Allow the message pump to be paused temporarily

[kbaley]

To stop receiving and processing messages, users have to stop the whole endpoint and restart it again when they want to consume messages again. This has several disadvantages:

• When the endpoint is stopped, no messages are being processed
• Restarting is an intensive operation
• Starting/stopping and endpoint doesn't work with the generic host (probably the most common host in the future) as NServiceBus uses the host-managed DI container and NServiceBus can't really handle this as it needs ServiceCollection access during start time which no longer possible when the host has been started.

Instead, the endpoint should allow to pause and resume just the message pump without shutting down anything else.

Relevant links

• Discourse thread opened by an user: https://discuss.particular.net/t/nservicebus-extensions-hosting-is-it-possible-to-stop-and-restart-an-endpoint/2159/6

[SeanFeldman]

Pausing receiving is a missing feature.
This would help in the scenarios described here. The ability to dial down concurrency on failures with automatic rate limitting is not applicable. It needs to be something that allows a temporary pause.

Also, when considering this feature, consider serverless scenarios where the transport is out of the picture (scenario 1) or when a timer trigger is used and the NSB receiver could be wired up (scenario 2).