xml-dev - Re: FW: XML Mail

[John Cowan <cowan@locke.ccil.org>]

Borden, Jonathan scripsit:

> 	XMTP is an XML <-> MIME mapping which transforms SMTP messages into XML.
> The mapping is described at http://jabr.ne.mediaone.net/documents/xmtp.htm

Very interesting stuff.  However, the DTD will not do, and indeed this
is an application that *shouldn't* really have a DTD, IMHO.

Your DTD treats "ANY" as a general-purpose wildcard in content models,
for example: <!ELEMENT BODY (#PCDATA|PARTS|ANY)*>.  That won't work.
ANY is treated as a wildcard only when it forms the entire content model,
e.g. <!ELEMENT MORE ANY>.  The use you make of it is syntactically
correct, but ANY will be interpreted as an element name, not what you
want!

In any event, your application is not suitable for a DTD, for this reason:
Your converter generates an element type for every different kind of
SMTP header line.  Since the set of header lines is unbounded, so is
the set of element types, and DTDs cannot cope with that situation even if
ANY is used, because ANY only allows any *declared* element type to
appear in the content model.

So don't use a DTD and stick to a prose explanation.

> Valid HTML can't be left alone because this is not required to be well
> formed XML hence HTML is escaped. XML is left alone if the
> content-type=text/xml

A very sound point.  However, it might be neater to use a CDATA section
instead of methodical &amp; and &lt; escaping, as someone else mentioned.
There is certainly no reason to do &apos; and &quote; escaping in
character data: that is only necessary in attributes, which you don't
use.

-- 
John Cowan					cowan@ccil.org
		e'osai ko sarji la lojban.

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