diffusion/src/node_modules/features/topics/subscription-proxy.js

Diffusion JavaScript client

/*eslint valid-jsdoc: "off"*/
var SubscriptionImpl = require('features/topics/subscription');
var Emitter = require('events/emitter');

/**
 * Internal proxy for Subscriptions.
 *
 * @param registry - StreamRegistry
 * @param selector - Topic selector
 * @param callback - Optional callback for subscription
 */
module.exports = function SubscriptionProxy(registry, selector, fallback) {
    var emitter = new Emitter();
    var stream = emitter.get();
    var self = this;

    var subscription = new SubscriptionImpl(registry, stream, fallback, selector);

    stream.on('close', function() {
        registry.remove(self);
    });

    this.subscription = subscription;
    this.emitter = emitter;

    this.selects = function() {
        return true;
    };

    this.onOpen = function() {
        emitter.emit('open', subscription);
    };

    this.onDelta = function(topic, details, specification, value) {
        emitter.emit('update', value, topic);
    };

    this.onValue = function(topic, details, specification, value) {
        emitter.emit('update', value, topic);
    };

    this.onSubscription = function(topic, details) {
        emitter.emit('subscribe', details, topic);
    };

    this.onUnsubscription = function(topic, details, specification, reason) {
        emitter.emit('unsubscribe', reason, topic);
    };

    this.onSubscriptionError = function (err) {
        emitter.error(err);
        registry.remove(self);
    };
};