Section: Scientific Foundations
Programming with Distributed Objects and Components
The paradigm of object-oriented programming, although not very recent, got a new momentum with the introduction of the Java language. The concept of object, despite its universal denotation, is clearly still not properly defined and implemented: notions like inheritance, sub-typing or overloading have as many definitions as there are different object languages. The introduction of concurrency into objects also increases the complexity. It appeared that standard Java constituents such as RMI (Remote Method Invocation) do not help building, in a transparent way, sequential, multi-threaded, or distributed applications. Indeed allowing, as RMI does, the execution of the same application to proceed on a shared-memory multiprocessors architecture as well as on a network of workstations (intranet, Internet), or on any hierarchical combination of both, is not sufficient for providing a convenient and reliable programming environment.
The question is thus: how to ease the construction, deployment and evolution of distributed applications ?
One of the answers we suggest relies on component-oriented programming. In particular, we have defined parallel and hierarchical distributed components starting from the Fractal component model developed by INRIA and France-Telecom [51] . We have been involved in the design of the Grid Component Model (GCM) [53] , which is one of the major results produced by the CoreGrid European Network of Excellence. The GCM is intended to become a standard for Grid components, and most of our research on component models are related to it. The GCM is an extension of the Fractal model. On the practical side, ProActive/GCM is a prototype implementation of the GCM above the ProActive library; not all GCM features are implemented in ProActive yet. ProActive/GCM is intended to become the reference implementation of the GCM, as was the goal of the European project GridCOMP.
For providing a better programming and runtime environment for object and component applications, we have developed competencies in both theoretical and applicative side fields, such as distribution, fault-tolerance, and the construction of a Java library dedicated to parallel, distributed, and concurrent computing.
