dgramx v1.0.0

dgramx

An enhanced Node.js dgram module.

This module extends the functionality of the internal dgram. By default, the on() and emit() method in dgram module acts just same as EventEmitter does, but this module change the way of how they bind a listener and emit an event.

This module allows you bind custom events, and instead of emitting them by the current object, the event will be emitted by the remote peer, just like how socket.io does, and build communication in a more easier way.

Example

const { createServer, createClient } = require("dgramx");

let addr = "udp://127.0.0.1:12345";
var server = createServer(addr);
var client = createClient(addr);

server.on("listening", () => {
    let { address, port } = server.address();
    console.log("Server listening at: %s:%d", address, port);
}).on("greet", (msg, rinfo) => {
    console.log(msg); // => Hello, World!

    // reply
    server.to(rinfo.address, rinfo.port).emit("reply", "Message recieved.");
});

client.bind(0); // the client binds a random port and wait for reply.
client.on("reply", (msg) => {
    console.log(msg); // => Message recieved.

    client.close();
    server.close();
}).emit("greet", "Hello, World!");

API

Socket

This class extends dgram.Socket, provides an easier way to communicate between two remote peers.

Socket.ReservedEvents: string[]

Sets what events are reserved by the module (or your module) and should be avoid using for remote emitting. By default, these events is reserved:

• close triggered when the socket is closed.
• error triggered when any error occurred.
• listening triggered when bind() method is called.
• message triggered when receiving any message.

Socket.prototype.on(event: string, listener: Function): Socket

If the event is reserved, then it acts just as talked above. But if the event is customized, then the listener function will be called when the remote peer emits the event. The signature of the listener function is:

(msg: any, rinfo: dgram.RemoteInfo) => void

• msg The message needed to be sent.
• rinfo Remote information contains:
  • address: string the address of the remote peer.
  • port: number binding port of the remote peer.
  • family: "IPv4" | "IPv6"

Socket.prototype.emit(event: string, msg: any): boolean

Apart from reserved events, you can emit any customized event to the remote peer, and sends data when the event fires. Be aware, the number of data should be equal to the one specified by the remote peer listener.

Socket.prototype.to()

Sets the receiver information of the remote peer, valid signatures are:

• to(addr: string) e.g. to("localhost:12345").
• to(port: number) e.g. to(1234).
• to(addr: string, port: number) e.g to("localhost", 12345)

You can call this method several times to set multiple receivers, but after emit() is called, the receivers will be set to empty.

createSocket()

The same as dgram.createSocket(), only it returns the Socket created by this module.

createServer(addr: string, callback?: () => void)

Creates a UDP server according to the given address. This is a short-hand for createSocket(type).bind(port, addr).

The addr must contain a protocol, could be either udp, udp4, udp6.

createClient(addr: string)

Creates a UDP client ready to the given server. This is a short-hand for createSocket(type).to(addr, port).

The addr of createClient() is the same and should be the same as the one of createServer().

The Data Frame

For efficiency concerns, this module uses JSON to encode and decode data into and from buffer.