What is a DEX

["Barker, Sean (UK)" <sean.barker@baesystems.com>]

At DEX 3 meeting, we had a discussion arising from the definition of a
DEX in the context of Task-list. The discussion is summarized in the
attached figure. Essentially the question is whether the message entity
is part of the DEX, but the argument goes as follows:

1) A DEX is a design, rather than a physical file (DEX as Realized).

2) Create temporary term "DEX content item", meaning everything but the
message.

3) An exchange consists of a message AND [[Exactly one DEX content item]
OR
							[Many DEX
content item]]

The user requirement (Norwegian Frigate) was for many DEX content items.

4) A DEX is either [The DEX content items] OR [The message entity AND
the DEX content items]

The preferred solution was [Message AND DEX content items] (Bottom
right, in red).

In the case of DEX 3, the content item is a Task, and
Message.Content_item[i] points to each Task.
No DEX can contain the content of any other DEX.

5) Note: the various items in the DEX are independent of each other, and
the fact that they come as a collection is merely a convenience, for
example, to avoid having to manage too many files. Tool vendors have a
valid input at this point. The number of items per DEX may be restricted
by business rule.

6) We can now delete the term "DEX content item", and say, say, DEX 3
contains a message and several Task descriptions.

Note: The users have decide to restrict the scope of DEX 3 to Task. This
is narrower than the original Task-set, wherein the Task-set would
define a collection for a specific purpose and provide any appropriate
meta-data. Discussions have been started about generalizing DEX 5 to
cove such a requirement.

DO NOT SHOOT THE MESSENGER.

Sean Barker
0117 302 8184



********************************************************************
This email and any attachments are confidential to the intended
recipient and may also be privileged. If you are not the intended
recipient please delete it from your system and notify the sender.
You should not copy it or use it for any purpose nor disclose or
distribute its contents to any other person.
********************************************************************

dex_is_a.ppt