David:
Can you please clarify what header elements, if present in the message being
encapsulated, need to be copied to the encapsulating message?
Also, if the purpose of the encapsulation is to have both the header
container and the payload container(s) of the original message encrypted,
are you assuming that all such encrypted messages destined for one PartyId
would be encrypted using the same encryption key and algorithm? Otherwise,
how can the encapsulated messages be properly decrypted by the same Service
(uri:www.oasis-open.org/messageService/)?
If the purpose of encapsulation is to send fragments of a large message as
multiple encapsulated messages, then the Receiving MSH must recombine the
fragments into the original message before "reprocessing it as a new
message".
Regards,
-Arvola