Specialization of PROV Ontology Classes

The following new classes were created in the CrimeFile Ontology by extending the PROV ontology classes:

				  <rdf:Description rdf:about="http://www.example.com/crime#Journalist">
					<rdfs:subClassOf rdf:resource="http://www.w3.org/ns/prov-o/Agent"/>
				  </rdf:Description>
				

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix prov: <http://www.w3.org/ns/prov-o/> .

<http://www.example.com/crime#Journalist> 
   rdfs:subClassOf prov:Agent
.
				

				  <rdf:Description rdf:about="http://www.example.com/crime#CrimeFile">
					<rdfs:subClassOf rdf:resource="http://www.w3.org/ns/prov-o/Entity"/>
				  </rdf:Description>
				

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix prov: <http://www.w3.org/ns/prov-o/> .

<http://www.example.com/crime#CrimeFile>
   rdfs:subClassOf prov:Entity
.
				

cf:FileCreation, cf:FileEditing, cf:FileAppending, cf:Emailing, cf:SpellChecking

The classes cf:FileCreation, cf:FileEditing, cf:FileAppending, cf:Emailing, cf:SpellChecking are specialization of the PROV ontology Activity and model the different activities in the provenance scenario. The following RDF/XML code illustrates the specialization of the prov:Activity to define class cf:FileCreation (other classes can be similarly defined by using the subClassOf property).

				  <rdf:Description rdf:about="http://www.example.com/crime#FileCreation">
					<rdfs:subClassOf rdf:resource="http://www.w3.org/ns/prov-o/Activity"/>
				  </rdf:Description>
				

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix prov: <http://www.w3.org/ns/prov-o/> .

<http://www.example.com/crime#FileCreation>
   rdfs:subClassOf prov:Activity
.
				

The following diagram illustrates the above class specializations:

Example extension of PROV ontology in order to describe the crime file scenario

Specialization of PROV Ontology Properties

The following new object property was created in the CrimeFile Ontology by extending the PROV ontology object property:

				  <rdf:Description rdf:about="http://www.example.com/crime#hadFilePath">
					<rdfs:subPropertyOf rdf:resource="http://www.w3.org/ns/prov-o/hadLocation"/>
				  </rdf:Description>
			  

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix prov: <http://www.w3.org/ns/prov-o/> .

<http://www.example.com/crime#hadFilePath>
   rdfs:subPropertyOf prov:hadLocation
.
				

The following diagram illustrates the above property specialization:

Workflow extensions to PROV classes

In order to describe workflow executions following the model above, the PROV ontology is extended with workflow-specific subclasses described below:

wf:Process

A subclass of prov:Activity to signify an execution of a process which wf:wasDefinedBy a a wf:ProcessDefinition, e.g. a workflow or a process in a workflow. A workflow process can also act as an prov:Agent when controlling nested process executions.

wf:WorkflowEngine

A subclass of prov:Agent to indicate that a workflow process was controlled by a workflow engine.

wf:Value

A subclass of prov:Entity, representing a value appearing in the workflow execution, it will typically be used or generated by wf:Process executions. The actual value can be provided as a literal with a wf:value property.

wf:FileValue

A wf:Value which has been read from a file. As an prov:Entity this represents an entity with both attributes wf:value and wf:file fixed, that is the entity describes the point when the given file contained the content. As the file might be read a while before the wf:Value is used by a wf:Process, at which point the file content might have changed, those values are declared as being derived from this file value using the wf:wasReadFrom property.

wf:ValueAtPort

A subclass of prov:QualifiedInvolvement, representing a value (given by wf:sawValue) observed at a given port in the workflow (given by wf:seenAtPort. This description is the range of wf:generatedValue and wf:usedValue on a wf:Process.

Workflow extensions to PROV properties

While for most cases subclassing will provide the additional expressionality the application needs, this example ontology also expands on the PROV ontology with more specific subproperties.

wf:wasDefinedBy

This sub-property of prov:hadRecipe links a wf:Process to the defining wf:ProcessDefinition. Thus, if there are multiple executions of the same workflow definition, each of the separate wf:Processes will link to the same definition.

wf:ranInWorkflowEngine

This subproperty of prov:wasControlledBy links a wf:Process to the wf:WorkflowEngine it was executed in. The engine instance might contain additional details such as which version of the workflow system was used.

wf:wasLaunchedBy

This second subproperty of prov:wasControlledBy links a wf:Process to a prov:Agent, indicating which person asked to execute the given wf:ProcessDefinition in the specified wf:WorkflowEngine.

wf:wasSubActivityOf

This subproperty of prov:wasControlledBy links a wf:Process to another prov:Process, indicating this is a child execution

Should there be a general way to state subprocesses? -Stian

wf:wasReadFrom

This subproperty of prov:wasDerivedFrom links a wf:Value to the wf:FileValue it was read from, typically when used as a workflow input. As described for wf:FileValue this distinction is done because at the time the workflow input is used in the workflow, the file input might be different and thus should not be described as an attribute of that wf:Value.

