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From "Andy Seaborne (Commented) (JIRA)" <>
Subject [jira] [Commented] (JENA-162) Add FROM/FROM NAMED support to Fuseki
Date Mon, 14 Nov 2011 21:28:51 GMT


Andy Seaborne commented on JENA-162:

The dataset description is still parsed out of the protocol by Fuseki (Fuseki being the SPARQL
protocol implementation).  It then places it in the execution environment.  There's now an
(ARQ) class DatasetDescription to hold the two lists of URIs (strings).  My style (these days)
is to name things that are architectural concepts.  

Various details get put in the context of a QueryExecution - the query, the algebra the value
of now() and more.

You can then access the dataset description object from the protocol and the dataset description
in the query at any point.  

The only downside is that the rule that the protocol dataset description modifies the request
in preference to the query isn't enforced.  There is all information around and having the
precedence rule in a static method seems adequate. See (in ARQ) DatasetDescription.create(Query,

When it gets to the query engine, no decisions have been made - a convenience piece of code
captures the SPARQL decision rule.

> Add FROM/FROM NAMED support to Fuseki
> -------------------------------------
>                 Key: JENA-162
>                 URL:
>             Project: Jena
>          Issue Type: New Feature
>          Components: Fuseki
>    Affects Versions: Fuseki 0.2.1
>            Reporter: Rob Vesse
>              Labels: from, from-named, sparql
>         Attachments: FusekiFromSupport.patch
> Fuseki currently does not support FROM/FROM NAMED clauses returning a HTTP 400 error
if a user tries to make use of them
> The attached patch provides for optional enabling of this feature by a user specified
--from or --allowFrom switch when the server is started or programmtically via ARQ.getContext().set(Fuseki.enableFromClauses,
true).  Therefore unless a user turns this feature on by default the old behavior remains
in place.
> When enabled Fuseki will not reject queries with FROM/FROM NAMED in them and will use
DynamicDatasets.dynamicDataset() to build the dataset for queries, there is minimal overhead
for queries without FROM/FROM NAMED clauses as the code in DynamicDatasets appears to leave
the default dataset unchanged if no dataset description is present in the query AFAICT
> A small number of tests has been added to to test the behaviour, more
tests might be desirable and I can probably supply those if necessary but the ones given test
all the obvious combinations with the trivial test data used by TestQuery

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