maintain long-lived servlet connection to receive serialized data?

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17 Apr 2007 21:08:15 -0700
Can anyone help me understand how I might use an HttpServlet to
maintain a socket connection with a client and repeatedly send
serialized data to this client without closing the connection?

The use case is I have a client application (non-browser) interested
in the Servlet's ever-changing data. Rather than poll the servlet for
new data, I'd like the client to establish a long-lived connection to
the Servlet and receive serialized Objects which the client can
deserialize and use. The problems I'm having relate to understanding
how the Servlet could indicate to the client that the data its sending
is complete and ready to be deserialized (i.e., what delimits the end
of an Object stream?) as well as the appropriate use of the servlet
outputstream's flush() and close() methods.

Here's some pseudo-code that hints at what I'm after:

while (true){
   ObjectOutputStream objstream = new


InputStream response = httpclient.getResponseStream();
ObjectInputStream objInputStream = new ObjectInputStream(response);
while (true){
   Object data = objInputStream.readObject();


Thanks in advance!

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