[oslc-core] Core Specification Version 2.0 Query Syntax: Prefixed Names
Arthur Ryman
ryman at ca.ibm.com
Mon Jul 16 17:09:39 EDT 2012
Steve,
In both of these cases, ":" and "foobar:" are simply short forms for URIs,
which means they are valid as RDF predicates. Recall that any URI may be
used as a predicate in an RDF triple.
We provide the ability to define prefixes in two ways. A service can define
the predefined prefixes used in its query capability using the
oslc:PrefixDefinition resource type. A query URL can contains an
oslc.prefix query string part.
However, it may be that the syntax of oslc.prefix requires a non-empty
name, so ":" is problematic there. oslc:PrefixDefinition might allow empty
strings and therefore be able to define ":". A domain spec might simply
state what ":" meant.
I agree these are edge cases and of limited usefulness.
Regards,
___________________________________________________________________________
Arthur Ryman
DE, Chief Architect, Reporting &
Portfolio Strategy and Management
IBM Software, Rational
Toronto Lab | +1-905-413-3077 (office) |
+1-416-939-5063 (mobile)
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|07/13/2012 03:46 PM |
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|Re: [oslc-core] Core Specification Version 2.0 Query Syntax: Prefixed Names |
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Arrthur,
If you had a
oslc.where=:="something"
what meaning do you ascribe to it? Similarly, what does
oslc.properties=foobar:
mean?
Regards,
Steve Pitschke
Development Lead for IBM Rational Connector for SAP Solution Manager
Wk: 978-899-4696
T/L: 276-4696
From: Arthur Ryman/Toronto/IBM at IBMCA
To: Steven B Pitschke/Lexington/IBM at IBMUS
Cc: oslc-core at open-services.net
Date: 07/13/2012 10:26 AM
Subject: Re: [oslc-core] Core Specification Version 2.0 Query Syntax:
Prefixed Names
Steve,
That syntax does have a well-defined meaning. All of those forms are
shortforms for URIs. They could therefore represent properties.
Regards,
___________________________________________________________________________
Arthur Ryman
DE, Chief Architect, Reporting &
Portfolio Strategy and Management
IBM Software, Rational
Toronto Lab | +1-905-413-3077 (office) |
+1-416-939-5063 (mobile)
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|Steven B Pitschke/Lexington/IBM at IBMUS |
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|Arthur Ryman/Toronto/IBM at IBMCA |
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|oslc-core at open-services.net |
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|07/10/2012 11:40 AM |
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|Re: [oslc-core] Core Specification Version 2.0 Query Syntax: Prefixed Names |
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Hi Arthur,
There's no problem with supporting the syntax. My view though, is that
there should
be recommendations about the meaning of the various forms of a prefixed
name. Beyond
that, I do believe that there are forms, such as PN_PREFIX ':' or just
plain ':', which
don't have any useful meanings. Supporting syntax that has no useful
meaning would
seem to me to be just a cause for confusion.
Regards,
Steve Pitschke
Development Lead for IBM Rational Connector for SAP Solution Manager
From: Arthur Ryman/Toronto/IBM at IBMCA
To: Steven B Pitschke/Lexington/IBM at IBMUS
Cc: oslc-core at open-services.net
Date: 07/10/2012 11:08 AM
Subject: Re: [oslc-core] Core Specification Version 2.0 Query Syntax:
Prefixed Names
Steve,
Given that the SPARQL grammar rules do make sense and that they are part of
the spec, what's the harm in supporting them?
