Re: Self-descriptive messages

Hi Roy,

thanks a lot for stepping in!

On Aug 28, 2012, at 12:07 AM, Roy T. Fielding wrote:

> 
> 
> I suggest folks worry less about that constraint (of visibility during
> a POST, which we already know isn't visible by nature) and more about
> what properties are lost by representation-by-reference. 

FWIW, the cart/order scenario discussed is just a special case of the more
general idea of 'action resources' (body-less POST to an action-triggering
URI), e.g.

POST /cart?order
Content-Length: 0

Does your argumentation apply equally to the question of whether such
'action resources' are suitable design?

Or is there a fundamental difference between the cart URI being part of
the body and the URI being the 'prefix' of the order-processor-resource?

After all, both could be discovered from hypermedia equally well.

Until now, I have used the self-descriptiveness constraint to argue against
both designs.

Since what you said makes sense to me, I am now in search for a new line of
argumentation against POST /foo?triggerSomeStuffWithFoo

A starting point for me would be that one design only uses a single ordering
resource (/order-processor) while the other yields an unlimited number
(/cart/{id};order)


Can you give a hint?



Jan




> Most of the
> value cases for REST apply to repeatable responses, not an application
> that can't be reused, can't be transformed, and can't be shared.
> I do not believe in trying to apply all of REST's constraints unless
> there is a reason for doing so (aside from buzzword compatibility).
> 
> My guess is that coupling would be more of a hazard than loss of
> visibility, but maybe even that wouldn't matter if the application is
> entirely driven via hypertext. It is really hard to get excited
> about the finer points of API design when the chosen method already
> says "do whatever you like with this".
> 
> ....Roy
> 
> 



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