance that is least-loaded (e.g., has the fewest pending client requests or fewest connected clients).
  • the preferred server is the server closest to the central server.
  • the various pieces of information are illustratively collected and assembled on the central server.
  • the central server's lookup table is updated with an identifier (e.g., a network address) of the preferred server and subsequent requests for the application or replicated service are directed to that server.
  • an identifier e.g., a network address
  • a DNS zone file is updated to indicate that requests for the Internet service or web page are to be routed to the preferred server.
  • a standard application programming interface is provided to construct and apply the load balancing framework described below.
  • API application programming interface
  • a programmer may generate application-specific status objects (described in detail below in conjunction with FIG. 2) which, when executed, gather the information described above.
  • the application-specific status objects may, in addition, interact with the application in accordance with an application-specific API.
  • Generating application-specific status objects or modules illustratively allows the collection of any information that could form the basis for load balancing client requests.
  • FIG. 1 is a block diagram depicting an illustrative environment in which an embodiment of the invention may be implemented to balance client requests among multiple instances of an application executing on multiple servers.
  • Central server 100 is illustratively a computer system that receives information from the various application instances (and possibly the servers hosting the application instances) and routes requests from clients such as client 120 to a preferred server.
  • central server 100 is a DNS server.
  • Back-end or host servers 110, 112 and 114 each offer one or more instances of application 104, represented by the numerals 104a, 104b and 104c. Servers 110, 112 and 114 may be geographically or logically separated from one another.
  • Central server 100 includes lookup table 102 for resolving requests for application program 104 to an address of a server offering an instance of the program.
  • Lookup table 102 thus includes an entry for the program's identity as exposed to clients (e.g., an alias or a virtual server name), to allow the clients to access an instance of the application on server 110, server 112 or server 114.
  • the lookup table entry for application 104 may indicate a network address (e.g., an IP or Internet protocol address) for one of servers 110, 112 and 114.
  • Client 120 is illustratively a personal computer or workstation configured to provide a user access to a network (e.g., the Internet) and various applications and services on servers 110, 112 and 114. Client 120 is thus coupled to central server 100 via network 122, and includes instructions (e.g., a web browser) for communicating via network 122. Client 120 further includes common components such as a processor, memory, storage, input and output devices, etc. Such common components are well known to those skilled in the art and are omitted from FIG. 1 for the purpose of clarity. In the environment of FIG. 1, when client 120 attempts to connect to application
  • central server 100 Central server 100, through lookup table 102, identifies a preferred server offering an instance of program 104 and routes the client request accordingly.
  • the server identified in lookup table 102 is illustratively determined according to a load-balancing policy, as discussed below. Further, the server identified in lookup table 102 is updated or changed from time to time in accordance with the selected policy in order to distribute client requests among the instances of the application.
  • information reflecting the status or operation of application instances 104a, 104b and 104c (and/or servers 110, 112 and 114) is collected and analyzed on a regular or periodic basis.
  • the information that is collected is identified in a load balancing policy that identifies one or more factors or pieces of information to be used to identify a "preferred" server to which client requests for application 104 are to be routed. Different policies thus require different information to be collected from the application instances, and the active policy can be changed during load balancing.
  • the various pieces of information that may be collected illustratively include data such as: whether a server or instance of application 104 is operational; the response time for a request submitted to a server or application instance; the number of requests processed by or pending on a server or application instance, a server's proximity to the central server (e.g., the number of network hops necessary to reach the server), etc.
  • status objects are generated or produced to collect application-specific data from the application instances.
  • the status objects are illustratively constructed according to a standard API for a present load-balancing framework. Status objects and the load-balancing framework are described in detail below with reference to FIG. 2.
  • status objects and other objects within the framework are designed (e.g., an object class is constructed) according to the standard API in a generation stage. Then, in a registration stage, individual objects are instantiated from the class(es). Finally, in a monitoring stage, the objects begin collecting information.
  • status objects periodically interact with instances of application 104 to collect application-specific statistics that will be used to select a preferred server. For example, if application 104 were a DBMS, a status object may gather the number of database accesses, the number of requests received or pending, etc. for one instance of the application. As another example, if application 104 were an electronic mail program, a status object may periodically gather the number of inbound and/or outbound messages in queue, the number and size of mailboxes, etc.
  • other computer-readable instructions e.g., in the form of objects, agents or modules
  • the objects or agents within a load balancing framework may be created in a suitable programming or script language and then configured and installed on each of servers 110, 112 and 114 and/or on central server 100.
  • the lookup table instead of returning an address of a server in response to a request for application 104, the lookup table returns an identifier (e.g., file name) of a set of instructions.
  • the instructions are executed, illustratively by central server 100, in order to perform a variety of actions (e.g., load or mount an alternate Internet or domain namespace).
  • FIG. 2 depicts an illustrative embodiment of the invention in which operational and statistical information is collected from application instances 104a, 104b and 104c on servers 110, 112 and 114, respectively.
  • the collected information is analyzed on central server 100 to choose a preferred server, and lookup table 102 is then modified to reflect an identity (e.g., a network address) of the preferred server.
  • identity e.g., a network address
  • application instances 104a, 104b and 104c include application-specific information that is to be considered in choosing the preferred server.
  • Status objects 200, 202 and 204 therefore execute on servers 110, 112 and 114, respectively, to gather the information or statistics from their associated application instances.
  • the status objects advantageously adhere to the format provided by a standard API, concerning the manner in which the information is to be communicated to the central server.
  • the status objects are designed to accumulate, store and/or provide application-specific data for retrieval by individual monitor obj ects 210, 212 and 214, which also execute on servers 110, 112 and 114, respectively.
  • the configuration of the status objects depends upon the policy that has been selected for choosing a preferred server. For example, where the selected policy requires choosing the least-loaded server (e.g., the server having the least- loaded instance of the application), a status object may be configured to retrieve the number of pending client requests or number of connected clients. As another example, status objects 200, 202 and 204 may be configured to retrieve a response time or throughput of their associated application instances.
  • status objects are configured to retrieve their specified information on a periodic basis. If a status object fails to gather its information, it may be assumed that the associated application instance is not operational. If an application instance is determined to be down, the associated server is illustratively removed from consideration as the preferred server for that application.
  • status objects 200, 202 and 204 communicate with or access application instances 104a, 104b and 104c in accordance with an application-specific API. Each status object also illustratively performs a single function or retrieves a single piece of application-specific information. In alternative embodiments of the invention, however, a single status object may perform multiple functions or produce multiple pieces of information.
  • a status object may retrieve multiple pieces of information concerning an application instance's load (e.g., number of connected clients, number of pending requests). The multiple pieces of information may then be combined (e.g., via a specified formula or function) to produce a single value or representation of the instance' s load.
  • individual monitor objects (IMO) 210, 212 and 214 also reside and execute on servers 110, 112 and 114. Individual monitor objects are known as server monitor objects in one embodiment of the invention. A separate IMO is depicted for each application instance. In particular, IMOs 210, 212 and 214 collect information from status objects 200, 202 and 204 respectively.
  • a status object collects the specified application-specific information and stores it on its host server for collection by the associated IMO.
  • status objects interface with and directly communicate the information to their IMOs.
  • different types of status objects are executed or invoked with differing degrees of regularity.
  • the status objects collect the application instances' response times, for example, status object 200 may execute relatively frequently (e.g., every 60 seconds).
  • status object 202 may execute only occasionally (e.g., once per day) because the distance from central server 100 to server 112 is unlikely to change very often.
  • an IMO may collect data from multiple status objects.
  • an IMO may interface with one status object to determine the response time of an application instance or server and another status object to determine the load on the instance or server.
  • Replicated monitor object (RMO) 220 retrieves the collected information produced from each IMO associated with an application. Therefore, in the illustrated embodiment where each of servers 110, 112 and 114 operate a separate instance of a load- balanced application, RMO 220 collects data from IMOs 210, 212 and 214.
  • a second RMO would illustratively operate on central server 100 for the purpose of retrieving information concerning that application from a different set of IMOs.
  • a replicated monitor object may also be known as a central monitor object due to its coordination role on behalf of a central server that receives multiple requests for an application.
  • Various means of communication may be employed between an RMO and the
  • IMOs associated with a particular application In a present embodiment of the invention Object Request Broker (ORB) technology is employed. In an alternative embodiment of the invention Remote Procedure Call (RPC) technology can be used.
  • ORB Object Request Broker
  • RPC Remote Procedure Call
  • a status object gathers load and/or operational information for an instance of the application being load-balanced.
  • An IMO interfaces with or otherwise retrieves the information from each status object and an RMO gathers the information from all application instances from the IMOs.
  • the data collected by RMO 220 from the various IMOs is analyzed in accordance with the selected policy and a preferred server is identified.
  • updater object 230 performs the analysis and selection of a preferred server.
  • the preferred server may, for example, be the one having the application instance with the fastest response time, the fewest pending client requests, the greatest capacity for client requests, etc.
  • RMO 220 maintains a data structure (e.g., array, vector, table, database) identifying each application instance and/or server that is being load-balanced, along with one or more values or other indicators or summaries of the collected information concerning each application instance.
  • updater object 230 updates lookup table 102 after the collected information is analyzed and a preferred server is selected. Illustratively, one updater object is used to update the lookup table for all applications being load-balanced.
  • FIG. 2 depicts an alternative embodiment of the invention in which servers offering an application are geographically dispersed.
  • FIG. 2 depicts an alternative embodiment of the invention in which servers offering an application are geographically dispersed.
  • server farm 300 represents a first collection of servers offering the application (e.g., application instances 104a and 104b) and server farm 310 represents a second collection of servers offering the same application (e.g., application instances 104c and 104d).
  • server farms are depicted in FIG. 3 with multiple members (i.e., servers 302 and 304 in server farm 300 and servers 312 and 314 in server farm 310), a server farm may consist of any number of members, even one.
  • Each server farm in the presently described embodiment includes an intermediate server (i.e., server 306 in server farm 300 and server 316 in server farm 310).
  • An intermediate server in this embodiment is to collect, from the servers in the farm that host instances of the application, information necessary to select a preferred server.
  • intermediate replicated monitor object (IRMO) 306a is operated on intermediate server 306 to collect data from servers 302 and 304.
  • IRMO 306a operates similarly to the RMO described above with reference to FIG. 2, but is illustratively located on a server situated between central server 100 and the servers offering the application.
  • the load balancing framework of the illustrated embodiment also includes status objects (e.g., depicted by numerals 302a, 304a, 312a and 314a) and IMOs (e.g., depicted by numerals 302b, 304b, 312b and 314b) operating on servers 302, 304, 312 and 314.
  • RMO 320 operates on central server 100 to collect data from the IRMOs within each server farm.
  • Updater object 322 updates lookup table 102 to reflect the preferred server identified from the data collected by RMO 320.
  • intermediate servers with IRMOs are employed in server farms comprising the remote servers, in order to pass data between the remote servers' IMOs and an RMO, as in the embodiment depicted in FIG. 3.
  • Local servers employ IMOs that communicate with the RMO without an intervening RMO, as in FIG. 2.
  • load balancing among instances of an application is performed among multiple participating servers wherein one or more of the servers are segregated (e.g., situated in a remote location and/or within a server farm).
  • a "local" load balancing policy may be implemented for distributing all client requests sent to the group and/or to a specific member of the group.
  • the segregated servers may be considered a single entity for the purposes of a "global" load balancing policy specifying the manner in which all client requests for the application are to be distributed among all participating servers.
  • the global and local policies need not be equivalent (e.g., the global policy may require selection of the closest server (or group of servers) while the local policy may require the least-loaded server or application instance).
  • a central server e.g., a DNS
  • Each instance of the application illustratively operates on a separate server and is modified to produce application-specific information needed to choose the preferred server.
  • FIG. 4 demonstrates an illustrative generation stage of the method, in which objects in the load-balancing framework are designed (e.g., object classes are constructed).
  • FIG. 5 demonstrates illustrative registration and monitoring stages, in which individual objects are created (e.g., instantiated) and begin collecting information from instances of the load-balanced application.
  • state 400 is a start state.
  • a policy to be applied to identify a preferred server is selected.
  • policies are possible, depending upon the nature of the application and the aspect(s) of the application that are conducive to load balancing.
  • Illustrative policies in a present embodiment of the invention focus upon the status or availability of the various instances of the application. Such policies reflect preferences for the least loaded instance, the instance with the fastest response time or throughput, the instance with the fewest connected clients, etc. For example, where access requests for a database management system (DBMS) are load balanced, illustrative policies may include routing requests to the server on which the fewest DBMS requests have been processed or the server having the fewest connected users or the fewest unfulfilled processing or access requests. For each application for which requests are load-balanced, separate policies may be employed.
  • DBMS database management system
  • policies require examination of the availability or status of the servers offering instances of the application.
  • policies may express preferences for the server having the shortest distance to the central server, the fastest response time, the best throughput, etc.
  • the selected policy reflects whichever aspect or aspects of the load- balanced application form the basis for distributing client requests among the various instances of the application and/or the servers hosting the application instances.
  • the information reflecting these aspects is periodically captured for each instance by status objects working in close cooperation with the application instances.
  • state 404 sequences of instructions or executable code are produced for performing the function(s) of the status objects (i.e., to collect the application-specific information needed to choose a preferred server).
  • the load balancing framework is constructed using an object-oriented programming language
  • a compatible language and basic building blocks provided by the framework are used to generate the status objects, IMOs, RMO and specialized object.
  • state 404 comprises the creation of one or more classes of status objects, from which individual instances will be created in the registration stage depicted in FIG. 5.
  • status objects are substantially similar for each instance of the application.
  • Status objects may be configured to store the information for retrieval by individual monitor objects or, alternatively, to interface with the IMOs directly in order to pass the information along.
  • the status objects may be configured to execute automatically on a regular basis, in response to action by another part of the load balancing framework (e.g., upon invocation by an IMO), the application or some other external entity, etc.
  • status objects are constructed using an object-oriented programming language.
  • object-oriented programming language e.g., a load balancing framework API
  • status objects substantially adhere to a common format (e.g., detailed in a load balancing framework API) in order to cooperate with the overall load balancing framework.
  • the existing load-balancing framework is examined to determine whether an IMO (e.g., an IMO class) already exists for collecting data concerning an instance of the load-balanced application. If an IMO already exists, the illustrated method continues at state 410. Otherwise, in state 408 an IMO structure (e.g., an object class) is constructed that is specific to the application instance. The IMO is designed such that it will collect the various data and statistics gathered by one or more status object(s). In an alternative embodiment of the invention, the IMOs generated for all instances of a particular application are substantially similar.
  • an IMO e.g., an IMO class
  • an RMO comprises a data structure for retaining application-specific information from the application instances. If an RMO already exists, the illustrated method continues at state 414. Otherwise, in state 412, an RMO structure (e.g., an object class) is constructed that is specific to the application. As with the status objects and IMOs, an actual RMO instance will be created as part of the registration stage depicted in FIG. 5.
  • an RMO structure e.g., an object class
  • the existing load balancing framework is examined once more. This time, it is determined if the sequence of instructions or executable code for the specialized object that will determine a preferred server already exists. If not, in state 416 a specialized object structure (e.g., an object class) is constructed to apply the selected load balancing policy to the results of the data collected concerning the various application instances (and/or their host servers) and select a preferred server. The specialized object is also designed to update the lookup table (or other data structure) to store an identity of the preferred server.
