GT 3.9.4 WS MDS Trigger Service: System Administrator's Guide

Introduction

The Trigger Service collects data from resources on the grid and, if administrator defined rules match, can perform various actions. An example use is to send email when queue length on a compute resource goes over a threshold value.

Grid resources, with matching rules, are registered to a trigger service. When a rule matches, an action script is run. This action script can perform a desired action, for example sending email or sending a pager message.

Building and Installing

[information about installing the component - may link to Installation Guide]

Configuring

Information on configuration settings and environment variables can be found in the public interface guide.

The trigger service is an MDS aggregator service, and so inherits much of its configuration system from the aggregator module. The configuration instructions for the aggregator should be read before this section.

In addition to the source parameters specified in the aggregator configuration guide, there is a trigger specific configuration element that must be added to all registrations made to the trigger service. This registration parameter, of type TriggerRuleType contains the following options:

  • matchingRule: XPath rule to be applied against incoming data. The XPath expression will be evaluated against aggregated data, and will be regarded as matching the incoming data if it matches one or more nodes in that data.
  • actionScript: the name of a script in $GLOBUS_LOCATION/libexec/trigger/ that will be executed when the matchingRule matches (except as rate limited by the following parameters).
  • minimumFiringInterval: the action script will not be executed more than once in this number of seconds. If unspecified, there will be no minimum interval.
  • minimumMatchTime: the matchingRule must be true for this number of seconds before the actionScript will be executed. If unspecified, there is no minimum time period that the rule must match and the rule will fire immediately the matchingRule becomes true.
  • outputXSL: (UNIMPLEMENTED in GT 3.9.3). The delivered message will be transformed by the specified XSLT stylesheet and fed into the stdin of the action script. It is intended that this will be implemented in a subsequent release of the GT3.9.x series.

The rate limiting parameters behave in such a way that the rate of action script executions can be decreased by increasing the minimumFiringInterval and/or by increasing the minimumMatchTime.

Deploying

[information about deploying the component into various containers/environments]

Testing

[procedures for how to test the configuration. must include examples of the tests ]

Security Considerations

[describe security considerations relevant for this component]

Troubleshooting

[help for common problems sysadmins may experience]