[DAS2] how to test features?

[Helt,Gregg]

In DAS/1 the types response can optionally include a count of the number
of features available for that particular type and source.  I do think
this would be a useful feature to preserve in DAS/2.  From that
information a client/validator could potentially tune its requested
range to return on average a desired number of features.

I don't think a server should return only some of the features that meet
the search criteria -- should return either all or none.  If a server
decides that a client is requesting too much data, I think servers
should be able to return some sort of "returned feature count too large"
error code response.  And maybe in the source or versioned source
response xml have an optional indication of how many features a server
is willing to serve up in a single request, so clients can know this
limit in advance.

	gregg

> -----Original Message-----
> From: das2-bounces at portal.open-bio.org
[mailto:das2-bounces at portal.open-
> bio.org] On Behalf Of Andrew Dalke
> Sent: Friday, June 10, 2005 1:31 AM
> To: DAS/2
> Subject: [DAS2] how to test features?
> 
> What's the appropriate way to test features on a
> server where I don't know what's present?
> 
> What I did with DAS/1 was search a range of a
> certain size and keep shifting the search range
> until I find something.
> 
> I would like to improve on that.  For example, I know
> all of the types in the system so I can do a type
> query and double-check that all the returned features
> have that type.
> 
> There's a good chance I'll have some enormous
> results lists if I do that.  Some queries may end
> up sucking up large chunks of the database.
> 
> I was thinking that a "limit" option might be useful.
> For example, "up to 1000 features in the range 1M to
> 2M."  'Course then the server may need to report
> "returned 1000 features but 234234 matched the query."
> 
> Perhaps a server may wish to enforce a max limit
> on the number of features even if not specified in
> the request?  Eg, for "http://.../features/".
> 
> If there is a limit, would the number be accessible
> by the client?  Would the spec state a lower bound
> for what a server must support?  If the number of
> hits is just barely over the limit, what's the right
> way for the client to get the remaining list of features?
> 
> 
> 					Andrew
> 					dalke at dalkescientific.com
> 
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