fh-wfm-mediator
v0.3.4
Published
An implementation of the mediator pattern for use with WFM
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FeedHenry RainCatcher mediator
An implementation of the mediator pattern for use with RainCatcher modules.
API
| Method | Description |
| --- | --- |
| mediator#publish( channel, [data] )
| Publish data to a channel |
| mediator#subscribe( channel, callback )
| Subscribe to events in a channel |
| mediator#remove( channel, [identifier] )
| Unsubscribe to events in a channel |
| mediator#once( channel, callback )
| A one-time subscribtion to events in a channel |
| mediator#promise( channel )
| A promise-based API for mediator#once
|
Topics
utilities
This module also provides a fluent, promise-based API for subscribing to convention and adhering to the request-response pattern used throughout the RainCatcher modules and available through mediator#request
.
Namely if a data:read
topic that is used to provide a feature such as reading data from a remote source asyncronously, the result of the operation is by convention published in the done:data:read
topic, and if it results in an error, it is published to the error:data:read
topic.
This utility module helps with enforcing the same namespace for a set of related topics without repeating string literals or constants, and adhering to the convention above. It is available under lib/topics
with jsdoc comments.
Example
var mediator = require('fh-wfm-mediator');
var Topics = require('fh-wfm-mediator/lib/topics');
var topics = new Topics(mediator)
.prefix('wfm')
.entity('user')
// This will subscribe to wfm:user:read
// and publish results to done:wfm:user:read:{id}
// and errors to error:wfm:user:read:{id}
.on('read', function(id) {
// will request to 'data:user:read'
return this.mediator.request(['data', this.entity, 'read'].join(':'), id);
})
// If you do not return a Promise from the handler function,
// you must manually publish the result to another topic so it can be consumed
.on('delete', function(id) {
var self = this;
this.mediator.request(this.entity + ':delete', id).then(function() {
self.mediator.publish('done:ui:user:deleted:' + id);
}).catch(function(e) {
self.mediator.publish('error:ui:user:deleted:' + id, e);
});
});
Usage in an Angular.js client
API
Besides the above operations, the current operations are available :
| Method | Description |
| --- | --- |
| mediator#subscribeForScope( channel, scope, callback )
| Subscribe to events in a channel and unsubscribe when the scope is destroyed|
Setup
This module is packaged in a CommonJS format, exporting the name of the Angular namespace. The module can be included in an angular.js as follows:
angular.module('app', [
, require('fh-wfm-mediator')
...
])
Integration
Inject the mediator
service to broadcast and subscribe to events
.controller('MyController', function (mediator) {
...
}
Usage in an node.js backend
Require the module to get an instance of the mediator. Be sure to use that same instance throughout the application to maintain a single list of subscribers.
mediator = require('fh-wfm-mediator/lib/mediator')