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From Stefano Mazzocchi <>
Subject Re: SoC between flow and sitemap
Date Mon, 19 May 2003 23:57:55 GMT
on 5/19/03 5:39 PM Bruno Dumon wrote:

> On Mon, 2003-05-19 at 23:28, Sylvain Wallez wrote:
> [...]
>>Yes, but you have to consider how this is actually implemented. If you 
>>put a farm of Tomcats behind an httpd with mod_jk, you will be 
>>guaranteed that requests for a given session will always be handled by 
>>the same Tomcat instance. This is called session affinity. But Tomcats 
>>don't communicate with each others to exchange session or application data.
>>This means that if a continuation ContA is created on Tomcat TC1, all 
>>subsequent requests referencing this continuation must be handled by the 
>>same TC1, and not TC2, since ContA doesn't exist on TC2. And the only 
>>means you have to achieve this if servlet engines don't communicate is 
>>through session affinity.
>>So continuations must be bound to sessions.
> Actually mod_jk only looks at a suffix appended to the session cookie,
> and it shouldn't be too difficult to hack mod_jk to use a different
> cookie especially for this purpose. So sessions are not really required
> for this.

What about BEA weblogic, IBM webshere, Oracle appserver, etc, etc, etc?

Hypothetical chat between a CTO and a cocoon proponent:

 - cocoon? we are interested at it, but is it fast?
 - the pipeline creation is very complex and can be much slower than
text-based tecnologies, but cocoon has a very good caching mechanism
that allows to reuse all possible content and provide your own caching
logic to components if you need to. The results in real life prove
cocoon to be highly efficient. In a highly critical environment (which I
can't name), the use of cocoon proved to be orders of magnitude faster
than a rival application based on Oracle Internet File System.

 - what about static stuff? cocoon is much slower than a web server!
 - yes, but I normally suggest to put a transparent proxy up front and
cocoon will serve static content only once, the remaining it done by the
proxy lightning fast. (it is also transparent if you have dynamically
generated resources like images, flash files or CSS stylesheets and
allows to maintain all your URI space in one comfortable location)

 - hmmm, ok, but does it scale for dynamic stuff?
 - sure, for a stateless cocoon environment, you can throw silicon at it
and balance the load transparently by replicating the cocoon environment
on different machines. A european company (which I can't name) did tests
that showed 12000 req/sec on a big clustered environment.

 - cool, but what about stateful cases, expecially with the flow and
this new continuation thing, does it scale?
 - only with tomcat and mod_jk

 - ok, we'll use struts then.


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