  • a specialized object structure e.g., an object class
  • the generation stage of the illustrated method then ends with end state 418.
  • registration refers to the registration of individual objects (e.g., status object, IMO, RMO, specialized object) within a load balancing framework, including their creation (e.g., instantiation) from the object structures (e.g., classes) produced in the generation stage depicted in FIG. 4.
  • object structures e.g., classes
  • information is collected for the purpose of identifying a preferred server in accordance with a selected load balancing policy.
  • state 500 is a start state.
  • state 502 a status object is registered with the load-balancing framework.
  • the standard API provided with the load balancing framework includes a command (e.g., "create") for creating an instance of each object within the framework.
  • a command e.g., "create”
  • creating an instance of an object involves the dynamic loading and executing of a sequence of instructions defining the object.
  • configurable parameters of the status object are set in accordance with the selected policy.
  • Illustrative parameters include the frequency of gathering the application-specific information, a network or port address for communicating with the application instance, information detailing how to communicate with the application instance and/or IMO, etc.
  • a status object may have a variety of configurable parameters, depending upon the nature of the application and the selected policy.
  • an individual monitor object is registered with the load- balancing framework.
  • one IMO is registered or created for each instance of the application.
  • Each IMO is illustratively installed on the server executing the associated instance of the application.
  • IMOs operate on the central server or an intermediate server located between the central server and the host servers.
  • IMOs are illustratively configured to collect and report certain information or data.
  • the collected information is received directly from a status object.
  • the information may be retrieved from a location in which it was placed by the status object (e.g., a storage device, a file or other data structure).
  • the collected information is illustratively determined by the selected load balancing policy, and will be used to identify a preferred server.
  • the active policy for an application may be changed without disrupting the handling of client requests. Illustratively, this is done by temporarily pausing the operation of IMOs for the application, installing new status objects reflecting the new policy, then resuming the IMOs.
  • the IMOs need not be altered or replaced.
  • parameters are set for the IMO created in state 506.
  • Illustrative parameters include a list of status objects from which to collect information, the frequency with which to collect the information, how to communicate with the status objects and/or RMO, etc.
  • a replicated monitor object is created for the load balanced application.
  • the RMO is illustratively installed on the central server and communicates with the IMOs using a suitable format or protocol (e.g., ORB or RPC).
  • a suitable format or protocol e.g., ORB or RPC.
  • intermediate servers e.g., where remote servers or server farms are included
  • RMO parameters are set, illustratively including a list of IMOs, the frequency with which data is to be collected from the IMOs, method of communicating with the IMOs, etc.
  • a back-end or host server e.g., server 110 from FIG. 1 may be removed from or added to the load-balancing scheme without significantly disrupting operation of the application.
  • a host server may, for example, become inoperative or require replacement.
  • each RMO maintains an index (e.g., in an array, linked list, vector, other data structure, etc.) of all servers participating in the load balancing (e.g., all servers offering an instance of the application).
  • This information may, for example, be included in a list of IMOs from which the RMO receives information.
  • the RMO will stop attempting to retrieve information for the removed server (i.e., the RMO will no longer communicate with the IMO associated with the server).
  • Servers may be added to the load-balancing scheme in a similar manner.
  • a specialized object is registered with the load-balancing framework (e.g., created from its object class).
  • parameters concerning the operation of the specialized object are set.
  • Illustrative parameters include an identity of the RMO, the frequency of information retrieval from the RMO, an identity of the lookup table, method of interfacing with the RMO and/or lookup table, etc.
  • the specialized object analyzes the information collected from the servers hosting the application instances, identifies a preferred server in accordance with the load- balancing framework and updates the lookup table.
  • the specialized object may take the form of a DNS updater configured on a DNS server to modify a DNS zone file to identify the server to which requests are to be routed.
  • the specialized object updates a data structure or entry indicating a preferred process or server.
  • the collection of server/application information can begin.
  • the created objects e.g., status objects, IMOs, RMO and specialized object
  • the created objects are activated or executed if they are not already executing.
  • a status object begins collecting or gathering information from its application instance. For example, where the selected policy favors the least-loaded application instance, a status object retrieves data concerning an instance's load (e.g., number of client requests or connected clients).
  • an IMO retrieves the information gathered by its associated status object(s). Then, in state 524, an RMO calls, invokes or otherwise communicates with the IMO to retrieve the information.
  • the RMO may similarly communicate with additional IMOs storing information concerning other servers or instances of the application. Illustratively, the RMO executes on the central server and stores the information retrieved from the IMOs for analysis by the specialized object.
  • state 526 the information collected by the RMO is analyzed in accordance with the selected policy to choose a preferred server.
  • the specialized object updates the lookup table for the central server to indicate the preferred server.
  • the update procedure comprises associating an alias or network address of the preferred server with the name of a virtual server/service through which clients access the application.
  • the central server is signaled to reload the lookup table.
  • State 530 is an end state.
  • clients access an instance of the application program directly (i.e., rather than connecting through a central server).
  • the program instances exchange information
  • an RMO may be designed to perform the functions of an IMO and collect information from one or more status objects.

Abstract

A method is provided for load balancing requests for an application among a plurality of instances of the application operating on a plurality of servers. A policy is selected for choosing a preferred server from the plurality of servers according to a specified status or operational characteristic of the application instances, such as the least-loaded instance or the instances with the fastest response time. The policy is encapsulated within multiple levels of objects or modules that are distributed among the servers offering the application and a central server that receives requests for the application. A first type of object, a status object, gathers or retrieves application-specific information concerning the specified status or operational characteristic of an instance of the application. Status objects interact with instances of the load-balanced application and are configured to store their collected information for retrieval by individual server monitor objects. An individual server monitor object illustratively operates for each server operating an instance of the application and retrieves the application-specific information from one or more status objects. A central replicated monitor object gathers the information from the individual server monitor objects. The information is then analyzed to select the server having the optimal status or operational characteristic. An update object updates the central server, such as a domain name server, to indicate the preferred server. Requests for the application are then directed to the preferred server until a different preferred server is identified.

Description

LOAD BALANCING IN A NETWORK ENVIRONMENT
BACKGROUND This invention relates to the field of computer systems. More particularly, a system and methods are provided for load balancing among application programs or replicated services.
In many computing environments, clients (e.g., computer systems and users) connect to servers offering a desired application or service - such as electronic mail or Internet browsing. One computer server may, however, only be capable of efficiently satisfying the needs of a limited number of clients. In such a case, an organization may employ multiple servers offering the same application or service, in which case the client may be connected to any of the multiple servers in order to satisfy the client's request.
A service offered simultaneously on multiple servers is often termed "replicated" in recognition of the fact that each instance of the service operates in substantially the same manner and provides substantially the same functionality as the others. The multiple servers may, however, be situated in various locations and serve different clients. Application programs may also operate simultaneously on multiple servers, with each instance of an application operating independently of, or in concert with, the others. In order to make effective use of an application or replicated service offered by multiple servers (e.g., to satisfy clients' requests), there must be a method of distributing clients' requests among the servers and/or among the instances of the application or service. This process is often known as load balancing. Methods of load balancing among instances of a replicated service have been developed, but are unsatisfactory for various reasons. In one method of load balancing a replicated service, clients' requests are assigned to the servers offering the service on a round-robin basis. In other words, client requests are routed to the servers in a rotational order. Each instance of the replicated service may thus receive substantially the same number of requests as the other instances. Unfortunately, this scheme can be very inefficient. Because the servers that offer the replicated service may be geographically distributed, a client's request may be routed to a relatively distant server, thus increasing the transmission time and cost incurred in submitting the request and receiving a response. In addition, the processing power of the servers may vary widely. One server may, for example, be capable of handling a larger number of requests or be able to process requests faster than another server. As a result, a more powerful server may periodically be idle while a slower server is over-burdened. In another method of load balancing, specialized hardware is employed to store information concerning the servers hosting instances of a replicated service. In particular, according to this method information is stored on a computer system other than the system that initially receives clients' requests. The stored information helps identify the server having the smallest load (e.g., fewest client requests). Based on that information, a user's request is routed to the least-loaded server. In a web-browsing environment, for example, when a user's service access request (e.g., a connection request to a particular Uniform Resource Locator (URL) or virtual server name) is received by a server offering Domain Name Services (DNS), the DNS server queries or passes the request to the specialized hardware. Based on the stored information, the user's request is then forwarded to the least-loaded server offering the requested service.
This method is also inefficient because it delays and adds a level of complexity to satisfying access requests. In particular, one purpose of a DNS server is to quickly resolve a client's request for a particular service to a specific server (e.g., a specific network address) offering an instance of the service. Requiring the DNS server to query or access another server in order to resolve the request is inefficient and delays the satisfaction of the request.
In yet other methods of balancing requests among multiple instances of a replicated service, client requests are randomly assigned to a server or are assigned to the closest server. Random assignment of client requests suffers the same disadvantages as a round-robin scheme, often causing requests to be routed to geographically distant servers and/or servers that are more burdened than others. This naturally results in unnecessary delay. Simply assigning requests to the closest server may also be inefficient because a faster response may be available from a server that, although further from the client, has less of a load. As mentioned above, present load balancing techniques are also limited in scope.
For example, the techniques described above are designed for replicated services only and, in addition, only consider the operational status or characteristics of the servers hosting the replicated service, not the service itself. In other words, present techniques do not allow load balancing among instances of an application program or, more generally, the collection or consideration of information concerning the status of individual instances of applications or services executing on multiple servers.
SUMMARY
In one embodiment of the invention a system and methods are provided for balancing client (e.g., user) requests among multiple instances of an application (e.g., application program or replicated service) in accordance with a selected policy. In this embodiment, each instance of the load-balanced application executes on a separate computer server.
A load balancing policy is selected for distributing the client requests among the multiple servers and instances of the application and, at periodic intervals, a "preferred" server is identified in accordance with the policy. The selected policy illustratively reflects or specifies one or more application-specific factors or characteristics to be considered in choosing the preferred server. Client requests are routed to the preferred server until such time as a different server is preferred. A selected load balancing policy may be replaced while the application continues operating.
Exemplary policies reflect preferences for the least-loaded instance of the application or the instance having the fastest response time. The least-loaded instance is illustratively that which has the fewest connected clients and/or the fewest pending client requests. In another policy, where the closest instance of the application is favored, the preferred server is illustratively the server that can be reached in the fewest network hops or connections. Another illustrative policy favors the server and/or the instance with the greatest throughput (e.g., the highest number of client requests satisfied in a given time period).
Depending upon the selected policy, status objects (e.g., agents, modules or other series of executable instructions) are configured to collect these various pieces of information from each instance of the application that is being load-balanced (and/or its server). Status objects in one embodiment of the invention thus retrieve application- specific information (e.g., number and/or type of pending client requests) and/or information concerning a server's general status (e.g., its distance from another network entity). Each instance of a load-balanced application is illustratively associated with its own status object(s). In one embodiment of the invention multiple status objects having different functions are associated with one instance.
Each instance of the application (or, alternatively, each server hosting an instance of the application) is also associated with an individual monitor object or IMO (e.g., another object, module or series of executable instructions). Each IMO invokes and stores information from one or more status object(s) collecting information concerning an instance of the application. In one embodiment of the invention each IMO is configured to interact with a single status object; in an alternative embodiment multiple status objects are associated with an IMO. In addition, in one embodiment of the invention an IMO interfaces directly with its status object(s); in another embodiment each status object stores its application-specific information for retrieval by the IMO.
A replicated monitor object (RMO) or module is employed to collect information from the IMOs associated with the various instances of the load-balanced application. The RMO stores this information, which is then analyzed to identify a preferred server in accordance with the selected policy.
In an embodiment of the invention in which clients access the application through a central server such as a Domain Name Services (DNS) server, a specialized updater object updates a lookup table (e.g., a DNS zone file) to identify the preferred server (e.g., by its network address or an alias). The lookup table is illustratively used to resolve a virtual server name (e.g., a virtual identity of the application) to a particular server offering an instance of the application. When a client requests an application via a virtual name, the central server directs the request to the server indicated in the lookup table (i.e., the preferred server). The specialized object is thus configured to update the lookup table (or other data structure) or otherwise cause the direction or re-direction of load-balanced requests to the preferred server.
In one embodiment of the invention the status object(s) and an IMO execute on each individual server hosting an instance of the load-balanced application. The RMO and updater objects illustratively operate on a central server. In an alternative embodiment, only the status object(s) execute on the individual servers with the application instances. The other objects are illustratively distributed among the central server and other intermediate servers. DESCRIPTION OF THE FIGURES
FIG. 1 is a block diagram depicting an illustrative environment in which an embodiment of the present invention may be implemented to load balance client requests among multiple instances of an application. FIG. 2 is a block diagram depicting a method of balancing client requests among application instances in accordance with an embodiment of the present invention.
FIG. 3 is a block diagram depicting a method of balancing client requests among geographically dispersed application instances in accordance with an embodiment of the present invention. FIG. 4 is a flow chart demonstrating the generation of objects in a load-balancing framework in accordance with an embodiment of the present invention.
FIG. 5 is a flow chart demonstrating the registration of objects within a load balancing framework and their use in monitoring an instance of a load-balanced application in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of particular applications of the invention and their requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. In particular, illustrative embodiments of the invention are described in the context of applications such as a database management system (DBMS), electronic mail, or web browsing. Various embodiments of the invention may therefore involve the use of a central server, such as a Domain Name Services (DNS) server, to resolve an access request for an application into an address of a physical machine such as a computer server. One skilled in the art will recognize that the present invention is not limited to the applications described herein or the use of a DNS server, and may be readily adapted to other applications and services for which load balancing is appropriate. The program environment in which a present embodiment of the invention is executed illustratively incorporates a general-purpose computer or a special purpose device such a hand-held computer. Details of such devices (e.g., processor, memory, data storage and display) are well known and are omitted for the sake of clarity. It should also be understood that the techniques of the present invention might be implemented using a variety of technologies. For example, the methods described herein may be implemented in software running on a computer system, or implemented in hardware utilizing either a combination of microprocessors or other specially designed application specific integrated circuits, programmable logic devices, or various combinations thereof. In particular, the methods described herein may be implemented by a series of computer-executable instructions residing on a storage medium such as a carrier wave, disk drive, or computer-readable medium. In addition, although specific embodiments of the invention are described using object-oriented software programming concepts, the invention is not so limited and is easily adapted to employ other forms of directing the operation of a computer.
In a present embodiment of the invention, information concerning instances of an application (e.g., an application program or replicated service) operating on multiple computer servers is collected and analyzed to identify a "preferred" server. A preferred server is illustratively the server to which client requests for the application are to be routed for processing. A preferred server is identified on a regular or periodic basis, and may be the same as or different from the server previously identified. By periodically changing the preferred server, client requests are load-balanced between the participating servers. Individual clients may thus be routed to, and their requests (e.g., database access, send electronic mail, browse a web page) satisfied by, any of the multiple servers. The information that may be collected concerning an instance of the program illustratively includes its response time for a client request, its operational status (e.g., whether it is up or down), the number of clients connected to the instance, the number of client requests pending with the instance, its throughput (e.g., number of client requests handled in a period of time), etc. Information concerning the status or performance of the host servers themselves (e.g., load, capacity, distance from a central server) may also be collected and analyzed as part of the process of choosing a preferred server.
