B4J Question Websocket: when terminated

wl · Nov 1, 2016

Hi,

When I call a b4j_connect I understand a new instance of the corresponding websocket class is instantiated.

When does this instance gets destroyed: is there some kind of timeout ?
For example: a websocket gets created (and the WebSocket_Connected is called) but then no call is being made (indefintely) ?

Thanks

billzhan · Nov 1, 2016

WebSocket_Disconnected is something you are looking for, close DB connections in this sub.

This sub may not be called immediately when the connection is broken.

B4X:

Private Sub WebSocket_Disconnected
End Sub

wl · Nov 2, 2016

billzhan said:
WebSocket_Disconnected is something you are looking for, close DB connections in this sub.

This sub may not be called immediately when the connection is broken.

B4X:

Private Sub WebSocket_Disconnected End Sub

Indeed this method is not called when the connection is not propertly closed.
For a server running 24/7 I guess there must be something to clean up these dangling connections ?

Tx

Erel · Nov 2, 2016

It will be eventually raised. If you want to have more control over it then run a JQuery method with a timer every few seconds. It will cause the logical connection to break if there is no actual connection.

wl · Nov 2, 2016

Erel said:
It will be eventually raised. If you want to have more control over it then run a JQuery method with a timer every few seconds. It will cause the logical connection to break if there is no actual connection.

When the connection drops a timed jquery from the client will never reach the server (and would thus make no difference), but I guess you meant that the server is to check (also with a timer) that a heartbeat was received. If so: that's exactly what I am doing at this moment/

Erel · Nov 2, 2016

wl said:
When the connection drops a timed jquery from the client will never reach the server (and would thus make no difference)

It will raise an error that will cause the connection to disconnect.

billzhan · Nov 2, 2016

Add a server side event(which does nothing) in a timer. B4J server will try to send a message.

B4X:

Sub Timer1_tick
   ws.Eval("null;",Null)
   ws.flush
End sub

billzhan · Nov 2, 2016

Remember to disable the timer

B4X:

Private Sub WebSocket_Disconnected
     timer1.enable = False
End Sub

mindful · Nov 2, 2016

billzhan said:
Add a server side event(which does nothing) in a timer. B4J server will try to send a message.

B4X:

Sub Timer1_tick ws.Eval("null;",Null) ws.flush End sub

I got faster disconnect times using :

B4X:

Sub Timer1_Tick
  Try
    Dim browserCheck as Future = ws.EvalWithResult("return null", Null)
    Dim getValue as Object = browserCheck.Value
    Log("Client browser reachable")
  Catch
    Log("Client browser NOT reachable")
  End Try
End Sub

The websocket raises the disconnected event faster in my case ... tested with a timer interval of 10 seconds, connecting from my phone and turning Airplane mode ON.

B4J Question Websocket: when terminated

wl

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billzhan

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wl

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Erel

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wl

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Erel

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billzhan

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billzhan

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mindful

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