Re: [Dynapi-Help] Simple communication questions...

[Andrew G. <an...@zo...>]

This may be a little off-topic, but another interesting site that's worth=
 a look at is www.pushlets.com.  Their basic setup is to use a Java servl=
et to push javascript down a HTTP connection to a hidden frame.  And they=
 have some impressive demos :)  The claim compatability with IE (back to =
4.01) and Netscape (back to 4.05).

It would be _so impressive_ if an IOElement could do a similar thing....


Andrew Gillett


Raymond Irving wrote:
> Hi,
>=20
> For some more information on server-push and
> client-pull visit the following website:
>=20
> http://wp.netscape.com/assist/net_sites/pushpull.html
>=20
> --
> Raymond Irving
>=20
> --- Leif W <war...@us...> wrote:
>=20
>>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.
>>
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
>>BEGIN - Perl script
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
>>#! /usr/bin/perl -w
>>use strict;
>>
>>use CGI qw/:standard :push/;
>>use CGI::Carp 'fatalsToBrowser';
>>
>>$CGI::POST_MAX =3D 1024 * 1024; # max 1M posts
>>$CGI::DISABLE_UPLOADS =3D 1;  # no uploads
>>$| =3D 1;
>>
>>print multipart_init(-boundary=3D>'----here we go!');
>>
>>foreach (0 .. 4) {
>>    print multipart_start(-type=3D>'text/plain'),
>>          "The current time is
>>",scalar(localtime),"\n";
>>    if ($_ < 4) {
>>            print multipart_end;
>>    } else {
>>            print multipart_final;
>>    }
>>    sleep 1;
>>}
>>
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
>>END - Perl script
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
>>
>>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=3D"----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 -----=20
>>From: "Raymond Irving" <xw...@ya...>
>>To: <dyn...@li...>
>>Sent: Monday, October 13, 2003 10:27 AM
>>Subject: Re: [Dynapi-Help] Simple communication
>>questions...
>>
>>
>>
>>>See below:
>>>
>>>--- Clemens Eisserer <Lin...@we...> wrote:
>>>
>>>>Hi again!
>>>>
>>>>I=B4m 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 f=FCr
>>
>>Multithreading
>>
>>>>:(
>>>
>>>Using synchronous GET or post will cause the app
>>
>>to
>>
>>>wait until the server returns a response.
>>>
>>>
>>>
>>>>Does anybody have better ideas, I=B4m 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!
>>>>
>>>>
>>>