JmeterAPEXPOSTProcessor.js

// grab the results of the page
var PAGE = prev == null ? null : prev.getResponseDataAsString();
// debug
OUT.println('PRE PROCESSING...');
function put(id){
        vars.put(id, getValue(PAGE,id,''));
}
  // simple function to grab the value from the page or return the default x
function getValue(page,id,v){ 

  if ( page == null ){
    return v;
   }
  var find = 'name="'+id+'" value="';
  var start = page.indexOf(find);
  var ret=null;
  var mypage = page;
  while ( start != -1 ) {
          start = start + find.length;
          var end = mypage.indexOf('"',start);
          if ( ret == null ) {
                  ret = mypage.substring(start ,end);
          } else {
                  ret = ret + "," + mypage.substring(start ,end);
          }
          mypage = mypage.substring(end+1);
          start = mypage.indexOf(find);
  }
  OUT.println(id + "=" + ret);
  return  ret == null ? v : ret ;
}

put('p_instance');
put('p_flow_id');
put('p_flow_step_id');
put('p_page_submission_id');
put('p_md5_checksum');
put('p_arg_names');