6.1 Introduction

   A proxy data provider is intended to enable multiple, independently developed data providers to be combined in one context. In the simpler DAF configurations no proxy is required. Multiple clients can share a single, data provider, which has a comprehensive schema and population. For example, the data provider might be a wrapper on an existing UMS.

   However, a data provider that handles only part of the overall data needed by clients may be combined with others to form a complete system. This leads to a configuration in which multiple clients share multiple data providers. It would arise when the DAF interfaces are used to wrap individual data providers in a UMS rather than the UMS as a whole. This permits independent developers to extend a UMS with data providers as well as clients.