README
Node Socket Packet Assembler
This wrapper for Node's net.Socket waits for and emits the previously set number of bytes read from the stream (not more, not fewer).
You can use custom event names instead of data, which may make your code more understandable.
It can be useful if you are implementing a custom protocol over TCP.
What problem does it solve?
No matter in what timing the bytes are received, no matter how many bytes are emitted in Socket's data event,
this wrapper emits the requested number of bytes (and no more) only when they all have been received.
So if the bytes you wait for from the stream are processable as a whole, you don't need to
check the length of Buffers nor slice and concatenate them.
Installation
Add it to your project using a package manager, eg.
npm install socket-packet-assembler --save
To run tests:
npm test
Public API
class SocketPacketAssembler extends events.EventEmitter
constructor(socket: net.Socket)
Initialize a new assembler on given socket.readonly origSocket: net.Socket
The Socket object which is wrapped.readBytes(bytesToRead: number, identifier: string = "data"): void
Set how many bytes you want to receive in the next event. You may use a custom event name (identifier).
If there are enough bytes in the internal buffer at the time of call, it triggers the event asynchronously.
It can't be called again until the event is triggered.
Example
const SocketPacketAssembler = require('socket-packet-assembler');
tcpServer.on('connection', socket => {
// Wrap new socket as soon as we get it
const assembler = new SocketPacketAssembler(socket);
assembler.on('greeting', buffer => {
// These are the first 64 bytes the client sent,
// you should process the buffer here
// (which contains exactly 64 bytes).
// Now we wait for the first 1024-byte message
assembler.readBytes(1024, 'message');
});
assembler.on('message', buffer => {
// This is a 1024-byte message,
// you should process the buffer here
// (which contains exactly 1024 bytes).
// Wait for another message
assembler.readBytes(1024, 'message');
});
// At first, we wait for some kind of greeting from client,
// which must be 64 bytes.
assembler.readBytes(64, 'greeting');
});