iAmNathanJ/pub-sub.md

## pub-sub.md

      
    Raw
  

              pub-sub.md
            
          
    Publish Subscribe


Some similarities to Observer and Observable pattern(s)
Could you use an Oberserver implementation as the middle of a pub/sub implementation? ie Publisher -> Observer -> Subscribers

Problems


Order of subscribes and publish makes for bootstrapping/bootup order requirements. Inexplicit coupling that's hard to debug
Data is the coupling - how to version?

Decisions on When to Use


Informational only
If you need certainty, acknowledgement is needed. (By directional messages?)
Discrete parts of a system - allow scaling of team(s) so each work on their own part given a contract

Implementations


Pusherapp
Pubnub
npm: pubsub-js (and the other 10m)


## pubsub-pseudo.js
/* the PubSub module keeps a list of functions that listen for  event */
PubSub.subscribe('eventName', function(eventInfo) {
  console.log(`the ${eventInfo.type} event was published.`);
});

PubSub.publish('eventName', data);
	/* the PubSub module keeps a list of functions that listen for event */
	PubSub.subscribe('eventName', function(eventInfo) {
	console.log(`the ${eventInfo.type} event was published.`);
	});

	PubSub.publish('eventName', data);