STAP is the protocol, Skynode and DSA are implementations

I have just had an interesting discussion with some of the British about the ADQL-Core implementations (BasicSkynode in the US, and DSA in the UK). There is a continual confusion of a single word (Skynode) to mean to mean several different things.

The immediate requirement is a standard interface that can expose a relational database to the web for simple select queries (ADQL-Core). Let us call this interface Simple Table Access Protocol (STAP) in order to distinguish the interface from the implementation (currently we are using the name Skynode for both). The current interface includes methods to find the data dictionary (table names and attributes). Let us not at the moment talk about the fancy stuff like crossmatch and STC regions, that will be extensions of this basic protocol.

We already have at least two implementations of STAP:

• BasicSkynode in dotNet and Java from NVO
• DSA from Astrogrid Are there other implementations? Code that is almost ready to be STAP?

However, there is a significant difference in how these three are implemented, in particular the data dictionary part. The BasicSkynode expects the data dictionary to be written into tables in the database itself, whereas the DSA expects the data dictionary to be available from the VO Registry.

Each of these has their own advantages and disadvantages, but the requirement for IVOA is to make a unified interface for STAP. Is it too much to ask for both? May I suggest that:

• We change the name of the Skynode interface to be called STAP, and
• The data dictionary methods remain part the STAP protocol, and
• The BasicSkynode implementation should be upgraded to be able to fetch data dictionary from the registry, and
• The DSA implementation should be upgraded so it can get data dictionary from the registry when it needs to service these methods.

Once we have agreed on STAP, I suggest that the extended protocol (with distributed crossmatch etc) be called Extended Table Access Protocol (ETAP). Received on 2006-05-18Z19:13:28