Illustratively, a central server that distributes client requests for the application among the various instances uses a lookup table or other data structure or means to store an identifier of the current preferred server. The central server is, in one embodiment of the invention, a Domain Name Services (DNS) server. In this embodiment, the application is exposed (e.g., identified) as a virtual server name to which clients connect and which the DNS resolves to an address of one of the multiple servers operating an instance of the application.
The specific information that is collected (from the various application instances and, possibly, the host servers) is determined by a load balancing policy that is illustratively selected by a system manager or administrator. The preferred server is then selected by analyzing the collected information. Thus, in one illustrative policy, the preferred server is the server offering the application instance that is least-loaded (e.g., has the fewest pending client requests or fewest connected clients). In another illustrative policy, the preferred server is the server closest to the central server.
The various pieces of information are illustratively collected and assembled on the central server. After a preferred server is identified, the central server's lookup table is updated with an identifier (e.g., a network address) of the preferred server and subsequent requests for the application or replicated service are directed to that server. For example, in a web-browsing environment a DNS zone file is updated to indicate that requests for the Internet service or web page are to be routed to the preferred server.
In one embodiment of the invention a standard application programming interface (API) is provided to construct and apply the load balancing framework described below. With the standard API, a programmer may generate application-specific status objects (described in detail below in conjunction with FIG. 2) which, when executed, gather the information described above. The application-specific status objects may, in addition, interact with the application in accordance with an application-specific API. Generating application-specific status objects or modules illustratively allows the collection of any information that could form the basis for load balancing client requests. For example, to load-balance a database application, it may be desirable to determine the number of users being serviced by each instance of the application, the number of users that have accessed an instance, or the number of access requests that are pending with or that have been processed by each instance. The information gathered by the application- specific status objects is used by other objects and/or modules in the load-balancing framework in order to determine a preferred server. FIG. 1 is a block diagram depicting an illustrative environment in which an embodiment of the invention may be implemented to balance client requests among multiple instances of an application executing on multiple servers. Central server 100 is illustratively a computer system that receives information from the various application instances (and possibly the servers hosting the application instances) and routes requests from clients such as client 120 to a preferred server. In one embodiment of the invention, central server 100 is a DNS server. Back-end or host servers 110, 112 and 114 each offer one or more instances of application 104, represented by the numerals 104a, 104b and 104c. Servers 110, 112 and 114 may be geographically or logically separated from one another.
Central server 100 includes lookup table 102 for resolving requests for application program 104 to an address of a server offering an instance of the program. Lookup table 102 thus includes an entry for the program's identity as exposed to clients (e.g., an alias or a virtual server name), to allow the clients to access an instance of the application on server 110, server 112 or server 114. Thus, the lookup table entry for application 104 may indicate a network address (e.g., an IP or Internet protocol address) for one of servers 110, 112 and 114.
Client 120 is illustratively a personal computer or workstation configured to provide a user access to a network (e.g., the Internet) and various applications and services on servers 110, 112 and 114. Client 120 is thus coupled to central server 100 via network 122, and includes instructions (e.g., a web browser) for communicating via network 122. Client 120 further includes common components such as a processor, memory, storage, input and output devices, etc. Such common components are well known to those skilled in the art and are omitted from FIG. 1 for the purpose of clarity. In the environment of FIG. 1, when client 120 attempts to connect to application
104, the access request is received by central server 100. Central server 100, through lookup table 102, identifies a preferred server offering an instance of program 104 and routes the client request accordingly. The server identified in lookup table 102 is illustratively determined according to a load-balancing policy, as discussed below. Further, the server identified in lookup table 102 is updated or changed from time to time in accordance with the selected policy in order to distribute client requests among the instances of the application. In a present embodiment of the invention, information reflecting the status or operation of application instances 104a, 104b and 104c (and/or servers 110, 112 and 114) is collected and analyzed on a regular or periodic basis. The information that is collected is identified in a load balancing policy that identifies one or more factors or pieces of information to be used to identify a "preferred" server to which client requests for application 104 are to be routed. Different policies thus require different information to be collected from the application instances, and the active policy can be changed during load balancing.
The various pieces of information that may be collected illustratively include data such as: whether a server or instance of application 104 is operational; the response time for a request submitted to a server or application instance; the number of requests processed by or pending on a server or application instance, a server's proximity to the central server (e.g., the number of network hops necessary to reach the server), etc.
In one embodiment of the invention, status objects are generated or produced to collect application-specific data from the application instances. The status objects are illustratively constructed according to a standard API for a present load-balancing framework. Status objects and the load-balancing framework are described in detail below with reference to FIG. 2. In one particular embodiment, status objects (and other objects within the framework) are designed (e.g., an object class is constructed) according to the standard API in a generation stage. Then, in a registration stage, individual objects are instantiated from the class(es). Finally, in a monitoring stage, the objects begin collecting information.
In the illustrated embodiment of the invention, status objects periodically interact with instances of application 104 to collect application-specific statistics that will be used to select a preferred server. For example, if application 104 were a DBMS, a status object may gather the number of database accesses, the number of requests received or pending, etc. for one instance of the application. As another example, if application 104 were an electronic mail program, a status object may periodically gather the number of inbound and/or outbound messages in queue, the number and size of mailboxes, etc. Besides status objects, other computer-readable instructions (e.g., in the form of objects, agents or modules) are also executed (also described below) to collect, assemble and analyze the various pieces of information provided by the status objects and to update lookup table 102. The objects or agents within a load balancing framework may be created in a suitable programming or script language and then configured and installed on each of servers 110, 112 and 114 and/or on central server 100.
In an alternative embodiment of the invention, instead of returning an address of a server in response to a request for application 104, the lookup table returns an identifier (e.g., file name) of a set of instructions. The instructions are executed, illustratively by central server 100, in order to perform a variety of actions (e.g., load or mount an alternate Internet or domain namespace).
FIG. 2 depicts an illustrative embodiment of the invention in which operational and statistical information is collected from application instances 104a, 104b and 104c on servers 110, 112 and 114, respectively. The collected information is analyzed on central server 100 to choose a preferred server, and lookup table 102 is then modified to reflect an identity (e.g., a network address) of the preferred server.
In the illustrated embodiment, application instances 104a, 104b and 104c include application-specific information that is to be considered in choosing the preferred server. Status objects 200, 202 and 204 therefore execute on servers 110, 112 and 114, respectively, to gather the information or statistics from their associated application instances. The status objects advantageously adhere to the format provided by a standard API, concerning the manner in which the information is to be communicated to the central server. In particular, the status objects are designed to accumulate, store and/or provide application-specific data for retrieval by individual monitor obj ects 210, 212 and 214, which also execute on servers 110, 112 and 114, respectively.
The configuration of the status objects (e.g., the data they collect) depends upon the policy that has been selected for choosing a preferred server. For example, where the selected policy requires choosing the least-loaded server (e.g., the server having the least- loaded instance of the application), a status object may be configured to retrieve the number of pending client requests or number of connected clients. As another example, status objects 200, 202 and 204 may be configured to retrieve a response time or throughput of their associated application instances.
In addition, status objects are configured to retrieve their specified information on a periodic basis. If a status object fails to gather its information, it may be assumed that the associated application instance is not operational. If an application instance is determined to be down, the associated server is illustratively removed from consideration as the preferred server for that application. Illustratively, status objects 200, 202 and 204 communicate with or access application instances 104a, 104b and 104c in accordance with an application-specific API. Each status object also illustratively performs a single function or retrieves a single piece of application-specific information. In alternative embodiments of the invention, however, a single status object may perform multiple functions or produce multiple pieces of information. For example, in one alternative embodiment, a status object may retrieve multiple pieces of information concerning an application instance's load (e.g., number of connected clients, number of pending requests). The multiple pieces of information may then be combined (e.g., via a specified formula or function) to produce a single value or representation of the instance' s load.
In FIG. 2, individual monitor objects (IMO) 210, 212 and 214 also reside and execute on servers 110, 112 and 114. Individual monitor objects are known as server monitor objects in one embodiment of the invention. A separate IMO is depicted for each application instance. In particular, IMOs 210, 212 and 214 collect information from status objects 200, 202 and 204 respectively.
In one embodiment of the invention, a status object collects the specified application-specific information and stores it on its host server for collection by the associated IMO. In another embodiment of the invention, status objects interface with and directly communicate the information to their IMOs. In the embodiment illustrated in FIG. 2, different types of status objects are executed or invoked with differing degrees of regularity. When the status objects collect the application instances' response times, for example, status object 200 may execute relatively frequently (e.g., every 60 seconds). In contrast, when the status objects reflect a policy preferring the closest server, status object 202 may execute only occasionally (e.g., once per day) because the distance from central server 100 to server 112 is unlikely to change very often.
Although each IMO is associated with only one status object and one application instance in the illustrated embodiment, in an alternative embodiment of the invention an IMO may collect data from multiple status objects. In this alternative embodiment, for example, an IMO may interface with one status object to determine the response time of an application instance or server and another status object to determine the load on the instance or server. Replicated monitor object (RMO) 220 retrieves the collected information produced from each IMO associated with an application. Therefore, in the illustrated embodiment where each of servers 110, 112 and 114 operate a separate instance of a load- balanced application, RMO 220 collects data from IMOs 210, 212 and 214. If the servers also offered another application or replicated service, a second RMO would illustratively operate on central server 100 for the purpose of retrieving information concerning that application from a different set of IMOs. A replicated monitor object may also be known as a central monitor object due to its coordination role on behalf of a central server that receives multiple requests for an application. Various means of communication may be employed between an RMO and the
IMOs associated with a particular application. In a present embodiment of the invention Object Request Broker (ORB) technology is employed. In an alternative embodiment of the invention Remote Procedure Call (RPC) technology can be used.
In summary, when load balancing is performed in accordance with the embodiments of the invention described above, a status object gathers load and/or operational information for an instance of the application being load-balanced. An IMO interfaces with or otherwise retrieves the information from each status object and an RMO gathers the information from all application instances from the IMOs.
The data collected by RMO 220 from the various IMOs is analyzed in accordance with the selected policy and a preferred server is identified. Illustratively, updater object 230 performs the analysis and selection of a preferred server. As discussed above, the preferred server may, for example, be the one having the application instance with the fastest response time, the fewest pending client requests, the greatest capacity for client requests, etc. Illustratively, RMO 220 maintains a data structure (e.g., array, vector, table, database) identifying each application instance and/or server that is being load-balanced, along with one or more values or other indicators or summaries of the collected information concerning each application instance.
Finally, updater object 230 updates lookup table 102 after the collected information is analyzed and a preferred server is selected. Illustratively, one updater object is used to update the lookup table for all applications being load-balanced.
However, in an alternative embodiment of the invention separate updater objects may be employed for each application. In the embodiment of the invention depicted in FIG. 2, RMO 220 retrieves the collected data and updater object 230 updates the lookup table on a periodic basis. The identity of the preferred server may thus change over time so that the client requests are distributed among all active application instances. The status objects, IMOs, RMO and updater object may be considered to comprise a load-balancing framework for distributing client requests among various instances of an application. As one skilled in the art will recognize, the different objects within the framework may be distributed among the servers hosting application instances, a central server, and other entities such as intermediate servers. FIG. 3 depicts an alternative embodiment of the invention in which servers offering an application are geographically dispersed. In FIG. 3, server farm 300 represents a first collection of servers offering the application (e.g., application instances 104a and 104b) and server farm 310 represents a second collection of servers offering the same application (e.g., application instances 104c and 104d). Although server farms are depicted in FIG. 3 with multiple members (i.e., servers 302 and 304 in server farm 300 and servers 312 and 314 in server farm 310), a server farm may consist of any number of members, even one.
Each server farm in the presently described embodiment includes an intermediate server (i.e., server 306 in server farm 300 and server 316 in server farm 310). One function of an intermediate server in this embodiment is to collect, from the servers in the farm that host instances of the application, information necessary to select a preferred server. For example, intermediate replicated monitor object (IRMO) 306a is operated on intermediate server 306 to collect data from servers 302 and 304. IRMO 306a operates similarly to the RMO described above with reference to FIG. 2, but is illustratively located on a server situated between central server 100 and the servers offering the application. The load balancing framework of the illustrated embodiment also includes status objects (e.g., depicted by numerals 302a, 304a, 312a and 314a) and IMOs (e.g., depicted by numerals 302b, 304b, 312b and 314b) operating on servers 302, 304, 312 and 314. RMO 320 operates on central server 100 to collect data from the IRMOs within each server farm. Updater object 322 updates lookup table 102 to reflect the preferred server identified from the data collected by RMO 320. In an alternative embodiment of the invention in which an application is offered on multiple servers, one or more of which are local and one or more of which are remote, aspects of the embodiments of the invention depicted in FIGs. 2 and 3 are combined. In this alternative embodiment, intermediate servers with IRMOs are employed in server farms comprising the remote servers, in order to pass data between the remote servers' IMOs and an RMO, as in the embodiment depicted in FIG. 3. Local servers, however, employ IMOs that communicate with the RMO without an intervening RMO, as in FIG. 2.
In another alternative embodiment of the invention, load balancing among instances of an application is performed among multiple participating servers wherein one or more of the servers are segregated (e.g., situated in a remote location and/or within a server farm). Within the group of segregated servers, a "local" load balancing policy may be implemented for distributing all client requests sent to the group and/or to a specific member of the group. In this alternative embodiment, the segregated servers may be considered a single entity for the purposes of a "global" load balancing policy specifying the manner in which all client requests for the application are to be distributed among all participating servers. The global and local policies need not be equivalent (e.g., the global policy may require selection of the closest server (or group of servers) while the local policy may require the least-loaded server or application instance). With reference now to FIGs. 4 and 5, an illustrative method of load balancing between multiple instances of an application is depicted. In the illustrated method, a central server (e.g., a DNS) resolves client requests for a virtual name by which the application is known into an identifier of a preferred server offering an instance of the application. Each instance of the application illustratively operates on a separate server and is modified to produce application-specific information needed to choose the preferred server.
FIG. 4 demonstrates an illustrative generation stage of the method, in which objects in the load-balancing framework are designed (e.g., object classes are constructed). FIG. 5 demonstrates illustrative registration and monitoring stages, in which individual objects are created (e.g., instantiated) and begin collecting information from instances of the load-balanced application.
With reference now to FIG. 4, state 400 is a start state. In state 402 a policy to be applied to identify a preferred server is selected. One skilled in the art will appreciate that various policies are possible, depending upon the nature of the application and the aspect(s) of the application that are conducive to load balancing.
Illustrative policies in a present embodiment of the invention focus upon the status or availability of the various instances of the application. Such policies reflect preferences for the least loaded instance, the instance with the fastest response time or throughput, the instance with the fewest connected clients, etc. For example, where access requests for a database management system (DBMS) are load balanced, illustrative policies may include routing requests to the server on which the fewest DBMS requests have been processed or the server having the fewest connected users or the fewest unfulfilled processing or access requests. For each application for which requests are load-balanced, separate policies may be employed.
