DDSIRTP2 — Clarify Writer Response to ACKNACK

Source:
Real-Time Innovations, Inc. (Ken Brophy, ken@rti.com)
Summary:
Requirement 8.4.2.2.4 should be clarified: a writer does not only respond with data or a GAP as stated. Rather, since a writer may have KEEP_LAST semantics and so may not offer the requested sample anymore, it may also respond with a new HB indicating the requested sample is no longer available. This is the mechanism to trigger a reader's onDataLost callback.

Resolution:
Clarify 8.4.2.2.4 to include a Writer's response of a HB to an ACKNACK requesting a sample that the writer does not have available.

Revised Text:
Revise first paragraph of 8.4.2.2.4:
When receiving an ACKNACK Message indicating a Reader is missing some data samples, the Writer must respond by either sending the missing data samples, sending a GAP when the sample is not relevant, or sending a Heartbeat when the sample is no longer available.

see above