Re: [xSocket-develop] General technical question (request for idea)

[Gregor R. <gre...@go...>]

Hi Thomas,

I would suggest to read the header data as a chunk, to avoid implementing a
complex state machine. This can be done by using the read mark support. For
an example see the tutorial and the implementation of the ConectionUtils
method  validateSufficientDatasizeByIntLengthField()  (
http://xsocket.svn.sourceforge.net/viewvc/xsocket/xsocket/core/trunk/src/main/java/org/xsocket/connection/ConnectionUtils.java?view=markup
).

To read the content I would attach the content handler to the connection.
See below

Gregor


Example:

MyProtocolHandler implements IDataHandler {

        public boolean onData(INonBlockingConnection connection) throws
IOException, BufferUnderflowException {

            ContentHandler ch = (ContentHandler) connection.getAttachment();
            // content handling mode?
            if (ch != null) {
                return ch.onData(connection);
            }


            // no -> read the header as chunk
            connection.resetToReadMark();  // reset (if former reads has
been failed)
            connection.markReadPosition();

            // if not enough data is available a BufferUnderFlowException
will be thrown
            String identifier = connection.readStringByDelimiter("\r\n");
            String checksum = connection.readStringByDelimiter("\r\n");
            String length = ...

            connection.removeReadMark(); // all read!

            ContentHandler ch = new ContentHandler(length, checksum)
            connection.setAttachment(ch);
            ch.onData(connection);

            return true;
       }



       class ContentHandler implements IDataHandler {

            private int remaining = 0;
            private int checkSum = 0;
            private ...

            ContentHandler(int length,int checkSum, ...) {
                this.remaining = length;
                ...

                // create the inflator
               ...
            }


            public boolean onData(INonBlockingConnection connection) throws
IOException, BufferUnderflowException {

                int available = connection.available();

                int readSize = available;
                if (available > remaining) {
                    readSize = reamaining
                }

                byte bytes = connection.readBytesByLength(readSize);
                reamaining  -= readSize;

                // call inflator
                ...


                if (remaining == 0) {
                    connection.setAttachment(null);
                }

                return true;
           }
      }
}




2008/2/17, Thomas Steinmaurer <ts...@ib...>:
>
> Hello,
>
> I'm in the process of writing a socket server which basically receives
> data according to a self-defined protocol from mobile devices. The data
> is a mix of line-oriented character data (terminated with a '\n') and
> some kind of payload, which is a ZLib compressed byte stream.
>
> E.g., the client sends the following data in the following sequence to
> the server.
>
> Identifier\n
> Checksum value\n
> Length of compressed payload\n
> ZLib compressed payload byte stream
>
> In a first step, I have written a multi-threaded socket server, which
> uses common IO classes like DataInputStream. Performance is ok on a
> local area network, but due to the blocking issue of any read method of
> a DataInputStream, performance is pretty bad, especially in a
> low-bandwith network.
>
> So I came across NIO and xSocket as one framework using Java NIO.
>
> How can I implement a socket server with xSocket which:
>
> * Implements the protocol as shown above (mix of line-oriented
> characters and a ZLib compressed byte stream)
> * Is non-blocking, so at least a few number of simultaneous clients are
> handled gracefully
> * Of course, each client needs to be isolated from each other
>
>
>
> Any hints, code snippets, ... are much appreciated.
>
>
> Thank you very much.
>
> Regards,
> Thomas
>
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