In an alternative embodiment of the invention, policies require examination of the availability or status of the servers offering instances of the application. Such policies may express preferences for the server having the shortest distance to the central server, the fastest response time, the best throughput, etc.
In general, the selected policy reflects whichever aspect or aspects of the load- balanced application form the basis for distributing client requests among the various instances of the application and/or the servers hosting the application instances. The information reflecting these aspects is periodically captured for each instance by status objects working in close cooperation with the application instances.
In state 404, sequences of instructions or executable code are produced for performing the function(s) of the status objects (i.e., to collect the application-specific information needed to choose a preferred server). In one embodiment of the invention in which the load balancing framework is constructed using an object-oriented programming language, a compatible language and basic building blocks provided by the framework are used to generate the status objects, IMOs, RMO and specialized object. Thus, in this embodiment of the invention state 404 comprises the creation of one or more classes of status objects, from which individual instances will be created in the registration stage depicted in FIG. 5. Illustratively, status objects are substantially similar for each instance of the application.
Status objects may be configured to store the information for retrieval by individual monitor objects or, alternatively, to interface with the IMOs directly in order to pass the information along. In addition, the status objects may be configured to execute automatically on a regular basis, in response to action by another part of the load balancing framework (e.g., upon invocation by an IMO), the application or some other external entity, etc.
As discussed above, in a current embodiment of the invention status objects (and other framework objects) are constructed using an object-oriented programming language. One skilled in the art will recognize that many suitable programming languages and tools exist and that the invention may be implemented using techniques than object-oriented programming. Illustratively, however, status objects substantially adhere to a common format (e.g., detailed in a load balancing framework API) in order to cooperate with the overall load balancing framework.
In state 406, the existing load-balancing framework is examined to determine whether an IMO (e.g., an IMO class) already exists for collecting data concerning an instance of the load-balanced application. If an IMO already exists, the illustrated method continues at state 410. Otherwise, in state 408 an IMO structure (e.g., an object class) is constructed that is specific to the application instance. The IMO is designed such that it will collect the various data and statistics gathered by one or more status object(s). In an alternative embodiment of the invention, the IMOs generated for all instances of a particular application are substantially similar.
In state 410, the existing load balancing framework is examined to determine whether an RMO already exists for receiving data from the IMOs that are associated with each instance of the application. As described above, in one embodiment of the invention an RMO comprises a data structure for retaining application-specific information from the application instances. If an RMO already exists, the illustrated method continues at state 414. Otherwise, in state 412, an RMO structure (e.g., an object class) is constructed that is specific to the application. As with the status objects and IMOs, an actual RMO instance will be created as part of the registration stage depicted in FIG. 5.
In state 414, the existing load balancing framework is examined once more. This time, it is determined if the sequence of instructions or executable code for the specialized object that will determine a preferred server already exists. If not, in state 416 a specialized object structure (e.g., an object class) is constructed to apply the selected load balancing policy to the results of the data collected concerning the various application instances (and/or their host servers) and select a preferred server. The specialized object is also designed to update the lookup table (or other data structure) to store an identity of the preferred server.
The generation stage of the illustrated method then ends with end state 418. With reference now to FIG. 5, illustrative registration and monitoring stages of the illustrated method are depicted. For present purposes, the term registration refers to the registration of individual objects (e.g., status object, IMO, RMO, specialized object) within a load balancing framework, including their creation (e.g., instantiation) from the object structures (e.g., classes) produced in the generation stage depicted in FIG. 4. In the monitoring stage, information is collected for the purpose of identifying a preferred server in accordance with a selected load balancing policy. In FIG. 5, state 500 is a start state. In state 502, a status object is registered with the load-balancing framework. In one embodiment of the invention, the standard API provided with the load balancing framework includes a command (e.g., "create") for creating an instance of each object within the framework. As one skilled in the art will appreciate, creating an instance of an object, such as a status object, involves the dynamic loading and executing of a sequence of instructions defining the object.
In state 504, configurable parameters of the status object are set in accordance with the selected policy. Illustrative parameters include the frequency of gathering the application-specific information, a network or port address for communicating with the application instance, information detailing how to communicate with the application instance and/or IMO, etc. One skilled in the art will appreciate that a status object may have a variety of configurable parameters, depending upon the nature of the application and the selected policy.
In state 506, an individual monitor object (IMO) is registered with the load- balancing framework. Illustratively, one IMO is registered or created for each instance of the application. Each IMO is illustratively installed on the server executing the associated instance of the application. In an alternative embodiment, however, IMOs operate on the central server or an intermediate server located between the central server and the host servers. As described above, IMOs are illustratively configured to collect and report certain information or data. In the presently described embodiment of the invention, the collected information is received directly from a status object. In an alternate embodiment of the invention, the information may be retrieved from a location in which it was placed by the status object (e.g., a storage device, a file or other data structure). As described above, the collected information is illustratively determined by the selected load balancing policy, and will be used to identify a preferred server. In a present embodiment of the invention, the active policy for an application may be changed without disrupting the handling of client requests. Illustratively, this is done by temporarily pausing the operation of IMOs for the application, installing new status objects reflecting the new policy, then resuming the IMOs. Advantageously, the IMOs need not be altered or replaced.
In state 508, parameters are set for the IMO created in state 506. Illustrative parameters include a list of status objects from which to collect information, the frequency with which to collect the information, how to communicate with the status objects and/or RMO, etc.
In state 510 a replicated monitor object is created for the load balanced application. As described above, the RMO is illustratively installed on the central server and communicates with the IMOs using a suitable format or protocol (e.g., ORB or RPC). In an alternative embodiment in which intermediate servers are employed (e.g., where remote servers or server farms are included), an intermediate RMO is created for each intermediate server. In state 512, RMO parameters are set, illustratively including a list of IMOs, the frequency with which data is to be collected from the IMOs, method of communicating with the IMOs, etc. A back-end or host server (e.g., server 110 from FIG. 1) may be removed from or added to the load-balancing scheme without significantly disrupting operation of the application. A host server may, for example, become inoperative or require replacement. Illustratively, each RMO maintains an index (e.g., in an array, linked list, vector, other data structure, etc.) of all servers participating in the load balancing (e.g., all servers offering an instance of the application). This information may, for example, be included in a list of IMOs from which the RMO receives information. By temporarily pausing the RMO, removing the IMO associated with the server from the list and restarting the RMO, the RMO will stop attempting to retrieve information for the removed server (i.e., the RMO will no longer communicate with the IMO associated with the server). Servers may be added to the load-balancing scheme in a similar manner.
In state 514, a specialized object is registered with the load-balancing framework (e.g., created from its object class). In state 516, parameters concerning the operation of the specialized object are set. Illustrative parameters include an identity of the RMO, the frequency of information retrieval from the RMO, an identity of the lookup table, method of interfacing with the RMO and/or lookup table, etc. In one embodiment of the invention, the specialized object analyzes the information collected from the servers hosting the application instances, identifies a preferred server in accordance with the load- balancing framework and updates the lookup table.
Where, for example, the application comprises web browsing on web servers, the specialized object may take the form of a DNS updater configured on a DNS server to modify a DNS zone file to identify the server to which requests are to be routed. Similarly, where load balancing is being performed for an application operating in a master/slave relationship (e.g., a master process or server routes requests to slave processes or servers), the specialized object updates a data structure or entry indicating a preferred process or server.
After the various executable objects or program modules are configured and installed in states 502 - 516, the collection of server/application information can begin. Thus, in state 518, the created objects (e.g., status objects, IMOs, RMO and specialized object) are activated or executed if they are not already executing.
In state 520, a status object begins collecting or gathering information from its application instance. For example, where the selected policy favors the least-loaded application instance, a status object retrieves data concerning an instance's load (e.g., number of client requests or connected clients).
In state 522 an IMO retrieves the information gathered by its associated status object(s). Then, in state 524, an RMO calls, invokes or otherwise communicates with the IMO to retrieve the information. The RMO may similarly communicate with additional IMOs storing information concerning other servers or instances of the application. Illustratively, the RMO executes on the central server and stores the information retrieved from the IMOs for analysis by the specialized object.
In state 526 the information collected by the RMO is analyzed in accordance with the selected policy to choose a preferred server. In state 528 the specialized object updates the lookup table for the central server to indicate the preferred server. Illustratively, the update procedure comprises associating an alias or network address of the preferred server with the name of a virtual server/service through which clients access the application. In addition, in a present embodiment of the invention the central server is signaled to reload the lookup table. State 530 is an end state. The foregoing descriptions of embodiments of the invention have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to practitioners skilled in the art. Accordingly, the above disclosure is not intended to limit the invention; the scope of the invention is defined by the appended claims.
In one alternative embodiment of the invention, for example, clients access an instance of the application program directly (i.e., rather than connecting through a central server). In this alternative embodiment, the program instances exchange information
(e.g., via status objects and/or other elements of a load-balancing framework) and redirect client requests as necessary to balance the requests in accordance with the selected policy.
In another alternative embodiment of the invention, one or more elements of a load-balancing framework are combined. By way of illustration, an RMO may be designed to perform the functions of an IMO and collect information from one or more status objects.

Claims

What Is Claimed Is:
1. A method of distributing requests for an application among a plurality of application instances operating on a plurality of servers, wherein the requests are received at a central server, the method comprising: selecting a policy, said policy demonstrating a first server-selection factor for selecting a preferred server to receive a request for the application; executing a first status module to determine a first status of said first server- selection factor for a first instance of the application; executing a second status module to determine a second status of said first server- selection factor for a second instance of the application; receiving said first status at the central server; receiving said second status at the central server; examining said first status and said second status to select a preferred server; and storing an identifier of said preferred server on the central server.
2. The method of claim 1, further comprising executing a third status module to determine a first status of a second server-selection factor for said first instance of the application.
3. The method of claim 2, wherein said first status module comprises said third status module.
4. The method of claim 1 , further comprising operating a server monitor module to receive said first status of said first server-selection factor from said first status module.
5. The method of claim 4, wherein said operating a server monitor module comprises receiving a first status of a second server-selection factor from a third status module.
6. The method of claim 4, wherein said server monitor module executes on said first server.
7. The method of claim 4, wherein said server monitor module executes on the central server.
8. The method of claim 1 , further comprising operating a central monitor module for receiving said first status and said second status.
9. The method of claim 8, wherein said central monitor module executes on the central server.
10. The method of claim 1, wherein said executing a first status module comprises operating a first status module residing on the first server.
11. The method of claim 1 , wherein said executing a first status module comprises communicating with a first instance of the application to determine a first status of said first server-selection factor.
12. The method of claim 1 , further comprising: selecting a local policy for a subset of the plurality of servers, said local policy specifying a local server-selection factor for selecting a server to receive a request for the application.
13. An apparatus for balancing requests for an application among multiple servers operating multiple instances of the application, wherein the requests are received at a central server, comprising: a first server for operating a first instance of the application; a second server for operating a second instance of the application; a first status module for determining a first status of said first instance; a second status module for determining a second status of said second instance; a first server monitor module for receiving said first status from said first status module; a second server monitor module for receiving said second status from said second status module; a central monitor module for receiving said first status and said second status; and an update module for updating the central server to indicate one of said first server and said second server to receive a request for the application.
14. The apparatus of claim 13, wherein said first status module resides on said first server.
15. The apparatus of claim 13, wherein said first status module determines said first status by receiving said first status from said first instance.
16. The apparatus of claim 13, wherein said first server monitor module operates on said first server.
17. The apparatus of claim 13, wherein said first server monitor module operates on the central server.
18. The apparatus of claim 13, wherein the central server comprises said central monitor module and said update module.
19. The apparatus of claim 13, further comprising a server farm, said server farm comprising: one or more servers; and an intermediate central monitor module for receiving a status of an instance of the application operating on one of said one or more servers and communicating said status to said central monitor module.
20. A method of load balancing requests for an application received at a central server among a set of servers, wherein each server in the set of servers operates an instance of the application, comprising: selecting a policy for directing a request for the application to a preferred server, wherein said policy reflects a server factor for selecting said preferred server from the set of servers; configuring a first status object to determine a first status of said server factor for a first instance of the application; configuring a first server monitor object to receive said first status; configuring a central monitor object to receive multiple statuses of said server factor for multiple instances of the application, including said first status; examining said multiple statuses to select a preferred server; and updating the central server to identify said preferred server.
21. The method of claim 20, further comprising: executing said first status object, wherein said first status object resides on said first server; receiving said first status by said first server monitor object; and receiving said first status at the central server, by said central monitor object, from said first server monitor object.
22. The method of claim 21 , wherein said executing said first status object comprises operating said first status object to periodically determine a status of said server factor for a first instance of the application.
23. The method of claim 21 , further comprising maintaining said first server monitor object on said first server.
24. The method of claim 20, further comprising: executing said first status object, wherein said first status object resides on said central server; and maintaining said server monitor object on the central server.
25. The method of claim 24, wherein said executing said first status object comprises operating said first status object to periodically determine a status of said server factor for a first instance of the application.
26. The method of claim 20, wherein said central server comprises a lookup table to associate said preferred server with the application, and wherein said updating comprises storing an address of said preferred server.
27. The method of claim 20, wherein the set of servers includes a subset, the method further comprising: configuring an intermediate central monitor object to collect one or more statuses of said server factor for one or more members of the subset; and receiving said one or more statuses at the central server from said intermediate central monitor object.
28. The method of claim 27, further comprising selecting a local policy for balancing requests for the application among members of the subset according to a local server factor.
29. The method of claim 28, wherein said local server policy is different from said policy.
30. A computer readable storage medium storing instructions that, when executed by a computer, cause the computer to perform a method for balancing requests for an application among a plurality of servers, wherein the requests are received at a central server, the method comprising: selecting a policy for directing a request for the application to a preferred server, wherein said policy reflects a server factor for selecting said preferred server from the set of servers; configuring a first status object to determine a first status of said server factor for a first instance of the application; configuring a first server monitor object to receive said first status; configuring a central monitor object to receive multiple statuses of said server factor for multiple instances of the application, including said first status; examining said multiple statuses to select a preferred server; and updating the central server to identify said preferred server.
31. An apparatus for load balancing requests for an application received at a central server, comprising: a first status determination means for determining a first status of a first instance of the application; a second status determination means for determining a second status of a second instance of the application; central monitor means for receiving said first status and said second status; server selection means for selecting a preferred server from one of said first server and said second server; and updating means for storing an identifier of said preferred server on the central server.
32. The apparatus of claim 31 , further comprising a first server monitor means for receiving said first status from said first status determination means.
