Re: [apps-discuss] JSON Schema considered harmful

On Thu, Sep 20, 2012 at 12:53 PM, Tim Bray <tbray@textuality.com> wrote:

> On Thu, Sep 20, 2012 at 9:26 AM, Erik Wilde <dret@berkeley.edu> wrote:
>
> > i have to admit that i am really curious why the seasoned spec writers
> that
> > have voiced general concerns about the usefulness of schema languages are
> > feeling this way, but so far i have not really understood what they are
> > saying. could somebody please try again, i'd really like to understand
> why
> > the general idea of describing protocol syntax in a semi-formal (as
> opposed
> > to non-formal) way is considered a bad idea.
>
> I gave a preso at IETF70 in Vancouver a few years ago which is advertised
> as being XML-centric, but has (I think) useful things to say about
> plain-text/binary/ASN.1/JSON/XML, and discusses about the proper place of
> schemas: http://www.ietf.org/proceedings/70/slides/xmltut-0.pdf
>
> I believe:
> - ASN.1 has been bypassed by history and has truly horrible tooling. Just
> don’t go there.
>
Perhaps what we need is "Abstract Syntax Notation V2.0 (i.e. ASN.2)" which
would do what ASN.1 was trying to do but benefit from all that we've
learned since the mid-80's...

> - If you’re interchanging documents, use XML; if (much more common) you’re
> interchanging data structures, use JSON.
> - Do not use multiple syntaxes for the same protocol. Pick one of XML or
> JSON and stick with it.
> - The most important thing in defining a protocol is good clean
> comprehensible human-readable prose.
> - All the protocols I’ve ever seen have important constraints that can’t
> be expressed usefully in declarative schema languages.
> - Therefore, the next most important thing is an automated
> validator/test-suite.
> - A schema is a nice-to-have.
> - If you’re in XML and want schema-ware, use RelaxNG. For an example, see
> RFC4287.
> - If your protocol is JSON, investment in a validator/test-suite has much
> higher ROI than chasing schema unicorns.
>
>
>
>
> >
> > thanks a lot and kind regards,
> >
> > dret.
> >
> > --
> > erik wilde | mailto:dret@berkeley.edu  -  tel:+1-510-2061079 |
> >            | UC Berkeley  -  School of Information (ISchool) |
> >            | http://dret.net/netdret http://twitter.com/dret |
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