Scripting and XML

[Ingo Macherius]

> Date:          Sat, 18 Oct 1997 23:50:08 -0400 ()
> From:          Rasmus Lerdorf <rasmus at lerdorf.on.ca>
> Subject:       Re: Scripting and XML

> So, a typical bit of code would look like:
> 
>   <?php
>     $result=mysql("db","select passwd from users where id='$cookie'");
>     if(mysql_result($result,"passwd")==crypt($input)) {
>         echo "Welcome $id<BR>\n";
>     }
>   ?>

What makes me nervous about the above code is that it is kind of 
self modifying code. The script replaces itself with it's own output, 
which may insert tags ("<br>"). So the document's structure may 
change after processing the PI, and it may no longer satisfy the DTD 
after that.

> I would
> like people to be able to create XML with an XML authoring tool that
> includes my PHP script tags.  

That is ok for the authoring tools, but does say nothing about the 
validity of XML documents that containined PHP/FI PI after delivery. 

And what about XLinks ? Pointing at a document containing e.g. a 
table of data created by querying a DB with PHP/FI is impossible.
You would only be able to point at a created element, if your server 
is aware if it was the output of PIs. This collides with the "just in 
time" translation of PHP/FI PIs, as the DB may have changed in 
between.

So PHP/FI could parse correctly before, but probably not 
after delivery. A possible solution is to batch-process your 
documents and validate after that, but before you put them online. 

	++im

 
--
Ingo Macherius // L'Aigler Platz 4 // D-38678 Clausthal-Zellerfeld
mailto:Ingo.Macherius at tu-clausthal.de    http://www.tu-clausthal.de/~inim/
Information!=Knowledge!=Wisdom!=Truth!=Beauty!=Love!=Music==BEST (Frank Zappa)

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