sforce.Transport = function(url) {
    this.url = url;
    this.connection = null;

    this.newConnection = function() {
        try {
            this.connection = new ActiveXObject('Msxml2.XMLHTTP');
        } catch(e) {
            try {
                this.connection = new ActiveXObject('Microsoft.XMLHTTP');
            } catch(e) {
                this.connection = new XMLHttpRequest();
            }
        }

        return this.connection;
    };

    this.send = function (envelope, callback, async, timeout) {
        this.newConnection();
        if (async) {
            this.connection.onreadystatechange = this.httpConnectionCallback;
        }
        var holder = new sforce.internal.ConnectionHolder(this.connection, callback);
        sforce.internal._connections.push(holder);
        this.connection.open("POST", this.url, async);
        this.connection.setRequestHeader("Content-Type", "text/xml; charset=UTF-8");
        this.connection.setRequestHeader("SOAPAction", "\"\"");
        this.connection.setRequestHeader("Accept", "text/xml");
     //   this.connection.setRequestHeader("User-Agent", "SFAJAX 1.0");
        this.connection.send(envelope);
        if (async && typeof(timeout) !== "undefined") {
            this.setTimeoutOn(holder, timeout);
        }
        if (!async) {
            this.httpConnectionCallback();
        }
    };

    this.setTimeoutOn = function (holder, timeout) {
        function abortConnection() {
            if (holder.connection.readyState !== 4) {
                holder.timedout = true;
                holder.connection.abort();
            }
        }
        setTimeout(abortConnection, timeout);
    };

    this.httpConnectionCallback = function () {

        for (var i = 0; i < sforce.internal._connections.length; i++) {
            var holder = sforce.internal._connections[i];
            if (holder !== null) {
                if (holder.timedout) {
                    sforce.internal._connections[i] = null;
                    sforce.internal._connections.slice(i,1);
                    holder.callback.httpCallback("Remote invocation timed out", false);
                } else  if (holder.connection.readyState == 4) {
                    sforce.internal._connections[i] = null;
                    sforce.internal._connections.slice(i,1);
                    var success = holder.connection.status == 200;
                    if (sforce.debug.trace) {
                        sforce.debug.log("Response : status - " + holder.connection.status);
                        sforce.debug.logXml(holder.connection.responseText);
                    }
                    if (sforce.debug.apexTrace) {
                        sforce.debug.logApex(holder.connection.responseText);
                    }
                    if (holder.connection.responseXML && holder.connection.responseXML.documentElement) {
                        holder.callback.httpCallback(holder.connection.responseXML.documentElement, success);
                    } else {
                        holder.callback.httpCallback("Remote invocation failed, due to: " + holder.connection.responseText +
                                                     " status code: ", holder.connection.status);
                    }
                }
            }
        }
    };
};