Last packet not arriving after binary data transfer

Question

Hi folks,
I have written a server app that receives a text header and a binary data block (e.g. an image). To read the text header I use a scanner "in" (to be more comfortable). Then after that I use the "bis" to get the binary data.
That works so far. I get a header and binary block and then I want to send back a header and a binary data block to the client in the same way.
My problem: In most of the cases (not always but mostly reproducable) delivering the result the last packet is not delivered to the client.
These are my streams, readers and writers:
bis = new BufferedInputStream(client.getInputStream());
sr = new InputStreamReader(bis);
in = new Scanner(sr);
bus = new BufferedOutputStream(client.getOutputStream());
response = new PrintWriter(bus);Here is the part of the file transfer back to the client:
int copyBytes = 0;
long copyTotal = 0;
byte[] copyBuf = new byte[client.getSendBufferSize()];
while ((copyBytes = cis.read(copyBuf)) != -1)
    bus.write(copyBuf, 0, copyBytes);
    copyTotal = copyTotal + copyBytes;
    System.out.println(copyBytes + "/" + copyTotal + " / " + fileSize);
    if (copyTotal >= fileSize)
        break;
bus.flush();
System.out.println("Finished copyStream");
[...]On the client I have basically the same (the other way round - first send a header + binary block and then receive it):
while ((bytesRead = bis.read(buffer)) != -1)
    fileStream.write(buffer, 0, bytesRead);
    bytesTotal = bytesTotal + bytesRead;
    System.out.println(bytesRead + "/" + bytesTotal + " / " + resultLength);
    if (bytesTotal >= resultLength)
        break;
System.out.println("here i am");The output on the server is something like:
Start copyStream
46966/46966 / 46966
Finished copyStreamOn the client it is like
38950/38950 / 46966It never comes to the point where it should say "here i am" although on the server it writes that everything has been transferred.
I found out that when I do a bus.close() at the server afterwards at the server then the last package arrives. But then I cannot continue using this connection, but I want to keep the connection waiting for additional header + binary block (or waiting for a "quit").
I tested this on Windows and Linux (for the case there could be an OS specific strange behavior).
What am I doing wrong? Wherever I search I don't find really different approaches to receive and send data. The only difference I can see from other samples is that I do use a reader and just when expecting binary data I use the underlying byte oriented stream. After flushing I go back reading from the "higher level" reader.
The strange thing is that receiving the text header and binary block on the server works fine but when sending response back to the client it does not work.
What I already tried:
I tried nulling my readers while reading from the underlying byte oriented stream for the case they get confused with the binary data and if data is read from the underlying byte oriented stream (did that on server and client side). That did not help.
I tried - as already mentioned - closing the bus stream - which closed my connection which I don't want but delivered the last package.
I also tried using different type of binary stream. I used a TIF image, JPG image and finally tried also with a text content (treated as binary data) and only with the last text content the problem did not occur. But this should not make a difference when reading the byte stream.
I am struggling now for two days with this problem and my last idea is trying to remove the readers in general and using just the binary oriented streams (which is more work for identifying the header lines which are plain text - anyway). But I have the doubt that this will not help because I already tried dropping them when transferring the binary block.
Another link that I found is [http://rox-xmlrpc.sourceforge.net/niotut/index.html|http://rox-xmlrpc.sourceforge.net/niotut/index.html] - is it possible that I have to use nio for this? - But why can I then see plenty of examples without the use of nio what sense would it then make having the "normal" sockets without nio?

Answer 1

jtahlborn wrote:
yes, you generally cannot mix Readers and InputStreams. you mentioned that you were reading "byte by byte". but you weren't. you were reading "char by char" (with some more buffering). as mentioned by a previous poster, put a DataInputStream on top of your BufferedInputStream and use that exclusively.Thanks, that was the reason - now it works! Thanks a very lot!
I have seen many samples and documentation where streams where taken to an upper level with readers with and without buffering. But I was not aware that I then have to use always exclusively the object on the upmost level. Reviewing some samples I can see that there is indeed no mixed usage.