A Distributed Architecture for Integrated Access to Legacy Database Systems

Workflow integration is a problem common to many organizations, that need to develop and run applications composed by multiple related tasks, possibly heterogeneous and performed on or by heterogeneous processing entities. Often some of the systems to be integrated have a very large autonomy, and concede only very limited visibility of their internal organization. The limit case is given by legacy applications, i.e. old, typically mainframe based applications designed with little or no interface with other applications. In this paper we discuss the design and the implementation of a prototype system for development and the management of such distributed workflow applications. To carry out the integration process we propose both a graphical formalism to represent the access procedure to legacy host, and global application that involve the access of several host. This formalism allows to represent such concurrent processing application in a totally structured way, and includes provisions to represent different kind of parallel processing, and the handling of asynchronous exceptions.