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From "Javier Ramos" <ra...@parsec.es>
Subject RE: Use the value of an XML attribute as sitemap parameter
Date Fri, 05 Sep 2003 14:45:59 GMT
Here is what I want to do:

	I will write a web application that does not deal with any
presentation issue. There is a central servlet which receives requests
in XML format via HTTP POST. The XML format of the request is under my
full control, I do not have to make any contract with the users of the
services provided by the servlet. The servlet analyzes the request and
assigns it to a controller, which in turn returns an XML response, also
in a format under y control.

	Now I want to give access to the services provided by the
servlet to the outside world. I want to have an HTML	 interface, as
well as several public XML interfaces.

	For this I will be using cocoon. For example, for the HTML site
I will be setting up a pipe with:

	- RequestGenerator
	- then use XSLTransformer to map request to my own format
	- custom transformer to send this XML as a request to the
servlet, and return the response from the servlet.
	- Evaluate an XML element from the response to see what kind of
response it is ( in my design sometimes the server can return several
responses to a request, depending on completion status, user,
environment... )
	- Select an XSLTransformer appropriate to the response type that
was received, to create an HTML page.
	- Serialize
	
	The last transformation is the one that I cannot figure how to
create in cocoon. Well, in fact, it seems not possible.

	As you see, I am not interested in the ordinary uses of cocoon.
I want it to do all the presentation, i18n, ¿ session handling ?,
integration of content from other sites... for my application, and keep
a very lightweight application core in another server.

	Is this a crazy idea? Would it be 'heretic' :-) practice to
instantiate and use a TraxTransformer inside a custom transformer
extending AbstractDOMTransformer to do the job? Anyone knows how can
this be done? Are there other solutions?

	I also thought if I could obtain the value of an HTTP header as
a parameter, which would be another solution. But it seems with a
HeaderSelector I can only do lengthy if-else-if checks, listing all the
possible values of the selecting parameter. I would like to do it in one
or two lines. 

	Hope this is not too long to read. Thanks for your comments.

Javier Ramos

-----Original Message-----
From: Geoff Howard [mailto:cocoon@leverageweb.com] 
Sent: viernes, 05 de septiembre de 2003 4:58
To: users@cocoon.apache.org
Subject: Re: Use the value of an XML attribute as sitemap parameter

Javier Ramos wrote:
> Hello,
> 
>             I would like to be able to extract from an XML document 
> transformed several times in a pipeline the name of one of its
elements, 
> and use it to create the src attribute of the next transformer in the 
> pipeline.
> 
>             Anyone thinks this is possible, and how?

No, it is impossible on purpose because situations like you describe can

lead to applications which are very difficult to maintain.  By the time 
generation begins, the complete pipeline must be set up, meaning all src

attributes must be fixed.  The src can only be affected by sitemap 
components executed before pipeline setup (matchers, selectors, input 
modules, actions and flow).

Perhaps you can describe a simplified version of your use case and 
someone can give pointers on how to best achieve this within Cocoon.

Geoff


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