frufin / js-bidirectional-pubsub

Bidirectional javascript pub/sub implementation

js-bidirectional-pubsub

Pub/sub is a very effective javascript pattern in order to avoid direct interaction between code modules. However its one way mode may require additional hard-coded pub/sub if you expect some reply… I suggest improving javascript pub/sub pattern in order to provide bidirectionality.

Under the hood

This implementation creates a temporary, silent reverse topic in order to avoid hard-coding a new pub/sub couple. You can find details here: https://www.medway.fr/bloog/javascript-bidirectional-pub-sub.php

Syntax

The "events" object functions names are similar to those found in any standard pub/sub implementation.

publish(topic, data [,callback])

Publishes with an optional callback function as a third argument. If such a callback exists, if will handle a potential response:

events.publish("myTopic", data, function(response){
	// some code handling response...
});

If not, the pub/sub pattern will work as usual...

events.publish("myTopic", data);

submit(topic, callback)

The submitter can "reply" in case the publisher provided a callback function:

var mySubmit = events.submit("myTopic", function(data, reply){
  // Some code generating a response...
  reply(response);
 });

If not, the pub/sub pattern will work as usual...

var mySubmit = events.submit("myTopic", function(data){
    ...
};

unsubmit()

Removes the callback:

mySubmit.unsubmit();

Caveats

If a callback function is provided when publishing, you should consider it only as a one-to-one communication, because in case of several subscribers, you may have to manage several responses...

Acknowledgments

• We started from Andy Osmany pub/sub vanilla JS implementation