Bug? jServer - websocket disconnected event doesn't fire

[LucaMs]

When my b4a websocket client loses connection (the client websocket disconnected event fires) the server websocket disconnected event doesn't fire.

 

[Erel]

It can take awhile. It will fire eventually.

 

[LucaMs]

I waited about 8 minutes... nothing.

 

[Erel]

Are you able to reproduce it when running the server in release mode?

 

[LucaMs]

Yes, I tested in release mode (both, client & server)

 

[Erel]

Are you able to reproduce it? Does it happen every time that the clients disconnects?

 

[LucaMs]

Are you able to reproduce it?

Well, I'm trying my proejcts.

Does it happen every time that the clients disconnects?

I forced the disconnection, turning off the device wifi; tried 4-5 times, same result.

 

[Erel]

Please try to reproduce it in a small server project and upload it.

 

[LucaMs]

Nothing special.

You should change "TO CHANGE" texts

 

[Erel]

I've tested your project. This is the output:

Waiting for debugger to connect...
Program started.
2017-05-12 08:08:14.755:INFO::main: Logging initialized @584ms
2017-05-12 08:08:14.823:INFOejs.Server:main: jetty-9.3.z-SNAPSHOT
2017-05-12 08:08:14.890:INFOejsh.ContextHandler:main: Started o.e.j.s.ServletContextHandler@5ebec15{/,file:///C:/Users/H/Downloads/tbookDemo/SERVER/Objects/www,AVAILABLE}
2017-05-12 08:08:14.892:INFOejs.AbstractNCSARequestLog:main: Opened C:\Users\H\Downloads\tbookDemo\SERVER\Objects\logs\b4j-2017_05_12.request.log
2017-05-12 08:08:15.087:INFOejs.ServerConnector:main: Started ServerConnector@4c83e535{HTTP/1.1,[http/1.1]}{0.0.0.0:51042}
2017-05-12 08:08:15.087:INFOejs.Server:main: Started @918ms
Emulated network latency: 100ms
RemoteIP: 192.168.0.7
WebSocket_Disconnected
RemoteIP: 192.168.0.7
WebSocket_Disconnected
RemoteIP: 192.168.0.7
WebSocket_Disconnected
RemoteIP: 192.168.0.7
WebSocket_Disconnected


My guess is that something on your network causes it to think that it is still connected. It will probably be disconnected eventually.

 

[LucaMs]

How did you disconnect the client?

 

[LucaMs]

How did you disconnect the client?

It does not matter; even by pressing the Disconnect button, the server does not trigger the disconnect event (here )

 

[LucaMs]

My guess is that something on your network causes it to think that it is still connected

It is very likely: I still have the problem UpgradeRequest.RemoteAddress, which returns the router wan IP.

 

[LucaMs]

It does not matter; even by pressing the Disconnect button, the server does not trigger the disconnect event (here )

This is not true: pressing the Disconnect button the disconnect event (on server) is raised; turning off the device wifi, not.
Anyway the problem should be somewhere in my LAN.

[changed the sources posted in #9]

 

[Erel]

I was able to reproduce it by turning off Wifi. The idle timeout is set to 3 hours. So the client will eventually disconnect.

You can add this code to help it find that there is no connection:

Private Sub WebSocket_Connected (WebSocket1 As WebSocket)
   ws = WebSocket1
   tmr.Initialize("tmr", 1000)
   tmr.Enabled = True
End Sub

Sub tmr_Tick
   ws.RunFunction("NOP", Null)
   ws.Flush
   Log("tick")
End Sub

 

[LucaMs]

Thank you, Erel.

Using your code I should add another timer (as you know I asked if there are problems in using many timers...).

Also, one of the useful characteristics of websocket is that there is no need (for client) to poll constantly the connection but with that workaround this feature is (almost) lost (almost, because the code is server code).

For the moment I'm glad that my LAN is not the problem (in this case ).

 

[Erel]

Using your code I should add another timer (as you know I asked if there are problems in using many timers...).

It will have zero effect on the server performance.

 

[LucaMs]

It will have zero effect on the server performance.

How is it possible? Every second the server will try to send a msg to each client!

By the way, by looking at the code again I do not understand what happens when the server is unable to "run" the "NOP" routine on clients.

 

[Erel]

I was talking about the fact that you add a timer for each connection.

Every second the server will try to send a msg to each client!

There are many messages being sent by the client and the server. It is unlikely that this will have any effect on the server performance. You can also change the timer to run every 10 seconds or more. It shouldn't really matter.

I recommend you to focus on getting the solution to work. It will not be slow because of a "ping" request.

I do not understand what happens when the server is unable to "run" the "NOP" routine on clients.

Nothing will happen. The CallSub will do nothing because there is no matching sub.

Anyway, for further discussion please start a new thread in the questions forum.

 

[LucaMs]

for further discussion please start a new thread in the questions forum

This is not a question :

The workaround Erel suggested, if I understand well, is not enough.

The timer (tmr in that example) should "run" a client routine but:

1) that routine should exist on client (with a name like "SrvPing")
2) the client should respond, calling a server routine (like "CltPong")
3) another timer is needed, to wait for the "client pong"; when this time is expired we can consider the client disconnected.

All this only because the Disconnected event does not fire (more exactly, the server websocket does not result disconnected).