[SignalR/Java clients] - null object reference on transportenum

[NunoPontes]

Is your feature request related to a problem? Please describe.

I'm trying to build an Android app that receives messages from SignalR.
The problem that I am having is that after the server timeout, which the default is 30 seconds, I won't receive anymore information and have to reconnect manually, meanwhile I might have missed data.

Example: I am trying to do a list that gets a new item when signalR sends the object to the app, however the interval between messages isn't constant, it can be 30 seconds or 1 hour.

Describe the solution you'd like

I would like a flag where we can disable server timeout, meaning that while we don't stop the connection the client is always listening for messages from SignalR. Perhaps the setServerTimeout can receive a null, and when it does it never timesout

Additional context

When we try to reconnect manually we might lose information.
I'm currently using version 3.1.11, because the 5.0.2 causes my app to constantly crash and this is the only version where I can make SignalR work

[BrennanConroy]

after the server timeout, which the default is 30 seconds, I won't receive anymore information

Is the connection getting closed? Did you modify the server-sides KeepAliveInterval?

5.0.2 causes my app to constantly crash

Are you getting the errors described in #29457?

[NunoPontes]

Hello @BrennanConroy,

I dont' have access to the server side, so I only changed on the Java client, by changing serverTimeout.

val timeout: Long = 100000
        hubConnection = HubConnectionBuilder.create(
            URL
        )
            .shouldSkipNegotiate(true)
            .withHandshakeResponseTimeout(timeout)
            .withTransport(TransportEnum.WEBSOCKETS)
            .build()
        hubConnection?.serverTimeout = timeout
        hubConnection?.keepAliveInterval = timeout

        hubConnection?.start()
        hubConnection?.onClosed { exception: Exception ->
            Timber.e("onClosed " + exception.message.toString())
            runOnUiThread {
                Toast.makeText(
                    this,
                    hubConnection?.connectionState?.name,
                    Toast.LENGTH_LONG
                ).show()
            }
            runOnUiThread(Runnable {
                Toast.makeText(this, "signalr " + exception.message.toString(), Toast.LENGTH_LONG)
                    .show()
            })
            hubConnection?.stop()
            startHub()
        }

Using the 5.0.2 I get the following crash, it's not the one you referenced:

java.lang.NullPointerException: Attempt to invoke virtual method 'int com.microsoft.signalr.TransportEnum.ordinal()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int com.microsoft.signalr.TransportEnum.ordinal()' on a null object reference
        at com.microsoft.signalr.HubConnection.lambda$start$10$HubConnection(HubConnection.java:267)
        at com.microsoft.signalr.-$$Lambda$HubConnection$l-M-k_a4jmA6PuMbiVuiDtdeomw.apply(Unknown Source:8)
        at io.reactivex.internal.operators.single.SingleFlatMapCompletable$FlatMapCompletableObserver.onSuccess(SingleFlatMapCompletable.java:83)
        at io.reactivex.internal.observers.ResumeSingleObserver.onSuccess(ResumeSingleObserver.java:46)
        at io.reactivex.internal.operators.single.SingleJust.subscribeActual(SingleJust.java:30)
        at io.reactivex.Single.subscribe(Single.java:3603)
        at io.reactivex.internal.operators.single.SingleDefer.subscribeActual(SingleDefer.java:43)
        at io.reactivex.Single.subscribe(Single.java:3603)
        at io.reactivex.internal.operators.single.SingleDelayWithCompletable$OtherObserver.onComplete(SingleDelayWithCompletable.java:69)
        at io.reactivex.subjects.CompletableSubject.subscribeActual(CompletableSubject.java:157)
        at io.reactivex.Completable.subscribe(Completable.java:2309)
        at io.reactivex.internal.operators.single.SingleDelayWithCompletable.subscribeActual(SingleDelayWithCompletable.java:36)
        at io.reactivex.Single.subscribe(Single.java:3603)
        at io.reactivex.internal.operators.single.SingleFlatMapCompletable.subscribeActual(SingleFlatMapCompletable.java:44)
        at io.reactivex.Completable.subscribe(Completable.java:2309)
        at io.reactivex.Completable.subscribe(Completable.java:2383)
        at com.microsoft.signalr.HubConnection.start(HubConnection.java:328)

I have talked to whom manages the server side and he's setting the following flags:

options.ClientTimeoutInterval = TimeSpan.FromMinutes(6);
options.KeepAliveInterval = TimeSpan.FromMinutes(3);

[BrennanConroy]

So you've set the server timeout to 100 seconds and the server is only sending keep alives every 180 seconds. It's recommended for the server timeout to be double the keep alive interval, and definitely not lower than the interval.

I've never seen that null reference before. I'll need to look into how that's possible.

Thanks for contacting us.
We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we are planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[dsuresh-ap]

We have been seeing Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int com.microsoft.signalr.TransportEnum.ordinal()' on a null object reference as well in our non-fatal logging from users. Not sure what is causing it.