To make your CEC useful in the IVO, you must register, in an IVOA-compliant resource registry, the CEC as a service. You do not need to register applications for the HTTP CEC.
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, but see the notes on mirroring applications, below.
Any HTTP-CEC can run any HTTP application that is pre-registered in the IVO registry. This mirroring is automatic and doesn't depend on local configuration. If you use automatic registration, your CEC will register itself to run all the HTTP applications that were registered at that point in time. This is the recommended arrangement. However, if you want to restrict the set of applications that you offer, then you should use manual 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 the "register" link from the sidebar. This generates the resource documents and submits them to the configured publishing-registry.
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 restricting the set of applications, you should edit the registration document produced by the CEC to remove the unwanted applications. In the service description, find the cea:ManagedApplications element. Delete from this all the cea:ApplicationReference elements except the ones for the applications you want to run in this CEC.
If you want to cease service of an application, then you should update the list of managed applications in the service registration of your CEC. Do this by changing the configuration - see the manual-registration section, above - 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 removes it from the IVO resource-register causing the IVO to forget its details. You must do this if you control the application implementation - i.e. the HTTP service that the HTTP-CECs call - and you are taking it out of service permanently.
To deregister an application, use the controls for the registry; 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".
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.