Re: RESTful Toggle

Hi Robby,

On 08 Jul 2014, at 23:28, 'Simpson, Robby (GE Energy Management)' robby.sim=
[email protected] [rest-discuss] <[email protected]> wrote:

> Hi,
>=20
> I've been scratching my head over this one for a while and am hoping I ca=
n
> get some help.
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> Imagine a light switch with one simple resource: /state , where state can
> be "On" or "Off."
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> One can PUT to /state , changing /state to either "On" or "Off."
> Similarly, a GET to /state will tell you if the light is currently "On" o=
r
> "Off."
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> Where I'm struggling is with a safe "Toggle" mechanism. That is, if
> /state is "On", change it to "Off" and vice versa.

Mint a resource that represents the =91on=92 state (e.g. an on-flag)

PUT (create) and DELETE the flag using conditional requests:

Create-if-not-exists

PUT /toggles/42?on-flag
If-None-Match: *

delete if exists:
DELETE /toggles/42?on-flag
If-Match: *

HTH,

Jan







>=20
> I understand that one solution would be to simply perform a GET on /state
> and then PUT the opposite. However, I am concerned with both the overhead
> and latency this entails as well as the potential for a race condition
> (what if /state changes between the GET and the PUT?).
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> Any solution I've looked at thus far seems to violate RESTful principles,
> particularly regarding idempotency. In short, can one safely toggle?
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> Any suggestions?
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> Thanks,
> Robby
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>=20
>=20



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