TapTrieste < IVOA

IVOA Web>IvoaDAL>TableAccess>TapTrieste (2008-10-25, DougTody)

Collaborative Page for the TAP Interface

The Table Access Protocol (TAP) is a second generation DAL interface being developed to provide a general access mechanism for tabular data, including but not limited to astronomical catalogs. TAP is part of the DAL family of data access interfaces.

Architecture

In general IVOA DAL services obey a simple conceptual model:

http://wiki.ivoa.net/internal/IVOA/TableAccess/

When investigating what a TAP service might provide there are a number of options:

From this can be seen the diveristy of requirements on TAP.

Definition Process

What has become clear (implicit in the lack of progress in the definition of the standard) is that there are many and various requirements on a TAP service from the different VO projects. Broadly these can be categorised as Paramemterised query operations (TAP/Param) and Query Language operations (TAP/QL). Each impose a set of requirements which are hard to reconcil with each other. It is for this reason that the Twin Track approach to TAP definition has been proposed. However, "hard" does not mean "impossible", so the plan is to get the two aspects of TAP defined, the common elements identified and enshrined in both and then to merge the standatrds at V2.

This is shown in the following diagram:

TAP Focus Groups

TAP/Param

TAP/QL

TAP Working Drafts

TAP/Param

TAP/Param V0.2 - TAP/Param draft (includes TAP/Param functionality). This is based upon the discussions from the tiger team meeting held at JHU last November (JHU November 2007), as well as follow-on discussions regarding VOSpace integration, multi-region queries, and other topics.

TAP/QL

TAP/QL V0.1 - TAP/QL Draft document focused on processing ADQL queries, synchronous and asynchronous execution, integration with other IVOA services and metadata provision using VOSI constructs.