(LWWE) is a cross-platform server that provides support for automation and orchestration of task execution.

The workflow tool is able to automate and orchestrate a number of independent and dependent workflow tasks that can have dependencies on time, execution counts, and the execution status of other tasks. These tasks perform internal or external process execution and report execution status of those processes, as well as being able to control tasks on a limited basis (restart, suspend at startup, abort, etc.). An example of such tasks would be running preparation and execution scripts for scientific models. Since execution state is tracked, workflows are able to resume in the event of system failure.

At NASA, users generally use run scripts to execute large sets of commands. This is all performed within a terminal. Monitoring the execution of the scripts usually meant watching output or checking batch job queues. The NASA Experiment Designer (NED) workflow software (of which LWWE is a component) is intended to assist in the configuration, operation, and monitoring of these scripts. Previously the NED software had been using the SMS software from the European Centre for Medium-Range Forecasts (ECWMF) as the workflow component. The LWWE software is the replacement for SMS.

LWWE is pluggable software that can be embedded in other software or run standalone. The APIs include socket and command line interfaces, as well as extension points for implementing more complex custom tasks. External processes such as scripts or operating system commands can be launched and monitored. Workflow state is persisted to allow the engine to restart workflows from a recently known state (with the caveat that external processes must handle their own restart correctly).

This work was done by Shawn Freeman of Northrop Grumman Information Systems for Goddard Space Flight Center. GSC-16083-1

NASA Tech Briefs Magazine

This article first appeared in the February, 2014 issue of NASA Tech Briefs Magazine.

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