EMBED and validation

[Peter Murray-Rust]

At 10:29 02/12/97 -0500, Rob McDougall wrote:
>Thanks to everyone for the replies.  I now (think I) understand how this
>would be used.  This method does require that the person creating the
>document specify all the URLs he will be "include"ing at the top of the
>file.  This is somewhat inconvenient for someone who only inserts things
>once into any given document.  If the documents are being generated on
>the fly from some application, the application may have to perform two
>passes to derive a list of filenames, or else "bulk up" the document
>with lots of entities that may never be substituted.

If you are going to 'include' binary 'files' (i.e. entities) then it gets
more complex. This is my current analysis. It's probably wrong. (Are there
any Java parsers which manage this?)

<!DOCTYPE CML [
<!NOTATION GIF
	 PUBLIC "+//IDN ds.internic.net/rfc/rfc2046.txt//NOTATION 
         Multipurpose Internet Mail Extensions::image/gif//EN">
<!-- I hope I have copied that right - please don't sue - typos are likely -->
<!ENTITY mygif SYSTEM "my.gif" NDATA GIF>
<!-- an ENTITY declaration is required for EVERY image??? -->
<!ELEMENT CML (IMG)*>
<!ELEMENT IMG (EMPTY)>
<!ATTLIST IMG SRC NOTATION (GIF) #REQUIRED> <!-- I could include JPEG, etc-->
]>
<CML>
<IMG SRC="mygif">
</CML>

This is all required for one GIF. Every GIF requires an ENTITY. There
*must* be an internal subset. There must be a registry for the FPIs, etc.

In XLL I can write a complete document:
<CML>
<IMG HREF="my.gif" XML-LINK="SIMPLE" SHOW="EMBED" ACTUATE="AUTO"
MIME="image/gif"/>
</CML>
(excuse the case insensitivity)


>It would be nice if there was also an "inline" way of doing includes
>that would allow the XML parser to validate the resulting content.

Well, XLL does this ***as long as we agree on the semantics***.  HREF (or
IMG/SRC) is so widely used in HTML that people will certainly start doing
their own thing. There are the following possibilities:
	- wait for a W3C body to pronounce (won't be this year, I suspect)
	- wait and see what commercial browsers do
	- invent nine-and-sixty ways of doing it
	- use XDEV: as at least a means of coordinating *some* people.
	
JUMBO will start with the latter, and junk it as soon as anything official
comes along... 

[BTW I am not very happy with the idea that FPIs are intended to be human-
but not machine-readable. That makes them useless for things like image/gif.]

	P.


Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS http://www.nottingham.ac.uk/vsms, Virtual Hyperglossary
http://www.venus.co.uk/vhg

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