A Middleware Framework for the Persistence and Querying of Java Objects

This paper presents the adaptable and flexible architecture of a middleware framework for the persistence and querying of Java objects. The framework is composed of two sub-frameworks, each responsible for one aspect: persistence and queries. The persistence framework considers two kinds of objects: Memory instances (MI), which represent Java objects holding the data to be made persistent, and Data Store instances (DSI), which represent data items stored within data stores. It thus concentrates on the binding chain between a DSI and an MI, providing the management of the structural projection of persistent objects to a particular data store when performing I/Os. The query framework makes it possible to express, optimize and evaluate queries over heterogeneous data stores and in particular over the persistence framework objects. Query expression is independent of any query language and can be mapped to several standards. The middleware presented in this paper has been integrated in several contexts, thus validating its adaptability and flexibility.