C2MS11 — REQUEST-ID as "Replacement" and related STOP

Numerous field tables in C2MS allow reusing the same REQUEST-ID for a request to provide a "replacement". For example, MVAL REQ Message says in the Fields table (Table 8-99) under REQUEST-ID:

"ID to identify the request message - if different request messages have the same value, the request is a replacement; else, it is a new request"

In all cases, this is the only explanatory text of what is meant by "replacement". This is pretty ambiguous about expected result. So, for example,

• If I send an initial request to start receiving MVAL A and B, and then send another request of the same REQUEST-ID for MVAL C, is the result that I'm now subscribed to A, B and C, or just to C?

• If I send a request to start receiving MVAL X and Y with a PUBLISH-RATE of 1 and then send another request for a duration of 120 minutes, and then send another request wit the same REQUEST-ID for MVAL Y with a PUBLISH-RATE of 5, am I subscribed to X at 1 and Y at 5, or just Y at 5?

There's no description of semantics regarding what is being replaced.

A related issue is STOP request, specifying non-symmetrical MVALs, and what to do in that situation.

• If I send a request to start receiving MVAL 11 and 12, and then send a STOP, but only specify MVAL 11, do I still get 12?

In C2MS 1.0, in every instance of sending a REQUEST-ID as part of a request, the Notes for the field states the identical, "ID to identify the request message – if different request messages have the same value, the request is a replacement; else, it is a new request." However this copy-paste doesn't always make sense.

Re-use of a REQUEST-ID only makes sense if the request leaves some process continuing to fulfill data streaming. Only two request messages have a start/stop concept. Therefore, this resolution assumes no other messages have a use case for 'replacement' and removes the confusing extra text.

Additionally, the concept of 'replacement' is not needed in the two cases where start/stop actions are present... just stop the old one and start a new one. Using 'replacement' can lead to confusion.

Do it in 1.1

Remove the reference about replacement from the Notes column of the corresponding table for messages that don't have any ongoing aspect controlled by start/stop. These are the following:

• Archive Message Retrieval Request Message (Table 8-20)
• Directive Request Message (Table 8-32)
• Archive Mnemonic Value Request Message (Table 8-114)
• Command Request Message (Table 8-131)
• Product Request Message (Table 8-146)
• Simple Service Request Message (Table 8-160)

Modify the text and table notes associated with the following messages to include explanation of the re-use of REQUEST-ID.

• Replay Telemetry Data Request
• Mnemonic Value Request Message