Re: Cookies! What are they and do we need them?
Roy T. Fielding (fielding@liege.ICS.UCI.EDU)
Mon, 02 Sep 1996 17:48:08 -0700
> I don't really think that we should be trying to standardize a policy for
> this, as it seems a higher-level issue than basic versioning support, but
> the idea is that I might check the same file out 3 times from the same
> server, creating 3 virtual sessions. When I later check the file back in, I
> may need to attach a particular update to a particular checkout operation.
> The cookie enables this (did I get it right, Chris?).
>
> The kind of solution that youare thinking of does not allow that kind of
> control: a server could let me check out v 2.1 of /docs/misc more than
> once, and on check in the "Derived-from:" header does not uniquely identify
> which of the 3 checkouts is being affected. This is because they would all
> share the same "Derived-from:" header.
I should clarify this. The value of Content-Version and Derived-From
is an opaque string or token. There is no reason why the server could
not produce a different Content-Version for each checkout (although
there is also no reason why it needs to, since the notion of virtual
sessions implies forking a resource, which is better expressed as a
different action upon committing those changes rather than as a pre-fork
every time the resource is checked out). In any case, it is impossible
for Cookies to be more expressive than Content-Version, since anything
that can be placed in a Cookie can also be placed in an opaque string.
.....Roy