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ISSUE 5.14 Closing Text

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Mon, 09 Dec 2002 11:59:11 -0500
Message-ID: <3DF4CBDF.F3F15821@cse.lehigh.edu>
To: WebOnt <www-webont-wg@w3.org>

As I was actioned at last Thursday's telecon, here is closing text for
the ontology versioning issue. I have essentially taken my proposal from
12/02 and made the agreed-upon changes:

 
We will add the following identifiers to the OWL namespace:

priorVersion
backCompatibleWith
incompatibleWith
deprecatedClass
deprecatedProperty

In short, all of these identifiers are "extralogical" in the sense that
they are not intended to be used by inference engines and that none of
them will have any additional impact on the semantics. In addition, we
will remove the following identifier from the OWL namespace.

versionInfo

Each of the new identifier are described below:

priorVersion
-------------
Triple usage: <newdoc> priorVersion <olddoc>

The ontology identified by <olddoc> is a priorVersion of the one
identified by <newdoc>. This has no meaning in the model theoretic
semantics other than that given by the RDF(S) model theory. However, it
may be used by software to organize ontologies by versions.


backCompatibleWith
-----------------------
Triple usage: <newdoc> backCompatibleWith <olddoc>

The ontology identified by <newdoc> is a a later version of the one
identified by <olddoc>, and is backward compatible with it. In
particular, this indicates that all identifiers from the previous
version have the same intended interpretations in the new version. Thus,
it is a hint to document authors that they can safely change their
documents to commit to the new version (by simply updating namespace
declarations and imports statements to refer to the URL of the new
version). If backCompatibleWith is not declared for two versions, then
compatibility should not be assumed. Like priorVersion, this
has no meaning in the model theoretic semantics other than that given by
the RDF(S) model theory.

Note, this approach does not address the problem described in Section
3.2 of the Requirements Document (under RDF(S) Support). There, we gave
an example where we wanted to "fix" an incorrect definition of Dolphin.
Solving this problem would require versioning capabilities that would
change the model theoretic semantics, but at this time it is not clear
what the correct approach would be. A later version of OWL may address
this issue.

incompatibleWith
-----------------
Triple usage: <newdoc> incompatibleWith <olddoc>

The ontology identified by <newdoc> is a a later version of the one
identified by <olddoc>, and is not backward compatible with it.
Essentially,
this is for use by ontology authors that want to be explicit that
documents cannot upgrade to use the new version without some changes.

deprecation:
---------------
Triple Usage:   <classId> rdf:type <owl:DeprecatedClass> or 
                <propertyId> rdf:type <owl:DeprecatedProperty>

Deprecation is a feature commonly used in versioning software (for
example, see the Java programming language) to indicate that a
particular feature is preserved for backward-compatibility purposes, but
may be phased out in the future. Here, a specific identifer is said to
be of type DeprecatedClass or DeprecatedProperty, where DeprecatedClass
is a subclass of rdfs:Class and DeprecatedProperty is a subclass of
rdf:Property. By deprecating the term, it means that the term should not
be used in new documents that commit to the ontology. This allows an
ontology to maintain backward-compatibility while phasing out an old
vocabulary (thus, it only makes sense to use deprecation in combination
with backward compatibility). As a result, it it easier for old data and
applications to migrate to a new version, and thus can increase the
level of adoption of the new version. Once again, this has no meaning in
the model theoretic semantics other than that given by the RDF(S) model
theory. However, authoring tools may use it to warn users when checking
OWL markup.


Example:
--------

<owl:Ontology rdf:about="">
   <rdfs:label>Vehicle Ontology, v. 1.1</rdfs:label>
   <owl:backCompatWith
rdf:resource="http://www.example.org/vehicle-1.0">
   <owl:priorVersion rdf:resource="http://www.example.org/vehicle-1.0">
</owl:Ontology>


<!-- assume Automobile is now the preferred term for Car -->
<owl:DeprecatedClass rdf:ID="Car" />

<owl:Class rdf:ID="Automobile" />
   <owl:sameClassAs rdf:resource="#Car" />
   <!-- note that sameClass only means that the classes have the same
        extension, so this DOES NOT lead to the entailment that
	Automobile is of type DeprecatedClass too -->	
</owl:Class>

<!-- assume hasDriver is obsolete and its inverse drives is preferred
-->
<owl:DeprecatedProperty rdf:ID="hasDriver" />

<owl:Property rdf:ID="drives" >
   <owl:inverseOf rdf:resource="#hasDriver" />
</owl:Property>

<!-- assume a hasWheels property should no longer used (maybe because a
more specific numWheels property is in favor) -->
<owl:DeprecatedProperty ID="hasWheels" />

<!-- other class and property definitions follow -->


Additions to http://www.w3.org/2002/07/owl
--------------------------------------------

<rdf:Property rdf:ID="priorVersion">
   <rdfs:domain rdf:resource="#Ontology" />
   <rdfs:range rdf:resource="#Ontology" />
</rdf:Property>

<rdf:Property rdf:ID="backCompatibleWith">
   <rdfs:domain rdf:resource="#Ontology" />
   <rdfs:range rdf:resource="#Ontology" />
   <rdfs:subPropertyOf rdf:resource="#priorVersion" />
</rdf:Property>

<rdf:Property rdf:ID="incompatibleWith">
   <rdfs:domain rdf:resource="#Ontology" />
   <rdfs:range rdf:resource="#Ontology" />
   <rdfs:subPropertyOf rdf:resource="#priorVersion" />
</rdf:Property>

<rdfs:Class rdf:ID="DeprecatedClass">
   <rdfs:subClassOf resource="Class" />
</rdfs:Class>

<rdfs:Class rdf:ID="DeprecatedProperty">
   <rdfs:subClassOf resource="Property" />
</rdfs:Class>
Received on Monday, 9 December 2002 11:59:20 GMT

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