[DAS] DAS Spec Question - Features request

[Thomas Down]

On Tue, Aug 27, 2002 at 10:29:35AM -0400, Cox, Greg wrote:
> Good day,
> 	The Format for the features request starts as
> "PREFIX/das/DSN/features?segment=REF:start,stop[;segment=REF:start,stop...]"
> which indicates the first segment argument is required, and others are
> optional.  However, in the text describing the arguments, it specifies that
> zero or more segment arguments are allowed.  Which is correct, or am I
> misinterpting the format syntax?

I'm inclined to believe the text.  There are a number of possible
requests which don't include any segment= parameters:

    - (Legacy only, this seems to be gone from the latest
      spec).  Old-style single segment requests:

              features?id=foo;start=1;stop=1000

    - (In DAS/1.5 or later) non-positional annotations, e.g.:

              features?feature_id=ENST000012345

It's never defined what happens if you just say

              features

Without providing any restrictions.  My first guess would have been
that it should return all the annotation the server knows about
(or a `request too large' error), but I come from BioJava, where
everything's done on a filtering paradigm.  Looking at the specification
of the feature_id and group_id attributes, things seem to be done
in an additive way.  So I guess the empty request returns nothing.

Maybe it would be safest for future versions to specify that
a features request contains either 1 or more segment paramaters,
or 1 or more feature_ids, or one or more group_ids.

     Thomas.