Section: Software
XtremWeb
Participant : Gilles Fedak [ correspondant ] .
XtremWeb is an open source middleware, generalizing global computing platforms for a multi-user and multi-parallel programming context. XtremWeb relies on the notion of services to deploy a Desktop Grid based on a 3 tiers architecture. This architecture gathers tree main services: Clients, Coordinators and Workers. Clients submit requests to the coordinator which uses the worker resources to execute the corresponding tasks. XtremWeb decouples access to data from tasks, which allows integration with network file service.
Coordinator sub-services provide resource discovery, service construction, service instantiation and data repository for parameters and results. A major concern is fault tolerance. XtremWeb relies on passive replication and message logging to tolerate Clients mobility, Coordinator transient and definitive crashes and Worker volatility. An extension of XtremWeb called RPC-V features failure-tolerance of the coordinator. The Client service provides a Java API which unifies the interactions between the applications and the Coordinator. Three client applications are available: the Java API that can be used in any Java applications, a command line (shell like) interface and a web interface allowing users to easily submit requests, consult status of their tasks and retrieve results. A second major issue is the security. The origins of the treats are the applications, the infrastructure, the data (parameters and results) and the participating nodes. Currently XtremWeb provides user right management, application sandboxing and communication encryption. XtremWeb provides a RPC interface for bag of tasks, parameter sweep, master worker and workflow applications.
XtremWeb has been tested extensively harnessing a thousand of Workers and computing a million of tasks. XtremWeb is deployed in several sites: LIFL, LIP, ID-IMAG, LRI, LAL (physics laboratory of Orsay), IBBMC (biology laboratory of Orsay), Université de Guadeloupe, IFP (Institut Français du Pétrole), EADS, CEA, University of Wisconsin Madison, University of Tsukuba (Japon), AIST (Australia), UCSD (USA). A Dutch company (AlmereGrid) maintain a Desktop Grid based on XtremWeb in the town of Almere. University of Paris Sud and University of California, San Diego have used XtremWeb to gather hosts availability traces. To our knowledge, several applications has been ported to XtremWeb: Aires belonging to the HEP Auger project (LAL), a protein conformation predictor using a molecular dynamic simulator (IBBMC), CFD code (IFP), PHYLIP Phylogenetic Package and Hand Writing recognition Application (Univ Tunisie), Application Based Iterative Methods (Hohai University, China). Several XtremWeb extension have been developed by research teams: XtremWeb-CH allows direct P2P communication between workers, YvetteML/XtremWeb allows XtremWeb to be used with a workflow frontend.
XtremWeb is available at http://www.xtremweb.net/
