On Sat, Aug 10, 2013 at 11:37 PM, Larry Masinter
<masinter(_at_)adobe(_dot_)com> wrote:
BCP 70 " Guidelines for the Use of Extensible Markup Language (XML)
within IETF Protocols"
attempted to outline some of the design considerations for data
representation using XML.
In 2003, it represented the consensus and also the disagreements about what
was "best current practice" at the time.
Section 3 of BCP 70, "Alternatives", lists some of the alternatives and
provides
a comparison.
I think what might be missing is an update to BCP 70 or a companion which
more
explicitly compares XML, JSON, CBOR and other alternatives in use in IETF
protocols.
If you're interested in this work, perhaps you might review BCP 70 and
suggest
updates.
Independently of CBOR, it would be worth revisiting this and writing best
practices for using JSON.
One of the areas that XML thought it had handled was extensibility. In
retrospect, I don't think extensibility was handled anywhere near as well
as people imagined at that time. We had to rewrite the SAML schema despite
having the input of one of the XML main authors leading the work. What we
thought would be a good extensibility mechanism turned out not to be in
practice.
At this point JSON has a reasonable extensibility story but not one that I
have seen committed to paper...
I think that we could learn something from XML Schema as well. XML Scema
and DTDs are really tools for validating documents and they are useful
there because they allow the validator to tell the user which line and
column an error occurred.
XML schema can be used as a tool for validating input to a Web Service but
much of the effort is counterproductive. Who cares which order the elements
are presented? I am not aware of any widely used programming language that
would, the order of definition of elements in a structure is only visible
at all in LISP like languages.
I see a value of using some sort of tool to define what elements do and do
not have specified semantics in a protocol and to describe the structure,
i.e. a 'schema' but we need something with a tenth the features of XML
Schema and we need to address extensibility.
--
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