Mailing-List: contact dev-help@tomcat.apache.org; run by ezmlm
Precedence: bulk
Reply-To: "Tomcat Developers List" <dev@tomcat.apache.org>
Received-SPF: pass (asf.osuosl.org: domain of san.tang@gmail.com designates
 64.233.162.205 as permitted sender)
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
        s=beta; d=gmail.com;
        h=received:message-id:date:from:to:subject:mime-version:content-type;
        b=CZzW1yixCfHxWY2auytmW9Cz4CFh1+hc+0Wu8tBNdXKHAcHU48R0yMFYu53GMzTIIM6fGrK92AqPoMi17A5tRmfSAmOL40UUaXys508T8hG4cMFwOqlhIh3sXK6aRkZj5wWDLGVkksM6UF+t+oJG0NSgUZKkOnUCYlW7F67EpHo=
Message-ID: <97b49b250608021445s50781364m4618557066a30a40@mail.gmail.com>
Date: Wed, 2 Aug 2006 17:45:21 -0400
From: "Hung Tang" <san.tang@gmail.com>
To: dev@tomcat.apache.org
Subject: persistent connections: understanding socket programming in tomcat
 help
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_Part_40820_20621821.1154555121082"

------=_Part_40820_20621821.1154555121082
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

Hi,

My requirement is to write a server that is capable of holding long
conversations with the client based on socket programming for Java.  I'm
using ServerSocket to create TCP sockets.  The problem I am running into is
that I am not able to do [read, write, read] sequence of operations reliably
on my socket.  Here is my [read, write, read] code:

1: int numBytesRead = socket.getInputStream().read(buffer);
2: System.out.println(numBytesRead);
3: socket.getOutputStream().write(new byte[] { 'a', 'b', 'c' });
4: socket.getOutputStream().flush();
5: numBytesRead = socket.getInputStream().read(buffer);
6: System.out.println(numBytesRead);

On line 5 in this code, the read operation is NOT blocking and will return
-1.  After some testing, I concluded that after flushing output [line 4],
the input stream will not block anymore.  However, if I comment out line 4,
the read operation will block again, and will continue to block on
subsequent attempts for read before any output flush.  What I want is to
implement persistent connections which enable me to read client's input,
respond, and repeat without closing the socket.  I believe this possible
with Tomcat but I can't figure out how Http11Processor implements it.

Can anyone give me any ideas as to WHY this is the behaviour to be expected
in my code?  Why is that a output flush causes my input stream to behave
unexpectedly? And how do I correctly implement read, write, read for support
persistent connections?  Surely this can be done right? I only hope so.


-- 
Hung Tang

------=_Part_40820_20621821.1154555121082--