DDSIRTP2 — Supporting Inline QoS by Stateful Readers

Source:
Real-Time Innovations, Inc. (Ken Brophy, ken@rti.com)
Summary:
Stateful readers should be allowed to rely on cached information propagated by discovery of remote writers. Thus, support for receiving and parsing inline QoS should be optional for stateful readers.

In the case of mutable QoS, a tradeoff happens, where not parsing these inline QoS may delay the point in time when a new QoS takes effect, as it first must be propagated through discovery. A stateful implementation may expose this tradeoff to the user: minimize bandwidth usage by not sending mutated inline QoS or avoid this delayed effect of certain mutable QoS for guaranteed semantics.

Resolution:
Allow stateful implementations the choice of whether or not to parse inline QoS.

Revised Text:
Add as last paragraph of 8.7.1:

Stateful implementations can ignore inline QoS and rely solely on cached values obtained through discovery in order to improve performance. Note that not parsing inline QoS may delay the point in time when a new QoS takes effect, as it first must be propagated through discovery

see above