Documentation

Pegasus Workflow Submission

Overview

With this version of submit new functionality has been introduced to support workflow management using Pegasus. Two use cases are available: automatic workflow generation for parametric sweeps on one or more variables, or user constructed workflows. In both instances submit is used to configure access to one or more computational resources eliminating the need for a user to supply a site catalog thereby simplifying use of the workflow management system.

Parametric Sweeps

submit command options -p/--parameters and -d/--data have added to provide support for specifying parameter sweeps in a compact general way. The user is relieved of the chore of generating entire sets of input files and command arguments comprising a parameter sweep. Substitutable parameters are declared on the submit command line. Values of these parameters can then be systematically substituted into data files or application command line parameters. submit performs the necessary substitutions to cover all parameter combination. Each combination of parameters is abstractly represented as a node in a workflow and concretely executed as a job on the designated computational resource. A simple curses interface is provided to monitor progress of the simulation run.

User Constructed Workflows

Parameter sweeps are represented as a simple workflow consisting of many individual independent nodes. That is data is not shared between nodes or jobs in the run. There are cases where this simple approach is not sufficient to describe a workflow required to achieve a developer's or user's objective. Under these circumstances a developer may create a workflow and build an application around where the user supplies values for selected inputs. In such cases the Pegasus API's may be used to generate the abstract workflow description in the form of a dax file. The dax file can then executed by a simple submit command.

submit pegasus-plan --dax daxFile

In cases where more than one venue is capable of executing Pegasus runs a specific venue can be requested on the command line, otherwise submit will choose a venue at random.

submit -v DiaGrid pegasus-plan --dax daxFile

There are several additional options to pegasus-plan command that are supplied by submit. A few of the command options may be provided on the command line. submit reserves the option to silently ignore options as it sees fit.

In addition to remote execution of Pegasus runs it is also possible to do the execution locally with in the tool session. Simply use the submit -l/--local option.

submit --local pegasus-plan --dax daxFile

The use command can be employed to put pegasus-plan and all other Pegasus commands in the PATH environment variable. In additional to setting PATH, other environment variables are set allowing use of the python and java dax generation API's.

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