websocketd | uses STDIN/STDOUT into a WebSocket server | Websocket library

What you're asking for is not how it works. You don't program websocketd and it doesn't have any events. You use as a stand-alone tool to wrap some other program and then each incoming connection starts an instance of the program you've configured it to wrap. Then, any incoming messages are send to stdin of that program and any stdout response from the program is sent back to the client that connected to the websocket server. You can think of it like a tool that just forwards incoming websockets messages to stdin of your app and captures the output and forwards that back to the client.

As you presumably know, the idea is that without doing any server programming yourself, you could create a remote interface to any command line tool on your computer (with the associated caveats/risks that has) that expects to get its input from stdin and writes its output to stdout. That remote interface could be in a web page or could be any other program you write that uses a webSocket to communicate with the websocketd server you configured and ran on your host. So you only write the client-side of things. The websocketd doc does not say what it does with output that it finds on stderr.

When a web socket client connects to this websocket server, an instance of your program will get started up. So, in essence, the onconnect event is that your program started. When the client disconnects, it will kill your program (that's essentially the onclose event).

It is not clear what it does if it gets webSocket errors in sending data back to the client. You'd have to dissect the code here https://github.com/joewalnes/websocketd to try to figure that out (it appears to be written in go. Presumably, since it's a server itself and there's no interface, probably the most that happens is that the error is logged or maybe the webSocket is disconnected. Without modifying the code, there's no provision for you to participate in what happens when there's a webSocket communication error. The daemon has a preprogrammed behavior.

I do see examples here in the code where it deals with errors from reading stdout and it logs those errors and then closes the stdout stream.

The code here appears to close the incoming webSocket if it gets errors while reading from it.

Ok, it seems to do anything beyond the basics in MIT App Inventor 2 you need to add "extensions" which is what I was missing from my google search terms.

Specifically the following extension did exactly what I was needing - hope it's of help to other people who stumble upon this question (including me in the future!):

https://community.appybuilder.com/t/websocket-client-extension/1761

Finally I noticed that using the websocketURI with the host-name of the server machine (in my case raspberrypi did NOT work - I had to use the IP address. If anyone know why that might be and how to make the host-name discoverable on android please let me know!

This stand-alone example will

1. Read a python script from a web socket
2. Write the script to the file system
3. Run the script with output buffering disabled
4. Read the script output one line at a time
5. Write each line of output to the web socket

A simpler solution would be to put this in your server script:

As far as I am aware, setting the value of an input programmatically will not focus it, nor will it trigger a keyup event to trigger. You can, however, trigger the focus event or keyup event manually after the WebSocket sends a message. This may be what you're looking for;

You said you cover your async_write with a strand. But you do no such thing. All you can be seen doing is wrapping the completion handlers in that strand. But you're posting the async operations directly.

What's worse, you're doing it from the main thread, while there are async operations underway on any of the threads associated with your WSClient instances which means you're concurrently accessing object instances that aren't thread-safe.

That's a data race, so you get Undefined Behaviour.

A naive fix might be:

Description of websocketd from the url you provided

It takes care of handling the WebSocket connections, launching your programs to handle the WebSockets, ....

So basically websocketd is trying to execute server.bash which doesn't work because windows doesn't recognize this file as executable. This script was probably meant to be run on linux in the first place however if you have installed bash already on windows u can try running it by replacing