SignalR Java client: disposing Completable returned by HubConnection.start() does nothing

[Bludator]

Describe the bug

It is not possible to prevent HubConnection from starting with dispose call on Completable returned by HubConnection.start().
By looking at the code there is no doOnDispose or alike

If one is unaware of this, it could lead to unwanted connections.

To Reproduce

HubConnection hubConnection= HubConnectionBuilder.create(...)...;
hubConnection
    .start()
    .subscribe(connection->/*do something*/)
    .dispose(); // this does nothing, connection is created

Further technical details

• Client version: 6.0.0-preview.7.21378.6

[BrennanConroy]

If one is unaware of this, it could lead to unwanted connections.

If we added some doOnDispose type thing you could still run into the same issue if start has already completed by the time you call dispose. I don't see this as being a very important scenario to fix as it has extremely limited scope unless I'm missing something.

[Bludator]

In the heat of debugging it didn't come to my mind that connection.stop() works even on not completely started connection. Now I realized I ultimately want that the connection.stop() is called in doOnDispose. Which I could do in my code but I think it is not unreasonable to add it directly to the start method.
(Well I could do in next version: #28608)

[BrennanConroy]

This sounds like adding "cancellation token" support to the Java client, not against it.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.