Asynchronous querying and tabular data
dtody at nrao.edu
Wed May 2 13:42:58 PDT 2007
On Wed, 2 May 2007, Patrick Dowler wrote:
> On Wednesday 02 May 2007 12:51, Doug Tody wrote:
>> o getData. Just an access reference (URL currently) as
>> elsewhere; so far in TAP this is only needed to retrieve data
>> from an async query.
> For this one at least I think we were going to totally punt and let VOSpace
> handle it. That is, an async query would synchronously return whatever
> identifier to the VOSpace resource is needed so the caller can go off and
> talk to the VOSpace.
It amounts to the same thing (getData is not an explicit method in any
case). Since the job management system will be returning information
to the client via either polling or messaging, to tell the client when
the job is done and the output ready to be picked up, this can include
information from the VOSpace such as an access reference for retrieval
(hence a simple client might not have to deal with VOSpace directly).
Of course, once the data is in VOSpace, the VOSpace API, or a management
GUI provided for the user, could be used as well.
> So I only see two TAP methods: a synchronous query and an asynchronous query.
> And I think it is important that they not be named queryData and stageData
> respectively. Both should have the word query in them, both should take the
> same ADQL string as the primary input, and async probably requires some
> additional stuff like credentials and preferences for VOSpace interactions to
> be passed around somehow.
Of course we also have getCapabilities and getAvailability, which
are required by both the VOSI and DAL (and probably Registry),
but these are not specific to TAP except for the contents of the
All the stuff you mention for defining an async operation is pretty
much what will be required for, e.g., a stageData in SIA as well.
That is, staging information for VOSpace, as well as something for
authentication. Standard stuff.
> Bit now I would like to wait for some others to comment, and they are all at
> home relaxing and maybe even asleep :)
Back to work on the SSAP version of getCapabilities for me.
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