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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001076159A1 (en) * 2000-03-31 2001-10-11 British Telecommunications Public Limited Company Processing capacity management
WO2001093530A2 (en) * 2000-05-26 2001-12-06 Akamai Technologies, Inc. Global load balancing across mirrored data centers
GB2363952A (en) * 2000-01-28 2002-01-09 Ibm Measuring response times to balance load among mirror servers
WO2002054705A2 (en) * 2000-12-29 2002-07-11 Nortel Networks Limited Network protocols for distributing functions within a network
WO2002097621A2 (en) * 2001-05-30 2002-12-05 International Business Machines Corporation Selection and configuration of servers
WO2003026244A2 (en) * 2001-09-18 2003-03-27 Marconi Uk Intellectual Property Ltd Client server networks
EP1371194A2 (en) * 2001-03-20 2003-12-17 Worldcom, Inc. Systems and methods for updating ip communication service attributes using an ldap
EP1436736A2 (en) * 2001-09-28 2004-07-14 Savvis Communications Corporation Configurable adaptive global traffic control and management
EP1444592A1 (en) * 2001-11-13 2004-08-11 Nokia Corporation Method and apparatus for a distributed server tree
WO2004086270A2 (en) * 2003-03-27 2004-10-07 Eci Telecom Ltd. Method for distributing subtasks to servers and maintaining load balancing among servers
US7124949B2 (en) 2003-06-17 2006-10-24 Symbol Technologies, Inc. Reducing speckle noise in electro-optical readers
CN100370775C (en) * 2005-01-25 2008-02-20 华为技术有限公司 Method for raising success rate of business insertion
CN100391178C (en) * 2003-08-19 2008-05-28 华为技术有限公司 Method for selecting server in network
US7644159B2 (en) 2001-08-15 2010-01-05 Nokia Corporation Load balancing for a server farm
GB2477642A (en) * 2010-02-03 2011-08-10 Orbital Multi Media Holdings Corp Selection of a streaming server which stores the required content in the highest (fastest access) hierarchical storage layer.
AU2010202981B2 (en) * 2000-05-26 2011-12-08 Akamai Technologies, Inc. Global load balancing across mirrored data centers
WO2013173026A1 (en) * 2012-05-14 2013-11-21 Volusion, Inc. Network security load balancing
US10009801B1 (en) 2016-12-05 2018-06-26 Motorola Solutions, Inc. Systems and methods for forming an incident area network

Families Citing this family (368)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9603582D0 (en) 1996-02-20 1996-04-17 Hewlett Packard Co Method of accessing service resource items that are for use in a telecommunications system
AU714336B2 (en) * 1996-07-25 1999-12-23 Clearway Acquisition, Inc. Web serving system with primary and secondary servers
US6775692B1 (en) 1997-07-31 2004-08-10 Cisco Technology, Inc. Proxying and unproxying a connection using a forwarding agent
US6418557B1 (en) * 1998-02-06 2002-07-09 Nec Corporation On-demand system enabling control of power-on/off of on-demand server
US8060613B2 (en) 1998-02-10 2011-11-15 Level 3 Communications, Llc Resource invalidation in a content delivery network
US6185598B1 (en) 1998-02-10 2001-02-06 Digital Island, Inc. Optimized network resource location
US6249801B1 (en) * 1998-07-15 2001-06-19 Radware Ltd. Load balancing
US6665702B1 (en) 1998-07-15 2003-12-16 Radware Ltd. Load balancing
US6622157B1 (en) * 1998-09-28 2003-09-16 Certeon, Inc. Extending network services using mobile agents
US6691165B1 (en) * 1998-11-10 2004-02-10 Rainfinity, Inc. Distributed server cluster for controlling network traffic
US6397255B1 (en) * 1998-12-23 2002-05-28 At&T Corp. Method and apparatus for providing intelligent network services
JP2000196677A (en) * 1998-12-28 2000-07-14 Fujitsu Ltd Repeater used for network system
US6671273B1 (en) * 1998-12-31 2003-12-30 Compaq Information Technologies Group L.P. Method for using outgoing TCP/IP sequence number fields to provide a desired cluster node
US6549538B1 (en) 1998-12-31 2003-04-15 Compaq Information Technologies Group, L.P. Computer method and apparatus for managing network ports cluster-wide using a lookaside list
US6665304B2 (en) * 1998-12-31 2003-12-16 Hewlett-Packard Development Company, L.P. Method and apparatus for providing an integrated cluster alias address
AU4168700A (en) * 1999-02-26 2000-09-14 Henry Haugland Mass generation of individual virtual servers, virtual web sites and virtual webobjects
DE69934871T2 (en) * 1999-03-05 2007-07-05 International Business Machines Corp. Method and system for optimally selecting a web firewall in a TCP / IP network
US6671259B1 (en) * 1999-03-30 2003-12-30 Fujitsu Limited Method and system for wide area network load balancing
US6782408B1 (en) * 1999-03-30 2004-08-24 International Business Machines Corporation Controlling a number of instances of an application running in a computing environment
US6801949B1 (en) 1999-04-12 2004-10-05 Rainfinity, Inc. Distributed server cluster with graphical user interface
US6463454B1 (en) * 1999-06-17 2002-10-08 International Business Machines Corporation System and method for integrated load distribution and resource management on internet environment
JP2001007844A (en) * 1999-06-24 2001-01-12 Canon Inc Network status server, information distribution system, and its control method and storage medium storing its control program
US6751191B1 (en) 1999-06-29 2004-06-15 Cisco Technology, Inc. Load sharing and redundancy scheme
US6446218B1 (en) * 1999-06-30 2002-09-03 B-Hub, Inc. Techniques for maintaining fault tolerance for software programs in a clustered computer system
US6628654B1 (en) * 1999-07-01 2003-09-30 Cisco Technology, Inc. Dispatching packets from a forwarding agent using tag switching
US6650641B1 (en) 1999-07-02 2003-11-18 Cisco Technology, Inc. Network address translation using a forwarding agent
US6606316B1 (en) 1999-07-02 2003-08-12 Cisco Technology, Inc. Gathering network statistics in a distributed network service environment
US6606315B1 (en) 1999-07-02 2003-08-12 Cisco Technology, Inc. Synchronizing service instructions among forwarding agents using a service manager
US6633560B1 (en) 1999-07-02 2003-10-14 Cisco Technology, Inc. Distribution of network services among multiple service managers without client involvement
US6549516B1 (en) 1999-07-02 2003-04-15 Cisco Technology, Inc. Sending instructions from a service manager to forwarding agents on a need to know basis
US6687222B1 (en) 1999-07-02 2004-02-03 Cisco Technology, Inc. Backup service managers for providing reliable network services in a distributed environment
US6735169B1 (en) 1999-07-02 2004-05-11 Cisco Technology, Inc. Cascading multiple services on a forwarding agent
US6970913B1 (en) * 1999-07-02 2005-11-29 Cisco Technology, Inc. Load balancing using distributed forwarding agents with application based feedback for different virtual machines
US6704278B1 (en) 1999-07-02 2004-03-09 Cisco Technology, Inc. Stateful failover of service managers
US6742045B1 (en) 1999-07-02 2004-05-25 Cisco Technology, Inc. Handling packet fragments in a distributed network service environment
US7051066B1 (en) 1999-07-02 2006-05-23 Cisco Technology, Inc. Integrating service managers into a routing infrastructure using forwarding agents
US6496477B1 (en) * 1999-07-09 2002-12-17 Texas Instruments Incorporated Processes, articles, and packets for network path diversity in media over packet applications
US6922729B1 (en) * 1999-07-30 2005-07-26 International Business Machines Corporation Multi-connection control system
US8448059B1 (en) * 1999-09-03 2013-05-21 Cisco Technology, Inc. Apparatus and method for providing browser audio control for voice enabled web applications
US7028298B1 (en) * 1999-09-10 2006-04-11 Sun Microsystems, Inc. Apparatus and methods for managing resource usage
WO2001025949A1 (en) * 1999-10-05 2001-04-12 Ejasent Inc. Ip virtualization
US7210147B1 (en) * 1999-10-05 2007-04-24 Veritas Operating Corporation IP virtualization
US6681251B1 (en) * 1999-11-18 2004-01-20 International Business Machines Corporation Workload balancing in clustered application servers
US6496948B1 (en) * 1999-11-19 2002-12-17 Unisys Corporation Method for estimating the availability of an operating server farm
US7062556B1 (en) * 1999-11-22 2006-06-13 Motorola, Inc. Load balancing method in a communication network
US6484143B1 (en) * 1999-11-22 2002-11-19 Speedera Networks, Inc. User device and system for traffic management and content distribution over a world wide area network
US6976258B1 (en) 1999-11-30 2005-12-13 Ensim Corporation Providing quality of service guarantees to virtual hosts
US7349979B1 (en) * 1999-12-02 2008-03-25 Cisco Technology, Inc. Method and apparatus for redirecting network traffic
AU2292001A (en) * 1999-12-22 2001-07-03 Setnet Corp. Industrial capacity clustered mail server system and method
US6839829B1 (en) 2000-01-18 2005-01-04 Cisco Technology, Inc. Routing protocol based redundancy design for shared-access networks
US7058007B1 (en) 2000-01-18 2006-06-06 Cisco Technology, Inc. Method for a cable modem to rapidly switch to a backup CMTS
US6711607B1 (en) 2000-02-04 2004-03-23 Ensim Corporation Dynamic scheduling of task streams in a multiple-resource system to ensure task stream quality of service
JP2001312484A (en) * 2000-05-02 2001-11-09 Internatl Business Mach Corp <Ibm> Method and system for fast web server selection
US6754716B1 (en) 2000-02-11 2004-06-22 Ensim Corporation Restricting communication between network devices on a common network
US7343421B1 (en) 2000-02-14 2008-03-11 Digital Asset Enterprises Llc Restricting communication of selected processes to a set of specific network addresses
US6658473B1 (en) * 2000-02-25 2003-12-02 Sun Microsystems, Inc. Method and apparatus for distributing load in a computer environment
US6948003B1 (en) 2000-03-15 2005-09-20 Ensim Corporation Enabling a service provider to provide intranet services
US7162539B2 (en) * 2000-03-16 2007-01-09 Adara Networks, Inc. System and method for discovering information objects and information object repositories in computer networks
US7552233B2 (en) * 2000-03-16 2009-06-23 Adara Networks, Inc. System and method for information object routing in computer networks
US7437456B1 (en) * 2000-03-17 2008-10-14 Fujitsu Limited Object reference generating device, object reference generating method and computer readable recording medium for recording an object reference generating program
US8380854B2 (en) 2000-03-21 2013-02-19 F5 Networks, Inc. Simplified method for processing multiple connections from the same client
US7343413B2 (en) 2000-03-21 2008-03-11 F5 Networks, Inc. Method and system for optimizing a network by independently scaling control segments and data flow
US7139282B1 (en) * 2000-03-24 2006-11-21 Juniper Networks, Inc. Bandwidth division for packet processing
US7164698B1 (en) 2000-03-24 2007-01-16 Juniper Networks, Inc. High-speed line interface for networking devices
US6963897B1 (en) * 2000-03-30 2005-11-08 United Devices, Inc. Customer services and advertising based upon device attributes and associated distributed processing system
US8010703B2 (en) 2000-03-30 2011-08-30 Prashtama Wireless Llc Data conversion services and associated distributed processing system
US6996616B1 (en) * 2000-04-17 2006-02-07 Akamai Technologies, Inc. HTML delivery from edge-of-network servers in a content delivery network (CDN)
US6671725B1 (en) * 2000-04-18 2003-12-30 International Business Machines Corporation Server cluster interconnection using network processor
US7908337B2 (en) * 2000-04-28 2011-03-15 Adara Networks, Inc. System and method for using network layer uniform resource locator routing to locate the closest server carrying specific content
US6922724B1 (en) * 2000-05-08 2005-07-26 Citrix Systems, Inc. Method and apparatus for managing server load
US6985937B1 (en) 2000-05-11 2006-01-10 Ensim Corporation Dynamically modifying the resources of a virtual server
US6907421B1 (en) 2000-05-16 2005-06-14 Ensim Corporation Regulating file access rates according to file type
US7401131B2 (en) 2000-05-22 2008-07-15 Verizon Business Global Llc Method and system for implementing improved containers in a global ecosystem of interrelated services
US6922685B2 (en) 2000-05-22 2005-07-26 Mci, Inc. Method and system for managing partitioned data resources
EP1285359B1 (en) * 2000-05-22 2004-07-28 Bango.Net Limited Addressing remote data objects via a computer network
US7251688B2 (en) * 2000-05-26 2007-07-31 Akamai Technologies, Inc. Method for generating a network map
US7020698B2 (en) * 2000-05-31 2006-03-28 Lucent Technologies Inc. System and method for locating a closest server in response to a client domain name request
US6751646B1 (en) * 2000-06-01 2004-06-15 Sprint Communications Company L.P. Method and apparatus for implementing CORBA compliant name services incorporating load balancing features
US6505200B1 (en) * 2000-07-06 2003-01-07 International Business Machines Corporation Application-independent data synchronization technique
US7143024B1 (en) 2000-07-07 2006-11-28 Ensim Corporation Associating identifiers with virtual processes
FR2811844B1 (en) * 2000-07-13 2002-11-29 Schneider Automation S A AUTOMATED INTERNAL BUS SUPPORTING THE TCP / IP PROTOCOL
US7225237B1 (en) * 2000-07-31 2007-05-29 Cisco Technology, Inc. System and method for providing persistent connections based on subnet natural class
US6909691B1 (en) 2000-08-07 2005-06-21 Ensim Corporation Fairly partitioning resources while limiting the maximum fair share
US7089301B1 (en) * 2000-08-11 2006-08-08 Napster, Inc. System and method for searching peer-to-peer computer networks by selecting a computer based on at least a number of files shared by the computer
US6836462B1 (en) 2000-08-30 2004-12-28 Cisco Technology, Inc. Distributed, rule based packet redirection
US7596784B2 (en) 2000-09-12 2009-09-29 Symantec Operating Corporation Method system and apparatus for providing pay-per-use distributed computing resources
US7657629B1 (en) 2000-09-26 2010-02-02 Foundry Networks, Inc. Global server load balancing
US7454500B1 (en) 2000-09-26 2008-11-18 Foundry Networks, Inc. Global server load balancing
US9130954B2 (en) 2000-09-26 2015-09-08 Brocade Communications Systems, Inc. Distributed health check for global server load balancing
US7509403B1 (en) * 2000-09-28 2009-03-24 Alcatel-Lucent Usa Inc. Method and apparatus for SONET/SDH ring load balancing
US7606898B1 (en) 2000-10-24 2009-10-20 Microsoft Corporation System and method for distributed management of shared computers
US6950849B1 (en) * 2000-11-01 2005-09-27 Hob Gmbh & Co. Kg Controlling load-balanced access by user computers to server computers in a computer network
US7035921B1 (en) * 2000-11-14 2006-04-25 Hewlett-Packard Development Company, L.P. Method of and apparatus for providing web service using a network of servers
US7739398B1 (en) * 2000-11-21 2010-06-15 Avaya Inc. Dynamic load balancer
US7216154B1 (en) * 2000-11-28 2007-05-08 Intel Corporation Apparatus and method for facilitating access to network resources
