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RE: Partitioning?

• To: <xml-dev@l...>
• Subject: RE: Partitioning?
• From: "Didier PH Martin" <martind@n...>
• Date: Sat, 27 Jul 2002 09:49:02 -0400
• Importance: Normal
• In-reply-to: <3D428D0B.2020104@o...>

Hi Steven,

Steven said:
Cocoon (http://xml.apache.org/cocoon/) is be able to do so using its 
BrowserSelector 
(http://xml.apache.org/cocoon/userdocs/selectors/selectors.html) or 
using DELI (CC/PP -
http://xml.apache.org/cocoon/developing/deliquick.html).

If you want an example sitemap configuration for this, please ask.

Didier replies:
I checked Cocoon thinking that they developed something new since the
last time I checked (last month) and it is the same thing. Cocoon still
doesn't support process partitioning. Let me explain why:

In cocoon, the xml document doesn't need to include the stylesheet
Processing instruction since cocoon uses the selector definition to
associate a style sheet to the xml document. So, the xml document
doesn't include a style sheet processing instruction. Moreover, to
support full partitioning, cocoon would need to include the style sheet
processing instruction in the xml document before sending it to the
client. Thus, if the client support XSLT, the server includes the style
sheet processing instruction in the xml document and otherwise performs
the transformation on the server side based on the selector definition.
It seems that cocoon still doesn't support full transformation process
partitioning. Deli just uses the more formal CC/PP model to provide
information on the client's capabilities.

Steven said:
Reverse-proxying what? I don't understand your question, please give an 
example.

Didier replies:
Now about the reverse proxy stuff it means that in front of an HTTP
server stands a transformation server. This latter receives the client's
request and performs the transformations. The HTTP server is located on
a different machine. This allows to manage the workload between a farm
of transformation servers and a farm of HTTP servers. Cocoon is designed
to have everything on the same server. This implies that you may
experiment scalability problems that could be prevented by allowing to
structure the servers in two sets: a) the transformation engines and b)
the HTTP server. Moreover, this structure allows you to get the servers
to balance the workload among the different HTTP servers.

Steven said:
Cocoon websites: http://xml.apache.org/cocoon/link/livesites.html and 
also parts of salon.com, nasa.gov - the users' mailing list sometimes 
reads like a Fortune 500 directory ;-)

Didier replies:
Yes indeed. However I would be curious to know what kind of traffic they
sustain and if the way they use cocoon could be used in other sites like
for instance e-bay. I checked several of these sites and none of them
perform a transformation on the client side even if my browser support
XSLT 1.0. So, their server do not leverage the client's transformation
power and thus these sites doesn't perform process partitioning. Seems
that we are still in the middle ages of distributed computing and that
we need a "renaissance" renewal. 

Thanks for your help and comments

Cheers
Didier PH Martin

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