twerk is a node.js module that makes sending and receiving messages on a stream a piece of cake.
$ npm install twerk
twerk turns an I/O stream into a set of individual messages using a simple framing protocol. It dices a stream into the pieces you actually intended to send them in. It works as an adapter, and the API works as a drop-in "replacement" for net.Stream:
var socket = twerk(stream);
socket.on("connect", function() {
console.log("I'm connected! Yes!");
});
socket.on("data", function(msg) {
console.log(data);
});
socket.on("close", function() {
console.log("Lost my connection! Oh noes!");
});
twerk uses a very simple protocol that allows it to quickly determine when it has received a complete message, and where the boundaries of messages are on the stream. At the stream level, twerk looks like this:
=> "0,"
<= "0,"
=> "5,hello"
<= "7,goodbye"
It's simple: the message length is sent as text followed by a comma, and then the message payload. Heartbeats are encoded as zero-length messages: "0,". When the connection is established, a simple handshake is used: both sides send a heartbeat message. When either side receives the first heartbeat, it's assumed that the other side is ready to receive messages.
As stated previous, twerk is just an adapter. It exposes itself as a function, which takes two arguments: the first being a stream, which is required, and the second being an options hash. It returns an object that has the same interface as a stream, but is doing message framing underneath the covers.
twerk(stream, {
heartbeatInterval: 5000, // milliseconds between heartbeat messages
heartbeatTimeout: 20000 // number of milliseconds to wait for a heartbeat
});
That's it.
- Twerk only supports UTF-8 message encoding right now.
- This is pretty new code, and while the test coverage is decent, it hasn't been put through enough rigor to be considered "production ready."