From Web Sites to Web Applications: New Issues for Conceptual Modeling

E-commerce, web-based booking systems, and on-line auction systems are only a few examples that demonstrate how web sites are evolving from essentially read-only information repositories to distributed applications. These new web applications blend navigation and browsing capabilities, common to hypermedia, with "classical" operations (or transactions), common to traditional information systems. The coupling between hypermedia and operational features raises a number of novel modeling issues. Conceptual modeling for web applications is not just the union of two activities performed in isolation - designing the operations and designing the hypermedia aspects. Rather, modeling the integration (and interference) of the two facets of design (hypermedia and operations) is the issue. The co-existence of operational and navigational aspects poses several new problems to designers: For example, how do information structures and navigation support operations? How do operations affect information structures and navigation? How do operations and navigation interplay? How are user tasks related to both navigation and operations? The paper discusses these and other questions, and provides a contribution toward possible solutions, based upon the W2000 design framework.