Re: [rest-discuss] Re: REST is Kafkarchitecture
- hello stan.
> I love this line of thinking. I confess I spend a lot of time thinking up these kind of examples. This is about the onlythat's a good one! and essentially i guess you can see an airport as a
> place where I don't feel weird admitting that. Can I submit my favorite example?
loosely coupled decentralized bureaucracy apparatus that isn't all that
different from 19th century offices (well, except for the airplanes
instead of horse carriages, of course).
my favorite "RESTful airport" anecdote: i once lost my ticket (back in
the days, when you still had to have a paper ticket for flying) and the
airline people honestly wanted me to buy a complete new one, telling me
(in REST terms) that the ticket state was all on my side and they did
not have any record of it. which of course wasn't true and just a matter
of policy, but that was their explanation. they ended up creating the
obvious wrong explanation for their policy (which of course was
implemented for money reasons, and not for technical reasons). you
could, btw, fairly easily create passenger systems that would work like
this, only keeping anonymized passenger state (for keeping passenger
count) on the service side. again, a fun design exercise to think about,
but i think the TSA might have something against implementing a system
erik wilde | mailto:dret@... - tel:+1-510-2061079 |
| UC Berkeley - School of Information (ISchool) |
| http://dret.net/netdret http://twitter.com/dret |
- Like the SMS example, this is another case of trying to avoid server state (i.e. be RESTful) in cases where the server needs to keep a permanent record of the transaction anyway, one per client. Statelessness is about avoiding the word "my". Pay for the items in my basket, vs Pay for the items in basket #54203. Replicating session files between load-balanced servers may even be cheaper than replicating database-based resources.As the linked post says: "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."Just because an architecture is good for document retrieval, doesn't mean it should be mindlessly applied to everything else too.Perhaps the next Roy Fielding can come along and deduce the optimum architectural constraints for a private, non-repeatable, yet scalable application, and from these direct the evolution of HTTP just as HTTP 1.1 was informed.
On 9 May 2013, at 19:27, Matt McClure <matthewlmcclure@...> wrote:
On Thu, May 9, 2013 at 9:43 AM, Bob Haugen <bob.haugen@...> wrote:
Eric Bowman wrote:
> My nutshell explanation of REST from 50,000ft is that a system
> designed to manipulate shopping carts MUST be based on
> transferring actual representations of shopping-cart contents.
I hesitated to get back into this issue after having lost an argument
with Mark Baker about it a couple of years ago, but: the typical
behavior of a system that saves shopping cart contents on servers
(e.g. Amazon) is to send a representation of the shopping cart
contents back to the client to confirm the order, in which case, a
representation of the shopping cart contents then gets sent back to
the server from the client.
Would e.g. Mark and Eric agree that this is RESTful?I've also been following this conversation as a lurker. If I understood some of the earlier comments, it sounded as though someone made a case that a request like:POST /cart/12345/purchaseContent-Length: 0would be stateful and undesirable for conformance with REST whereas:POST /purchaseContent-Length: 1234items=...&in_quantities=...&with_payment_method=...would be more RESTful and less stateful.I guess I'm unclear why the former would violate statelessness. The state in the former is resource state, identified by an implicit /cart/12345 resource (assume I got the /cart/12345/purchase link from the cart resource).To contrast:POST /purchaseContent-Length: 0Cookie: client=12345seems decidedly stateful because it requires shared state identified by the ID in the Cookie header rather than the URI to disambiguate which thing the client wants to purchase.It seems to me that a client need not include all of the detail of the cart contents and payment method in the purchase request to conform with a statelessness constraint. I'd be happy to hear why I'm wrong if I am.Matt--