There are many fields in Astrophysics with a strong need of direct and rigorous comparisons between theoretical models or simulations and real data. However, the different architectures, programming codes, formats, etc, make it, most of the times, extremely difficult and inefficient.
In order to define the requirements needed for a full interoperability between observations and models, an IVOA Theory Group was created in January 2004. Dr. Miguel Cerviño (IAA-CSIC) will be the contact point for the SVO.
Access protocols to theoretical data
One of the first issues undertaken by the IVOA Theory Group was the definition of query protocols adequate for theoretical data: the VO protocols already defined for observational data (Conesearch, SSAP, SIAP,...) are based on absolute positions on the sky and, in most cases, cannot be applied to theoretical models. Moreover, for theoretical models, there is not a common set of input parameters that could play the role of the coordinates for observational data as each model has its own collection of input parameters that normally differ from one model to another.
To handle this problem, SVO-LAEFF and ESA-VO proposed TSAP (Theoretical Spectra Access Protocol) as an attempt to incorporate theoretical spectra into the VO. With TSAP, a http-get dialog is stablished so that the client can get all the necessary information from the server to be able to make subsequent queries. TSAP is now considered part of the Simple Spectra Access Protocol (SSAP), as a use case for theoretical spectra. More info
The same philosophy used in TSAP can be used too for other kind of theoretical data. In order to allow this, S3 was suggested as a new protocol, using an approach simmilar to the TSAP one, the ability of the data server to describe itself in a simple standardized way, and useful not only for spectra but for other kind of data.More info