Understanding security and topic filtering

Topic security is validated by the PubSub Engine before a publication is forwarded to a subscriber. If the subscriber is not permitted to receive the topic data, the subscriber receives a "no more publishers" message for the topic instead. This message is the only indication the subscriber receives if the publication is blocked for security reasons.

Subscribers are free to apply additional filtering after a publication is delivered. A common example of this is when a subscriber skips processing a topic because it does not match the desired topic name or pattern.