Because of the nature of Grid to be heterogeneous and distributed environment, the database systems which should works on Grid must support this architecture. OGSA-DAI is an example of such extensible service based framework that allow data resources to be incorporated into Grid fabrics. On the other side, many algorithms (for example, for data mining) are not built in Java, they aren't open source projects and can't be easily incorporated in OGSA-DAI workflows. For that reason, we propose OGSA-DAI extension with new computational resources and activities that allow executing of external jobs, and returning data into OGSA DAI workflow. In this paper, we introduce heterogeneous and distributed databases, then we discuss our proposed model, and finally, we report our initial implementation.