Appendix
Schemata of properties files, RDM files and the ooXmlQL query language.
This tutorial explains how to configure, install and write applications using GRIA's contextualised registry component
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Registry Properties
The registry properties file will have entries like this
######################################################################### # # Registry properties specification # ######################################################################### # database administrator for installing and configuration of the registry database db.admin.user=<admin login name> db.admin.password=<admin password> db.admin.group=<group name all registry users belong to, e.g.‘all’> # namespace of registry domain model # e.g. 'http://www.gria.org/registrydomainmodel.owl' registry.domain.model.ns=<namespace> # XML database URI # e.g. 'xmldb:exist://localhost:8080/exist/xmlrpc' xml.db.uri=<location of eXist> # Registration default policy. Used during registration. # Usage: r|w|u, e.g. for an owner who should have read, # write and update access: xml.db.perm.owner=rwu # In general these rules should be applied like this… # entities # owner xml.db.perm.entity.owner=rwu # group xml.db.perm.entity.group=r # other xml.db.perm.entity.other= # concepts # owner xml.db.perm.concept.owner=rwu # group xml.db.perm.concept.group=rw # other xml.db.perm.concept.other=
Registry Domain Model (RDM)
The RDM can be specified using OWL. The following OWL concepts are currently supported by the registry component:
- owl:Class (rdfs:label specifies the name of the concept used within the registry, it is therefore always REQUIRED and has to be UNIQUE)
- rdfs:subClassOf (only simple inheritance is supported)
- owl:ObjectProperty (rdfs:label specifies the name of the relationship used within the registry, it is therefore always REQUIRED and has to be UNIQUE)
- owl:inverseOf definition of inverse relationships
The following shows an example RDM
<rdf:RDF
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:owl="http://www.w3.org/2002/07/owl#"
xmlns:xsd="http://www.w3.org/2001/XMLSchema#">
<owl:Ontology rdf:about="">
<rdfs:comment>Registry Domain Model for GRIA Client Management. (C) 2007, University of Southampton IT Innovation Center</rdfs:comment>
<owl:versionInfo>$Id:RegistryDomainModel.owl,v 1.0 2006/10/31 Uwe Radetzki$</owl:versionInfo>
</owl:Ontology>
<!-- -->
<!-- Concepts -->
<!-- -->
<owl:Class rdf:ID="ReferenceAble">
<rdfs:comment>
Reference-able elements have a unique reference (EPR)
</rdfs:comment>
<rdfs:label>ReferenceAble</rdfs:label>
</owl:Class>
<owl:Class rdf:ID="Reference">
<rdfs:comment>Reference could be an EPR</rdfs:comment>
<rdfs:label>Reference</rdfs:label>
</owl:Class>
<!-- -->
<!-- Relationships between concepts -->
<!-- -->
<owl:ObjectProperty rdf:ID="Reference-holdBy-ReferenceAble">
<rdfs:range rdf:resource="#ReferenceAble"/>
<rdfs:label>holdBy</rdfs:label>
<rdfs:domain rdf:resource="#Reference"/>
<owl:inverseOf rdf:resource="#ReferenceAble-has-Reference"/>
</owl:ObjectProperty>
<owl:ObjectProperty rdf:ID="ReferenceAble-has-Reference">
<rdfs:domain rdf:resource="#ReferenceAble"/>
<rdfs:label>has</rdfs:label>
<rdfs:range rdf:resource="#Reference"/>
<owl:inverseOf rdf:resource="#Reference-holdBy-ReferenceAble"/>
</owl:ObjectProperty>
</rdf:RDF>
Predefined queries
The following example defines a lookup query that retrieves a document by its identifier. Users can execute this query by specifying the query name (“LookupByDocId”) and the required variables (“docId”).
<queries>
<query name="LookupByDocId">
<definition>
xquery version "1.0";
for $col in fn:collection("/db/registry/")
for $doc in util:document-name($col)
where $doc = $docId
return $col
</definition>
<parameter name="docId"/>
</query>
</queries>
ooXmlQL Specification and Example
The following EBNF grammar specifies sound ooXmlQL queries. Remark: A strange behavior can be observed when using variables where one variable is a prefix of another variable, e.g. $ref and $refAlias. It seems there is a bug in the XQuery processor. Therefore this variable setting should be avoided.
ooXmlQuery = query.
query = ‘<query>’ ( queryelements ) ( declareNS)* ‘</query>’.
queryelements = ( select )?
from
( declareVar )*
( restriction )?
( where )?.
select = ‘<select>’ ( ‘*’ | xpath expression+ ) ‘</select>’.
declareNS = ‘<declare name=“’name’”>’ namespace ‘</declare>’.
from = ‘<from as=“’var‘”>’ ( class | setOperation ) ( join )? ‘</from>’.
setOperation = ‘<union>’ ( class | setOperation )+ ‘</union>’ |
‘<intersect>’ ( class | setOperation )+ ‘</intersect>’ |
‘<except>’ ( class | setOperation )+ ‘</except>’.
class = ‘<class name=“’classname’”/>.
join = ‘<join on=“’relation’” as=“’var’” class=“’class’”>’
( restriction )? ( join )?
‘</join>’.
declareVar = ‘<declare var=“’var’”>’ xpath expression ‘</declare>’.
where = ‘<where>’ xpath or xquery expression ‘</where>’.
restriction = subquery | and | or | not.
subquery = ‘<query return=“’relationship’”>’
queryelements
‘</query>’.
and = ‘<and>’ restriction+ ‘</and>’
or = ‘<or>’ restriction+ ‘</or>’.
not = ‘<not>’ restriction ‘</not>’.
Variables can be used in the following elements of the query:
- where clause <where>
- select clause <select>
- declare variable clause <declareVar>
Example ooXmlQL query:
<query>
<select>*</select>
<declare name="ns1">http://it-innovation.soton.ac.uk/2005/grid</declare>
<declare name="ns2">http://www.w3.org/2005/08/addressing</declare>
<from as="$sla">
<class name="Sla"/>
<join on="provides" as="$res" class="Resource"/>
</from>
<declare var="$min">fn:min($sla//cpu)</declare>
<declare var="$max">fn:max($sla//cpu)</declare>
<query return="providedBy">
<from class="Resource" as="$res"/>
<declare var="$avg">fn:avg($res//cpu)</declare>
<where>
$res//ns2:Metadata/ns1:type = "uk.ac.soton.ecs.iam.grid.comms.client.RemoteDataService"
</where>
</query>
<where>$sla//cpu = $min or $sla//cpu = $max</where>
</query>
See the GRIA Client section about discovery
for more information about ooXmlQL.
