NPM p2psub

Mesh peer to peer JSON Pub/Sub with no extremal dependencies. Each peer can act as server and client, just a client or a simple relay peer. Topics can be subscribed to using a simple string or regex pattern.

Features

• Mesh peer to peer network forwards messages to all connected, even if they are not directly connected.
• Peers can be added and removed on the fly.
• PubSub topics can be subscribed using patter RegExp.
• Peer to peer and pub/sub is 2 separate importable classes for even more customization.
• No dependencies.

Install

npm install p2psub --save

Usage

Instantiate a P2PSub instance:

const {P2PSub} = require('p2psub');

const p2p = new P2PSub({
	listenPort: 7575,
	peers:[
		'10.10.10.11:7575',
		'10.10.10.12:7575',
		'172.16.24.2:8637'
	]
});

Now we can listen for and publish topics across the whole network:

// Local peer

p2p.publish('announcement', {message: 'p2p pubsub is awesome!'});

// Remote peer

p2p.subscribe('announcement', (data)=> console.log(data.message));

# p2p pubsub is awesome!

We can also use regex patterns in our subscribes to catch more, or all topics:

// Local peer

p2p.publish('announcement', {message: 'p2p pubsub is awesome!'});
p2p.publish('announcement-group1', {message: 'Mesh is the future!'});
p2p.publish('resource-block-added', {id: '123', name:'block0'});

// Remote peer

p2p.subscribe(\^announcement\, (data, topic)=> console.log(topic, data.message));

# announcement p2p pubsub is awesome!
# announcement-group1 Mesh is the future!

// Another remote peer

p2p.subscribe(\.\, (data, topic)=> console.log(topic, data));

# announcement {message: 'p2p pubsub is awesome!'}
# announcement-group1 {message: 'Mesh is the future!'}
# resource-block-added {id: '123', name:'block0'}

P2PSub instance options

All of these are provided by, and passed to the P2P class. PubSub takes no instance options.

listenPort Optional, type Number or String. Sets the incoming TCP port for the local peer to listen on. If this is left blank, the local peer will not accept incoming peers. Default is undefined

peers: Optional, type Array of Strings. The list of peers this peer will try to connect with. Peers should be specified as {host}:{port{}. The host can be an IP or a hostname the system can resolve. Default is []

logLevel: Optional, type Array of Strings or false. Sets how the instance logs to STDIN out. Options are info, warn and error if one or more are passed in the logLevel Array, messages will be printed to STDIN/STDERR. Passing false or leaving it blank will suppress all message except if the listening port is in use.

preBroadcast(data, topic): Optional function to be ran before a topic is published across the network. The message body Object is passed as the first argument and the topic as the second. Return the Object to be broadcasted across the network or false to prevent propagation. This is useful to prevent data from leaving the local node. This is only used on P2PSub class instances.

Example of striping data from a message:

const p2p = new P2PSub({
	listenPort: 7575,
	preBroadcast: function(data, topic){
		let thisData = {...data} // copy the object or all local subscriptions will lose the data too
		delete this.data.sensitiveInformation;

		return thisData
	}
});

CLI usage

A simple relay peer can be set up using just the CLI, no code required. This peer will only relay messages to all its connected peers. The logging level is set to info.

./app.js 7575 10.1.0.1:7575 10.2.0.1:7575 10.3.0.1:7575 ...

The first argument is the listening port, optionally followed by space separated list of peers to connect with.

Methods and attributes

Methods are provided by either the P2P or PubSub classes. The P2PSub class is a mix of both classes and merges the Pub/Sub with p2p functions.

The P2PSub class provides subscribe(), publish(), addPeer() and removePeer(). Please see the methods below for detailed usage.

Provided by PubSub class

• subscribe(topic, callback-function) Sets a function to be called on topic publish. A RegExp pattern can be passed as the topic and will match to topic on publish. a String will perform an exact match. The message and topic are passed to callback function as first and second argument.

• publish(topic, Object-body) Executes each callback attached to the passed topic. To prevent a publication from propagating across the network, pass __local = true in the message body.

• topics An instance attribute holding an Object on topics and bound callbacks. This is not exposed by the P2PSub class.

Provided by P2P class

• addPeer(peer) Adds a remote peer to the local peers connections. peer can passed as a single string with a hostname and port, 'remotehost.com:7575', or an Array of Strings with peers ['remotehost.com:7575', '10.10.2.1:7575']. Duplicate and existing peers will be ignored.

• removePeer(peer) Disconnect the passed peer and removes it from the list of peers this instances auto reconnects to. peer is passed as a single sting with a hostname and port, 'remotehost.com:7575'

• onData(callback) Pass a listener to called when this peer receives a message from the network. The message is passed to the callback as native JSON object. This is not exposed by the P2PSub class, subscribe should be used.

• broadcast(message, <excludes>) Sends a JSON message to all connected peers. message is JSON object that will be stringified. excludes is a Array of Strings containing peerID's that this broadcast should not be sent you, and is for internal use at this time. This is not exposed by the P2PSub class, publish should be used.

• peerID An instance attribute holding a String for the local peerID. This is randomly generated and is for internal use. This is not exposed by the P2PSub class.

Notes

This project is in active development. Please report any issue and ask for new features. PR's are also welcomed.

Todo

• Add timestamps to each message.
• Change the parsing of the message move sentTo in the prototype before passing the class.
• Add optional TSL
• Internal ability to publish new peers across the network.
• Add config file for CLI mode.