Package Exports

polo

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Readme

Polo

Polo is a zero configuration service discovery module written completely in Javascript. It's available through npm:

npm install polo

What problem does it solve?

Polo allows your servers/programs to discover eachother without having to talk to a central server and without the use of any static configuration as long as they are connected to the same network.

All Polo instances find eachother using UDP multicast and all following communication is done over HTTP.

Usage

First create a polo instance:

var polo = require('polo');
var map = polo();

Now let's add a service:

map.put({
    name:'hello-world', // required - the name of the service
    host:'example.com', // defaults to the network ip of the machine
    http: 8080 // we speak http on port 8080. 
               // Instead of http it could be https or any other protocol you supply
});

If you choose to put multiple services with the same Polo will load balance them for you. Now spin up another node process and polo will automatically distribute information about this service:

// in another process
var polo = require('polo');
var map = polo();

setTimeout(function() { // let's give polo a little time to discover it self
    console.log(map('http://hello-world/')); // should print http://example.com:8080/
}, 1000);

It's that easy!

Example

Let's create an HTTP service. Try to run the program below in a couple of processes:

var http = require('http');
var polo = require('polo');
var map = polo();

var server = http.createServer(function(req, res) {
    res.end('hello-http is available at '+map('http://hello-http/')); 
})

server.listen(0, function() {
    var port = server.address().port; // let's find out which port we binded to

    console.log('visit: http://localhost:'+port);
    
    map.put({
        name: 'hello-http',
        http: port
    });
});