HTTP is a stateless environment. You have no way of hanging on to the browser connection from the server.
Usually, if a user has to wait more than a few seconds for a response from the server you would forward them to a page that refreshes itself every n seconds via a META-REFRESH tag. Each time it refreshes, it checks the status on the server. On Tuesday 16 December 2003 10:32 am, [EMAIL PROTECTED] wrote: > Im trying to create a servlet that is able to push back to the browser > rather than just operate a a pull mechanism. > To create this, there is a piece of javascript embedded within the html > outputted to the browser, so when additional javascript code is written in > at a later stage calling that function, that user can be notified of events > he is registered to. > Perhaps not the way servlets were made to work but anyway! > Unless you are able to come up with a better solution? > > How do i stop the response from ending then? I have left the html open at > the end so no /html code and I have not closed the output to the browser. > -----Original Message----- > From: Ben Souther [mailto:[EMAIL PROTECTED] > Sent: Tue 16/12/2003 15:32 > To: Tomcat Users List > Cc: > Subject: Re: Having problems with stored PrintWriter. > > > > > > I am trying to store users PrintWriter and use them again at a later > > date > > Just out of curiosity, why? > > > > > On Tuesday 16 December 2003 10:12 am, [EMAIL PROTECTED] wrote: > > > Im having a problem with PrintWriter in a servlet. > > > > I am trying to store users PrintWriter and use them again at a later > > date to output javascript commands to the browsers at a later date. it > > store as a coyotewriter - [EMAIL PROTECTED] > > To do this they are dumped in a hashtable. But they dont seem to work > > when i try to write output with them? Is there any way around this?? > > this is the error I get but only when i include the flush() line. > > > > If anybody can help it would be most appreciated > > > > To write out to users browser - retrieves from hashtable > > -------------------------------------------- > > System.out.println("Is this even working: Receivedevent!!!!!!! > > "+useroutputstream); PrintWriter usersout = > > (PrintWriter)useroutputstream.get("derrick"); usersout.println("Testing > > received event status"+receivedevent); > > usersout.print("<script type=\"text/javascript\">"); > > usersout.print("receivedEvent('your dinner is ready');"); > > usersout.print("</script>"); > > //extraline > > usersout.flush(); -----> Exception: > > lbp.LBPServlet.doGet(LBPServlet.java:98) > > > > I dont know if this is also part of the problem but if i use the > > .flush(), it seems to start throwing exceptions. > > > > java.lang.NullPointerException > > org.apache.coyote.http11.InternalOutputBuffer.commit(InternalOutputBuffe > >r.j ava:547) > > org.apache.coyote.http11.Http11Processor.action(Http11Processor.java:735 > >) org.apache.coyote.Response.action(Response.java:223) > > org.apache.coyote.http11.InternalOutputBuffer.doWrite(InternalOutputBuff > >er. java:518) org.apache.coyote.Response.doWrite(Response.java:532) > > org.apache.coyote.tomcat5.OutputBuffer.realWriteBytes(OutputBuffer.java: > >392 ) > > org.apache.tomcat.util.buf.ByteChunk.flushBuffer(ByteChunk.java:439) > > org.apache.coyote.tomcat5.OutputBuffer.flush(OutputBuffer.java:350) > > org.apache.coyote.tomcat5.CoyoteWriter.flush(CoyoteWriter.java:119) > > lbp.LBPServlet.doGet(LBPServlet.java:98) > > javax.servlet.http.HttpServlet.service(HttpServlet.java:743) > > javax.servlet.http.HttpServlet.service(HttpServlet.java:856) > > org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet. > >jav a:466) > > org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:18 > >0) javax.servlet.http.HttpServlet.service(HttpServlet.java:743) > > javax.servlet.http.HttpServlet.service(HttpServlet.java:856) > > filters.ExampleFilter.doFilter(ExampleFilter.java:149) > > filters.ExampleFilter.doFilter(ExampleFilter.java:149) > > > -- > Ben Souther > F.W. Davison & Company, Inc. > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > -- Ben Souther F.W. Davison & Company, Inc. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
