Network sales system

1. A network-based sales system, comprising:

a merchant database comprising a plurality of digital advertisements and a plurality of respective product fulfillment items;

at least one creation computer for creating said merchant database; and

at least one merchant computer for causing said digital advertisements to be transmitted to a user and for causing advertised products to be transmitted to said user;

said creation computer and said merchant computer being interconnected by a computer network;

said creation computer being programmed to create said merchant database, and to transmit said digital advertisements and said product fulfillment items to said merchant computer;

said merchant computer being programmed to receive said digital advertisements and product fulfillment items, to receive a request for a digital advertisement from a user, to cause said digital advertisement to be sent to said user, to receive from said user an access message identifying an advertised product, and to cause said product to be sent to said user in accordance with a product fulfillment item corresponding to said product.

2. A network-based sales system in accordance with claim 1, wherein each of said digital advertisements comprises an abstract of a product and a price.

3. A network-based sales system in accordance with claim 2, wherein:

at least one of said product fulfillment items comprises a product itself; and

said creation computer is programmed to transmit said product to said merchant computer with said digital advertisements.

4. A method of processing shopping cart messages sent between a first computer and a second computer, the first computer and the second computer being interconnected by a public packet switched computer network in which communications between the first computer and the second computer are according to hypertext transfer protocol, the method comprising:

at the second computer, receiving from the first computer a shopping cart message, the shopping cart message comprising a universal resource locator that includes at least one identifier incorporated therein pertaining to a respective shopping cart and an authenticator that comprises a digital signature based on a cryptographic key, and

examining the shopping cart message at the second computer and returning shopping cart data to the first computer in response to the shopping cart message.

5. The method of claim 4 wherein the first computer is a client computer and the second computer is a server computer.

6. The method of claim 4 wherein the digital signature is a hash of information in the universal resource locator.

7. The method of claim 4 further comprising the step of authenticating the shopping cart message by checking the authenticator.

8. The method of claim 4 wherein the at least one identifier pertaining to the shopping cart comprises a product identifier.

9. The method of claim 4 wherein the at least one identifier of pertaining to the shopping cart comprises a domain identifier.

10. The method of claim 4 wherein the at least one identifier of pertaining to the shopping cart comprises a payment amount.

11. The method of claim 4 wherein the at least one identifier pertaining to the shopping cart comprises a merchant computer identifier.

12. The method of claim 4 wherein the at least one identifier pertaining to the shopping cart comprises a merchant account identifier.

13. The method of claim 4 wherein the at least one identifier pertaining to the shopping cart comprises a duration time.

14. The method of claim 4 wherein the at least one identifier pertaining to the shopping cart comprises an expiration time.

15. The method of claim 4 further comprising receiving at the second computer from the first computerfurther shopping cart messages related to the shopping cart and updating a payment universal resource locator corresponding to the shopping cart in response to the further shopping cart messages.

16. A network-based system for processing shopping cart messages, comprising:

a first computer; and

a second computer;

the first computer and the second computer being interconnected by a public packet switched computer network in which communications between the first computer and the second computer are according to hypertext transfer protocol;

the first computer being programmed to transmit a shopping cart message to the second computer, the shopping cart message comprising a universal resource locator that includes at least one identifier incorporated therein pertaining to a respective shopping cart and an authenticator that comprises a digital signature based on a cryptographic key;

the second computer being programmed to examine the shopping cart message at the second computer and to return shopping cart data to the first computer in response to the shopping cart message.

17. The system of claim 16 wherein the first computer is a client computer and the second computer is a server computer.

18. A method of operating a payment computer in a public packet switched computer network comprising at least one buyer computer for operation by a user desiring to buy a product and at least one payment computer, the method comprising:

receiving, at the payment computer, a payment message that the buyer computer has sent to the payment computer for purchasing a product in response to a user request, the payment message comprising a product identifier identifying the product, the payment message comprising a universal resource locator containing all information required by the payment computer for authorizing purchase of the product and an authenticator that comprises a digital signature based on a cryptographic key; and

at the payment computer, authorizing, based on the payment message, purchase of the product.

19. The method of claim 18 wherein the digital signature is a hash of information in the universal resource locator.

20. The method of claim 18 further comprising the step of authenticating the payment message by checking the authenticator.

21. A network-based system for processing payment messages, comprising:

a buyer computer; and

a payment computer;

the buyer computer and the payment computer being interconnected by a public packet switched computer network;

the buyer computer being programmed to send to the payment computer a payment message for purchasing a product in response to a user request, the payment message comprising a product identifier identifying the product, the payment message comprising a universal resource locator containing all information required by the payment computer for authorizing purchase of the product and an authenticator that comprises a digital signature based on a cryptographic key;

the payment computer being programmed to receive the payment message and to authorize, based on the payment message, purchase of the product.

22. A method of processing shopping cart messages sent between a client computer and a server computer, the client computer and the server computer being interconnected by a public packet switched computer network in which communications between the client computer and the server computer are according to hypertext transfer protocol, the method comprising:

responding to a shopping cart message received from the client computer through the network, by returning to the client computer a hypertext page corresponding to a shopping cart associated with the shopping cart message; and

responding to further shopping cart requests related to the shopping cart, the further shopping cart messages being universal resource locators that include at least one identifier incorporated therein pertaining to respective shopping carts and an authenticator that comprises a digital signature based on a cryptographic key, and tracking the further shopping cart requests related to the shopping cart.

23. A network-based system for processing shopping cart messages, comprising:

a client computer; and

a server computer;

the client computer and the server computer being interconnected by a public packet-switched computer network in which communications between the client computer and the server computer are according to hypertext transfer protocol;

the client computer being programmed to incorporate into a universal resource locator at least one identifier pertaining to a respective shopping cart;

the server computer being programmed to respond to a shopping cart message received from the client computer through the network, the shopping cart message comprising the universal resource locator, by returning to the client computer a hypertext page corresponding to the shopping cart message; and

the server computer being programmed to respond to further shopping cart messages related to the shopping cart, the further shopping cart messages being universal resource locators that include at least one identifier incorporated therein pertaining to respective shopping carts and an authenticator that comprises a digital signature based on a cryptographic key, and to track the further shopping cart messages related to the shopping cart.