function BASE() {
    if(window.XMLHttpRequest) {
        try {
            req = new XMLHttpRequest();
        } catch(e) {
            req = false;
        }
    } else if(window.ActiveXObject) {
           try {
            req = new ActiveXObject("Msxml2.XMLHTTP");
          } catch(e) {
            try {
                req = new ActiveXObject("Microsoft.XMLHTTP");
            } catch(e) {
                req = false;
            }
        }
    }

    if (req) {
        this.HTTP = req;
        this.error = "";
    } else {
        this.HTTP = null;
        this.error = "El Navegador no soporta HTTP_REQUEST.";
    }

    this.result;
    this.commandFile = "";
    this.params = "";
    this.error = "";
    this.onreadystatechangeFunction = null;
    this.respuesta = "";
}

BASE.prototype.send = function(parameter) {
    if(this.HTTP != null){
        this.parameter = parameter == undefined ? this.parameter : parameter;
        this.parameter = this.commandFile + this.parameter;
        this.HTTP.open("POST", this.parameter , true);
        this.HTTP.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;charset=ISO-8859-1;');
        this.HTTP.send();
        if (this.onreadystatechangeFunction != null && typeof this.onreadystatechangeFunction == "function") {
            this.HTTP.onreadystatechange = this.onreadystatechangeFunction;
        } else {
            this.HTTP.onreadystatechange = function() {
                if (this.readyState == 4) {
                    if (this.status == 200) {
                        this.respuesta = JSON.parse(this.response);
                    } else {
                        this.error = "Error: "+this.status +"\n"+ this.statusText;
                        return "";
                    }
                } else {
                    this.error = "readyState: "+this.readyState;
                    return "";
                }
            }
        }
        
    }
}

BASE.prototype.sendSync = function(parameter) {
    if(this.HTTP != null){
        this.parameter = parameter == undefined ? this.parameter : parameter;
        this.parameter = this.commandFile + this.parameter;
        this.HTTP.open("POST", this.parameter , false);
        this.HTTP.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;charset=ISO-8859-1;');
        this.HTTP.send();
        return this.HTTP;
    }
}