Treffer: Integrating Existing Object-Oriented Databases with Distributed Object Management Platforms : Developed and evaluated on the example of ODBMS ObjectStore and CORBA

A common characteristic of today's information systems is the distribution of data among a number of autonomous systems and heterogeneous repositories. The key to their unification is the ability to access these multiple databases transparently, irrespective of their kind and location. However, direct database-level interoperation is not always possible because of the extreme heterogeneity of already existing applications, software environments and hardware platforms. A necessary infrastructure to deal with the heterogeneity and remote access in the object-oriented context can be provided by modern distributed object management platforms, such as a Common Object Request Broker Architecture (CORBA). The thesis puts forward the concept of a framework for providing object persistence in object-oriented programming languages by integrating the powerful database facilities with the heterogeneous CORBA environment - the eXtensible Database Adapter (XDA). Providing a highly customisable environment with pre-defined adaptable, ready to use components the framework simplifies the development of the middle-tier level mediating between a database and CORBA. The conceptual basis of the framework is a distributed persistent object model that on the one hand provides the property of transparent access to persistent objects for usual CORBA objects and, on the other hand allows a soft, non-intrusive integration for existing databases. Thus, the solution possesses various valuable advantages such as the facility of creating high performance CORBA/ODBMS systems coupled with maximal flexibility, as well as the ability to build new, smoothly integrated, legacy database applications within the CORBA environment. The vitality of the proposed concept is demonstrated on two implementations of the XDA, which has allowed us to identify the crucial problems appearing in the integration process and to propose corresponding solutions. Implementing new approaches for efficient request dispatching and transaction management the XDA permits ...