simple-local-swarm

A localhost-only socket swarm. Useful for IPC or local replication of data structures. This uses unix domain sockets (or named pipes on windows) to open bidirectional streams between processes interested in a topic. A topic is a 32 byte buffer (if you pass a string, it will be hashed into a 32 byte buffer).

Example

Below is a simple CLI example that lets any number of processes talk to each other. See test.js for an example that replicates hypercores.

const Swarm = require('.')
 
const topic = process.argv[2]
const name = process.argv[3]
 
const swarm = Swarm()
swarm.join(topic)
 
swarm.on('connection', (stream, details) => {
  stream.on('data', data => console.log('incoming:: ' + data.toString()))
  stream.write(`hello i am ${name}`)
})

# in a terminal 
> node example.js mytopic alice
incoming: hello i am bob
incoming: hello i am claire
 
# in another terminal 
> node example.js mytopic bob
incoming: hello i am alice
incoming: hello i am claire
 
# in another terminal 
> node example.js mytopic claire
incoming: hello i am alice
incoming: hello i am bob

API

const LocalSwarm = require('simple-local-swarm')

const swarm = new LocalSwarm(opts)

Open a swarm. opts are:

• shortcircuit: bool if multiple swarms from the same process are interested in a topic, connect them directly without going through sockets (default: true)
• basedir: string a path to a directory where to store sockets and topic files. has to be the same between all processes that want to share swarms. default: /tmp/simple-local-swarm

swarm.join(topic)

Join a topic. topic can either be a 32 byte long buffer, or a string (which will be hashed into a 32 byte buffer).

swarm.on('connection', function (socket, details) {})

Register a connection handler. socket is a binary duplex stream. details is an object with keys:

• client: boolean: true if the connection was initiated from this process, false if coming from another process

swarm.close(cb)

Close the server and delete the topic file. This is also registered as an exit hook in node that when the process exits the topic file is deleted.