The STScI reference implementation Reg/TAP service provides an interface into the VAO registry at Space Telescope.
This page contains simple web forms that can manage synchronous and asynchronous ADQL queries to that TAP service, which will return the results of a basic table query in a VOTable.
VOSI Queries - Availability, Capabilities, and Schema
VOSI gives us the ability to query metadata about the service itself. Any of the following buttons will issue a VOSI query about the service which can be used to determine whether the underlying service and its database are available, and to plan your query itself.
DALI examples give us the ability to see sample queries for the service.
Synchronous queries are run immediately on the server. There is not yet any hard maximum limit on the amount of data returned, and there is a great deal of data to be pontentially returned. It is suggested that you use "top n" in the select statement of your ADQL query itself. When submitting your query, you will be redirected to your VOTable-encoded result set or error page.
Asynchronous Query (using the Universal Worker Service)
Asynchronous queries are managed using the UWS protocol, which allows queries with much larger result sets to be efficiently managed by the service. In short, they are set up by the client, potentially negotiated with regards to the amount of time they are allowed to run or be stored on the server, then run by the client. The client then polls the server to discover when the query has run and where potential error or completed result sets are stored.
This is all managed via a 'job ID'. To run a UWS query, first enter your ADQL - based query. Given the RESTful nature of UWS as implemented, you will be forwarded to a status page with a job number. Copy down this job number - you will use it for the rest of the lifetime of your query. You can also query the UWS engine for a list of currently existent jobs.
Asynchronous Query Management
Once you have a job number, you can come back to this page with the browser 'back' button' after any step of the UWS query process. Here, you can enter your job number in the form below to renegotiate the deletion time of your results (if you expect it to take a long time to run, or will be personally unable to check up on your results before they would be automatically deleted), to trigger the job to be run, to poll your job for another status page giving the URL of its result set or error documentation, and to delete your job when it is finished. Job deletion will bring you back to the job summary page.
The following links may help to explain the basic query language and systems at work.