Community feedback re TAP metadata

[Yuji SHIRASAKI]

Hi All,

Before describing my comments on the subject, I have to apologize that
I cannot attend today's telecon. I have a cold, so going back home to
sleep early...

Here are my opinions on TAP metadata:

1. I don't think TAP should define an interface to return the service metadata
   and also it metadata structure. These things are related to the mechanism 
   to find a service that user wants to access, so they should be defined in the 
   registry WG. 

   I don't agree that the interface should be mandatory for TAP service.
   We already have a path to register the metadata using the publishing
   registry, that is enough. Why we need another way to register the metadata ?

   And if many complex operations are defined, it will become more difficult for
   service provider to imlement and maintain the service so that it correctly 
   reacts to the query.

   I don't like to have two paths to expose the service metadata.

2. TAP should have an access mechanism to query the table/column information.
   SQL is an approriate language for that purpose. All the relation DB has such
   functionality. This should be a mandatory operation, since without these 
   information it is impossible to write a correct SQL. VOTable is enough for
   retruned format. Tabular format is easy to use. Structure data is not easy
   to use and also not easy to define.

   It is better that these information is accessible directly from a TAP service
   rather than from a registry. These inoformation is frequently refered by a client, 
   so I am afraied the registry becomes very busy if such important information is 
   centralized to the registry servcice.
   

Yuji SHIRASAKI.