XML

ODRL Policy expressions can be encoded in XML [[xml]] serialisations as defined by XML Schema [[xmlschema11-1]] and XML Datatypes [[xmlschema11-2]]. All of the ODRL Vocabulary IRIs used in ODRL XML instances MUST follow those defined in the ODRL Vocabulary.

Each of the classes from the ODRL Information Model [[!odrl-model]] will be represented by an XML element of the same name. Additionally, each class property will be represented as an XML attribute of the parent element. The fixed values defined in the ODRL Information Model are represented as enumerated types. Cardinalities are also represented with XML Schema occurrence rules. Attributes are optional unless explicitly noted as REQUIRED.

Note that the Rule class is not represented in the XML encoding, only the child classes; Permission, Prohibition, and Duty.

Note that the Policy Type MAY infer additional constraints and requirements on the cardinalities of XML elements. See the definition of the Policy Subclasses for further details.

XML Elements and Attributes

The Policy element contains the following attributes:

• uid - an IRI (REQUIRED)
• type -an IRI (REQUIRED)
• conflict - fixed enumeration (defined in XML Schema)
• inheritFrom - an IRI
• profile - an IRI (REQUIRED when using an ODRL Profile)

NOTE: The type attribute is used to express the ODRL Policy subclass.

The Policy element MAY contain the following elements:

• permission, and/or
• prohibition, and/or
• obligation

The Policy element MAY contain the following policy-level elements that apply to all Rules (see ODRL Rule Composition).

• asset,
• party, and/or
• action

The Policy element MAY also contain Dublin Core elements to support Policy metadata.

The Policy element MAY also contain constraint elements which are Constraints referenced by either another constraint element or Logical Constraint within a Rule. Note that these Constraints are not to be interpreted as a direct constraint of all Rules.

The Asset class is a single asset element to represent both the Asset uid and how it is related to the Rule. The Asset element contains the following attributes:

• uid - an IRI
• relation - an IRI
• type - an IRI
• partOf - an IRI
• source - an IRI
• id - an local identifier for this element
• idref - a reference to an Asset element

Asset element attributes MUST be used as defined by one of the sets of attributes and their cardinalities below:

1. uid (REQUIRED), relation (REQUIRED), type (OPTIONAL), id (OPTIONAL), or
2. idref (REQUIRED)

The asset element may also contain the refinement element for asset collections.

The Party class is a single party element to represent both the Party uid and the functional role to the Rule. The Party element contains the following attributes:

• uid - an IRI
• function - an IRI
• type - an IRI
• partOf - an IRI
• source - an IRI
• id - a local identifier for this element
• idref - a reference to a Party element

Party element attributes MUST be used as defined by one of the sets of attributes and their cardinalities below:

1. uid (REQUIRED), function (REQUIRED), type (OPTIONAL), id (OPTIONAL), or
2. idref (REQUIRED)

The party element may also contain the refinement element for party collections.

The Permission element contains the following elements:

• asset (REQUIRED)
• action (REQUIRED)
• constraint
• party
• duty

The Prohibition element contains the following elements:

• asset (REQUIRED)
• action (REQUIRED)
• constraint
• party
• remedy

The Duty element contains the following elements:

• action (REQUIRED)
• constraint
• asset
• party
• consequence

The Duty element contains the following attributes:

• uid - an IRI
• id - a local identifier for this element
• idref - a reference to an Duty element

Duty element attributes MUST be used as defined by one of the sets of attributes and their cardinalities below:

1. uid (OPTIONAL), or
2. id (REQUIRED), or
3. idref (REQUIRED)

The Action element contains the following attributes:

• name - an IRI
• id - a local identifier for this element
• idref - a reference to an Action element

Action element attributes MUST be used as defined by one of the sets of attributes and their cardinalities below:

1. name (REQUIRED), id (OPTIONAL), or
2. idref (REQUIRED)

The action element may also contain the refinement element.

The Constraint element contains the following attributes:

• name - an IRI for the leftOperand or logical operand (for Logical Constraints)
• operator - an IRI
• rightOperand - string or IRI, space separated list for set values (must be a list of Constraint identifiers for a Logical Constraint)
• rightOperandReference - an IRI
• dataType - an IRI
• unit - an IRI
• status - string
• id - a local identifier for this element
• idref - a reference to an Constraint element

NOTE: The Constraint name attribute is called leftOperand in the ODRL Information Model.

Constraint element attributes MUST be used as defined by one of the sets of attributes and their cardinalities below:

1. name (REQUIRED), operator (REQUIRED), rightOperand and/or rightOperandReference (REQUIRED), dataType (OPTIONAL), unit (OPTIONAL), status (OPTIONAL), id (OPTIONAL), or
2. idref (REQUIRED)

Logical Constraint element attributes MUST be used as defined by the sets of attributes and their cardinalities below:

1. name (REQUIRED), rightOperand (REQUIRED)

In some cases where Duties refer to (external) Assets, it will be necessary to package the ODRL XML expression with the representation of that (external) Asset. This XML Encoding specification does not mandate any specific packaging mechanism as communities will utilise their preferred options for data interoperability.

XML Example

The below example shows the XML serialisation of an ODRL Policy including some metadata about the Policy. In this example, the target asset and assigner and assignee parties are defined at the policy-level, and hence, are applied to both permission rules. The first permission allows the assignee to play the target asset as long as they accept they will be tracked. The second permission allows the assignee to distribute the target asset to the identified country (Italy) for a compensation payment of EUR5,000.

