[decentralization] Re: REST and POST

Clay Shirky clay@shirky.com
Thu, 23 Aug 2001 15:07:45 -0400 (EDT)


> TimBL's web axioms talks about this (though I'm still undecided whether
> this one should count as an axiom - it seems more a practical issue to me,
> not a fundamental one - could be wrong though);
> 
> http://www.w3.org/DesignIssues/Axioms.html#state

Regarding "Calls with no side effects" as "A" and GET as "B", TB-L has
a symmetric axiom: All A are B, and all Not-A are Not-B.

Note, however, that this axiom is assymetric in practice. The actual
web development community has many members who work with the "Use POST
unless you specifically want it bookmarked" axiom, which leaves many
places where POST is used without side effects, or "Some A are Not-B".

This I think is one of the big challenges to REST's legitimacy, namely
that the axioms adopted by the theoreticians are not enforced by the
software and are routinely violated in practice by the practitioners,
weakening the claim that the Web is itself a RESTful entity.

The thing I'm most uncomfortable about with REST is this notion is
that it describes the Web not as it is but as it should be. Reality is
frequently a local maxima, and most people who say "Situation X is
perfect except for these two teensy flaws which we will now correct"
find that Situation X _relies_ on on its flaws for its continued
existence.

-clay