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https://issues.apache.org/jira/browse/JENA-2207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17454573#comment-17454573
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Andy Seaborne edited comment on JENA-2207 at 12/7/21, 10:50 AM:
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See comment in PR :-) and the "{{if ( false )}}" block in {{Service.exec}}.
Rename used to be applied but got missed out in the reworked Service.java in
4.3.0.
It is easier said than done to avoid renaming. It risks contamination because
the variable name may be used elsewhere.
The SERVICE block can still be specialised for outer defined variables in the
query making the SERVICE call more specific. This then has small results,
quicker - potentially important for remote services that restrictions and
timeouts.
If substitution wasn't being done, using the original query syntax or
unmodified algebra would be possible. (And IIRC as done in the earliest
implementation.)
So short term - the PR puts back what should have been there and is the safest
change. Long term, we can consider redesign.
was (Author: andy.seaborne):
See comment in PR :-)
Rename used to be applied but got lost in the mostly-new Service.java in 4.3.0.
It is easier said than done to avoid and risks contamination because the
variable name may be used elsewhere.
The SERVICE block can still be specialised for already defined variables in the
query making the SERVICE call more specific. This then has small results,
quicker - important for remote services that restrictions and timeouts.
> A SERVICE call involving a SELECT projection may generate illegal syntax
> ------------------------------------------------------------------------
>
> Key: JENA-2207
> URL: https://issues.apache.org/jira/browse/JENA-2207
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ, SPARQL
> Affects Versions: Jena 4.3.0
> Reporter: Andy Seaborne
> Assignee: Andy Seaborne
> Priority: Major
> Fix For: Jena 4.4.0
>
>
> This is a regression in Jena 4.3.0.
> Example:
> {noformat}
> SELECT * {
> SERVICE <http://localhost:3030/ds> {
> SELECT ?s { ?s ?p ?o }
> }
> }
> {noformat}
> will have a compiled inner pattern with {{?/p}} and {{?/o}}. The {{?p}} and
> {{?o}} variables were rewritten to hide them (they are not in the {{SELECT
> ?s}}).
> This rewrite needs to be reversed before sending the service-query.
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