router

this is an experiment to see if i can develop a way to route processes both locally and across networks using a simple standard ...

basic idea

hub and routers

you start by creating a hub to which you add some routers to.

import { hub } from '@kewp/router';

let h = hub(); // create new hub

h.router('cat'); // create router named 'cat'
h.router('dog'); // create router named 'dog'

at the moment you pass in a name to the router as a string to make things easier to debug. this might change.

sending packets

you can send a packet to one of the routers with the send command

// send packet {message:'ping'}
// from router 'cat' to router 'dog'
h.send('cat', 'dog', {message:'ping'})

if you run this now you'll see a warning message

warning: no handler for packet from [cat] to [dog] with message 'ping'

this is because we haven't set up handlers on dog.

handlers

a handler is a set of rules which react to a packet coming in.

let handler = {
    source: null,
    message: 'ping',
    fn: (source,message,id) => {
        console.log(`[dog] got message '${message}' with id ${id} from [${source}]`);
        send('dog',source,{ message: 'pong', id });
    }
}

it's just an object with particular fields - source, message, etc. what this handler is saying is:

if we get a packet from any source (null means not-specified) with message hello, run said function.

handlers can send packets as well. fn logs the ping out and sends pong back to the source.

packet ids

unless specified, each packet has a random id attached to it when it is sent out. this is so that packets coming back in response can be matched.

here we send ping to dog and wait for a pong to come back (which the hub does using the id):

hub.send('dog', 'cat', {message:'ping'}, [
    {
        // watch for message 'pong' in reply (i.e. with same id)
        message: 'pong',
        fn: (source,message,id) => console.log(`[dog] got message '${message}' with id ${id} from [${source}]`),
    }
]);

it's important to understand why we need to match with ids. the communication happening here is ... asynchronous? for any packet arriving anywhere we do not know what it means - is it a reply? a request for something? the id tells us 'this is a reply to another message'...

timeouts

tutorial

everything covered thus far is in tutorial.js which you can just run to see the output

> node tutorial.js
[]

kewp / router