DDSIRTP26 — How to implement ignore_subscription for remote subscribers?

The DDS API spec allows me to ignore a (remote) subscription, meaning that I act as if it doesn't exist. That means for a publisher that it will not have a proxy-reader for that participant, and it will never unicast data to it.

But what if:

• The Writer has three remote readers: A, B and C to which it is connected.
• The writer's participant decides to ignore reader C.

Since our writer is still connected to Readers A and B, it is still multi-casting its data to them. Since in this case the readerId mentioned the header of this data is set to ENTITYID_UNKOWN, the reader has no way of knowing it was supposed to be ignored by its Writer, unless there is a special protocol message which informs the reader that it is now considered ignored by the Writer, and it isn't supposed to accept its messages anymore. However, such a protocol message currently doesn't exist.

For secure communication we could make it work without adding an additional protocol message (since there the Writer may list the GUIDs of all destination readers, and in case a Reader isn't listed anymore it could skip the message). But for non-secure communication we need to come up with some kind of solution here.

This doesn't concern just the ignore_subscription function, but also the ignore_participant function since I would assume I do not intend to just ignore the publishers of a remote participant, but also its subscribers.