ESP8266 Community Forum

I'm trying to evaluate using the ESP8266 for a new product and I'm stuck. I set up a simple test app that's supposed to connect, send a short message, get the reply, disconnect, and then repeat.

I am able to connect and send/receive data, but the socket close command doesn't seem to work correctly.

I noticed that I wasn't always seeing the print statement I had in the close callback and that the available heap kept getting smaller with every iteration. At some point I noticed that the close messages that I do get all have a "something went wrong" exit code -99, and I assume that is the root of my problem.

I simplified the code as much as possible so that now it's pretty much the same as the example code from the nodemcu.readthedocs page. I tried putting the ws:close call in the receive callback and I've also tried calling it from a tmr.create():alarm(1000, tmr.ALARM_SINGLE... function and the results are the same.

Here's the minimal version of the code that's failing:

    local ws = websocket.createClient()
    ws:on("connection", function(ws)
      print('got ws connection')
      ws:send('hello!')
    end)
    ws:on("receive", function(_, msg, opcode)
      print('got message:', msg, opcode) -- opcode is 1 for text message, 2 for binary
      ws:close()
    end)
    ws:on("close", function(_, status)
      print('connection closed', status)
      ws = nil -- required to lua gc the websocket client
    end)
   
    ws:connect('ws://echo.websocket.org')

Here are the results from Lualoader:
dofile("websocket2.lua")
> got ws connection
got message: hello! 1
connection closed -99

I should have the latest version - I did a build from the master branch at nodemcu-build.com earlier this week.
Am I doing something wrong? Have other people successfully used websockets with this device?

Thanks
Glen

I got an email back from the developer of this module. Apparently the -99 return code is a minor bug and always happens when you initiate a close. I still haven't been able to make the test where I open the socket, send a message, and then close the socket work reliably though.

The following is the terminal output with my current code after adding some manual garbage collection statements to see if that is a part of the problem. It looks like quite often something just isn't letting go when I try to close - and it takes the module 10 minutes to figure it out and resume normal operation.



I have concerns about scope in my code where I'm relying on the callbacks that live inside the send_websocket_message function to still work after the function has exited, but I ran into problems trying to move the callbacks outside of send_websocket_message. When I do that with the ws_connect function my call to ws:send results in a panic message because the websocket isn't connected - but the whole reason we got into ws_connect was because of the "connection" event. I don't know what I'm doing wrong - I'm pretty new to lua scripting.

Here's the code with the calls inside the send_websocket_message function. This code resulted in the output I posted above:


Here is the code with the callbacks moved out - this code doesn't work at all, but I don't know why