The VO Directory is the web framework for an Open Archive Initiatives Metadata Registry of astronomical data services, intended to run on IIS and Microsoft SQL Server. The main implementation runs the VO Directory at Space Telescope, http://vao.stsci.edu/directory.
The project was begun as a collaboration under the National Virtual Observatory and is currently maintained by the Mikulski Archive at Space Telescope, with significant contributions from other NVO/VAO/NAVO members. It contains libraries and interactive and programmatic web interfaces for registry search, OAI-PMH harvesting, form-based resource publication, and basic curation and record administration.