Writing an Associator Provider

The objectName argument in each of the association methods called by your client program, that is, CIMObjectPath, must be the object path of an instance, not a class.

Unless the CIM Object Manager sees the object path of an instance, it assumes that the client wants to see the class definitions of the association (the templates from which the association's member instances are derived) in the CIM Object Manager Repository, and will use the client API's association method and not that of the provider's.

The most important part of designing and coding an association is the association class itself. Your association will only be as complex as the contents of the association class. The number of members of the association equals the number of references in the association class. Roles can be used to model more complicated associations. Following are some sample association classes:

• An asymmetrical pair relationship, such as a one-to-one relationship between a teacher and a student, with two roles defined (teaches and taughtby):

  class TeacherStudent { Teacher REF teaches; Student REF taughtby; };

• A one-to-many relationship:

  class Classroom { Teacher REF teaches; Student1 REF taughtby; Student2 REF taughtby; Student3 REF taughtby; Student4 REF taughtby; };

• A many-to-many relationship:

  class TeachingAssistants { Assistant1 REF assists; Assistant2 REF assists; Student1 REF assistedby; Student2 REF assistedby; Student3 REF assistedby; Student4 REF assistedby; Student5 REF assistedby; };

• An association of more than two members of equal standing:

  class Club { Member1 REF; Member2 REF; Member3 REF; };

The following code sample implements the associators method. The CIM Object Manager passes values for associatorNames, objectName, role, resultRole, includeQualifiers, includeClassOrigin, and propertyList to the association provider. In addition, the code prints the name of the CIM associator class and the CIM class or instance whose associated objects are to be returned. This provider handles instances of example_teacher and example_student classes.

Example 4-3 CIMAssociator Provider

...

public CIMInstance[] associators(CCIMObjectPath assocName, CIMObjectPath 
                objectName, String resultClass, String role, String
                resultRole, boolean includeQualifiers, boolean 
                includeClassOrigin, String[] propertyList)
                throws CIMException {
        System.out.println("Associators "+assocName+" "+objectName);
      if (objectName.getObjectName()equalsIgnoreCase("example_teacher")) {
      Vector v = new Vector();
      if ((role != null)  && (!role.equalsIgnoreCase("teaches"))) {
        // Teachers only play the teaches role.
            return v;
        }
        if ((resultRole != null)  && (!resultRole.equalsIgnoreCase
                                     ("taughtby"))) {
        // Teachers only result in taughtby role
        return v;
        }
        // Get the associators of a teacher
        CIMProperty nameProp = (CIMProperty)objectName.getKeys().elementAt
                               (0);
        String name = (String)nameProp.getValue().getValue();
        // Get the student class
        CIMObjectPath tempOp = new CIMObjectPath("example_student");
        tempOp.setNameSpace(assocName.getNameSpace());
        CIMClass cc = cimom.getClass(tempOp, false);
        // Test the instance name passed by objectName
        // and return the associated instances of the student class.
        if(name.equals("teacher1")) {
                // Get students for teacher1
                CIMInstance ci = cc.newInstance();
                ci.setProperty("name", new CIMValue("student1"));
                v.addElement(ci.filterProperties(propertyList, 
                             includeQualifiers,
                        includeClassOrigin));
                ci = cc.newInstance();
                ci.setProperty("name", new CIMValue("student2"));
                v.addElement(ci.filterProperties(propertyList,
                        includeQualifiers, includeClassOrigin));
                return v;
        }
}