public static String thead(){
        return  "<thead>" +
                "<tr>"+
                "<th>"+"instance id"+"</th>"+
                "<th>"+"txid"+"</th>"+
                "<th>"+"BPEL"+"</th>"+
                "<th>"+"course id"+"</th>"+
                "<th>"+"course provider"+"</th>"+
                "<th>"+"state"+"</th>"+
                "<th>"+"time"+"</th>"+
                "<th>"+"duration"+"</th>"+
                "</tr>" +
                "</thead>";
    }