Creating Relationships Between Objects: Associations

You can create an Association object and use it to specify a relationship between any two objects. The ebXML specification specifies an AssociationType classification scheme that contains a number of canonical concepts you can use when you create an Association. You can also create your own concepts within the AssociationType classification scheme.

The canonical association types are as follows:

• AccessControlPolicyFor

• AffiliatedWith, which has the subconcepts EmployeeOf and MemberOf

• Contains

• ContentManagementServiceFor

• EquivalentTo

• Extends

• ExternallyLinks

• HasFederationMember

• HasMember

• Implements

• InstanceOf

• InvocationControlFileFor, which has the subconcepts CatalogingControlFileFor and ValidationControlFileFor

• OffersService

• OwnerOf

• RelatedTo

• Replaces

• ResponsibleFor

• SubmitterOf

• Supersedes

• Uses

The Registry uses some of these association types automatically. For example, when you add a Service to an Organization, the Registry creates an OffersService association with the Organization as the source and the Service as the target.

Associations are directional: each Association object has a source object and a target object. Establishing an association between two objects is a three-step process:

1. Find the AssociationType concept that you want to use, or create one.

2. Use the LifeCycleManager.createAssociation method to create the association. This method takes two arguments, the target object and the concept that identifies the relationship.

3. Use the RegistryObject.addAssociation method to add the association to the source object.

For example, suppose you have two objects, obj1 and obj2, and you want to establish a RelatedTo relationship between them. (In this relationship, which object is the source and which is the target is arbitrary.) First, locate the RelatedTo concept:

// Find RelatedTo concept for Association
String concString = 
    CanonicalConstants.CANONICAL_ASSOCIATION_TYPE_ID_RelatedTo;
Concept relConcept = (Concept) bqm.getRegistryObject(concString);

Create the association, specifying obj2 as the target:

Association relAssoc =
     blcm.createAssociation(obj2, relConcept);

Add the association to the source object, obj1:

obj1.addAssociation(relAssoc);

Finally, save the association:

Collection associations = new ArrayList();
associations.add(relAssoc1);
BulkResponse response = blcm.saveObjects(associations);

Associations can be of two types, intramural and extramural. You create an intramural association when both the source and target object are owned by you. You create an extramural association when at least one of these objects is not owned by you. The owner of an object can use an access control policy to restrict the right to create an extramural association with that object as a source or target.

Creating Associations: Example

For an example of creating an association, see JAXRPublishAssociation.java in the directory <INSTALL>/registry/samples/publish-association/src/. This example creates a RelatedTo association between any two objects whose unique identifiers you specify. For example, you could specify the two child organizations created in Creating and Retrieving an Organization Hierarchy: Examples.

To Run the JAXRPublishAssociation Example

Steps

1. Go to the directory <INSTALL>/registry/samples/organizations.

2. Retrieve the organization hierarchy by running the following command:

   asant search-fam

   Notice the key ID strings of the two child organizations.

3. Go to the directory <INSTALL>/registry/samples/publish-association.

4. Type the following command:

   asant run -Did1=string1 -Did2=string2

   Replace string1 and string2 with the two child organization ID strings.

   Whether the association is intramural or extramural depends upon who owns the two objects. In this case, the association is intramural.