Dynamic argument embedding: preserving state on the World Wide Web

Abstract

At the IBM T.J. Watson Research Center we implemented a way of preserving state during HTTP sessions by modifying hypertext links to encode state information. We call the method dynamic argument embedding, and it was developed in response to problems we encountered implementing the Coyote Virtual Store, a transaction-processing system prototype. Virtual store applications, such as IBM's NetCommerce and Netscape's Merchant System, typically need to maintain information such as the contents of shopping baskets while customers are shopping. We wanted our application to be flexible enough to maintain such state information without restricting the sorts of HTML pages a customer might view. We also wanted a system that did not require extensions to the hypertext transfer protocol (HTTP) and so could be implemented on any standard Web server and client browser. Finally, we wanted to permit customers to access several accounts at once by using the browser's cache to concurrently store pages corresponding to multiple invocations of the virtual store application.