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:
 
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-V0.2.pdf - TAP draft (includes TAP/Param
functionality)
 TAP/QL 
[TAP/QL first draft to be added]
 TAP related IVOA Notes 
  
 TAP Meetings 
TAP planning meeting (
JHU November 2007).
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KeithNoddle - 17 Apr 2008