You are incorrect in that in fact no DTD is needed in XML; XML schema
definitions provide similar information in a more modern format. The
relevant .XSD schema is indicated by (is implied by) the namespace; an
explicit technical linkage to the schema is not necessary (nor even
desirable, as it opens up attacks). Of course, it's very convenient if
the .xsd schema definition is online somewhere, though, being for
developer consumption only, it doesn't matter particularly where.
Think of it this way: the .xsd is compile time information whereas the
.xml data itself is runtime info, specific to a given domain.
Which is why the .xml data is published in the domain's DNS data,
whereas the .xsd is not.
It would be good if much of the marketing information in the draft
were
removed. It makes finding details difficult.
I am unhappy to hear the element of agreement reached between CID and
SPF was the use of XML.
(Pg14) The example in the draft for the TXT record is to use UTF-8
limited to a 2048 bytes of information. I suspect this size will be
the
case in general use. Does this mean that all the information is
contained within this 2K bytes? No.
To understand the content of this information, one needs to obtain a
http Document Type Definition file. XML is very extensible, as such,
every variable must be defined. If not in the 2K single page of
information, which is far to small for this needed text, then from
another source. Hence the ubiquitous doctype =
http://my.definitions.com/my-dtd-file at the beginning of the example
definitions. See: RFC3688 for how to register these templates.
For an example:
http://www.iana.org/assignments/xml-registry/schema/host-1.0.xsd
Not clearly explaining this in the draft seems to have hidden the
camels
nose under the tent. Nearly everything is pushed into this document
including version information! One wonders why use DNS to do any more
than reference such redirection? But if this is to be registered and
hard-coded, why even include a reference unless to REQUIRE http
redirection? For what is is worth, this schema in the proposal
requires
3486 bytes (not including spaces). XML is not ideal for conserving
space, and it is clear constraining a TXT record result to being under
512 bytes has been thrown out the window.
Just declare all SMTP mail servers MUST have a specific public http
server such as _ep.my.domain.com: my-host, with
http://my-host/MARID/my.domain/MS-IP-XML to include the encyclopedia
of
data types, schemas, as well as the IP address list, the certificates
required, invented-here stuff, the licensing agreements need to access
the page, etc. If the vast amount of text is going to require TCP
anyway, http is far better engineered for this, and with the use of
XML,
http is already being required. Why kill DNS to implement a tracking
tag on Mail-From?
-Doug