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Re: Load balancing and Web Services

From: Aleksander Slominski <aslom@cs.indiana.edu>
Date: Sat, 30 Oct 2004 03:04:22 -0500
Message-ID: <41834B06.5070909@cs.indiana.edu>
To: general@ws.apache.org
CC: www-ws@w3.org

Hi Sabrina,

we have done something like what you want with WS-Addressing although in 
different context: in our case we wanted to have way for web services to 
talk to internal services that are not directly accessible (possibly 
load balanced) and on the other hand we wanted clients that are not web 
services (such as applet) to become web service peers.

for synchronous SOAP request-response this was achieved by forwarding 
HTTP connections and for asynchronous case we are doing dynamic 
rewriting of WS-Addressing WSA:destination and replyTo headers in 
WS-Dispatcher (SOAP intermediary node).

we were also thinking that intermediary (our ws-dispatcher) not only can 
do load-balancing but can provide also rudimentary fault-tolerance when 
it acts as forwarding agent - when destination service is not available 
dispatcher holds messages until service is available again (possibly 
when it migrated to new location).

for more details please see presentation:
and general overview of goals: 

if you are interested we can make ws-dispatcher code available to you  
(it is open source and we were thinking making it available like in 
sf.net but we do not have enough manpower to do it :))



James M Snell wrote:

> I've seen a number of examples that do exactly what you have in mind 
> but nothing that uses WS-Addressing, although it is certainly 
> possible.  One idea would be to implement a message bus in which 
> messages are received by a web services endpoint and are routed to an 
> appropriate backend handler.  In any case, your idea sounds viable. 
>  The challenge is that there are lots of ways of accomplishing it.
> - James M Snell
>  jasnell@us.ibm.com
>  http://www.ibm.com
>  (877) 511-5082 / Office
>  930-1979 / Tie Line
> *Sabrina Leandro <saleandro@yahoo.com>*
> 10/29/2004 01:27 PM
> Please respond to
> general
> To
> 	general@ws.apache.org
> cc
> Subject
> 	Re: Load balancing and Web Services
> Hi James,
> Thanks for your reply.
> > There are definitely several different ways of
> > accomplishing this.  One
> > method that I have been researching lately has been
> > embodied in a new IETF
> > Internet-Draft called DNS-EPD which has been
> > published at the IETF site:
> >
> http://www.ietf.org/internet-drafts/draft-snell-dnsepd-00.txt
> That is a very good example. But I have to keep my
> research much simpler, afterall itīs just a graduation
> project :)
> I was wondering if you know about solutions that rely
> on Web Service specifications, such as WS-Addressing.
> If not, do you think that it is possible to use a
> "service dispatcher" that receives all messages
> arriving to a "service cluster", and that changes the
> destination address to the appropriate service using
> WS-Addressing? Is this a good solution?
> thanks for your help.
> all opinions are appreciated :)
> Sabrina Leandro
> __________________________________
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Received on Saturday, 30 October 2004 08:05:02 UTC

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