n2n-overlay-wrtc

This project aims to ease the creation of overlay networks on top of WebRTC. Additional WebRTC-specific constraints make such projects more difficult than they should be. For instance, establishing a connection requires a round-trip of "offers". Such messages usually transit a dedicated signaling server. The peers of this project still require a signaling server for their entrance in the network. Afterwards, peers become signaling servers too, i.e., they mediate connections between their direct neighbors.

This module divides the entering arcs (inview) from the outgoing arcs (outview).

The way connections are handled are left to the discretion of overlay protocols built on top of this module. A peer with two neighbors can ask to one of them to connect to the other. Several overlay network protocols use neighbor-to-neighbor interactions to converge to a topology exposing the desired properties.

Principle

There exists a network comprising at least Peer :|. Peer :] wants to join this network. :| knows it and opens an access to the network thanks to a signaling server. The signaling server is in charge of transmitting the necessary WebRTC data from both sides. The figure shows this protocol with the 1->2->3->4 steps that can be repeated many times depending on network configurations. If the protocol is successful, it creates a direct browser-to-browser connection from :] to :|.

Peers already in the network do not need to use a signaling server to establish connections, for each of them can act as a signaling server, i.e. as a bridge from a neighbor to another. In the figure, :3, :], and :| are in the network. :3 can establish a WebRTC connection to :| using :]. Such neighbor-to-neighbor connections are common in distributed peer-sampling protocols.

Installation

$ npm install n2n-overlay-wrtc

API

The API is avalaible here

Example

A live example is available here.

The module spray-wrtc extends n2n-overlay-wrtc to implement a random peer-sampling protocol.