Integration of Workflows into a Federated Database System with SQL/MED.
Ralf Wagner · 2001
ing interfaces (APIs) of these application systems must be used instead, i.e. the datacentered view is extended to include also a function-centered view [HH00]. Therefore, the given functions must be integrated into the FDBS by means of an explicit mechanism. For this purpose the Management of External Data (MED), a recently passed part of the SQL3 standard, can be used [ISO00]. The SQL/MED standard facilitates the integration of external data through employment of wrappers serving as connecting links between an FDBS and external data sources, i.e. wrappers can be used to access external functions (see figure 2(a)). By doing so, in addition to data federation a so-called function federation can be established. Function federation can be considered as a preliminary stage of enterprise application integration. Reque. s 2eply / FDBMS /_Request Be.%! /Request Reply! ' ' Wr,,er '/ (a) Local (b) Sequence of (c) Global Func- (d) Federated Func- Local Function fion/ Federated Function as