This property hints of an undescribed "Read file" process execution which is not described. This is therefore an example of how the provenance asserter is limiting the scope of its provenance. The engine knows that the file was read, but is not able or willing to provide any deeper assertions, because its primary scope is at the level of executing workflow definitions.

wf:sawValue

A subproperty of prov:hadQualifiedEntity which indicates that an wf:Value was wf:seenAtPort within an wf:ValueAtPort.

wf:seenAtPort

A subproperty of prov:hadRole indicating which wf:Port (in the workflow definition) a wf:ValueAtPort was seen at. Thus one can see at which output port a value was generated, or at which input port(s) it was used.

wf:generatedValue

A subproperty of prov:hadQualifiedGeneration, specifying which port we wf:sawValue and where it wf:wasSeenAtPort as it was generated. The domain of this property is wf:Process, the range wf:ValueAtPort (and implied prov:Generation)

wf:usedValue

A subproperty of prov:hadQualifiedUsage, specifying which port we wf:sawValue and where it wf:wasSeenAtPort as it was used. The domain of this property is wf:Process, the range wf:ValueAtPort (and implied prov:Usage)

wf:sameValueAs

A subproperty of prov:wasComplementOf and prov:wasDerivedFrom, specifying that an wf:Value was the same as another wf:Value. This is used to indicate that a value at an workflow output port is the same as the value at a processor output port, although they have different history of generation, they both represent the same wf:value and are the same "thing".

Example workflow

This is an example workflow which defines a workflow input input, three processes String_constant, Concatenate_two_strings and sha1, and finally two workflow outputs combined and sha1. When executed, it will execute from top to bottom, first concatenating the provided input with the string constant, which is returned on the combined output, but also provided to the sha1 process, which output is given to the other workflow port.

An example of abstract definition of this workflow can be seen as RDF/XML and Turtle

Example workflow run

This example shows how using the workflow extensions together with PROV can provide the provenance of executing the workflow defined above.

<rdf:RDF xmlns="http://www.example.com/scientific-workflow#"
    xmlns:foaf="http://xmlns.com/foaf/0.1/"
    xmlns:prov="http://www.w3.org/ns/prov-o/"
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:time="http://www.w3.org/2006/time#"
    xmlns:wf="http://www.example.com/scientific-workflow#">

    <Process rdf:about="#workflowRun">
        <ranInWorkflowEngine>
            <WorkflowEngine rdf:about="#workflowEngine" />
        </ranInWorkflowEngine>
        <wasDefinedBy rdf:resource="http://www.example.com/workflow1#workflow"/>
        <wasLaunchedBy>
            <prov:Agent rdf:about="#aUser">
                <rdf:type rdf:resource="http://xmlns.com/foaf/0.1/Person"/>
                <foaf:name>Stian Soiland-Reyes</foaf:name>
            </prov:Agent>
        </wasLaunchedBy>
        <prov:startedAt rdf:parseType="Resource">
            <time:inDateTimeXSD>2011-10-21T09:20:15Z</time:inDateTimeXSD>
        </prov:startedAt>
        <prov:endedAt rdf:parseType="Resource">
            <time:inDateTimeXSD>2011-10-21T09:23:32Z</time:inDateTimeXSD>
        </prov:endedAt>
        <wf:usedValue>
            <prov:Usage>
                <sawValue>
                    <Value rdf:about="#input">
                        <value>Steve</value>
                        <wasReadFrom>
                            <FileValue rdf:about="#inputFile">
                                <file>/tmp/myinput.txt</file>
                                <value>Steve</value>
                            </FileValue>
                        </wasReadFrom>
                    </Value>
                </sawValue>    
                <seenAtPort rdf:resource="http://www.example.com/workflow1#inName"/>
                <prov:hadTemporalValue rdf:parseType="Resource">
                    <time:inDateTimeXSD>2011-10-21T09:21:31Z</time:inDateTimeXSD>
                </prov:hadTemporalValue>
            </prov:Usage>
        </wf:usedValue>
        <wf:generatedValue>
            <prov:Generation>
                <sawValue>
                    <Value rdf:about="#sha1FromWorkflow">
                        <value>a33d1fb1658d4fbf017de59ab67437a3eb5ff50d</value>
                        <wf:sameValueAs rdf:resource="#sha1"/>
                    </Value>
                </sawValue>    
                <wasSeenAt rdf:resource="http://www.example.com/workflow1#sha1"/>
            </prov:Generation>
        </wf:generatedValue>
    </Process>

