Post to WebSocket Broadcaster (Dart)

A little server application that listens for HTTP POST requests and broadcasts the body of the request to all connected websockets.

Built using Shelf, Shelf Router, Web Socket Channel, and Shelf Web Socket.

Running the server application

By default, the POST server listens on port 8080 and the WebSocket server listens on port 8081, but you can set the POST_PORT and WS_PORT environment variables to change the ports that each server listens on.

Only supports binding to IPV4 addresses.

With the Dart SDK

Please install the Dart SDK if you haven't already.

Pre-compiling

You can compile the server to a native executable, and run that:

$ dart pub get && dart compile exe bin/server.dart && bin/server.exe
POST Server listening on port 8080
WebSocket Server broadcasting on port 8081

Running directly

You can also run the script directly with the dart command.
This is worse for performance (CPU & RAM) than pre-compiling, however.

$ dart pub get && dart run bin/server.dart
POST Server listening on port 8080
WebSocket Server broadcasting on port 8081

With Docker

If you have Docker installed, you can build and run with the docker command.

$ docker build . -t myserver
$ docker run -it -p 8080:8080 -p 8081:8081 myserver
POST Server listening on port 8080
WebSocket Server broadcasting on port 8081

Connecting to and using the server application

You'll need to have the server application running somewhere, on your own localhost for example.

Firstly, you should connect a websocket client, otherwise the received POST messages will have nowhere to be broadcast to.

For example, you can use the websocat command line tool:

$ websocat ws://127.0.0.1:8081/
Hello from the server!

Then, you can send a POST request to the server. You'll get the message echoed back to you.

You can use curl to do this:

$ curl -X POST 127.0.0.1:8080/post -d "Hello from a POST request"
Hello, World

Then, you should see the message printed in the websocket client:

$ websocat ws://127.0.0.1:8081/
Hello from the server!
+ Hello from a POST request

In the server terminal, you should see some logs printed:

POST Server listening on port 8080
WebSocket Server broadcasting on port 8081
WebSocket connection established
+ post: Hello from a POST request
+ 2023-10-13T16:52:26.601238  0:00:00.011524 POST    [201] /post