Regards,
___________________________________________________________________________
Arthur Ryman
DE, Chief Architect, Reporting &
Portfolio Strategy and Management
IBM Software, Rational
Toronto Lab | +1-905-413-3077 (office) |
+1-416-939-5063 (mobile)
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|Nick Crossley/Irvine/IBM at IBMUS |
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|oslc-core at open-services.net, Arthur Ryman <ryman at ca.ibm.com> |
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|Re: [oslc-core] Core Specification Version 2.0 Query Syntax: Prefixed Names |
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I would object to disallowing predicates of the form ':comment' in OSLC
queries. As Arthur mentioned, in our SPARQL and Turtle examples, we
frequently use precisely this form with the prefix ':' defined as the URI
for some local server - such as those generated for custom properties. So
while the OSLC specs themselves do not need to use prefixed names of the
form ':comment', a user of one of our OSLC providers might well want to do
precisely this when writing a query for several custom properties.
I would have no particular objection to removing support for PN_PREFIX ':'
or just plain ':', though I question the value of the restriction.
Nick.
From: Steven B Pitschke/Lexington/IBM at IBMUS
To: Arthur Ryman <ryman at ca.ibm.com>,
Cc: oslc-core at open-services.net,
oslc-core-bounces at open-services.net
Date: 07/10/2012 06:35 AM
Subject: Re: [oslc-core] Core Specification Version 2.0 Query Syntax:
Prefixed Names
Sent by: oslc-core-bounces at open-services.net
Hi Arthur,
Yes, I am exactly suggesting we restrict it to
PrefixedName := PN_PREFIX ':' PN_LOCAL
I am currently working on an implementation of the server side of query for
the Lyo project. I will change my grammar to use the above, What is the
procedure for changing the OSLC core spec?
Steve Pitschke
Development Lead for IBM Rational Connector for SAP Solution Manager
From: Arthur Ryman <ryman at ca.ibm.com>
To: Steven B Pitschke/Lexington/IBM at IBMUS
Cc: oslc-core at open-services.net, oslc-core-bounces at open-services.net
Date: 07/10/2012 07:57 AM
Subject: Re: [oslc-core] Core Specification Version 2.0 Query
Syntax: Prefixed Names
Steven,
All of your examples ( ":", "dcterms:" or ":comment") have clear semantics
and are frequently used in SPARQL and Turtle.
":" means the URI associated with the prefix ":"
"dcterms:" means just the URI associated with the prefix "dcterms:"
Neither of the above is likely to appear in a query string.
":comment" is the concatenation of the URI associate with the prefix ":"
and the local part "comment". This could be a valid predicate that might
appear in a query string.
In practice, no OSLC spec uses ":" as a prefix.
Are you suggesting we restrict the grammar to only allow "reasonable"
prefixed names? In that case, I believe the practice is to use prefixed
names of the form:
PrefixedName := PN_PREFIX ':' PN_LOCAL
Regards,
___________________________________________________________________________
Arthur Ryman
DE, Chief Architect, Reporting &
Portfolio Strategy and Management
IBM Software, Rational
Toronto Lab | +1-905-413-3077 (office) | +1-416-939-5063 (mobile)
From:
Steven B Pitschke <pitschke at us.ibm.com>
To:
oslc-core at open-services.net
Date:
06/29/2012 01:15 PM
Subject:
[oslc-core] Core Specification Version 2.0 Query Syntax: Prefixed Names
Sent by:
oslc-core-bounces at open-services.net
The core query specification
http://open-services.net/bin/view/Main/OSLCCoreSpecQuery
defers to the SPAQL specifction for Prefixed Names
PrefixedName ::= /* see "SPARQL Query Language for RDF",
http://www.w3.org/TR/rdf-sparql-query/#rPrefixedName */
However, the semantics and usefulness of some the allowed terminals are
not clear
to me:
[68] PrefixedName := PNAME_LN | PNAME_NS
[71] PNAME_NS := PN_PREFIX? ':'
[72] PNAME_LN := PNAME_NS PN_LOCAL
For example, what would the prefixed names of ":", "dcterms:" or
":comment" mean? I think
it would be better to only support
PrefixedName := ( PN_PREFIX ':' PN_LOCAL ) | PN_LOCAL
which have fairly clear semantics.
Steve Pitschke
Senior Software Engineer and Architect
Rational Software, IBM_______________________________________________
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