ProActive is a GRID Java library (Source code under LGPL licence) for parallel, distributed, and concurrent computing, also featuring mobility and security in a uniform framework. With a reduced set of simple primitives, ProActive provides a comprehensive API allowing to simplify the programming of applications that are distributed on Local Area Network (LAN), on cluster of workstations, or on Internet Grids. The library is based on an Active Object pattern that is a uniform way to encapsulate: - a remotely accessible object - a thread as an asynchronous activity - an actor with its own script - a server of incoming requests, - a mobile and potentially secure agent. ProActive and the (de facto) Standards: the library has an architecture to interoperate with: - Web Service Exportation - HTTP Transport - ssh, rsh, RMI/ssh Tunneling - Globus: GT2 and GT3, sshGSI - LSF, PBS, Sun Grid Engine ProActive is only made of standard Java classes, and requires no changes to the Java Virtual Machine, no preprocessing or compiler modification; programmers write standard Java code. Based on a simple Meta-Object Protocol, the library is itself extensible, making the system open for adaptations and optimizations. ProActive currently uses the RMI Java standard library as default portable transport layer. Proactive 2.2 includes new features such as: - First release of Fault tolerance and Checkpointing mechanism for ProActive distributed applications - Machines Lists provided in XML Deployment Descriptors. Interface with OAR improved. Easy deployment on Grid5000 - Components exposed as Web services, Interoperability with .NET Framework - Improved OOSPMD - New NBody example that combines Groups and Fault-Tolerance features. - First release of the GUI for Grid Components. - Improved P2P Infrastructure - First release of the ProActive Classloader For more information, visit : Proactive WebSite : ObjectWeb WebSite :