feat: extract message routing from the message pump

[stijnmoreels]

Extracts the message routing that includes the selection of the correct registered message handler for the incoming message to be processed.

Because the MessagePump and by result the AzureServiceBusMessagePump already contained methods like ProcessMessageAsync which handles this message routing, we can only mark them as obsolete but can't change them in any way.

This PR includes the introduction of the IMessageRouter and IAzureServiceBusMessageRouter which is the exact functionality of this message routing. The AzureServiceBusMessagePump already uses this router so the existing tests will suffice to make sure that this routing is still valid. An extra interface for the Service Bus was required, because the message handling required specific Service Bus operations calls and the original Service Bus message upon fallback.

Implementation of POC: https://github.com/stijnmoreels/arcus.messaging.azurefunctions
Relates to #127

[stijnmoreels]

Currently WIP, TODO list:

• Message routing implementation
• Unit tests to proof message routing implementation
• Feature docs update to specify how consumers can use this routing in their own projects (ex. Azure Functions).

[stijnmoreels]

I've not updated the MessagePump (yet) with using the IMessageRouter instead, because that would mean that we require such a registration in the IServiceProvider; which would mean that we fail when there's no such registration. And this is actually a breaking change, so I've let the protected methods on the pump as-is but marked them all obsolete until we can safely in a new major version break this.

[stijnmoreels]

OK, after reading all the remaining comments, there's only 2 that remains unsolved, and that's the mentioning of the .AddMessageRouting in the Customization feature docs (which we will discuss offline).

And the question how this extraction should be called 'Router' or 'Processor' or ... (honestly, if it were 'Processor' it would be confusing in combination with the handlers. "Process" <> "Handle" message?)

[tomkerkhove]

Let's stick with Router then.

OK, after reading all the remaining comments, there's only 2 that remains unsolved, and that's the mentioning of the .AddMessageRouting in the Customization feature docs (which we will discuss offline).

What is this topic again?

[stijnmoreels]

Let's stick with Router then.

OK, after reading all the remaining comments, there's only 2 that remains unsolved, and that's the mentioning of the .AddMessageRouting in the Customization feature docs (which we will discuss offline).

What is this topic again?

Described here: https://github.com/arcus-azure/arcus.messaging/pull/141/files#diff-a29b66ed26917dda14cce134994c1fd15605f0ecfbc72dd180eb355be4ee0b7cR71
Under the topic Extending the Message Router
Altough it seems reasonable to mention this if we're talking about extending and customization. It's already an advanced topic.

[tomkerkhove]

Let's stick with Router then.

OK, after reading all the remaining comments, there's only 2 that remains unsolved, and that's the mentioning of the .AddMessageRouting in the Customization feature docs (which we will discuss offline).

What is this topic again?

Described here: #141 (files)
Under the topic Extending the Message Router
Altough it seems reasonable to mention this if we're talking about extending and customization. It's already an advanced topic.

Sure thing, but it's pending a reply from you, no?

[stijnmoreels]

Let's stick with Router then.

OK, after reading all the remaining comments, there's only 2 that remains unsolved, and that's the mentioning of the .AddMessageRouting in the Customization feature docs (which we will discuss offline).

What is this topic again?

Described here: #141 (files)
Under the topic Extending the Message Router
Altough it seems reasonable to mention this if we're talking about extending and customization. It's already an advanced topic.

Sure thing, but it's pending a reply from you, no?

No, it's anwsered here: #141 (comment), but can be disussed offline.

[stijnmoreels]

Hm then I'm confused - Do I always have to call AddMessageRouting or not? Because you've mentioned that the message pump registration handles it for us; or is it only for Azure Service Bus?

Yes, we have to call it always, but it's being called behind the scenes with the Azure Service Bus message pump registration.

This was the latest awnsered question. But maybe you'll need to revisit the PR to know what's going on again 😄 .

[tomkerkhove]

Super helpful, thanks!

[tomkerkhove]

I see the PR closes the issue, did we add the handler for Functions as well? Think I saw it but want to be sure.

[stijnmoreels]

I see the PR closes the issue, did we add the handler for Functions as well? Think I saw it but want to be sure.

We can include that in #154 I guess. But I'll change it bc it's technically indeed not completely done. ☺️