US6904602B1 (en) 2000-11-30 2005-06-07 Sprint Communications Company L.P. Method and apparatus for implementing persistence in trader services associated with a computer system
US7299276B1 (en) * 2000-12-14 2007-11-20 Cisco Technology, Inc. Technique for monitoring health of network device using data format verification
US7219354B1 (en) 2000-12-22 2007-05-15 Ensim Corporation Virtualizing super-user privileges for multiple virtual processes
US7131140B1 (en) * 2000-12-29 2006-10-31 Cisco Technology, Inc. Method for protecting a firewall load balancer from a denial of service attack
US7975023B2 (en) * 2001-01-26 2011-07-05 Dell Products L.P. System and method for using resources of a computer system in conjunction with a thin media client
US7328263B1 (en) * 2001-01-30 2008-02-05 Cisco Technology, Inc. Controlling access of concurrent users of computer resources in a distributed system using an improved semaphore counting approach
US7392307B2 (en) * 2001-02-14 2008-06-24 Ricoh Co., Ltd. Method and system of remote diagnostic, control and information collection using a shared resource
US7849190B2 (en) * 2001-02-23 2010-12-07 Nokia Siemens Networks Oy Internet protocol based service architecture
US7003572B1 (en) * 2001-02-28 2006-02-21 Packeteer, Inc. System and method for efficiently forwarding client requests from a proxy server in a TCP/IP computing environment
US20020133597A1 (en) * 2001-03-14 2002-09-19 Nikhil Jhingan Global storage system
US7035919B1 (en) * 2001-03-21 2006-04-25 Unisys Corporation Method for calculating user weights for thin client sizing tool
US7472178B2 (en) * 2001-04-02 2008-12-30 Akamai Technologies, Inc. Scalable, high performance and highly available distributed storage system for Internet content
US20020174247A1 (en) * 2001-04-02 2002-11-21 Bo Shen System and method for dynamic routing to service providers
US20020152310A1 (en) * 2001-04-12 2002-10-17 International Business Machines Corporation Method and apparatus to dynamically determine the optimal capacity of a server in a server farm
US7426546B2 (en) * 2001-04-18 2008-09-16 International Business Machines Corporation Method for selecting an edge server computer
US7292571B2 (en) * 2001-04-30 2007-11-06 Aol Llc, A Delaware Limited Liability Company Load balancing with direct terminal response
US8572278B2 (en) 2001-04-30 2013-10-29 Facebook, Inc. Generating multiple data streams from a single data source
WO2003105006A1 (en) * 2001-04-30 2003-12-18 America Online, Inc. Load balancing with direct terminal response
US7124166B2 (en) 2001-04-30 2006-10-17 Aol Llc Duplicating digital streams for digital conferencing using switching technologies
US7430609B2 (en) * 2001-04-30 2008-09-30 Aol Llc, A Delaware Limited Liability Company Managing access to streams hosted on duplicating switches
US6785750B1 (en) * 2001-04-30 2004-08-31 Lsi Logic Corporation Integrated dynamic load balancing by an input/output interface
US7237033B2 (en) 2001-04-30 2007-06-26 Aol Llc Duplicating switch for streaming data units to a terminal
US6813656B1 (en) * 2001-04-30 2004-11-02 Lsi Logic Corporation Integrated dynamic multipathing filter
US7266609B2 (en) * 2001-04-30 2007-09-04 Aol Llc Generating multiple data streams from a single data source
US8019807B2 (en) * 2001-05-23 2011-09-13 Wireless Enterprise Solutions Technology Limited Method and system for communication between computer systems
US8004971B1 (en) 2001-05-24 2011-08-23 F5 Networks, Inc. Method and system for scaling network traffic managers using connection keys
US7102996B1 (en) * 2001-05-24 2006-09-05 F5 Networks, Inc. Method and system for scaling network traffic managers
US8175257B1 (en) 2001-05-31 2012-05-08 Cisco Technology, Inc. Method and apparatus for scheduling automatic call distribution system callers
US7881208B1 (en) 2001-06-18 2011-02-01 Cisco Technology, Inc. Gateway load balancing protocol
US7130305B2 (en) * 2001-07-02 2006-10-31 Stonesoft Oy Processing of data packets within a network element cluster
GB2377775A (en) * 2001-07-18 2003-01-22 Ibm Distributing programs to processing units in a network using information on the capabilities of the units
US7174379B2 (en) * 2001-08-03 2007-02-06 International Business Machines Corporation Managing server resources for hosted applications
US7113980B2 (en) * 2001-09-06 2006-09-26 Bea Systems, Inc. Exactly once JMS communication
US6826601B2 (en) * 2001-09-06 2004-11-30 Bea Systems, Inc. Exactly one cache framework
US7389332B1 (en) 2001-09-07 2008-06-17 Cisco Technology, Inc. Method and apparatus for supporting communications between nodes operating in a master-slave configuration
US7860964B2 (en) 2001-09-28 2010-12-28 Level 3 Communications, Llc Policy-based content delivery network selection
US7822860B2 (en) * 2001-12-11 2010-10-26 International Business Machines Corporation Method and apparatus for dynamic reconfiguration of web services infrastructure
US7298746B1 (en) 2002-02-11 2007-11-20 Extreme Networks Method and system for reassembling and parsing packets in a network environment
US7814204B1 (en) 2002-02-11 2010-10-12 Extreme Networks, Inc. Method of and system for analyzing the content of resource requests
US7447777B1 (en) * 2002-02-11 2008-11-04 Extreme Networks Switching system
US7321926B1 (en) 2002-02-11 2008-01-22 Extreme Networks Method of and system for allocating resources to resource requests
US7584262B1 (en) 2002-02-11 2009-09-01 Extreme Networks Method of and system for allocating resources to resource requests based on application of persistence policies
AU2003216332A1 (en) * 2002-02-21 2003-09-09 Bea Systems, Inc. System and method for message driven bean service migration
JP4080765B2 (en) * 2002-03-01 2008-04-23 株式会社日立製作所 Network system
US7421478B1 (en) * 2002-03-07 2008-09-02 Cisco Technology, Inc. Method and apparatus for exchanging heartbeat messages and configuration information between nodes operating in a master-slave configuration
US7130874B2 (en) * 2002-03-12 2006-10-31 International Business Machines Corporation Method, system, and program for maintaining data in a distributed computing environment for processing transaction requests
US20030182410A1 (en) * 2002-03-20 2003-09-25 Sapna Balan Method and apparatus for determination of optimum path routing
US7181527B2 (en) * 2002-03-29 2007-02-20 Intel Corporation Method for transmitting load balancing in mixed speed environments
US7415535B1 (en) 2002-04-22 2008-08-19 Cisco Technology, Inc. Virtual MAC address system and method
US7165258B1 (en) 2002-04-22 2007-01-16 Cisco Technology, Inc. SCSI-based storage area network having a SCSI router that routes traffic between SCSI and IP networks
US7587465B1 (en) 2002-04-22 2009-09-08 Cisco Technology, Inc. Method and apparatus for configuring nodes as masters or slaves
US7188194B1 (en) 2002-04-22 2007-03-06 Cisco Technology, Inc. Session-based target/LUN mapping for a storage area network and associated method
US7509436B1 (en) 2002-05-09 2009-03-24 Cisco Technology, Inc. System and method for increased virtual driver throughput
US6785794B2 (en) * 2002-05-17 2004-08-31 International Business Machines Corporation Differentiated storage resource provisioning
JP2004005249A (en) * 2002-05-31 2004-01-08 Fujitsu Ltd Signal distributing device to load distributed multiprocessor
WO2003105439A1 (en) * 2002-06-10 2003-12-18 Caplin Systems Limited Resource management
US8028092B2 (en) 2002-06-28 2011-09-27 Aol Inc. Inserting advertising content
US20040006622A1 (en) * 2002-07-03 2004-01-08 Burkes Don L. Optimized process for balancing load for data mirroring
JP3923863B2 (en) * 2002-07-09 2007-06-06 株式会社日立製作所 Request router device
US7334124B2 (en) 2002-07-22 2008-02-19 Vormetric, Inc. Logical access block processing protocol for transparent secure file storage
US6931530B2 (en) 2002-07-22 2005-08-16 Vormetric, Inc. Secure network file access controller implementing access control and auditing
US7584131B1 (en) 2002-07-31 2009-09-01 Ameriprise Financial, Inc. Method for migrating financial and indicative plan data between computerized record keeping systems without a blackout period
US7086061B1 (en) * 2002-08-01 2006-08-01 Foundry Networks, Inc. Statistical tracking of global server load balancing for selecting the best network address from ordered list of network addresses based on a set of performance metrics
US7676576B1 (en) 2002-08-01 2010-03-09 Foundry Networks, Inc. Method and system to clear counters used for statistical tracking for global server load balancing
US7574508B1 (en) 2002-08-07 2009-08-11 Foundry Networks, Inc. Canonical name (CNAME) handling for global server load balancing
JP4201550B2 (en) * 2002-08-30 2008-12-24 富士通株式会社 Load balancer
US7136922B2 (en) * 2002-10-15 2006-11-14 Akamai Technologies, Inc. Method and system for providing on-demand content delivery for an origin server
US7143288B2 (en) 2002-10-16 2006-11-28 Vormetric, Inc. Secure file system server architecture and methods
US20040088408A1 (en) * 2002-11-01 2004-05-06 Igor Tsyganskiy Methods and systems for routing requests at a network switch
JP3995580B2 (en) * 2002-11-05 2007-10-24 富士通株式会社 Load balancing processing system
ITMI20022347A1 (en) * 2002-11-06 2004-05-07 Pasqua Roberto Della COMMUNICATION METHOD WITH RESPONSE TIME REDUCED IN
US7461146B2 (en) * 2003-01-20 2008-12-02 Equallogic, Inc. Adaptive storage block data distribution
US7406692B2 (en) * 2003-02-24 2008-07-29 Bea Systems, Inc. System and method for server load balancing and server affinity
GB0306971D0 (en) * 2003-03-26 2003-04-30 British Telecomm Client server model
US7680897B1 (en) 2003-04-08 2010-03-16 Novell, Inc. Methods and systems for managing network traffic
US7222195B2 (en) * 2003-04-22 2007-05-22 Cisco Technology, Inc. System and method for distributing information in a network environment
DK1629624T3 (en) 2003-05-30 2013-06-24 Privaris Inc IN-CIRCUIT SECURITY SYSTEM AND PROCEDURES FOR MANAGING ACCESS TO AND USING SENSITIVE DATA
US20040260745A1 (en) * 2003-06-18 2004-12-23 Gage Christopher A. S. Load balancer performance using affinity modification
US7650402B1 (en) 2003-06-25 2010-01-19 Cisco Technology, Inc. System and method for tracking end users in a loadbalancing environment
US7567504B2 (en) * 2003-06-30 2009-07-28 Microsoft Corporation Network load balancing with traffic routing
US7636917B2 (en) 2003-06-30 2009-12-22 Microsoft Corporation Network load balancing with host status information
US7590736B2 (en) 2003-06-30 2009-09-15 Microsoft Corporation Flexible network load balancing
US7606929B2 (en) 2003-06-30 2009-10-20 Microsoft Corporation Network load balancing with connection manipulation
US7613822B2 (en) 2003-06-30 2009-11-03 Microsoft Corporation Network load balancing with session information
US7529200B2 (en) * 2003-07-24 2009-05-05 3E Technologies International, Inc. Method and system for fast setup of group voice over IP communications
US7441033B2 (en) 2003-08-14 2008-10-21 Oracle International Corporation On demand node and server instance allocation and de-allocation
US7437460B2 (en) 2003-08-14 2008-10-14 Oracle International Corporation Service placement for enforcing performance and availability levels in a multi-node system
US20050256971A1 (en) * 2003-08-14 2005-11-17 Oracle International Corporation Runtime load balancing of work across a clustered computing system using current service performance levels
US7953860B2 (en) * 2003-08-14 2011-05-31 Oracle International Corporation Fast reorganization of connections in response to an event in a clustered computing system
US20060064400A1 (en) 2004-09-21 2006-03-23 Oracle International Corporation, A California Corporation Methods, systems and software for identifying and managing database work
CN100547583C (en) * 2003-08-14 2009-10-07 甲骨文国际公司 Database automatically and the method that dynamically provides
US8365193B2 (en) 2003-08-14 2013-01-29 Oracle International Corporation Recoverable asynchronous message driven processing in a multi-node system
US7437459B2 (en) 2003-08-14 2008-10-14 Oracle International Corporation Calculation of service performance grades in a multi-node environment that hosts the services
US7664847B2 (en) 2003-08-14 2010-02-16 Oracle International Corporation Managing workload by service
US7552171B2 (en) * 2003-08-14 2009-06-23 Oracle International Corporation Incremental run-time session balancing in a multi-node system
US7516221B2 (en) 2003-08-14 2009-04-07 Oracle International Corporation Hierarchical management of the dynamic allocation of resources in a multi-node system
US9584360B2 (en) 2003-09-29 2017-02-28 Foundry Networks, Llc Global server load balancing support for private VIP addresses
US7756040B1 (en) 2003-10-08 2010-07-13 Cisco Technology, Inc. System and method for relaying information in order to enable services in a network environment
US20050108397A1 (en) * 2003-11-14 2005-05-19 International Business Machines Corporation Reducing number of messages processed by control processor by bundling control and data messages and offloading the TCP connection setup and termination messages
US8050275B1 (en) 2003-11-18 2011-11-01 Cisco Technology, Inc. System and method for offering quality of service in a network environment
US7493380B2 (en) * 2003-12-02 2009-02-17 International Business Machines Corporation Method for determining load balancing weights using application instance topology information
US7873724B2 (en) * 2003-12-05 2011-01-18 Microsoft Corporation Systems and methods for guiding allocation of computational resources in automated perceptual systems
US7269603B1 (en) 2003-12-17 2007-09-11 Sprint Communications Company L.P. Enterprise naming service system and method
US7115096B2 (en) 2003-12-24 2006-10-03 Cardiac Pacemakers, Inc. Third heart sound activity index for heart failure monitoring
US7431699B2 (en) 2003-12-24 2008-10-07 Cardiac Pacemakers, Inc. Method and apparatus for third heart sound detection
FR2865051B1 (en) * 2004-01-14 2006-03-03 Stg Interactive METHOD AND SYSTEM FOR OPERATING A COMPUTER NETWORK FOR CONTENT RELEASE
US7546367B2 (en) * 2004-01-15 2009-06-09 Novell, Inc. Methods and systems for managing network traffic by multiple constraints
US7693991B2 (en) * 2004-01-16 2010-04-06 International Business Machines Corporation Virtual clustering and load balancing servers
US7596107B1 (en) 2004-01-26 2009-09-29 Cisco Technology, Inc. System and method for enabling multicast group services in a network environment
US7827279B2 (en) * 2004-01-30 2010-11-02 Hewlett-Packard Development Company, L.P. Selecting nodes close to another node in a network using location information for the nodes
US7644167B2 (en) * 2004-01-30 2010-01-05 Hewlett-Packard Development Company, L.P. Identifying a service node in a network
TW200532466A (en) * 2004-02-03 2005-10-01 Sony Corp Information processing device, information processing method, information processing system and information processing program of accessible media
