How to add Execution Occurrences to sequence diagrams via the API in Rational Rhapsody

Answer

You need to add the Execution Occurrence directly to the diagram message, rather than to the diagram's collaboration object.

1. Setup objects for sequence diagram:
   IRPApplication app = RhapsodyAppServer.getActiveRhapsodyApplication();
 IRPPackage pkg = (IRPPackage)app.getSelectedElement();
 IRPClass ClassA = pkg.addClass("ClassA");
 IRPClass ClassB = pkg.addClass("ClassB");
 IRPOperation OpB = ClassB.addOperation("OperationB");
   
   
   
2. Create collaboration for SD behaviour:
   IRPCollaboration Collab = app.activeProject().getNewCollaboration();
   
   
   
3. Add objects to Collab object:
   IRPClassifierRole crClassA = Collab.addClassifierRole("ClassA", ClassA);
 IRPClassifierRole crClassB = Collab.addClassifierRole("ClassB", ClassB);
 IRPMessage msg = Collab.addMessage(OpB, "", crClassA, crClassB);
   
   
   
4. Add SE to message
   IRPExecutionOccurrence eo = msg.addSourceExecutionOccurrence();
   
   
   
5. Create sequence diagram from collaboration object:
   IRPSequenceDiagram SD = Collab.generateSequence("MySD", pkg);