HttpURLConnection simply doesn't work as it should!

Question

Hi everybody. I've been stuck for a week with these related problems. answers to any of them would be very, very appreciated (i'm working in Java 1.2.2)
I am sending a POST request from a client applet to a Web server (a CGI made in Perl). I have checked the server code: it's all right. When I try to send a POST message I do this at the client:
URL url = new URL(Direccion);
HttpURLConnection http = (HttpURLConnection)url.openConnection();
http.setDoInput(true);
http.setDoOutput(true);
http.setUseCaches(false);
http.setRequestMethod("POST");
http.setRequestProperty ("Content-Encoding","multipart/form-data");
http.setRequestProperty ("Content-Type","multipart/form-data; boundary=" + sep);
Then I connect:
http.connect();
System.out.println("Client : Connected");
Then supposedly I send a message in HTTP format:
DataOutputStream DOSSalida = new DataOutputStream (http.getOutputStream ());
System.out.println("Client : Writing Content");
DOSSalida.writeBytes(sContent); //post message
DOSSalida.writeBytes(sEnd); //post end of transmission
System.out.println("Client : Flushing Stream");
DOSSalida.flush();
DOSSalida.close();
I send file contents on the message; I mean, usually is a large post (most than 1 Mb).
Question 1: At this point, the message is supposed to be sent, isn't it? But, hey, check this out: the message is not really sent yet! (I mean, I have a log for the web server and the CGI: nothing happens). �Shouldn't the message have been sent at this moment? Shouldn't I even be able to close the connection (http.close()) at this time and the message should have been sent? (I have even tried with the http.setDoInput(false) set).
Question 2: The message is really sent (I can't see why) when I do the getInputStream (!!) code.
System.out.println("Client : Waiting for response from Server");
AreaInformacion.setForeground(new java.awt.Color(0, 0, 0));
AreaInformacion.setText("Estado: archivos enviados. Esperando respuesta");
System.out.println ("Creamos el amortiguador.\n");
BufferedReader in = new BufferedReader(new InputStreamReader(http.getInputStream())); // <- Here it is where the message seems to be really being sent!!
// The answer is received too (that's OK)
System.out.println("Client : Opened input stream");
String input = "", response = "";
while((input = in.readLine()) != null)
response += input + "\r";
System.out.println("Client : received : "+response);
The message is sent, as I was saying, and an answer is always, at least, sent from the server.
Question 3: Even further, I am having a third problem. Sometimes the getInputStream line seems to hang. Look: the message arrives fine to the web server, a message from thre web server to the client is received but the program keeps stuck on the getInputStreamLine. Why??
Question 4: For the previous problem (the important one), after craving and poring over this forum, I found a message that seems to explain that sometimes HttpURLConnection hangs (GetInputStream) (http://forum.java.sun.com/thread.jsp?forum=4&thread=347082). I implemented a threaded solution for when the getInputStream hangs:
1) The main process open the getInputStream in a different thread.
2) The main process gets asleep for X seconds.
3) The child process opens the GetInputStream
4) The child process "awakes the main process.
5) Everythings keep going on.
This works: if the GetInputStream method gets stuck (step 3), its parent kill him. I show the client a fancy web page, equal to the one received if getInputStream wouldn't have stuck.
Nonetheless, if the message sent is too long (remember: they're long posts, usually 5 mb. or more long) it can happen that the parent kills the thread befor the message is sent (the message is sent with the getInputStream, remember?) So the process is killed before it really gets stuck and the fancy page telling that the message has been sent says nothing but lies!
Would you please help me? Excuse me, i have tried to do the shortest possible.
Thanks a lot.
Regards,
Mario R.

Answer 1

HttpURLConnection wasnt designed to send large chunks of data
part of a POST request is a header "Content-length", which can only be calculated when all the data has been assembled in a buffer (before anything is sent), must be that flushing and closing the OutputStream is not what the programmers use as a signal that all data has been declared (by you)
I would either use a Socket and work out th Http bit my self or write a CGI script that compiles the data in smaller chunks (~1k blocks), you could do this in a temp file on the server