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- From: Chris Pratt <chris@planetpratt.com>
- To: David Megginson <david@megginson.com>,XML Development Interest Group <xml-dev@lists.xml.org>
- Date: Wed, 12 Jul 2000 13:07:25 -0700
No, let me see if an example will make this clearer, sorry about the Rich
Text Format and the length of the message. I have this XHTML:
<?xml version="1.0"
encoding="iso-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Strict//EN" "DTD/xhtml1-strict.dtd" [
<!ENTITY % aml SYSTEM
"DTD/aml.dtd">
%aml;
]>
<html
xmlns="http://www.w3.org/1999/xhtml" xmlns:aml="DTD/aml.dtd" xml:lang="en"
lang="en">
<head>
<title>Andalay
Application Server</title>
</head>
<body
background="/images/binder.jpg" bgcolor="white">
<table border="0" height="100%"
width="100%">
<tr
valign="top">
<!-- Binding -->
<td
width="75" height="100%"><img src="/xml/images/blank.gif"
width="75"/></td>
<!-- Data -->
<td
width="100%">
<form action="getpricequote.html"
method="post">
Product: <input type="text" name="product" value="&echo.product;" size="50"
maxlength="256"/>
</form>
<aml:test name="pricequotelist"
isnull="false">
<hr/>
<table border="1"
bgcolor="#c0c0c0">
<tr
bgcolor="pink">
<th>Product
Name</th>
<th>Product
Description</th>
<th>Merchant</th>
<th>Price</th>
<th>Available</th>
</tr>
<aml:list name="pricequotelist"
value="pricequote">
<tr>
<td>&pricequote.product;</td>
<td>&pricequote.description;</td>
<td><a href="&pricequote.url;">&pricequote.merchant;</a></td>
<td>&pricequote.amount;</td>
<td>&pricequote.available;</td>
</tr>
</aml:list>
</table>
<aml:else/>
<aml:test name="pricequote"
isnull="false">
<hr/>
<table border="1"
bgcolor="#c0c0c0">
<tr
bgcolor="pink">
<th>Product
Name</th>
<th>Product
Description</th>
<th>Merchant</th>
<th>Price</th>
<th>Available</th>
</tr>
<tr>
<td>&pricequote.product;</td>
<td>&pricequote.description;</td>
<td><a href="&pricequote.url;">&pricequote.merchant;</a></td>
<td>&pricequote.amount;</td>
<td>&pricequote.available;</td>
</tr>
</table>
</aml:test>
</aml:test>
</td>
</tr>
</table>
</body>
</html>
Which, depending on the current user's context, may end up looking like the
following HTML:
<html>
<head>
<title>Andalay Application
Server</title>
</head>
<body
background="/images/binder.jpg" bgcolor="white">
<table border="0" height="100%"
width="100%">
<tr
valign="top">
<!-- Binding -->
<td
width="75" height="100%"><img src="/xml/images/blank.gif"
width="75"></td>
<!-- Data -->
<td
width="100%">
<form action="getpricequote.html"
method="post">
Product: <input type="text" name="product" value="Palm
V" size="50"
maxlength="256">
</form>
<hr>
<table
border="1"
bgcolor="#c0c0c0">
<tr
bgcolor="pink">
<th>Product
Name</th>
<th>Product
Description</th>
<th>Merchant</th>
<th>Price</th>
<th>Available</th>
</tr>
<tr>
<td>3Com Palm
V</td>
<td>The Palm V is the Sleekest, Coolest PDA
Available.</td>
<td><a href="http://www.buy.com/computers/whatever/palm+v.html">Buy.com</a></td>
<td>$329.00</td>
<td>15</td>
</tr>
</table>
</td>
</tr>
</table>
</body>
</html>
The XHTML/AML was initially processed into a directed graph that would
resemble this:
StaticPageNode
EchoEntityNode
(&echo.product;)
StaticPageNode
+---TestPageNode (pricequotelist)
| StaticPageNode
| +-ListPageNode (pricequotelist)
| | StaticPageNode
| | PriceQuoteEntityNode
(&pricequote.product;)
f ^ StaticPageNode
a | PriceQuoteEntityNode
(&pricequote.description;)
l | StaticPageNode
s ^ PriceQuoteEntityNode
(&pricequote.url;)
e | StaticPageNode
| | PriceQuoteEntityNode
(&pricequote.merchant;)
v ^ StaticPageNode
| | PriceQuoteEntityNode
(&pricequote.amount;)
| | StaticPageNode
| ^ PriceQuoteEntityNode
(&pricequote.availability;)
v | StaticPageNode
|
+-LoopPageNode
+---ElsePageNode
| +-TestPageNode (pricequote)
| | StaticPageNode
| | PriceQuoteEntityNode
(&pricequote.product;)
| | StaticPageNode
t f PriceQuoteEntityNode
(&pricequote.description;)
r a StaticPageNode
u l PriceQuoteEntityNode
(&pricequote.url;)
e s StaticPageNode
| e PriceQuoteEntityNode
(&pricequote.merchant;)
v | StaticPageNode
| | PriceQuoteEntityNode
(&pricequote.amount;)
| v StaticPageNode
v | PriceQuoteEntityNode
(&pricequote.availability;)
| | StaticPageNode | +-NoopPageNode
+---NoopPageNode
StaticPageNode
So when each page request comes in the directed graph is executed to
generate the output. The line:
<td><a href="&pricequote.url;">&pricequote.merchant;</a></td>
shows the problem most clearly. In SAX, the data from the
&pricequote.url; entity reference is reported as an entry in the
Attributes Object passed to the startElement() call, where as the
&pricequote.merchant; is reported in the character() call. I need to
know how this entity was found in the document to know what should preceed and
follow it in the directed graph. I also need to know which of
the Attributes actually started life as an Entity Reference so that the
proper EntityNode can be added to the graph instead of the replacement text that
the parser found in the DTD. If this isn't clear enough, please let me
know.
(*Chris*)
----- Original Message -----
Sent: Wednesday, July 12, 2000 12:32 PM
Subject: Re: SAX2 Lexical Handler Suggestions
> Chris Pratt wrote:
>
> > How does XSL
deal with these problems? There's no control over entity
> >
references in XSL? I am basically doing what XSL enables except that
I'm
> > caching it in between. I don't understand how XSL is able
to do this using
> > a SAX parser if the rest of us mortals
aren't?
>
> XSL doesn't expose internal entity boundaries, but it
does expose
> elements and processing instructions.
>
>
There's been a lot of terminological confusion in this discussion -- it
>
started dealing with entities, but then you (Chris) wrote at length
>
about attributes. I assumed that that was just a slip for
'entities',
> but I may have been wrong.
>
>
> All the
best,
>
>
> David
>
> --
> David
Megginson
david@megginson.com
>
http://www.megginson.com/
>
| 