No. 86 (00207)

Family name : Peters
Given name : Andreas-Joachim
Affiliation : CERN
Abbreviation : 
E-mail address : Andreas.Peters@cern.ch
Title : Distributed Analysis with AliEn and ROOT
Authors : A.-J. Peters, R. Brun, P. Buncic, F. Carminati, J.-F. 
          Grosse-Oestinghaus, E. Imamagic, F. Rademakers, P. Saiz, for
          the Alice Collaboration
Abstract : 
New classes for analysis sessions with the AliEn Grid service have been
integrated into ROOT to allow parallel analysis of worldwide distributed
data sets. A batch and an interactive analysis model is under
developement.

In the batch analysis model jobs are splitted by a Job Optimizer in the
AliEn queue system corresponding to the data location and executed in
parallel, when needed ressources become available. ROOT result files can
be merged on demand.  Analysis jobs are configured, executed and stored
using a new ROOT analysis class object.

The interactive model uses the PROOF parallel ROOT facility to
constitute an interactive grid analysis framework. PROOF daemons are
assigned on demand corresponding to the queried data set.  Results are
available on the fly using a client/server architecture.  The PROOF
client connects to a PROOF master server running on a AliEn core service
machine. The PROOF master connects to PROOF daemons in distributed sites
through an AliEn TCP routing service. This enables connectivity and
connection control to computing farms on private networks.

A dedicated PROOF Grid service opens TCP routes through site mutliplexer
and maintains the population of PROOF daemons corresponding to the
computational needs of the user community.  The user interface is
compatible with the standard implementation of PROOF.