go-ethereum/lib/websocket.js

/*
    This file is part of ethereum.js.

    ethereum.js is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    ethereum.js is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with ethereum.js.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file websocket.js
 * @authors:
 *   Jeffrey Wilcke <jeff@ethdev.com>
 *   Marek Kotewicz <marek@ethdev.com>
 *   Marian Oancea <marian@ethdev.com>
 * @date 2014
 */

// TODO: is these line is supposed to be here? 
if (process.env.NODE_ENV !== 'build') {
    var WebSocket = require('ws'); // jshint ignore:line
}

/**
 * WebSocketProvider object prototype is implementing 'provider protocol'
 * Should be used when we want to connect to ethereum backend over websockets
 * It's compatible with go client
 * The constructor allows to specify host uri
 */
var WebSocketProvider = function(host) {

    // onmessage handlers
    this.handlers = [];

    // queue will be filled with messages if send is invoked before the ws is ready
    this.queued = [];
    this.ready = false;

    this.ws = new WebSocket(host);

    var self = this;
    this.ws.onmessage = function(event) {
        for(var i = 0; i < self.handlers.length; i++) {
            self.handlers[i].call(self, JSON.parse(event.data), event);
        }
    };

    this.ws.onopen = function() {
        self.ready = true;

        for (var i = 0; i < self.queued.length; i++) {
            // Resend
            self.send(self.queued[i]);
        }
    };
};

/// Prototype object method
/// Should be called when we want to send single api request to server
/// Asynchronous, it's using websockets
/// Response for the call will be received by ws.onmessage
/// @param payload is inner message object
WebSocketProvider.prototype.send = function(payload) {
    if (this.ready) {
        var data = JSON.stringify(payload);

        this.ws.send(data);
    } else {
        this.queued.push(payload);
    }
};

/// Prototype object method
/// Should be called to add handlers
WebSocketProvider.prototype.onMessage = function(handler) {
    this.handlers.push(handler);
};

/// Prototype object method
/// Should be called to close websockets connection
WebSocketProvider.prototype.unload = function() {
    this.ws.close();
};

/// Prototype object property
/// Should be used to set message handlers for this provider
Object.defineProperty(WebSocketProvider.prototype, "onmessage", {
    set: function(provider) { this.onMessage(provider); }
});

if (typeof(module) !== "undefined")
    module.exports = WebSocketProvider;