Fwd: Should data errors from federated calls be ignored when silent?

[Claude Warren <cl...@xenei.com>]

---------- Forwarded message ----------
From: Claude Warren <cl...@xenei.com>
Date: Fri, Mar 30, 2012 at 4:52 PM
Subject: Should data errors from federated calls be ignored when silent?
To: jena-users@incubator.apache.org


I have a case where I am using multiple federated calls where each call is
of the form
Service silent <uri> {
--snip--
 }

One of the endpoints is returning bad data in that the XML does not parse
and so the XML parser throws an exception and my entire query dies.

Now the best answer would be to get the data corected but I don't own that
data and have no idea if they will fix it.

What I want to know is shouldn't the "Silent" keyword on the Service call
indicate that if the remote fails it should be ignored.

>From http://www.w3.org/2009/sparql/docs/fed/service#serviceFailure it
appears that a single solution with no bindings should be returned.  If
this is a correct interpretation I am willing to report a bug and implement
a bug fix.  The issue that I see is that the error is not detected until a
hasNext() is called on the iterator.  This means that the service could
have returned some data before the error was detected.  I would propose
that the solution be to have the iterator return "false" at that point and
move forward with the partial data that was already returned.

Does anyone have a different interpretation of the specification or see an
issue with the possible solution?

Many thanks,
Claude

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