Copyright © 2006 Open Geospatial Consortium, Inc. All Rights Reserved.
Copyright © 2006 Open Geospatial Consortium, Inc. All Rights Reserved.
Page 54 of 131 Item
Reference in
Reference in
Comparison Resource
Licence. Resource
Resource. Identity
Equal or consistent with a larger group. Parameter
Values Process.
Request Licence.
Constraints. Parameters
Consistency, usually as a containment test.
Issuer Licence.
Issuer Resource.
Owner The licence must have been issued by the
owner of the resource or by his agent. The owner
→ agent relation must be available to the Licence validation process.
Each right can be associated to conditions based on the semantics of the right. Once a right is established its definition cannot change without affecting existing licences.
Therefore, once defined and accepted as a standard, a right shall not change in its meaning or structure. Each right defined in the schema shall maintain its fundamental
definition in the documents associated to the schema. Each right defined in an external registry will carry a dated definition in that registry.
Further, once a licence is issued, it must not be changed only the issuer prior to delivery may change a licence. A licence that needs to be modified shall be replaced by the
issuer. This frozen nature of a licence is a fundamental part of the security and trust model within DRM, and once changed a licence is invalid.
A licence shall specify an Issuer. The Issuer of a licence must have the right to grant rights specified in the licence
9.2 User Metadata
The basic user metadata is identity. Participants in a DRM system principals in terms of ISO 21000 shall be identified uniquely, so that associations by reference can be traced to
them.
9.3 Properties and patterns
In this reference model for the informational viewpoint, property formalisms were chosen to support the evaluation of conditions. In such formalisms, descriptors are associated to
base objects, as opposed to embedded within them in attribute formalisms. In implementations, either formalism may be used since carry the same information. The
property formalisms are more appropriate here since the actual structure of abstract classes, types and interfaces are not known.
Property formalisms in implementations can be very flexible in handling ad hoc situations without the need to extend or modify classes. They have the disadvantage of
requiring a more flexible and adjustable code, as structure is often being discovered at the same time that instance values are found. Implementations for document metadata using
property formalism are quite common for example, Microsoft
®
Office.
Copyright © 2006 Open Geospatial Consortium, Inc. All Rights Reserved.
Copyright © 2006 Open Geospatial Consortium, Inc. All Rights Reserved.
Page 55 of 131 Attribute formalisms have the advantage of predetermined data structures, which can
make a non-object-oriented code much simpler. The disadvantage is the lack of flexibility in ad hoc situations.
Patterns are collections of conditions that define collections of entities. As such, it is easy to match a pattern to a particular instance, but difficult to enumerate the set that the
pattern defines. For example, it is easy to ask, “Is this principal a US resident?”, meaning that there must be a verifiable property attached to the principal declaring his citizenship
or resident status, but it is difficult to ask, “Who are the US residents?”, so much so that the US government tries for an accurate list only once every 10 years, during the census,
after which there is a constant debate as to its accuracy until the next one is taken.
All entities in this information model shall be “matchable” to patterns based on their attributes, properties and relations. All match requests return true if and only if verifiable
information is available to assure a logical match. A failure to find such information shall always result in a “no match” or false result within or from the GeoDRM Gatekeeper.
9.4 Resource Metadata
