Ericsson, Jonas C.2009-06-302009-06-302009-06-30http://hdl.handle.net/2077/20560Modern IS/IT systems tend to use several sources of data and many developers process the this data manually. A homogeneous system for processing the data will make their systems less error-prone and reduce the time to market. This article will present an architecture and a query processing technique for homogeneously retrieving data from multiple heterogeneous data sources. The approach presented has studied several similar systems, i.e. Garlic, TSIMMIS, SIMS and Starburst. These systems solves similar problems to ours in various ways. It turns out that a higher abstraction and a constructional processing technique in combination with a mediation architecture is a solid choice for homogeneously retrieving data from heterogeneous data sources.engText