web3.js/lib/web3/httpprovider.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 httpprovider.js
 * @authors:
 *   Marek Kotewicz <marek@ethdev.com>
 *   Marian Oancea <marian@ethdev.com>
 *   Fabian Vogelsteller <fabian@ethdev.com>
 * @date 2015
 */

"use strict";

var XMLHttpRequest = (typeof window !== 'undefined' && window.XMLHttpRequest) ? window.XMLHttpRequest : require('xmlhttprequest').XMLHttpRequest; // jshint ignore:line
var errors = require('./errors');

var HttpProvider = function (host) {
    this.host = host || 'http://localhost:8545';
};

HttpProvider.prototype.isConnected = function() {
    var request = new XMLHttpRequest();

    request.open('POST', this.host, false);
    request.setRequestHeader('Content-type','application/json');
    
    try {
        request.send(JSON.stringify({
            id: 9999999999,
            jsonrpc: '2.0',
            method: 'net_listening',
            params: []
        }));
        return true;
    } catch(e) {
        return false;
    }
};

HttpProvider.prototype.send = function (payload) {
    var request = new XMLHttpRequest();

    request.open('POST', this.host, false);
    request.setRequestHeader('Content-type','application/json');
    
    try {
        request.send(JSON.stringify(payload));
    } catch(error) {
        throw errors.InvalidConnection(this.host);
    }


    // check request.status
    // TODO: throw an error here! it cannot silently fail!!!
    //if (request.status !== 200) {
        //return;
    //}

    var result = request.responseText;

    try {
        result = JSON.parse(result);
    } catch(e) {
        throw errors.InvalidResponse(request.responseText);                
    }

    return result;
};

HttpProvider.prototype.sendAsync = function (payload, callback) {
    var request = new XMLHttpRequest();
    request.onreadystatechange = function() {
        if (request.readyState === 4) {
            var result = request.responseText;
            var error = null;

            try {
                result = JSON.parse(result);
            } catch(e) {
                error = errors.InvalidResponse(request.responseText);                
            }

            callback(error, result);
        }
    };

    request.open('POST', this.host, true);
    request.setRequestHeader('Content-type','application/json');
    
    try {
        request.send(JSON.stringify(payload));
    } catch(error) {
        callback(errors.InvalidConnection(this.host));
    }
};

module.exports = HttpProvider;