digger-radio

digger-radio
============

!Build status

Pub/Sub client for digger-client

installation

$ npm install digger-radio --save

usage

The radio is a pub/sub wrapper to a backend server infrastructure.

It 'subscribes' by sending the subscription key and registering a local function as a callback for that key.

``js
var Radio = require('digger-radio');
var radio = new Radio();

radio.listen('apples', function(payload){
// we heard 10!
})

radio.talk('apples', 10);

`

$3

`
var radio = new Radio();

radio.listen('apples.*', function(payload){
// we heard 10!
})

radio.talk('apples.pears', 10);
`

$3

`
var radio = new Radio('my.section.with.dots.');

radio.listen('apples.*', function(payload){
// the actual path written:
// my.section.with.dots.apples.pears
})


radio.talk('apples.pears', 10);
`

$3

`js
var radio = new Radio('apples.');

var count = 0;
var handler = function(){
count++;
if(count>1){
throw new Error('should not happen twice');
}
}

radio.listen('pears', handler);
radio.talk('pears', 10);
radio.cancel('pears', handler);
radio.talk('pears', 10);

`

Transport layer

The radio does not try to handle getting messages sent to the pub/sub server.

Instead - it emits the following events - allowing whatever transport layer (WebSockets, ZeroMQ) to handle the packet:

$3

This is used to send a subscription key to the pub/sub server.

This is effectively saying 'tell me about these messages'.

An example of the digger-sockets transport layer:

`js

var radio = new Radio();

radio.on('talk', function(channel, payload){
socket.send(JSON.stringify({
type:'radio:talk',
data:{
channel:channel,
payload:payload
}
}))
})

radio.on('listen', function(channel){
socket.send(JSON.stringify({
type:'radio:listen',
data:channel
}))
})

radio.on('cancel', function(channel, payload){
socket.send(JSON.stringify({
type:'radio:cancel',
data:channel
}))
})

``

Licence

MIT