ODRL Requirement 1.9 - Issues List

"Provide an aligned constraint data model."

Last modified: 29th November 2004

Editor(s): The ODRL Initiative

Constraint Model Draft:

ODRL supports the expression of Rights Constraints. This is the recognised set of restrictions on the Permissions over the Asset.

<constraint>  
 <CONSTRAINT-ELEMENT type="TYPE" status="VALUE">
  <OPERATOR type="METER">value/right operand </OPERATOR>
 </CONSTRAINT-ELEMENT>
</constraint>

The operator type is always infix. The constraint element, such as country and datetime, serve as "left operand". The value within the operator element is always the "right operand". When the constraint is evaluated by the DRM system, the mathematical operation " operator " is solved and delivers a boolean value. The "left operand" triggers the "current" value of the constraint type, e.g. current datetime, current location, current number of uses. (Note that for all constraints the DRM systems requires a "sensor", i.e. a function that can determine the current time, current location, etc.) If the operation result is true, the parent permission will be granted. If several constraints apply, all constraints have to be evaluated before the permission is granted.

This is the list of issues the ODRL Initiative has considered, when addressing the respective requirement (see above).

Issue Summary:

IssueID:	State:	Comment:
issue01 - Shall ODRLv2 allow for a context element to further specify the constraint?	in discussion	-
issue02 - Shall ODRLv2 allow for nested constraints?	in discussion	-
issue03 - How do we express "and", "or", "xor" constraints?	in discussion	-
issue04 - Do we need type for a meter in the "right operand"?	in discussion	-
issue05 - Do we need type for a meter in the "constraint"?	in discussion	-
issue06 - Do we keep "count"? What does count exactly mean?	in discussion	-
issue07 - How does the constraint - duty fulfilled look like?	in discussion	-
issue08 - How does the OMA profile change with ODRLv2?	in discussion	-
issue09 - Do we want to allow Unicode Mathematical Operators?	in discussion	-

Please send additional comments to the odrlV2 discussion list at any time.

Issue Details:

issue01 -Shall ODRLv2 allow for a context element to further specify the constraint?
Pro:
- OMA uses the context element in their ODRL profile.
- Version 1.1 suggests to use uid of context element to further specify user constraints, device constraints, watermark constraint.
- Allows to further specify the constraint - also for the human reader
Contra:
- Allowing extra information in the context element makes is harder to exactly identify the constraint that has to be evaluated. Constraint might get ambiguous.
Solution Approaches:
- As mostly only the UID is required of the context element, a special operator "equals" could be used. For example:
```
<constraint>  
 <individual>
 <equals>sguth </equals>
 </individual>
</constraint>
```
issue02 - Shall ODRLv2 allow for nested constraints?
Pro:
- Two constraints can be nested together, i.e. cond. A and cond B have to be met.
Contra:
- Nesting gets ambiguous with three constraints.
Solution Approaches:
- No, do not allow for neste constraint. Group constraints that belong together (connected by "and", "or", "xor") on the same level. Relate the constraints directly to the respective permission.
issue03 - How do we express "and", "or", "xor" constraints?
For example, the permission is granted if one/all/either one or the other constraint(s) is met.
Solution Approaches:
- Creating various permissions with different constraints. Depending on the environmental conditions either the one or the other (or non) Permission will be granted.
issue04 - Do we need type for a meter in the "right operand"?
For example, to indicate a time zone for datetime.
issue05 - Do we need type for a meter in the "constraint"?
For example, to indicate the granularity of the spatial constraint (Country, City, Continent, etc.)
issue06 - Do we keep "count"? What does count exactly mean?
Does count always refer to the parent permission/or parent constraint? (See ODRL example #3 in version 1.1)

issue07 - How does the constraint - duty fulfilled look like? Solution Approaches:

<constraint>  
 <duty>
 <fulfilled>duty01</fulfilled>
 </duty>
</constraint>

issue08 - How does the OMA profile change with ODRLv2?