def _pingThread(host,
                port,
                pingEvent,
                dummy):
    """
    Ping the node defined by the given host name/port number.

    host:        Hostname (string).

    port:        Port number (integer).

    pingEvent:   Used to communicate back to calling thread if a connection
                 to the specified host could be established (threading.Event).
    
    Returns:     Void.
    """
    import httplib, thread
    try:
        httpObj = httplib.HTTPConnection(host, port)
        httpObj.request("GET", "/STATUS")
        respObj = httpObj.getresponse()
        respObj.read()
        pingEvent.set()
        try:
            thread.exit()
        except:
            pass
    except Exception, e:
        try:
            thread.exit()
        except:
            pass


def ngasPingHost(host,
                 port,
                 timeOut = 0.5):
    """
    Pings a specific host/port to check if a connection can be opened. This is
    done by issuing a STATUS Command to the node. Will max. wait for a response
    for the specified timeout.

    host:        NGAS host to ping (string).
    
    port:        Port on NGAS host to ping (integer).
    
    timeOut:     Timeout in seconds (float).

    Returns:     1 in case the NGAS Node could be accessed within the given
                 timeout, otherwise 0 is returned (integer/0|1).
    """
    pingEvent = None
    pingThread = None
    try:
        pingEvent = threading.Event() 
        args = (host, port, pingEvent, None)
        pingThread = threading.Thread(None, _pingThread, "PING-THREAD", args)
        print ">>>>> pingThread=",pingThread
        print ">>>>> dir(pingThread)=",dir(pingThread)
        print ">>>>> dir(pingThread._Thread__stop)=",\
              dir(pingThread._Thread__stop)
        pingThread.setDaemon(1)
        pingThread.start()
        pingEvent.wait(timeOut)
        if (pingEvent.isSet()):
            stat = 1
        else:
            stat = 0
        del pingEvent
        try:
            pingThread.exit()
        except Exception, e:
            print ">>>>>  pingThread.exit()/e=",str(e)
        del pingThread
        return stat
    except:
        if (pingEvent): del pingEvent
        if (pingThread):
            pingThread.exit()
            del pingThread