halsim_ws_client sending unnecessary web socket messages even for undefined devices?

[nl2005]

Hello all

I am trying to work on some hardware via the websocket protocol. What I noticed is that halsim_ws_client seems sending a lot of requests even for devices that's not defined in the FRC code. For example, there are only 2 motors in the java code, but the WS messages is sending message like "{
"data": {
"<init": false
},
"device": "15",
"type": "PWM"
}"

There is really no device 15. Is that expected behavior? How can we tell the simulator only send data/request for defined devices?

For a fast laptop or newer device (e.g. Romi), that did not create a problem. However for lower-end CPU device (e.g. Lego Ev3), the web socket server can not keep it up - even for optimized micropython code - the data is just too much, causing a significant delay on robot movement.

I did find the undocumented "HALSIMWS_FILTERS" environment variable that limit message type, that dramatically cutdown the volume and allow the robot to function well, but no messages should be sent for non-exist device to flood the web socket server though even just for allowed message type (e.g. PWM).

Any insight is appreciated!

[sciencewhiz]

You might want to look at halsim_xrp, which is much more efficient then the web sockets, and was created since the XRP couldn't keep up.
https://github.com/wpilibsuite/allwpilib/tree/18321e55515bf441ba2b0a5c5e67032c18c177a9/simulation/halsim_xrp

[nl2005]

Thanks. But I am not sure if I follow you… when student run their code, they set up host ip in gradle config file, select run simulation code, which launches this halsim client DLL and communicates with a WS server on that IP. Are you saying the xrp simulator can be launched independently and replace the halsim client DLL for non-xrp hardware?(i do not plan to buy xrp robot). If so, how?

[PeterJohnson]

Yes, both the WS protocol and the XRP protocol are implemented with halsim extensions. The XRP template build.gradle shows how to enable/configure that extension (https://github.com/wpilibsuite/vscode-wpilib/blob/7f0180f7a3aeaded52beccba2f33481834f593f2/vscode-wpilib/resources/gradle/javaxrp/build.gradle#L44).

[nl2005]

Thanks. Looks like I'll have to write a non-WS server running on my EV3 because although JSON message format is same, the server receive messages differently (UDP vs TCP/Http/WS?). I switched the setting in build.gradle from WSClient to XRPClient and the robot did not move, which was expected.

I guess for now I'll stick with WSClient + HALSIMWS_FILTERS to filter out only the active message type, then see if anyone else will comment on why WSClient is sending those extra, seemly unnecessary (e.g. non-exist device ) messages, and if there is a way to restrict them.