JP4291174B2 (en) * 2004-02-16 2009-07-08 株式会社日立製作所 Web service delegation processing method, execution apparatus, and processing program
KR20060123559A (en) * 2004-02-17 2006-12-01 코닌클리케 필립스 일렉트로닉스 엔.브이. System, receiver, method and program for distributing content
KR100435985B1 (en) * 2004-02-25 2004-06-12 엔에이치엔(주) Nonstop service system using voting and, information updating and providing method in the same
US7778422B2 (en) 2004-02-27 2010-08-17 Microsoft Corporation Security associations for devices
US7607132B2 (en) * 2004-04-08 2009-10-20 Taiwan Semiconductor Manufacturing Co., Ltd. Process scheduling system and method
US8316099B2 (en) * 2004-04-21 2012-11-20 Oracle America, Inc. Directory distributor
US20050246529A1 (en) 2004-04-30 2005-11-03 Microsoft Corporation Isolated persistent identity storage for authentication of computing devies
US7496651B1 (en) 2004-05-06 2009-02-24 Foundry Networks, Inc. Configurable geographic prefixes for global server load balancing
US7584301B1 (en) 2004-05-06 2009-09-01 Foundry Networks, Inc. Host-level policies for global server load balancing
US20060031521A1 (en) * 2004-05-10 2006-02-09 International Business Machines Corporation Method for early failure detection in a server system and a computer system utilizing the same
US7020090B2 (en) * 2004-06-21 2006-03-28 Cisco Technology, Inc. System and method for loadbalancing in a network environment using feedback information
US7757236B1 (en) * 2004-06-28 2010-07-13 Oracle America, Inc. Load-balancing framework for a cluster
US7502824B2 (en) 2004-08-12 2009-03-10 Oracle International Corporation Database shutdown with session migration
JP2006058921A (en) * 2004-08-17 2006-03-02 Fujitsu Ltd Cooperation application starting program
US8954584B1 (en) * 2004-08-18 2015-02-10 Oracle America, Inc. Policy engine for automating management of scalable distributed persistent applications in a grid
US7423977B1 (en) 2004-08-23 2008-09-09 Foundry Networks Inc. Smoothing algorithm for round trip time (RTT) measurements
US20060080273A1 (en) * 2004-10-12 2006-04-13 International Business Machines Corporation Middleware for externally applied partitioning of applications
US7788671B2 (en) * 2004-11-01 2010-08-31 International Business Machines Corporation On-demand application resource allocation through dynamic reconfiguration of application cluster size and placement
CN100512526C (en) * 2004-11-26 2009-07-08 中国移动通信集团公司 Method and system for proxy re-orienting terminal request
US9489424B2 (en) * 2004-12-20 2016-11-08 Oracle International Corporation Cursor pre-fetching
US20060149741A1 (en) * 2005-01-04 2006-07-06 Oracle International Corporation Efficient Approach to Implement Applications on Server Systems in a Networked Environment
US7917625B1 (en) * 2005-01-14 2011-03-29 Sprint Communications Company L.P. Predictive processing resource level control
US9176772B2 (en) 2005-02-11 2015-11-03 Oracle International Corporation Suspending and resuming of sessions
US7640339B1 (en) * 2005-02-14 2009-12-29 Sun Microsystems, Inc. Method and apparatus for monitoring a node in a distributed system
US7852831B2 (en) 2005-02-22 2010-12-14 Akbar Imran M Method and system for providing private virtual secure Voice over Internet Protocol communications
US7340744B2 (en) * 2005-04-08 2008-03-04 Cisco Technology, Inc. System and method for optimizing sessions and network resources in a loadbalancing environment
JP4241660B2 (en) * 2005-04-25 2009-03-18 株式会社日立製作所 Load balancer
US20060265499A1 (en) * 2005-05-23 2006-11-23 Menasce Daniel A Service Allocation Mechanism
GB2426862B (en) * 2005-06-04 2007-04-11 Alan Charles Sturt Thermonuclear power generation
US7922669B2 (en) 2005-06-08 2011-04-12 Cardiac Pacemakers, Inc. Ischemia detection using a heart sound sensor
US7877755B2 (en) * 2005-07-25 2011-01-25 International Business Machines Corporation Dynamic application placement with allocation restrictions and even load distribution
US8009676B2 (en) * 2005-07-26 2011-08-30 Cisco Technology, Inc. Dynamically providing a quality of service for a mobile node
EP1753195B1 (en) * 2005-07-27 2012-03-07 Sap Ag Server computer, client device and web service implemented data processing method
US7630486B2 (en) * 2005-09-20 2009-12-08 Cisco Technology, Inc. Method and system for handling a queued automatic call distributor call
US8429297B1 (en) * 2005-09-28 2013-04-23 Oracle America, Inc. Web service invocation framework with integrated directory-based distributor
US7941309B2 (en) 2005-11-02 2011-05-10 Microsoft Corporation Modeling IT operations/policies
WO2007053940A1 (en) * 2005-11-09 2007-05-18 Generation 5 Mathematical Technologies Inc. Automatic generation of sales and marketing information
US8140695B2 (en) * 2005-12-12 2012-03-20 International Business Machines Corporation Load balancing and failover of distributed media resources in a media server
US8015304B2 (en) * 2005-12-12 2011-09-06 International Business Machines Corporation Method to distribute speech resources in a media server
ITTO20060149A1 (en) * 2006-03-01 2007-09-02 Cisco Tech Inc TECHNIQUE FOR THE OPTIMIZED FLOW OF DATA FLOWS ON AN IP DORSAL IN A COMPUTER NETWORK.
US7780606B2 (en) 2006-03-29 2010-08-24 Cardiac Pacemakers, Inc. Hemodynamic stability assessment based on heart sounds
CN100525378C (en) * 2006-11-17 2009-08-05 华为技术有限公司 Management method, system and device to update distributed set top box
US20080119749A1 (en) 2006-11-20 2008-05-22 Cardiac Pacemakers, Inc. Respiration-synchronized heart sound trending
CN1968147B (en) * 2006-11-27 2010-04-14 华为技术有限公司 Service processing method, network device, and service processing system
US8096954B2 (en) 2006-11-29 2012-01-17 Cardiac Pacemakers, Inc. Adaptive sampling of heart sounds
US8185909B2 (en) * 2007-03-06 2012-05-22 Sap Ag Predictive database resource utilization and load balancing using neural network model
US8484656B2 (en) * 2007-03-12 2013-07-09 Citrix Systems, Inc. Systems and methods for providing global server load balancing of heterogeneous devices
JP5246157B2 (en) * 2007-04-04 2013-07-24 富士通株式会社 Load balancing system
US7853327B2 (en) 2007-04-17 2010-12-14 Cardiac Pacemakers, Inc. Heart sound tracking system and method
US9027025B2 (en) 2007-04-17 2015-05-05 Oracle International Corporation Real-time database exception monitoring tool using instance eviction data
US20080307036A1 (en) * 2007-06-07 2008-12-11 Microsoft Corporation Central service allocation system
US8065537B2 (en) * 2007-06-12 2011-11-22 Hewlett-Packard Development Company, L.P. Adjusting cap settings of electronic devices according to measured workloads
US20080313492A1 (en) * 2007-06-12 2008-12-18 Hansen Peter A Adjusting a Cooling Device and a Server in Response to a Thermal Event
US8239505B2 (en) 2007-06-29 2012-08-07 Microsoft Corporation Progressively implementing declarative models in distributed systems
US8615008B2 (en) 2007-07-11 2013-12-24 Foundry Networks Llc Duplicating network traffic through transparent VLAN flooding
US8230386B2 (en) 2007-08-23 2012-07-24 Microsoft Corporation Monitoring distributed applications
US8248928B1 (en) 2007-10-09 2012-08-21 Foundry Networks, Llc Monitoring server load balancing
US8099720B2 (en) 2007-10-26 2012-01-17 Microsoft Corporation Translating declarative models
US7974939B2 (en) * 2007-10-26 2011-07-05 Microsoft Corporation Processing model-based commands for distributed applications
CN101562784B (en) * 2008-04-14 2012-06-06 华为技术有限公司 Method, device and system for distributing messages
US8806053B1 (en) 2008-04-29 2014-08-12 F5 Networks, Inc. Methods and systems for optimizing network traffic using preemptive acknowledgment signals
WO2010002400A1 (en) * 2008-07-01 2010-01-07 Hewlett-Packard Development Company, L.P. Remote computing services
US20100042723A1 (en) * 2008-08-12 2010-02-18 Srikanth Sundarrajan Method and system for managing load in a network
DE102008040009A1 (en) * 2008-08-27 2010-03-04 Siemens Aktiengesellschaft Load-balanced allocation of medical taskflows to servers of a server farm
US8843630B1 (en) * 2008-08-27 2014-09-23 Amazon Technologies, Inc. Decentralized request routing
US8621065B1 (en) 2008-10-23 2013-12-31 Amazon Technologies, Inc. Dynamic blocking of suspicious electronic submissions
US8566444B1 (en) 2008-10-30 2013-10-22 F5 Networks, Inc. Methods and system for simultaneous multiple rules checking
US8429650B2 (en) * 2008-11-14 2013-04-23 Oracle International Corporation System and method of security management for a virtual environment
US9128895B2 (en) 2009-02-19 2015-09-08 Oracle International Corporation Intelligent flood control management
US7966383B2 (en) * 2009-03-27 2011-06-21 Business Objects Software Ltd. Client-server systems and methods for accessing metadata information across a network using proxies
US8238538B2 (en) 2009-05-28 2012-08-07 Comcast Cable Communications, Llc Stateful home phone service
US10157280B2 (en) 2009-09-23 2018-12-18 F5 Networks, Inc. System and method for identifying security breach attempts of a website
US10721269B1 (en) 2009-11-06 2020-07-21 F5 Networks, Inc. Methods and system for returning requests with javascript for clients before passing a request to a server
US8868961B1 (en) 2009-11-06 2014-10-21 F5 Networks, Inc. Methods for acquiring hyper transport timing and devices thereof
US9313047B2 (en) 2009-11-06 2016-04-12 F5 Networks, Inc. Handling high throughput and low latency network data packets in a traffic management device
US20110167039A1 (en) * 2010-01-05 2011-07-07 Microsoft Corporation Distributed throttling for mailbox data replication
US9165086B2 (en) 2010-01-20 2015-10-20 Oracle International Corporation Hybrid binary XML storage model for efficient XML processing
US9667569B1 (en) 2010-04-29 2017-05-30 Amazon Technologies, Inc. System and method for adaptive server shielding
US9141625B1 (en) 2010-06-22 2015-09-22 F5 Networks, Inc. Methods for preserving flow state during virtual machine migration and devices thereof
US10015286B1 (en) 2010-06-23 2018-07-03 F5 Networks, Inc. System and method for proxying HTTP single sign on across network domains
US8908545B1 (en) 2010-07-08 2014-12-09 F5 Networks, Inc. System and method for handling TCP performance in network access with driver initiated application tunnel
US8347100B1 (en) 2010-07-14 2013-01-01 F5 Networks, Inc. Methods for DNSSEC proxying and deployment amelioration and systems thereof
US9083760B1 (en) 2010-08-09 2015-07-14 F5 Networks, Inc. Dynamic cloning and reservation of detached idle connections
US8630174B1 (en) 2010-09-14 2014-01-14 F5 Networks, Inc. System and method for post shaping TCP packetization
US8886981B1 (en) 2010-09-15 2014-11-11 F5 Networks, Inc. Systems and methods for idle driven scheduling
US8463909B1 (en) 2010-09-15 2013-06-11 F5 Networks, Inc. Systems and methods for managing server resources
US8804504B1 (en) 2010-09-16 2014-08-12 F5 Networks, Inc. System and method for reducing CPU load in processing PPP packets on a SSL-VPN tunneling device
US8458530B2 (en) 2010-09-21 2013-06-04 Oracle International Corporation Continuous system health indicator for managing computer system alerts
US8549148B2 (en) 2010-10-15 2013-10-01 Brocade Communications Systems, Inc. Domain name system security extensions (DNSSEC) for global server load balancing
WO2012058643A2 (en) 2010-10-29 2012-05-03 F5 Networks, Inc. System and method for on the fly protocol conversion in obtaining policy enforcement information
US8959571B2 (en) 2010-10-29 2015-02-17 F5 Networks, Inc. Automated policy builder
US8627467B2 (en) 2011-01-14 2014-01-07 F5 Networks, Inc. System and method for selectively storing web objects in a cache memory based on policy decisions
US10162726B2 (en) * 2011-01-18 2018-12-25 Accenture Global Services Limited Managing computing resources
US10135831B2 (en) 2011-01-28 2018-11-20 F5 Networks, Inc. System and method for combining an access control system with a traffic management system
US9705977B2 (en) * 2011-04-20 2017-07-11 Symantec Corporation Load balancing for network devices
US10169094B2 (en) * 2011-04-27 2019-01-01 Hewlett Packard Enterprise Development Lp Dynamic transaction-persistent server load balancing
US9246819B1 (en) 2011-06-20 2016-01-26 F5 Networks, Inc. System and method for performing message-based load balancing
US9055076B1 (en) 2011-06-23 2015-06-09 Amazon Technologies, Inc. System and method for distributed load balancing with load balancer clients for hosts
US8812727B1 (en) 2011-06-23 2014-08-19 Amazon Technologies, Inc. System and method for distributed load balancing with distributed direct server return
US20130054817A1 (en) * 2011-08-29 2013-02-28 Cisco Technology, Inc. Disaggregated server load balancing
US9372733B2 (en) * 2011-08-30 2016-06-21 Open Text S.A. System and method for a distribution manager
US9450875B1 (en) 2011-09-23 2016-09-20 Google Inc. Cooperative fault tolerance and load balancing
US8898271B2 (en) * 2011-09-29 2014-11-25 Oracle International Corporation System and method for supporting accurate load balancing in a transactional middleware machine environment
US8219684B1 (en) * 2011-11-02 2012-07-10 Google Inc. Redundant data requests with cancellation
US9270766B2 (en) 2011-12-30 2016-02-23 F5 Networks, Inc. Methods for identifying network traffic characteristics to correlate and manage one or more subsequent flows and devices thereof
US10348573B2 (en) * 2012-01-11 2019-07-09 Saguna Networks Ltd. Methods, circuits, devices, systems and associated computer executable code for facilitating local hosting and access of internet based information
US10230566B1 (en) 2012-02-17 2019-03-12 F5 Networks, Inc. Methods for dynamically constructing a service principal name and devices thereof
US9172753B1 (en) 2012-02-20 2015-10-27 F5 Networks, Inc. Methods for optimizing HTTP header based authentication and devices thereof
US9231879B1 (en) 2012-02-20 2016-01-05 F5 Networks, Inc. Methods for policy-based network traffic queue management and devices thereof
US10097616B2 (en) 2012-04-27 2018-10-09 F5 Networks, Inc. Methods for optimizing service of content requests and devices thereof
US9154423B1 (en) 2012-05-01 2015-10-06 F5 Networks, Inc. Minimize SYN-flood issues with flow cache while maintaining performance
US9338095B2 (en) 2012-05-01 2016-05-10 F5 Networks, Inc. Data flow segment optimized for hot flows
US9525632B1 (en) 2012-05-01 2016-12-20 F5 Networks, Inc. Minimize recycle SYN issues for split TCP hot flows to improve system reliability and performance
US9203771B1 (en) 2012-07-23 2015-12-01 F5 Networks, Inc. Hot service flow hardware offloads based on service priority and resource usage
US10375155B1 (en) 2013-02-19 2019-08-06 F5 Networks, Inc. System and method for achieving hardware acceleration for asymmetric flow connections
US9998530B2 (en) * 2013-10-15 2018-06-12 Nicira, Inc. Distributed global load-balancing system for software-defined data centers
US10187317B1 (en) 2013-11-15 2019-01-22 F5 Networks, Inc. Methods for traffic rate control and devices thereof
