C2MS11 — All Messages Subclass Message Header

The way the UML is shown for each message, each C2MS message inherits the Message Header type. This isn't really semantically correct.

Consider the diagram from section 8.6.3.3 (although this is true throughout all message specifications), which is included as Attachment 1. Organized this way, this UML means that Telemetry TDM Frame Message IS A Message Header, rather than that it contains a Message Header.

THere are two options for making this a little more clear:

Option A is that Instead, they should be subclasses of something called "C2MS Message" that itself contains a Message Header, as shown in Attachment 2, in which Telemetry TDM Frame Message IS A C2MS Message, and all C2MS Messages contain a Message Header.

Option B is to use composition where each message contains a message header. This is as shown in Attachment 3.

It's not a major point, but would increase readability and have better optics.

After discussion, Option B seems like the right choice.

Documentation Change to be Made in 1.1

The following changes will be made:

1. Update text in Section 8.1 C2MS Message Header to remove the concept that all C2MS Messages are sub-classes of C2MS Message Header, but rather are sub-classes of a new C2MS Message class that comprises a C2MS Message Header.
2. Modify Figure 8-2. Message Header Diagram to show the new C2MS Message class containing the Message Header, as shown in the attachments.
3. Make the changes to all Message Diagrams, beginning with Figure 8-4. Archive Message Retrieval Request Diagram and ending with Figure 8-40. Tracking Data Message Diagram to make the message contain, rather than specialize the C2MS Message Header.
   • This is illustrated in the attached before and after diagrams for the Telemetry TDM Frame Message.
   • The identical pattern will be applied across all the above mentioned figures.

If this proposal is accepted, a complete set of before and after images will be provided as part of the RTF Report

• Note that the final images may be a convergence with other voted in global changes, such as is proposed with C2MS11-59. In other words, if this proposal is accepted and C2MS11-59 is also accepted, both sets of changes will be made in the final "after" images in the RTF Report.