[exprla-devel] XFA and XML Script

[reid_spencer <ras...@re...>]

--- In xpl-dev@y..., "Alexander E. Gutman" <gutman@m...> wrote:
Hello, friends.

I have briefly read the basics of XFA and XML Script.
My raw conclusion: They are not what I want XPL to be alike.
The two main distinctions/disadvantages are as follows:

  1. Their purposes are different from that of XPL.
  2. They are not purely XML-based languages.

Now some details follow.

XFA vs XPL

  0. An XFA program is not a well-formed XML document.
     As a result, XSLT is useless here.
     Fortunately, there is a strict XML version.
     Therefore, I will consider that only case.

  1. The output of an XFA program is an HTML document.
     Thus, an XFA document looks like and works like just an ASP.
     So why not using HTML+JavaScript, as ASPs do?
     Just because XFA is an XML instance?
     This argument is not very strong due to the disadvantage #2.

     By the way, even though XFA has additional advantages
     as compared to ASPs (and it does have them),
     the output of an XFA program is still an HTML document.
     This is not the case if we consider XPL.

     Of course, one of the XFA benefits consists in the fact that,
     by communicating with an XFA interpreter, you can make
     pages active. Actually, an XFA interpreter is a "universal"
     script which handles requests from XFA-generated HTML pages.
     But this feature does not concern XFA as a language.

  2. XFA is not a purely XML-based language.
     The XFA documentation states: "Other approaches to processing
     XML require the use of another language such as Java or Perl.
     With XFA, the only language needed is XML."
     Actually, this is not so. Examining the following example

       <xfa:val exp='f1("first","This is the first call to f1")'/>

     we see that another, non-XML, language is employed.
     The question arises again: ASPs also use another language
     (JavaScript), so why not using HTML+JavaScript instead?
     Contrary to XFA, XPL should be a purely XML-based language.

XML Script vs XPL

  1. An XML Script is a transformation program.
     Its purpose coincides with that of XSLT.
     This is not the case if we consider XPL.

  2. XML Script is not a purely XML-based language.
     Examining the following example

       \# myvalue := 1 \#
       \# ++ myvalue \#

     we see that another, non-XML, language is employed.
     Contrary to XML Script, XPL should be a purely
     XML-based language.

--
Alexander E. Gutman
--- End forwarded message ---