Why XML (was: Re: What I see as problems to solve ... and a strawman solution)

At 15:10 04/02/01 +0000, Paul Smith wrote:

>However, thinking about it a bit more, I can see reasons for XML -
><header>
><to><name>fred bloggs</name><address>[email protected]</address></to>
><to><address>[email protected]</address><name>Jim 
>Smith</name><comment>Director</comment></to>
>...
></header>
>would be more useful than the many ways to encode a To: field at the 
>moment, but that's about the only reason that I can come up with. The 
>added complexity of XML parsing & generation, and the data overhead may or 
>may not be worth it, IMHO, there are almost definitely non-XML ways of 
>doing this.

One thing where I think XML could help a lot is to get some order
into the current header confusions. In particular, the From:, Sender:,
Reply-to:,... headers have been developed in a somewhat ad-hoc fashion.

Rather than a mostly flat header structure and a two-level distinction
between (transport/SMTP) envelope and email body (including headers),
it seems to me more appropriate to have a single format with some
rather general wrapping conventions. More on that maybe in another
message.

A particularly interesting property for XML in the context of email
is that with XML digital signatures (http://www.ietf.org/rfc/rfc3275.txt/
http://www.w3.org/TR/xmldsig-core/), you can sign arbitrary pieces
of a document, i.e. you can sign the body and some headers, but
not others. Also, the signature is not on the bytestream, but on
canonical XML. Together, these two properties can alleviate quite
a bit of the current problems with signing email messages.


>At 03:56 31/01/2004, Chuq Von Rospach wrote:

>>And anyway, why build a custom format that needs custom code to decode, 
>>when you can use an existing system that allows for existing tools to do 
>>the packing and unpacking?
>
>Because this assumes you have access to libraries which work on your 
>system which support parsing/creating XML. Let's assume you're writing a 
>mailing system for a hardware device with a limited amount of RAM & ROM, 
>and you only have assembler and C (if you're lucky) to use, would you 
>still want XML?

Yes. The chances are that there are a few other things going on on this
system, even if it's very small. And a few of them easily also use XML.
You might be surprised, but as far as I know, most of the higher-end
mobile phones these days support XML.


Regards,   Martin.