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Re: [xmlblaster] Using xmlblaster to push internet callbacks

Paul Power wrote:

Hi all,

It's been a while since I looked at xmlblaster and it's great to see it still going from strength to strength !

The reason I'm here again is because I'm looking for a flexible, and efficient, way of pushing xml to internet
clients through just about every firewall config known :-)

OK, there are several options:
- email
- Polling from client side
- ...

But the only 'real-time' callback is probably an established
socket between client and server:

 - The client needs to establish the connection.
   You usually can't address any port in the clients
   environment form server side.

- The push back messages need to go through
  the socket established by the client

- The server needs to follow http protocol when pushing
  back, since proxies will drop the connection if for
  example the callback data is strange.

- You need to have a minimum data rate and probably
  ping often enough (to minimize timeouts from
  proxies, webservers, browsers)

This is all very tricky, our http pushback solves it
for mozilla/netscape and IE5.0

If you use an applet, you need to do it similar
to the browser and have the advantage of more control
on TCP/IP.

The applet usually reuses the proxy settings of the browser
so firewalls and proxies are tunneled fine.

Good luck, if you are successful with your applet we are happy for any contributions


I know that xmlblaster has a http callback framework but I've read in some postings to this list that a new communications piece is being worked on. Can anyone fill me in a bit more ?

What I'm looking for is a java component I can embed
in an applet and have updated across the internet where
the client is most likely behind a NAT and firewalls and the server is definitly behind firewalls. I am probably able to get the server firewall opened for incoming connections and outgoing traffic but I cannot assume that the client can ( especially for applets ).

There are usually two problems, firewal and proxies.

Has anyone done this before in a reasonably large scale system ( 100 - 1000 users ? ) or have any alternative suggestions.

Any help would be much appreciated :-)


"Tous pur un, un pour tous"

Paul Power - OTG
Cognotec Limited			
* + 353 1 6099 292
* paul.power at cognotec.com
* www.cognotec.com