Max Mustermann Folientitel Veranstaltung

Online Steering of HEP Applications

Daniel LorenzUniversity of Siegen

Cracow Grid Workshop 0614. 10. 2006 – 19.10. 2006

Daniel Lorenz Online Steering of HEP Applications CGW `06

Max Mustermann Vortragstitel Veranstaltung

Background: D-Grid

• German Grid initiative • Funded by the Bundesministerium für Bildung und

Forschung, BMBF• 6 Community Grids and one common integration

project

• HEP Community Grid (HEPCG)

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Introduction

• New particle accelerator LHC at CERN (CH) • Several different experiments• Experiments struggle with huge amounts of data• Deploy the LHC Computing Grid (LCG)

• Online steering tool for ATLAS experiment– Basic functionality just requires to change the job

options– Advanced functionality can be added with source

code instrumentation

Online steering saves time and resources

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Environment (1)

Daniel Lorenz Online Steering of HEP Applications

• Integration into ATLAS experiment software Athena and ROOT visualization toolkit

• Athena framework:– Event based

– List of algorithms

– Executed for every

event

– Easy to add new algorithms and services

algorithm1algorithm2algorithm3algorithm4algorithm5

Svc1

Svc2

Athena Job

job options

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Environment (2)

• Integration into Athena:– New algorithm RM_Spy

• Job execution steering• Most common results in ROOT files• Restart with changed job options without resubmitting the

job• Only changes in job options (no source code changes)

– New service RM_SteeringSvc• Steering and monitoring of user defined data• Source code instrumentation necessary

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Environment (3)

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• Visualization tool ROOT– Command line for C++ commands

– Extendable with shared libraries

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Layered architecture

Daniel Lorenz

communication

visualization

data consistency

application

data consistency

communication

data processingdata processing

steering tool grid job

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Communication (1)

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• Secure communication– User side– Administrator side

• Cope with typical site configurations– Firewalls– Private IP

• Job runs on unknown host• Connection by job id• Hide complexity from user• Dynamically deal with different site topologies • Enable steering in as many cases as possible

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Communication (2)

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• Job registers itself to naming service (NS) e.g. R-GMA

• Steering tool gets location from NS

• Steering tool connects to communication service (CS)

• Connection between CS and job

• All connections use Globus GSSAPI

• Additional end to end authentication

WNCEUI

NS

CS

fire

wall

fire

wall

steering tool job

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private IPnetworkinternet

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Communication (3)

Daniel Lorenz

TCP connection

message layer

security layer

grid connection

security layer

TCP connection

message layer

security layer

grid connection

security layer

grid connection

naming service

steering tool communication service grid job

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Conclusion and outlook

• Goals:– Secure online connection – Easy integration into ATLAS software framework

• Status:– Prototype has been implemented– First release scheduled for November

• Outlook:– Extend for automated error detection and handling– Steering of parallel jobs– Communication between jobs

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