I was thinking of how to approach this problem a while back (for the case of
a simple online cardgame) but never came to anything concrete. However, I
did remember playing with some script (it was in Perl but you could use any
language) which acts as a server-push, but it only works for Mozilla, not
IE, and not tested in Opera or Safari. So, if you want a true client-server
model with bidirectional communication I guess you're best off coding a Java
applet for the browser, and whatever language specialized server with your
own protocol.
Anyways here's the example code I was using. Also, I was testing on an
Apache server and the script would not work unless the filename began with
"nph-" which stands for non-parsed headers.
=============================
BEGIN - Perl script
=============================
#! /usr/bin/perl -w
use strict;
use CGI qw/:standard :push/;
use CGI::Carp 'fatalsToBrowser';
$CGI::POST_MAX = 1024 * 1024; # max 1M posts
$CGI::DISABLE_UPLOADS = 1; # no uploads
$| = 1;
print multipart_init(-boundary=>'----here we go!');
foreach (0 .. 4) {
print multipart_start(-type=>'text/plain'),
"The current time is ",scalar(localtime),"\n";
if ($_ < 4) {
print multipart_end;
} else {
print multipart_final;
}
sleep 1;
}
=============================
END - Perl script
=============================
As you can see, most of the actual server-push code is handled by the CGI
Perl Module. So just taking a quick peek inside to show the relevent bits
of raw HTTP and HTML tricks used, or just using telnet or wget to fetch from
the server.
Headers: (first three added by Apache, last one added by the script)
HTTP/1.0 200 OK
Server: Apache/2.0.47 (Unix) mod_ssl/2.0.47 OpenSSL/0.9.7c DAV/2
PHP/4.3.4RC1
Date: Tue, 14 Oct 2003 13:39:48 GMT
Content-Type: multipart/x-mixed-replace;boundary="----here we go!"
Content:
WARNING: YOUR BROWSER DOESN'T SUPPORT THIS SERVER-PUSH TECHNOLOGY.
------here we go!
Content-Type: text/plain
The current time is Tue Oct 14 09:39:48 2003
------here we go!
Content-Type: text/plain
The current time is Tue Oct 14 09:39:49 2003
------here we go!
Content-Type: text/plain
The current time is Tue Oct 14 09:39:50 2003
------here we go!
Content-Type: text/plain
The current time is Tue Oct 14 09:39:51 2003
------here we go!
Content-Type: text/plain
The current time is Tue Oct 14 09:39:52 2003
------here we go!--
WARNING: YOUR BROWSER DOESN'T SUPPORT THIS SERVER-PUSH TECHNOLOGY.
----- Original Message -----
From: "Raymond Irving" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, October 13, 2003 10:27 AM
Subject: Re: [Dynapi-Help] Simple communication questions...
>
> See below:
>
> --- Clemens Eisserer <[EMAIL PROTECTED]> wrote:
> > Hi again!
> >
> > I´m currently thinking about writing a simple
> > JS-Chat, so that the chat doent need to reload
> > always when
> > new messages recieve.
> > The problem is, that the server should connect to
> > the client, which is not possible as far as I know,
> > this
> > means the client has to use possling and aks all x
> > seconds the server for new messages.
> >
> > 1.) Is there no other was to do this than polling?
>
> Not that I know of
>
> > 2.) These are the only polling-ideas I had:
> > * Blocking soda-rpc function. Blocks till messages
> > are on server. (Problem with blocking - no events
> > etc?)
> > * Non-Blocking soda-rpc function. Returns -1 if
> > nothing is there...
> >
> > Is the blocking version possible, or will it cause
> > the application to hand in the poll-loop. This is a
> > problem
> > in my eyes since JS hasnt support für Multithreading
> > :(
>
> Using synchronous GET or post will cause the app to
> wait until the server returns a response.
>
>
> > Does anybody have better ideas, I´m not really happy
> > with my stuff..
>
> In the future there might be an easier method
>
> --
> Raymond Irving
>
> > lg Clemens
> >
> > PS1: How hard would it be to adopt dynapi to
> > knoqueror? (only because it interrests me why so
> > many
> > examples dont work..)
> > PS2: Dynapi is great!
> >
> >
>
____________________________________________________________________________
__
> > Zwei Mal Platz 1 mit dem jeweils besten
> > Testergebnis! WEB.DE FreeMail
> > und WEB.DE Club bei Stiftung Warentest!
> > http://f.web.de/?mc=021183
> >
> >
> >
> >
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> > _______________________________________________
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> >
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