B4J Question How To Tell Websocket Is Already Initialized

B4XDev · Jan 17, 2023

I have a button a user can push to subscribe to additional channels (using websocket client). How do I tell after the first subscription is started that the websocket client is already ~~up and running~~ connected/initialized and doesn't need to be initialized again?

There is no isInitialized() method, so is it just a matter of using a Try...Catch?

I'm going to experiment in the meantime, but what's the preferred method?

EDIT: Clarified some terms

Chris2 · Jan 18, 2023

If you're using WebSocketClient there's a connected property:

B4X:

Private wsc As WebSocketClient

Public Sub isConnected As Boolean
    Return wsc.Connected
End Sub

Although I guess it might fail if the WebSocketClient hadn't been initialised?

teddybear · Jan 17, 2023

I can't get your question, what is that the websocket is already up and running? you mean using jserver or a b4j app?

B4XDev · Jan 17, 2023

I'm connecting to a remote server's websocket. It is not under my control.

I've modified my OP to more clearly state that I'm asking about the websocket client, not server.

I don't have to connect to the websocket until the user wants to open a channel. I want to see if the websocket has already been initialized.

It would also be helpful to know if the websocket was initialized prior to closing the app, as I attempt a websocket.close call.

teddybear · Jan 17, 2023

I guess you do websocket at client. you have to do new websocket at first, but you may set a boolean as its initialized state after conneting success.
or you also check websocket.readyState to see if it has already been initialized.

B4XDev · Jan 17, 2023

teddybear said:
...but you may set a boolean as its initialized state after conneting success.

Yes, a global var would do it, but that seems smelly.

teddybear said:
or you also check websocket.readyState to see if it has already been initialized.

I can't find a readyState() on the websocket. I will do a search for it.

ADDED: There doesn't seem to be a readyState() for a websocket client. I did notice one available for websocket servers.

teddybear · Jan 18, 2023

B4XDev said:
I can't find a readyState() on the websocket. I will do a search for it.

ADDED: There doesn't seem to be a readyState() for a websocket client. I did notice one available for websocket servers.

The readyState is a state of websocket, as I said, you have to new WebSocket at the first, you can do like this

B4X:

ws = new WebSocket("yoururl");
console.log(ws.readyState)

You can also test ws whether it is be defined or ws.readyState to see if it has already been initialized.

A way to do this is to initialize the websocket once after page onloaded, and then use it in send or onmessage event each time，you don't need to consider whether it has been initialized

B4XDev · Jan 18, 2023

teddybear said:
The readyState is a state of websocket, as I said, you have to new WebSocket at the first, you can do like this

B4X:

ws = new WebSocket("yoururl"); console.log(ws.readyState)

I am looking for a B4X solution, not a Javascript solution.

Chris2 · Jan 18, 2023

If you're using WebSocketClient there's a connected property:

B4X:

Private wsc As WebSocketClient

Public Sub isConnected As Boolean
    Return wsc.Connected
End Sub

Although I guess it might fail if the WebSocketClient hadn't been initialised?

B4XDev · Jan 18, 2023

Chris2 said:
If you're using WebSocketClient there's a connected property:

B4X:

Private wsc As WebSocketClient Public Sub isConnected As Boolean Return wsc.Connected End Sub

Although I guess it might fail if the WebSocketClient hadn't been initialised?

Wait wait wait. How did I miss that?!!? Wow. I got tunnel vision on that one, for sure! Looking for "IsInitialized" and completely missed "Connected." Wow.

Thank you!

BTW: Using ws.Connected prior to ws.Initialize() seems to work just fine and provides the functionality I was needing.

B4J Question How To Tell Websocket Is Already Initialized

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