token as a *composition* of tokenLocator

This is feedback on my usage of WS-CDL CR:

 

 

The association between token and tokenLocator in CDL is composition, rather
than aggregation. I am using the UML definition of composition: it means the
tokenLocator cannot exist before, after, or independently of its token.

 

As a composition association I would expect tokenLocator to appear as a
child element of token. In the CDL CR XML Schema schema token and
tokenLocator are siblings, which is what I would expect if the association
was aggregation and not composition.

 

The problem I have is that the text of the CDL specification leads me to
think the association is composition, whereas the CDL schema leads me to
think the association is aggregation. From reading the specification I would
instead expect to see:

 

            <complexType name="tToken">

                        <complexContent>

                                    <extension
base="cdl:tExtensibleElements">

                                                <sequence>

                                                            <element
name="tokenLocator" type="cdl:tTokenLocator" minOccurs="0"
maxOccurs="unbounded"/>

                                                </sequence>

                                                <attribute name="name"
type="NCName" use="required"/>

                                                <attribute
name="informationType" type="QName" use="required"/>

                                    </extension>

                        </complexContent>

            </complexType>

 

Was the distinction between composition and aggregation ever formalized in
the WS Choreography Model Overview? Is there an updated version of the Model
Overview available?

 

Matthew Rawlings

+44 791 539 7824