Configuration

You must configure the CL-CEC in two ways:

1. write a file describing the applications the CL-CEC may run;
2. write environment entries into the web container.

The environment entries describe the use of the resource registry, directories for scratch files, etc. You can set them using Tomcat's "admin" tool.

Describing the applications

You must produce an XML file describing to the CL-CEC how to run the applications of choice. The XML vocabulary for this file is defined by CEA. The easiest way is to copy an example of the file and edit it to suit your site.

If you are connecting the same applications as in the example, then the parameter lists will probably be the same (you should check that this is really true for your installation). You will typically need to change the ExecutionPath elements to point to the locations where your applications are installed.

Please see the reference document for configuration for a fuller description of the application-description language.

You may give the application-description file any name you wish and may store it on disc in any place that Tomcat can read. You can also store the file on a web server if you wish. You will tell Tomcat how to find the file by setting one of its environment entries.

Environment entries

You must set the following environment entries as the defaults will not be right for your site.

cea.local.apps.config

The URL for the file describing the local applications to the CL-CEC (see above).

cea.job.records

The absolute path (not a URL) to the directory where the CL-CEC can store records of its jobs.

cea.job.temp.files

The absolute path (not a URL) to a directory where the CL-CEC can store temporary files associated with the jobs its runs.

You may need to adjust the following environment entries.

registry.query.endpoint

The endpoint URL of the registry web-service from which your CL-CEC can read back the application registrations. The default is the central registry in AstroGrid.

There are some other environment entries defined for the CL-CEC but you should not need to change these.

Please see the reference document for CL-CEC configuration for more details.

Preserving the configuration

Upgrades, operator errors and bugs in Tomcat are all likely to destroy your configuration. Restoring a configuration from a back-up is easy; reinventing the configuration metadata is hard. Take a back-up of your configuration now, and keep it safe, in storage that is not connected with Tomcat.

Save the environment-entry values by going to the "fingerprint" page of the web-application and saving that page. This gives you a human-readable copy of the environment.

Save a machine-readable copy of the environment entries by copying a file out of Tomcat. The location of the file varies with the version and configuration of Tomcat, so you may need to read the Tomcat documentation. In Tomcat v5.0.x, in the default configuration of Tomcat, the file will be at (Windows)

%CATALINA_HOME%\conf\Catalina\localhost\(context).xml
			

$CATALINA_HOME/conf/Catalina/localhost/(context).xml
			

Save the application-description file by making a copy outside Tomcat. (If the working copy is stored outside Tomcat's directory tree .

Restoring a configuration

Given the configuration back-ups above, you can restore the configuration of the CL-CEC.

Restore the application description by copying the XML file to the location specified in the environment entry cea.local.apps.config. This part of the configuration takes effect next time the web-application is restarted (e.g. using the "reload" command in Tomcat's manager page). A running copy of the CL-CEC will not notice the change in configuration.

Restore the environment entries by one of these methods:

• type them in using Tomcat's "admin" tool and the human-readable back-up;
• copy the machine-readable back-up of the environment back into the place in Tomcat from which you copied it (see the preservation section, above).

Re-entering the environment through the admin tool makes it available to a running CL-CEC at the next restart of the CL-CEC web-application. (Remember to press the "commit-changes" button in the admin tool before restarting the web-application.) An environment reloaded by copying the file is only available to the CL-CEC after Tomcat itself is restarted.