# DRMAA C binding library for Grid Engine

# Overview

The purpose of this library is to provide an implementation of the DRMAA C binding standard based on Grid Engine DRM system. The best way to describe DRMAA is to cite the DRMAA-WG Charter:

"Develop an API specification for the submission and control of jobs to one or more Distributed Resource Management (DRM) systems. The scope of this specification is all the high level functionality which is necessary for an application to consign a job to a DRM system including common operations on jobs like termination or suspension.

The objective is to facilitate the direct interfacing of applications to today's DRM systems by application's builders, portal builders, and Independent Software Vendors (ISVs)."

For more details on the Global Grid Forum standards body working group refer to the page of the GGF DRMAA working group .

# Documentation

The following DRMAA related documentation is recommended DRMAA 1.0 language independent specification, DRMAA C language binding specification, Grid Engine/DRMAA job state mapping table and HTML version of Grid Engine DRMAA C binding man pages (only those in section 3 with drmaa_* prefixes) .

# Example application

The C test program example.c is a good example of an application that uses the DRMAA C binding interface. It illustrates submission of both single and bulk remote jobs. After submission drmaa_synchronize() call is used to synchronize the remote jobs execution. The call returns after all the jobs have finished executing. Finally, drmaa_wait() call is used to retrieve and print out the remote jobs' execution information.

A full path for the remote command is passed as the first argument to the test program. That value is directly used as "drmaa_remote_command" job template attribute. The C binding example uses value "5" as a first argument to the job template vector attribute "drmaa_v_argv". Passing "/bin/sleep" as a first argument to the test program will for example cause 32 sleep jobs to be run that sleep for "5" seconds each before finishing execution. Note that we expect to find "/bin/sleep" command on all of the remote nodes.

To build this example run

aimk -no-mt example

This is necessary because "example" is not part of the standard build procedure.

# Notes on implementation

The Grid Engine implementation of DRMAA bases on Grid Engine Job API library (JAPI). As a result DRMAA library inherits MT safety from JAPI library.

Interfaces operations of Grid Engine JAPI library and DRMAA library have lots in common. The big difference amongst them is that JAPI allows any characteristic of the Grid Engine job that is submitted through JAPI be influenced, whereas DRMAA allows only those characteristics be influenced that are interfaced by DRMAA. Note that this ostensible drawback of DRMAA library is not as meaningful as it seems: Firstly DRMAA job template attributes "drmaa_job_category" and "drmaa_native_specification" will allow nearly all of the qsub(1) job characteristics be influenced. Secondly by building an integration upon DRMAA library you don't need to change your application code each time when a new Grid Engine version is released. When using JAPI library interface you must be prepared to change your application code in this case. This is because JAPI directly exports Grid Engine internal data structures that usually are subject of change with new releases.

# Grid Engine DRMAA library QA

The DRMAA application "test_drmaa" is used by Grid Engine testsuite QA tool to ensure quality of DRMAA library. It covers a growing number of tests. There are so-called standalone tests that can be accomplished autonomously by the test_drmaa application. To run all these tests standalone "test_drmaa" can be started with the "ALL_AUTOMATED" option plus some option arguments. To run all DRMAA related tests so far implemented choose "api/drmaa" in testsuite and have testsuite do the work for you.

Copyright 2003 Sun Microsystems, Inc. All rights reserved.