<o:Policy xmlns:o="http://www.w3.org/ns/odrl/2/" xmlns:dc="http://purl.org/dc/terms/" 
          type="http://www.w3.org/ns/odrl/2/Agreement"
          uid="http://example.com/policy:9001" 
          profile="http://example.com/odrl:profile:10X">
    <dc:creator>Acme Enterprises</dc:creator>
    <dc:issued>2017-01-01T12:00</dc:issued> 
    <o:asset uid="http://example.com/music:4545" 
             relation="http://www.w3.org/ns/odrl/2/target"/>
    <o:party uid="http://example.com/sony"
             function="http://www.w3.org/ns/odrl/2/assigner"/>
    <o:party uid="http://example.com/billie"
             function="http://www.w3.org/ns/odrl/2/assignee"/>
    <o:permission>
        <o:action name="http://www.w3.org/ns/odrl/2/play"/>
        <o:duty>
            <o:action name="http://www.w3.org/ns/odrl/2/acceptTracking"/>
        </o:duty>
    </o:permission>
    <o:permission>
        <o:action name="http://www.w3.org/ns/odrl/2/distribute"/>
        <o:constraint name="http://www.w3.org/ns/odrl/2/spatial" 
                      operator="http://www.w3.org/ns/odrl/2/eq" 
                      rightOperand="http://vocab.getty.edu/tgn/1000080"/>
        <o:duty>
            <o:action name="http://www.w3.org/ns/odrl/2/compensate">
               <o:refinement name="http://www.w3.org/ns/odrl/2/payAmount"
                   operator="http://www.w3.org/ns/odrl/2/eq"
                   rightOperand="5000.00" 
                   unit="http://dbpedia.org/resource/Euro"/>
            </o:action>
        </o:duty>
    </o:permission>  
</o:Policy>

XML Linking

To support repeating the same element content across Permissions and Prohibitions, the Asset, Party, Constraint, Action, and Duty elements support the xml id and idref attributes. Any of these element that has been identified using the id attribute can then be referred to by an element with the same name using the idref attribute. In this case, the referring element must have no other content.

As shown in the below example, the Prohibition refers to elements defined in the Permission, except for the Constraint element. In this case, the assignee can play the music asset in Italy but not in France.

<o:Policy xmlns:o="http://www.w3.org/ns/odrl/2/"
          type="http://www.w3.org/ns/odrl/2/Set"
          uid="http://example.com/policy:Z1XZ"
          profile="http://example.com/odrl:profile:10X">
  <o:permission>
     <o:asset id="as1" uid="http://example.com/music:1234908"
                 relation="http://www.w3.org/ns/odrl/2/target"/>
     <o:action id="ac1" name="http://www.w3.org/ns/odrl/2/play"/>
     <o:constraint id="c1" name="http://www.w3.org/ns/odrl/2/spatial"
                       operator="http://www.w3.org/ns/odrl/2/eq"
                       rightOperand="http://www.itu.int/tML/tML-ISO-3166:it"/>
     <o:party id="p1" uid="http://example.com/sony:10" 
                 function="http://www.w3.org/ns/odrl/2/assigner"/>
     <o:party id= "p2" uid="http://example.com/billie:888" 
                 function="http://www.w3.org/ns/odrl/2/assignee"/>
   </o:permission>
   <o:prohibition>
     <o:asset idref="as1"/>
     <o:action idref="ac1"/>
     <o:constraint name="http://www.w3.org/ns/odrl/2/spatial" 
                      operator="http://www.w3.org/ns/odrl/2/eq"
                      rightOperand="http://www.itu.int/tML/tML-ISO-3166:fr"/>
     <o:party idref="p1"/>
     <o:party idref="p2"/>
   </o:prohibition>
</o:Policy>

Note that there is an important distinction when using this feature with the Duty element which also has the uid attribute. The uid attribute is used to refer to the same Duty from multiple Permissions. In this case the Duty has to be performed only once to gain access to all the Permissions. When using the id and idref attributes then the semantics change as in this case the Duty must be performed for each time it is referenced (potentially, many times). Note that the use of the uid and id attribute for the same Duty element is not permitted.

Logical Constraints

To support Logical Constraints, Constraint objects can be expressed at the Policy level and locally identified with the id attribute. The Logical Constraint (in the Rule) can then refer to these Constraints using its #id in the leftOperand, and the logical relationship in the name attribute.

ODRL XML processing systems MUST detect the use of #id in the rightOperand in Logical Constraints. If detected, the processing model for Logical Constraints (defined in [[!odrl-model]]) MUST then be followed.

The below example shows two Constraints defined with ids C1 and C2. The Logical Constraint in the Permission refers to these using the #C1 and #C2 values in the rightOperand, and the logical relationship (xone) in the name attribute.

<o:Policy xmlns:o="http://www.w3.org/ns/odrl/2/"
          type="http://www.w3.org/ns/odrl/2/Offer"
          uid="http://example.com/policy:9001"
          profile="http://example.com/odrl:profile:10X">
    <o:party uid="http://example.com/billie"
             function="http://www.w3.org/ns/odrl/2/assignee"/>
    <o:permission>
        <o:asset uid="http://example.com/music:4545" 
                 relation="http://www.w3.org/ns/odrl/2/target"/>
        <o:action name="http://www.w3.org/ns/odrl/2/distribute"/>
        <o:constraint name="http://www.w3.org/ns/odrl/2/xone"
                      rightOperand="#C1 #C2"/>
    </o:permission> 
</o:Policy>
...
<o:constraint id="C1" name="http://www.w3.org/ns/odrl/2/spatial" 
                  operator="http://www.w3.org/ns/odrl/2/eq" 
                  rightOperand="http://vocab.getty.edu/tgn/1000080"/>
				  
<o:constraint id="C2" name="http://www.w3.org/ns/odrl/2/spatial" 
                  operator="http://www.w3.org/ns/odrl/2/eq" 
                 rightOperand="http://vocab.getty.edu/tgn/1000090"/>