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

Diffusion JavaScript client

var ValueStreamProxy = require('features/topics/value-stream-proxy');
var Emitter = require('events/emitter');


function SubscriptionImpl(registry, stream, fallback, selector) {
    for (var fn in stream) {
        this[fn] = stream[fn];
    }

    this.selector = selector;
    var self = this;

    this.asType = function(datatype, callback) {
        var proxy = new ValueStreamProxy(registry, selector, datatype, fallback, callback);
        self.on('error', function(error) {
            proxy.onSubscriptionError(error);
        });
        return proxy.subscription;
    };

    this.transform = function(fn) {
        var e = new Emitter();

        self.on('open', function(selector) {
            e.emit('open', selector, self);
        });

        self.on('close', function() {
            e.emit('close');
        });

        self.on('update', function(update, topic) {
            e.emit('update', fn(update), topic);
        });

        self.on('subscribe', function(details) {
            e.emit('subscribe', details);
        });

        self.on('unsubscribe', function(reason, topic) {
            e.emit('unsubscribe', reason, topic);
        });

        self.on('error', function(error) {
            e.error(error);
        });

        return new SubscriptionImpl(registry, e.get(), selector);
    };
}

module.exports = SubscriptionImpl;