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0.1 CREAM CLI commands

The most relevant commands to interact with CREAM based CEs are:

  • glite-ce-job-submit <jdl_file>
  • glite-ce-delegate-proxy <delegation_Id>
  • glite-ce-job-status <job_Ids>
  • glite-ce-job-list <host[:port]>
  • glite-ce-job-cancel <job_Ids>
  • glite-ce-job-suspend <job_Ids>
  • glite-ce-job-resume <job_Ids>
  • glite-ce-job-output <job_Ids>
  • glite-ce-job-purge <job_Ids>
  • glite-ce-proxy-renew <delegation_Ids>
  • glite-ce-service-info <host[:port]>
  • glite-ce-get-cemon-url <host[:port]>
  • glite-ce-enable-submission <host[:port]>
  • glite-ce-disable-submission <host[:port]>
  • glite-ce-allowed-submission <host[:port]>
Man pages are available for all the CREAM client commands. You can also access information about the usage of each command by issuing:

$ <command> --help

glite-ce-job-submit submits a job to a CREAM based CE. It requires a JDL file as input and returns a CREAM job identifier.

glite-ce-delegate-proxy allows the user to delegate her proxy credential to the CREAM service. This delegated credential can then be used for job submissions.

glite-ce-job-status displays information (in particular the states) of jobs previously submitted to CREAM based CEs.

glite-ce-job-list lists the identifiers of jobs submitted to a CREAM based CE by the user issuing the command.

glite-ce-job-cancel cancels one or more jobs previously submitted to CREAM based CEs.

glite-ce-job-suspend suspends the execution of one or more jobs previously submitted to CREAM based CEs.

glite-ce-job-resume resumes the execution of one or more jobs which have been previously suspended.

glite-ce-job-output retrieves the output sandbox files of one or more jobs previously submitted to CREAM based CEs.

glite-ce-job-purge clears one or more jobs from CREAM based CEs. After this operation the purged jobs can’t be managed anymore.

glite-ce-proxy-renew renews delegations, and therefore refreshes the proxy of the jobs submitted to CREAM based CEs using the considered delegations.

glite-ce-service-info returns information about the CREAM service (version, status, etc.).

glite-ce-get-cemon-url returns the end-point of the CEMon service coupled with the considered CREAM CE.

glite-ce-enable-submission (re-)enables job submissions on the specified CREAM CE.

glite-ce-disable-submission disables job submissions on the specified CREAM CE.

glite-ce-allowed-submission checks if jobs submissions on the specified CREAM CE are allowed or have been disabled.

All these commands are described in the following sections.

0.2 Submitting jobs to CREAM based CEs

To submit jobs to CREAM based CEs, the command glite-ce-job-submit must be used. The glite-ce-job-submit command requires as input a job description file, which describes the job characteristics and requirements through the JDL (Job Description Language). A typical example of a JDL job description file is:

[
Type = "Job";
JobType = "Normal";
Executable = "myexe";
StdInput = "myinput.txt";
StdOutput = "message.txt";
StdError = "error.txt";
InputSandbox = {"/users/seredova/example/myinput.txt",
"/users/seredova/example/myexe"};
OutputSandbox = {"message.txt", "error.txt"};
OutputSandboxBaseDestUri = "gsiftp://se.pd.infn.it/data/seredova";
]

Such a JDL would make the myexe executable be transferred on the remote CREAM CE and be run taking the myinput.txt file (also copied from the client node) as input. The standard streams of the job are redirected to files message.txt and error.txt, and when job completes its execution they are automatically uploaded on gsiftp://se.pd.infn.it/data/seredova.

A detailed description of the available JDL attributes and of the rules for building correct JDL files is provided at http://wiki.italiangrid.org/twiki/bin/view/CREAM/JdlGuide.

Each job submitted to a CREAM based CE is given the delegated credentials of the user who submitted it. These credentials can then be used when operations requiring security support has to be performed by the job.

There are two possible options to deal with proxy delegation:

  • asking the “automatic” delegation of the credentials during the submission operation;
  • explicitly delegating credentials, and then asking to rely on these previously delegated credentials on the actual submission operations.

It is highly suggested to rely on this latter mechanism, using the same delegated proxy for multiple job submissions, instead of delegating each time a proxy. Delegating a proxy, in fact, is an operation that can require a non negligible time.

The command glite-ce-delegate-proxy is the command to be used to explicitly delegate the user credentials to a CREAM CE.

The following shows an example of job submission, performed explicitly delegating credentials. So first of all the credentials are delegated to a CREAM based CE (whose endpoint is specified with the option –endpoint (-e):

> glite-ce-delegate-proxy -e cream-ce-01.pd.infn.it mydelid
2006-02-26 15:03:37,286 NOTICE - Proxy with delegation id [mydelid] successfully
delegated to endpoint [https://cream-ce-01.pd.infn.it:8443//ce-cream/services/CREAMDelegation]

The identifier of the delegation is then specified with the –delegationId (-D) option in the job submit operation:

> glite-ce-job-submit -D mydelid -r cream-ce-01.pd.infn.it:8443/cream-lsf-grid02 myjob1.jdl

The option -r (–resource) has been used to specify the identifier of the CREAM CE where the job has to be submitted to.

myjob1.jdl is the JDL file describing the job to be submitted.

The command returns the CREAM job identifier associated with this job (e.g. https://cream-ce-01.pd.infn.it:8443/CREAM116j9vgnf) which identifies it in clear and unique way all over the Grid system scope.

0.3 Monitoring jobs

 

1 Man pages for CREAM Command Line Interface

 
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