Required registrations

To make your CEC useful in the IVO, you must register, in an IVOA-compliant resource registry:

  1. each application that the CEC can run (but see the notes on mirrors, below);
  2. the CEC as a service.

The application registrations state the interfaces of the applications. The service registration states the service endpoint (the URL for access) and lists the applications that the CEC can run. For each registration, you submit a resource document (an XML file) stating the necessary metadata in a machine-readable format.

You have a choice: either prepare and submit your resource documents manually, or let the CEC register itself automatically on your behalf. AstroGrid recommends automatic registration except in the case where you are mirroring applications previously registered; in that case you must use manual registration as the automatic registration can't cope. This flaw should be fixed in a later version of the CEC software.

Mirroring applications

If you are setting up your CEC to run applications already defined and published in the IVO, then you do not need to register these. You must still register the CEC itself.

If you do this, you are declaring your service as a mirror of the existing services running the applications in question; you are promising that your service will produce the same results as those services for given inputs. The AstroGrid UIs and workflow agents will then distribute jobs indiscriminately between the services mirroring the application. Mirroring is very valuable to the IVO for load balancing and high availablity, but please don't publish your service as a mirror of an application unless you are sure that you have installed the right version of the application!

One way to check that your mirroring is exactly correct is to generate the registration document for your configuration using the "show registration document" link in the sidebar. Compare the application descriptions in your document with those in the IVO registry: they should be the same.

Automatic registration

First, check the content of the registration using the "show registration document" link in the side-bar. If the content isn't right, go back to the configuration stage and fix it.

Second, make sure that your CEC is working properly, using the self-test features. If it isn't working, go back to configuration and find out why.

Remember: registration publishes your resources into the IVO and invites science users to depend on them. It is best not to register until everything is right.

Use "register" link from the sidebar. This generates the resource documents and submits them to the configured publishing-registry.

Manual registration

Most registries have a web-browser interface whereby you can submit resource documents manually. Typically, and especially in the AstroGrid implementation of the registry, you upload the registration documents from files on disc.

You can get a registration document using the "show registration document" link in the sidebar. Save this to disc and edit it as necessary. You need to be very careful not to "break" the structure of the document. Refer to the registration template in your configuration directory for advice on what to write.

In the special case of a CEC that mirrors applications, you should edit the registration document produced by the CEC to remove the application description, leaving only the service description.

Deregistering obsolete resources

Ceasing service of an application

If you want to cease service of an application, then you should update the list of managed applications in the service registration of your CL-CEC. Do this by changing the configuration - see the configuration guide - and repeating the registration of the CEC as described above. This states to the IVO that your own CEC no longer provides the application. It doesn't eliminate the registered description of the application; thus you can do this whether or not you originally registered the application and whether or not other services are offerring the same application.

Unregistering an application

Unregistering an application removes it from the IVO resource-register causing the IVO to forget its details. You should do this only if you were the party who originally registered the application and if no CECs anywhere in the IVO are offering the application. Therefore, cease service, as described above, in your own CEC before deregistering.

For Java-class applications, you will have to make a registry to make sure that no other CECs are offering the application.

To deregister an application, use the controls for the register; you can't do this from the CEC's local controls. The exact technique varies between registry implementations, but typically you set the status attribute of the registration to "deleted".

Deregistering the CEC service

If you want to withdraw your CEC from service permanently or for a lengthy period (but not just for short down-time), then you should deregister it. You do this by editing the service resource-document, changing the value of the status attribute on the Resource element to "deleted" and re-registering it, as described above, under the same identifier.