    <Process rdf:about="#constant">
        <wasDefinedBy rdf:resource="http://www.example.com/workflow1#String_Constant"/>
        <wasSubActivityOf rdf:resource="#workflowRun"/>
        <prov:startedAt>
            <time:Instant rdf:about="#t0">
                <time:inDateTimeXSD>2011-10-21T09:20:15Z</time:inDateTimeXSD>
            </time:Instant>
        </prov:startedAt>

        <prov:endedAt rdf:resource="#t0"/>
        <wf:generatedValue>
            <prov:Generation>
                <sawValue rdf:resource="http://www.example.com/workflow1#String_Constant_value"/>
                <prov:hadQualifiedEntity>
                    <Value rdf:about="#hello">
                        <value>Hello, </value>
                    </Value>
                </prov:hadQualifiedEntity>
                <prov:hadTemporalValue rdf:resource="#t0"/>
            </prov:Generation>
        </wf:generatedValue>
    </Process>

    <Process rdf:about="#combine">
        <wasDefinedBy rdf:resource="http://www.example.com/workflow1#cat"/>
        <wasSubActivityOf rdf:resource="#workflowRun"/>
        <prov:startedAt rdf:parseType="Resource">
            <time:inDateTimeXSD>2011-10-21T09:20:20Z</time:inDateTimeXSD>
        </prov:startedAt>
        <prov:endedAt rdf:parseType="Resource">
            <time:inDateTimeXSD>2011-10-21T09:20:25Z</time:inDateTimeXSD>
        </prov:endedAt>
        <wf:usedValue>
            <prov:Usage>
                <seenAtPort rdf:resource="http://www.example.com/workflow1#catIn1"/>
                <prov:hadQualifiedEntity rdf:resource="#hello"/>
                <prov:hadTemporalValue rdf:parseType="Resource">
                    <time:inDateTimeXSD>2011-10-21T09:20:21Z</time:inDateTimeXSD>
                </prov:hadTemporalValue>
            </prov:Usage>
        </wf:usedValue>
        <wf:usedValue>
            <prov:Usage>
                <sawValue rdf:resource="#input"/>
                <seenAtPort rdf:resource="http://www.example.com/workflow1#catIn2"/>
                <prov:hadTemporalValue rdf:parseType="Resource">
                    <time:inDateTimeXSD>2011-10-21T09:20:23Z</time:inDateTimeXSD>
                </prov:hadTemporalValue>
            </prov:Usage>
        </wf:usedValue>
        <wf:generatedValue>
            <prov:Generation>
                <sawValue>
                    <Value rdf:about="#combined">
                        <value>Hello, Steve</value>
                    </Value>
                </sawValue>    
                <seenAtPort rdf:resource="http://www.example.com/workflow1#catOut"/>
            </prov:Generation>
        </wf:generatedValue>
    </Process>
    <Process rdf:about="#shasum">
        <wasDefinedBy rdf:resource="http://www.example.com/workflow1#shasum"/>
        <wasSubActivityOf rdf:resource="#workflowRun"/>
        <prov:startedAt rdf:parseType="Resource">
            <time:inDateTimeXSD>2011-10-21T09:20:30Z</time:inDateTimeXSD>
        </prov:startedAt>
        <prov:endedAt rdf:parseType="Resource">
            <time:inDateTimeXSD>2011-10-21T09:21:00Z</time:inDateTimeXSD>
        </prov:endedAt>
        <wf:generatedValue>
            <prov:Generation>
                <sawValue>
                    <Value rdf:about="#sha1">
                        <value>a33d1fb1658d4fbf017de59ab67437a3eb5ff50d</value>
                    </Value>
                </sawValue>
                <wasSeenAt rdf:resource="http://www.example.com/workflow1#shaOut"/>
            </prov:Generation>
        </wf:generatedValue>
    </Process>
</rdf:RDF>
            

@prefix prov: <http://www.w3.org/ns/prov-o/> .
@prefix time: <http://www.w3.org/2006/time#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .

@prefix wf:   <http://www.example.com/scientific-workflow#> .
@prefix run:  <http://www.example.com/run1#> .
@prefix :     <http://example.com/aWorkflow> .

