[xsl] HTTP server-side check [Corrected]

["Schimon Jehudah sch@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Ladies and Getlemen. Good evening.

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* This is a corrected message.            *
* Content of "Possibilities" was changed. *
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I am specifying a what-is-called "middleware" to check two concerns of
client request.

1) Whether XSLT is available.

2) Whether ECMAScript (i.e. JS) is available.

I wrote about this concern, a month ago or so; and, now, I intend to
implement it.


Possibilities
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* If XSLT is detected, then XML document be loaded.

* If XSLT is not detected, and JS is detected; then, the server would
  redirect to a page with a frame with module XSLTProcessor (or
  SaxonJS, or xslt-processor) to process the XML document.

* If neither is detected; then, the server would redirect to a raw
  (X)HTML document.

* Alternatively, it might be that the server would redirect from XML,
  to (X)HTML with JS, to (X)HTML without JS.


Technicalities
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* XSLT be checked by an image (e.g. an invisible pixel).

* JS be checked by "XML HTTP Request".

I ask for your advisories, as to the proper logic to implement this.

If you have other comments or criticism about any of the
technicalities; then, please, write.


Thank you,
Schimon