Assistance with Relationships

[kirk.wilson@ca.com]

Ive been struggling through the discussion of Relationships in MUWS2, and finding it rather difficult.

First, it is not clear what resource supports the RelationshipAccess capabilitythe participant or a resource representing the relationship itselfand precisely what the RelationshipAccess capability provides.

Secondly, there are several typos.  I detailed the most serious one (bogus reference to section 4.2.2) in my previous email to the list.  There are also several minor errors:  In section 4.1.1 the multiplicity of the Relationship property is [1]it should be [*] as shown in 4.1.3; in section 4.1.2.2, line 1081 refers to AccessEndpointReference, whereas 1121 uses an AccessEndpoint element; also line 1153 should be EndpointRefERence.  The XML example in 4.1.4.1 lines 1193-1195 isnt even well formed XML--see line 1194.

I believe a relationship type corresponds to an association in UML and relationship itself corresponds to a link in UML, i.e., an instance of an association.  Does anyone know if that is the intention?  (If that is the case, the text probably shouldnt talk about instance of a relationship, because a relationship is already an instance.  It should talk about instances of relationship TYPES.)

There is a difference between the arity of a relationship type (UML association) and the multiplicity of the relationship type.  Basically, arity relates to how many roles there are in the relationship and thus, basically, how many <Participant> elements there is in a <Relationship> element.  Multiplicity relates to how many <Relationship> elements (links) there will be for each relationship type.  For example, a three way relationship type will basically have three participants in all of its <Relationship> elements.  On the other hand, a relationship type, whose multiplicity is 1 to many would return the following <Relationship> elements when queried on the Participant1 endpoint (assuming an arity of 2, of course):

<Relationship>
	<Type></Type>
	<Participant>Participant1</Participant>
	<Participant>Participant2</Participant>
</Relationship>
<Relationship>
	<Type></Type>
	<Participant>Participant1</Participant>
	<Participant>Participant3</Participant>
</Relationship>
<Relationship>
	<Type></Type>
	<Participant>Participant1</Participant>
	<Participant>Participant4</Participant>
</Relationship>
etc.

The Relationship Name element is optional and Im unclear whether it is expected that each relationship (link) in a 1 to many relationship type should have a same or different name.  The <Type> definition should be same.

Is my interpretation correct?  Any assistance on this would be greatly appreciated.