:workflowRun
    a wf:Process ;
    wf:wasDefinedBy <http://www.example.com/workflow1#workflow> ;
    wf:usedValue [
        a prov:Usage ;
        wf:sawValue   :input ;
        wf:seenAtPort <http://www.example.com/workflow1#inName> ;
        prov:hadTemporalValue [
            time:inDateTimeXSD "2011-10-21T09:21:31Z"
        ]
    ] ;
    wf:generatedValue [
        a prov:Generation
        wf:sawValue :sha1FromWorkflow ;
        wf:wasSeenAt <http://www.example.com/workflow1#sha1> ;
    ] ;
    wf:ranInWorkflowEngine :workflowEngine ;
    wf:wasLaunchedBy :aUser ;
    prov:endedAt [
        time:inDateTimeXSD "2011-10-21T09:23:32Z"
    ] ;
    prov:startedAt [
        time:inDateTimeXSD "2011-10-21T09:20:15Z"
    ] .

:aUser
    a prov:Agent, foaf:Person ;
    foaf:name "Stian Soiland-Reyes" .

:combine
    a wf:Process ;
    wf:generatedValue [
        a prov:Generation
        wf:sawValue :combined ;
        wf:seenAtPort <http://www.example.com/workflow1#catOut> ;
    ] ;
    wf:usedValue [
        a prov:Usage ;
        wf:seenAtPort <http://www.example.com/workflow1#catIn1> ;
        prov:hadQualifiedEntity :hello ;
        prov:hadTemporalValue [
            time:inDateTimeXSD "2011-10-21T09:20:21Z"
        ]
    ], [
        a prov:Usage ;
        wf:sawValue   :input ;
        wf:seenAtPort <http://www.example.com/workflow1#catIn2> ;
        prov:hadTemporalValue [
            time:inDateTimeXSD "2011-10-21T09:20:23Z"
        ]
    ] ;
    wf:wasDefinedBy <http://www.example.com/workflow1#cat> ;
    wf:wasSubProcessExecutionOf :workflowRun ;
    prov:endedAt [
        time:inDateTimeXSD "2011-10-21T09:20:25Z"
    ] ;
    prov:startedAt [
        time:inDateTimeXSD "2011-10-21T09:20:20Z"
    ] .

:combined
    wf:value "Hello, Steve" ;
    a wf:Value .

:constant
    wf:generatedValue [
        a prov:Generation ;
        wf:sawValue <http://www.example.com/workflow1#String_Constant_value> ;
        prov:hadQualifiedEntity :hello ;
        prov:hadTemporalValue   :t0
    ] ;
    wf:wasDefinedBy <http://www.example.com/workflow1#String_Constant> ;
    wf:wasSubProcessExecutionOf :workflowRun ;
    a wf:Process ;
    prov:endedAt   :t0 ;
    prov:startedAt :t0 .

:hello
    wf:value "Hello, " ;
    a wf:Value .

:input
    wf:value "Steve" ;
    wf:wasReadFrom :inputFile ;
    a wf:Value .

:inputFile
    wf:file "/tmp/myinput.txt" ;
    wf:value "Steve" ;
    a wf:FileValue .

:sha1
    wf:value "a33d1fb1658d4fbf017de59ab67437a3eb5ff50d" ;
    a wf:Value .

:sha1FromWorkflow
    wf:sameValueAs :sha1 ;
    wf:value "a33d1fb1658d4fbf017de59ab67437a3eb5ff50d" ;
    a wf:Value .

:shasum
    a wf:Process ;
    wf:generatedValue [
        wf:sawValue :sha1 ;
        wf:wasSeenAt <http://www.example.com/workflow1#shaOut> ;
        a prov:Generation
    ] ;
    wf:wasDefinedBy <http://www.example.com/workflow1#shasum> ;
    wf:wasSubProcessExecutionOf :workflowRun ;
    prov:endedAt [
        time:inDateTimeXSD "2011-10-21T09:21:00Z"
    ] ;
    prov:startedAt [
        time:inDateTimeXSD "2011-10-21T09:20:30Z"
    ] .

:t0
    a time:Instant ;
    time:inDateTimeXSD "2011-10-21T09:20:15Z" .

:workflowEngine
    a wf:WorkflowEngine .
				

Note that for brevity, the example above does not show the inferred classes and properties from the PROV ontology. For interoperability, applications should also expressed such inferred statements in its serialisations, so that the provenance can be read without using OWL2 inferencing and the customized ontologies.

See the workflow-inferred.rdf for the complete example showing both domain-specific and PROV ontology terms used side by side.