Exception Handling in Workflow-Driven Web Applications

As the Web becomes a platform for implementing B2B applications, the need arises of Web conceptual models for describing Web oriented workflow applications implementing business processes. In this context, new problems about process correctness arise, due to the loose control of Web applications upon the behavior of their Web clients. Indeed, incoherent user's behavior can lead to inconsistent processes.This paper presents a high level approach to the management of exceptions that occur during the execution of processes on the Web. We present a classification of exceptions that can be raised inside workflow-driven Web applications, and recovery policies to retrieve coherent status and data after an exception. We devise these concepts at high level and then we exploit them using a Web modeling language (WebML) that in turn provides development facilities like automatic code generation, validation of hypertext models, and so on. An industrial implementation experience is briefly presented too.