Registry Services
The registry services are meant to facilitate publication and discovery of services. Each registry has three kinds of interface: publish, query, and harvest. People can publish to a registry by filling in web forms in a web portal, thereby defining services, data collections, projects, organizations, and other entities. The registry may also accept queries in a one or more languages (for example an IVOA standard Query Language), and thereby discover entities that satisfy the specified criteria. The third interface, harvesting, allows registries to exchange information between themselves, so that a query executed at one registry may discover a resource that was published at another.
Registry services expect to label each VO resource through a universal identifier, that can be recognized by the initial string ivo://. Resources can contain links to related resources, as well as external links to the literature, especially to the Astronomical Data System. The IVOA registry architecture is compliant with digital library standards for metadata harvesting and metadata schema, with the intention that IVOA-compliant resources can appear as part of every University library.
There are currently three NVO implementations of the VO registry architecture, from NCSA , STScI , or Caltech.