CREAM Functional Description

The CREAM (Computing Resource Execution And Management) Service is a simple, lightweight service that implements all the operations at the Computing Element (CE) level; its well-defined WebService-based interface and its implementation as an extension of the Java-Axis servlet (running inside the Apache Tomcat container) provide interoperability with clients written in any programming language and running on any computer platform.

The CREAM interface is well-defined using the Web Service Description Language (WSDL); anyone can generate his/her CREAM client by simply filling in the stub code generated by WSDL parser (gSOAP for C/C++, Axis for Java, Perl module for perl).

CREAM functionality:

• Job Submission
  • Possibility of direct staging of input sandbox files
  • gLite JDL compliance (with CREAM-specific extensions)
  • Support for batch and parallel jobs
• Manual and automatic proxy delegation
• Job Cancellation
• Job Info with configurable level of verbosity and filtering based on submission time and/or job status
• Job List
• Job Suspension and Resume
• Job output retrieval
• Job Purge for terminated jobs
• Possibility (for admin) to disable new submissions
• Self limiting CREAM behavior
  • CREAM is able to protect itself if the load, memory usage, etc. is too high. This happens disabling new job submissions, while the other commands are still allowed
• ARGUS or gJAF based authorization
• Possibility to forward requirements to the batch system
• Integration with APEL and DGAS accounting systems

CREAM can be used

• by the Workload Management System (WMS), via the ICE (Interface to CREAM Environment) service
• by a generic client, e.g. an end-user willing to directly submit jobs to a CREAM CE. A C++ command line interface (CLI) is available

-- MassimoSgaravatto - 2011-04-18