Dear Registry Group
I am in the midst of writing about VOEvents, and I found myself producing the material below, which concerns IVO identifiers, and how to use the Registry to resolve them. Basically, what it says is that if the identifier has a # symbol in it, then resolution is a two-stage process: first invoke any Registry to find out which VOEvent repository to invoke. But if there is no # symbol, then it can be done in one call.
Is this correct?
Roy
For these reasons, VOEvent packets will often contain VO identifiers, as defined and discussed in [16]. These take the general form "ivo://authorityID/resourceID#localID", and are references to metadata packets that may be found at a VO registry or VOEvent database. When such an identifier is resolved, it means that the VOEvent metadata packet is obtained in exchange for the identifier. Such resolution happens through the global, distributed IVOA registry in two stages: first use any VO registry to find out which VOEvent repository has the relevant record, then send a query to that repository asking for the record itself. The part of the identifier before the # symbol points to the repository itself; the identifier that includes the localID points to the event. Here is an example:
ivo://nvo.caltech/VOEventRepo
can be looked up in any VO registry, returning a description of the
repository, such as who runs it, how many events it has, what is the
service endpoint so it can be used.
ivo://nvo.caltech/VOEventRepo#60601
points to a specific VOEvent (number 60601) that is known to the
Caltech VOEvent repository, but is not known to the VO registry.
California Institute of Technology
626 395 3670
Received on 2006-04-20Z09:03:32