Coupling of FDBS and WfMS for Integrating Database and Application Systems: Architecture, Complexity, Performance
With the emergence of so-called application systems which encapsulate databases and related application components, pure data integration using, for example, a federated database system is not possible anymore. Instead, access via predefined functions is the only way to get data from an application system. As a result, retrieval of such heterogeneous and encapsulated data sources needs the combination of generic query as well as predefined function access. In this paper, we present a middleware approach supporting such novel and extended kind of integration. In particular, so-called federated functions combining functionality of one or more application system calls (local functions) have to be integrated. Starting with the overall architecture, we explain the functionality and cooperation of its core components: a federated database system and, connected via a wrapper, a workflow management system composing and executing the federated functions. Due to missing wrapper support in commercial products, we also explore the use of user-defined table functions. In addition to our workflow solution, we present several alternative architectures where the federated database system directly controls the execution of the requested local functions. These two different approaches are primarily compared w.r.t. their mapping complexity and their performance.
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