US9565138B2 (en) 2013-12-20 2017-02-07 Brocade Communications Systems, Inc. Rule-based network traffic interception and distribution scheme
US9648542B2 (en) 2014-01-28 2017-05-09 Brocade Communications Systems, Inc. Session-based packet routing for facilitating analytics
US10015143B1 (en) 2014-06-05 2018-07-03 F5 Networks, Inc. Methods for securing one or more license entitlement grants and devices thereof
US11838851B1 (en) 2014-07-15 2023-12-05 F5, Inc. Methods for managing L7 traffic classification and devices thereof
US10122630B1 (en) 2014-08-15 2018-11-06 F5 Networks, Inc. Methods for network traffic presteering and devices thereof
US20160094645A1 (en) * 2014-09-26 2016-03-31 Microsoft Corporation Dns-based load balancing
US10182013B1 (en) 2014-12-01 2019-01-15 F5 Networks, Inc. Methods for managing progressive image delivery and devices thereof
US11895138B1 (en) 2015-02-02 2024-02-06 F5, Inc. Methods for improving web scanner accuracy and devices thereof
US10129088B2 (en) 2015-06-17 2018-11-13 Extreme Networks, Inc. Configuration of rules in a network visibility system
US10771475B2 (en) 2015-03-23 2020-09-08 Extreme Networks, Inc. Techniques for exchanging control and configuration information in a network visibility system
US10911353B2 (en) 2015-06-17 2021-02-02 Extreme Networks, Inc. Architecture for a network visibility system
US9866478B2 (en) 2015-03-23 2018-01-09 Extreme Networks, Inc. Techniques for user-defined tagging of traffic in a network visibility system
US10834065B1 (en) 2015-03-31 2020-11-10 F5 Networks, Inc. Methods for SSL protected NTLM re-authentication and devices thereof
US11350254B1 (en) 2015-05-05 2022-05-31 F5, Inc. Methods for enforcing compliance policies and devices thereof
US10505818B1 (en) 2015-05-05 2019-12-10 F5 Networks. Inc. Methods for analyzing and load balancing based on server health and devices thereof
US10530688B2 (en) 2015-06-17 2020-01-07 Extreme Networks, Inc. Configuration of load-sharing components of a network visibility router in a network visibility system
US10057126B2 (en) 2015-06-17 2018-08-21 Extreme Networks, Inc. Configuration of a network visibility system
US11757946B1 (en) 2015-12-22 2023-09-12 F5, Inc. Methods for analyzing network traffic and enforcing network policies and devices thereof
US10404698B1 (en) 2016-01-15 2019-09-03 F5 Networks, Inc. Methods for adaptive organization of web application access points in webtops and devices thereof
US10797888B1 (en) 2016-01-20 2020-10-06 F5 Networks, Inc. Methods for secured SCEP enrollment for client devices and devices thereof
US11178150B1 (en) 2016-01-20 2021-11-16 F5 Networks, Inc. Methods for enforcing access control list based on managed application and devices thereof
US10243813B2 (en) 2016-02-12 2019-03-26 Extreme Networks, Inc. Software-based packet broker
US10999200B2 (en) 2016-03-24 2021-05-04 Extreme Networks, Inc. Offline, intelligent load balancing of SCTP traffic
US10791088B1 (en) 2016-06-17 2020-09-29 F5 Networks, Inc. Methods for disaggregating subscribers via DHCP address translation and devices thereof
US10474653B2 (en) 2016-09-30 2019-11-12 Oracle International Corporation Flexible in-memory column store placement
US10567259B2 (en) 2016-10-19 2020-02-18 Extreme Networks, Inc. Smart filter generator
US11063758B1 (en) 2016-11-01 2021-07-13 F5 Networks, Inc. Methods for facilitating cipher selection and devices thereof
US10505792B1 (en) 2016-11-02 2019-12-10 F5 Networks, Inc. Methods for facilitating network traffic analytics and devices thereof
US10749954B2 (en) * 2016-12-20 2020-08-18 Futurewei Technologies, Inc. Cross-data center hierarchical consensus scheme with geo-aware leader election
US10476945B2 (en) * 2017-02-01 2019-11-12 Juniper Networks, Inc. Consistent flow assignment in load balancing
US11496438B1 (en) 2017-02-07 2022-11-08 F5, Inc. Methods for improved network security using asymmetric traffic delivery and devices thereof
US10791119B1 (en) 2017-03-14 2020-09-29 F5 Networks, Inc. Methods for temporal password injection and devices thereof
US10812266B1 (en) 2017-03-17 2020-10-20 F5 Networks, Inc. Methods for managing security tokens based on security violations and devices thereof
US10931662B1 (en) 2017-04-10 2021-02-23 F5 Networks, Inc. Methods for ephemeral authentication screening and devices thereof
US10972453B1 (en) 2017-05-03 2021-04-06 F5 Networks, Inc. Methods for token refreshment based on single sign-on (SSO) for federated identity environments and devices thereof
US11343237B1 (en) 2017-05-12 2022-05-24 F5, Inc. Methods for managing a federated identity environment using security and access control data and devices thereof
US11122042B1 (en) 2017-05-12 2021-09-14 F5 Networks, Inc. Methods for dynamically managing user access control and devices thereof
US11122083B1 (en) 2017-09-08 2021-09-14 F5 Networks, Inc. Methods for managing network connections based on DNS data and network policies and devices thereof
US20190102401A1 (en) 2017-09-29 2019-04-04 Oracle International Corporation Session state tracking
US11658995B1 (en) 2018-03-20 2023-05-23 F5, Inc. Methods for dynamically mitigating network attacks and devices thereof
US11044200B1 (en) 2018-07-06 2021-06-22 F5 Networks, Inc. Methods for service stitching using a packet header and devices thereof
US11936739B2 (en) 2019-09-12 2024-03-19 Oracle International Corporation Automated reset of session state
US11451627B2 (en) * 2020-04-03 2022-09-20 Open Text Holdings, Inc. System and method for content management with intelligent data store access across distributed stores
CN111597047A (en) * 2020-05-15 2020-08-28 北京金山云网络技术有限公司 Service deployment method, device, electronic equipment and storage medium

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5459837A (en) * 1993-04-21 1995-10-17 Digital Equipment Corporation System to facilitate efficient utilization of network resources in a computer network
EP0715257A1 (en) * 1994-11-30 1996-06-05 Bull S.A. Tool for assisting the load balancing of a distributed application
WO1998026559A1 (en) * 1996-12-09 1998-06-18 Gte Internetworking Incorporated Distributed computing system and method for distributing user requests to replicated network servers
US5790789A (en) * 1996-08-02 1998-08-04 Suarez; Larry Method and architecture for the creation, control and deployment of services within a distributed computer environment

Family Cites Families (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2076293A1 (en) * 1991-10-11 1993-04-12 Prathima Agrawal Multiprocessor computer for solving sets of equations
US5371852A (en) 1992-10-14 1994-12-06 International Business Machines Corporation Method and apparatus for making a cluster of computers appear as a single host on a network
US5583994A (en) 1994-02-07 1996-12-10 Regents Of The University Of California System for efficient delivery of multimedia information using hierarchical network of servers selectively caching program for a selected time period
US5774668A (en) * 1995-06-07 1998-06-30 Microsoft Corporation System for on-line service in which gateway computer uses service map which includes loading condition of servers broadcasted by application servers for load balancing
US5603029A (en) 1995-06-07 1997-02-11 International Business Machines Corporation System of assigning work requests based on classifying into an eligible class where the criteria is goal oriented and capacity information is available
US5915095A (en) * 1995-08-08 1999-06-22 Ncr Corporation Method and apparatus for balancing processing requests among a plurality of servers based on measurable characteristics off network node and common application
US5966695A (en) * 1995-10-17 1999-10-12 Citibank, N.A. Sales and marketing support system using a graphical query prospect database
US5742598A (en) 1995-10-19 1998-04-21 International Business Machines Corp. Network for efficiently locating resources and routing service requests received from individual node connections
US5848241A (en) * 1996-01-11 1998-12-08 Openframe Corporation Ltd. Resource sharing facility functions as a controller for secondary storage device and is accessible to all computers via inter system links
US5870561A (en) * 1996-03-15 1999-02-09 Novell, Inc. Network traffic manager server for providing policy-based recommendations to clients
US5828843A (en) 1996-03-21 1998-10-27 Mpath Interactive, Inc. Object-oriented method for matching clients together with servers according to attributes included in join request
AU714336B2 (en) * 1996-07-25 1999-12-23 Clearway Acquisition, Inc. Web serving system with primary and secondary servers
US5774660A (en) * 1996-08-05 1998-06-30 Resonate, Inc. World-wide-web server with delayed resource-binding for resource-based load balancing on a distributed resource multi-node network
US5937165A (en) 1996-09-10 1999-08-10 Ganymede Software, Inc Systems, methods and computer program products for applications traffic based communications network performance testing
US5938732A (en) 1996-12-09 1999-08-17 Sun Microsystems, Inc. Load balancing and failover of network services
US6052718A (en) * 1997-01-07 2000-04-18 Sightpath, Inc Replica routing
US6038599A (en) 1997-04-23 2000-03-14 Mpath Interactive, Inc. Latency server and matchmaker
US5931900A (en) * 1997-08-25 1999-08-03 I2 Technologies, Inc. System and process for inter-domain interaction across an inter-domain connectivity plane
US5991878A (en) * 1997-09-08 1999-11-23 Fmr Corp. Controlling access to information
US6092178A (en) * 1998-09-03 2000-07-18 Sun Microsystems, Inc. System for responding to a resource request

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5459837A (en) * 1993-04-21 1995-10-17 Digital Equipment Corporation System to facilitate efficient utilization of network resources in a computer network
EP0715257A1 (en) * 1994-11-30 1996-06-05 Bull S.A. Tool for assisting the load balancing of a distributed application
US5790789A (en) * 1996-08-02 1998-08-04 Suarez; Larry Method and architecture for the creation, control and deployment of services within a distributed computer environment
WO1998026559A1 (en) * 1996-12-09 1998-06-18 Gte Internetworking Incorporated Distributed computing system and method for distributing user requests to replicated network servers

Cited By (39)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2363952A (en) * 2000-01-28 2002-01-09 Ibm Measuring response times to balance load among mirror servers
GB2363952B (en) * 2000-01-28 2004-04-07 Ibm A method of balancing load among mirror servers
WO2001076159A1 (en) * 2000-03-31 2001-10-11 British Telecommunications Public Limited Company Processing capacity management
WO2001093530A2 (en) * 2000-05-26 2001-12-06 Akamai Technologies, Inc. Global load balancing across mirrored data centers
WO2001093530A3 (en) * 2000-05-26 2002-10-17 Akamai Tech Inc Global load balancing across mirrored data centers
AU2010202981B2 (en) * 2000-05-26 2011-12-08 Akamai Technologies, Inc. Global load balancing across mirrored data centers
WO2002054705A3 (en) * 2000-12-29 2003-11-13 Nortel Networks Ltd Network protocols for distributing functions within a network
WO2002054705A2 (en) * 2000-12-29 2002-07-11 Nortel Networks Limited Network protocols for distributing functions within a network
EP1371194A4 (en) * 2001-03-20 2004-11-17 Worldcom Inc Systems and methods for updating ip communication service attributes using an ldap
EP1371194A2 (en) * 2001-03-20 2003-12-17 Worldcom, Inc. Systems and methods for updating ip communication service attributes using an ldap
US8660017B2 (en) 2001-03-20 2014-02-25 Verizon Business Global Llc Systems and methods for updating IP communication service attributes using an LDAP
WO2002097621A3 (en) * 2001-05-30 2003-11-06 Ibm Selection and configuration of servers
WO2002097621A2 (en) * 2001-05-30 2002-12-05 International Business Machines Corporation Selection and configuration of servers
US8819196B2 (en) 2001-05-30 2014-08-26 International Business Machines Corporation Selection and configuration of servers
US7644159B2 (en) 2001-08-15 2010-01-05 Nokia Corporation Load balancing for a server farm
US7519710B2 (en) 2001-09-18 2009-04-14 Ericsson Ab Client server networks
WO2003026244A2 (en) * 2001-09-18 2003-03-27 Marconi Uk Intellectual Property Ltd Client server networks
WO2003026244A3 (en) * 2001-09-18 2003-06-19 Marconi Comm Ltd Client server networks
CN100459608C (en) * 2001-09-18 2009-02-04 爱立信股份有限公司 Client server networks
US9203636B2 (en) 2001-09-28 2015-12-01 Level 3 Communications, Llc Distributing requests across multiple content delivery networks based on subscriber policy
EP1436736A2 (en) * 2001-09-28 2004-07-14 Savvis Communications Corporation Configurable adaptive global traffic control and management
US10911531B2 (en) 2001-09-28 2021-02-02 Level 3 Communications, Llc Multi-tiered server network
US10116738B2 (en) 2001-09-28 2018-10-30 Level 3 Communications, Llc Detecting anomalous conditions in a name server network
US7418509B2 (en) 2001-11-13 2008-08-26 Nokia Corporation Method and apparatus for a distributed server tree
EP1444592A4 (en) * 2001-11-13 2006-06-28 Nokia Corp Method and apparatus for a distributed server tree
EP1444592A1 (en) * 2001-11-13 2004-08-11 Nokia Corporation Method and apparatus for a distributed server tree
WO2004086270A3 (en) * 2003-03-27 2005-04-07 Eci Telecom Ltd Method for distributing subtasks to servers and maintaining load balancing among servers
WO2004086270A2 (en) * 2003-03-27 2004-10-07 Eci Telecom Ltd. Method for distributing subtasks to servers and maintaining load balancing among servers
US7124949B2 (en) 2003-06-17 2006-10-24 Symbol Technologies, Inc. Reducing speckle noise in electro-optical readers
CN100391178C (en) * 2003-08-19 2008-05-28 华为技术有限公司 Method for selecting server in network
CN100370775C (en) * 2005-01-25 2008-02-20 华为技术有限公司 Method for raising success rate of business insertion
GB2477642B (en) * 2010-02-03 2012-03-14 Orbital Multi Media Holdings Corp Redirection apparatus and method
GB2477642A (en) * 2010-02-03 2011-08-10 Orbital Multi Media Holdings Corp Selection of a streaming server which stores the required content in the highest (fastest access) hierarchical storage layer.
US9787736B2 (en) 2010-02-03 2017-10-10 Orbital Multi Media Holdings Corporation Redirection apparatus and method
WO2013173026A1 (en) * 2012-05-14 2013-11-21 Volusion, Inc. Network security load balancing
US9264409B2 (en) 2012-05-14 2016-02-16 Volusion, Inc. Network security load balancing
US10009801B1 (en) 2016-12-05 2018-06-26 Motorola Solutions, Inc. Systems and methods for forming an incident area network
GB2558396A (en) * 2016-12-05 2018-07-11 Motorola Solutions Inc Systems and methods for forming an incident area network
GB2558396B (en) * 2016-12-05 2019-02-20 Motorola Solutions Inc Systems and methods for forming an incident area network

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