function BuchXmlHttp() {
    // create the request
    function createReq() {
        var request = null;
		/**
		 * Die ActiveX-Bezeichner sind bei 5.x und 6.x/7.x unterschiedlich:
		 **/
		if (window.ActiveXObject) {
			try {
				// MSIE 6.x
				request = new ActiveXObject("Msxml2.XMLHTTP");
			} catch(e) {
				try {
					// MSIE 5.x
					request = new ActiveXObject("Micorosoft.XMLHTTP");
				} catch(e) {
					request = false;
				}
			}
		/**
		 * ... hier ist es einheitlich:
		 */
		} else if (window.XMLHttpRequest) {
			// Safari, KHTML, Mozilla, Opera
			try {
				request = new XMLHttpRequest();
			} catch(e) {
				request = false;
			}
		}
		
		return (request) ? request : null;
    }
    this.createReq = createReq;

    // opens a request
    function openReq(request, url, callback) {
        request.open("GET", url);
        request.onreadystatechange = callback;
    }
    this.openReq = openReq;

    // send a request
    function sendReq(request) {
        request.send(null);
    }
    this.sendReq = sendReq;
}