Information exchange decomposition across ports

[c_mathur@yahoo.com]

MD 18.5, SP2, UPDM 2

Hello, I’m trying to figure out how best to represent information exchange (IE)
decomposition as it flows to various layers of the architecture. Please refer to the attached diagram.
Here, an external system interacts via System Port A. The information exchange IE1 represents some abstract of information being exchanged between the external and the system.
This information is then ‘decomposed’ into IE2 and relayed to a part of the system, ResourceRole 1, via Port B.

What should be the proper relationship between IE1 and IE2? Composition? Inheritance? Details?
What is the correct way to represent the ports in this case? Full ports typed by a structured type which in turn is responsible for decomposing IE1 into IE2?

Thank you,

Cm.