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Re: Hierarchical URLs and Collections

From: Roy T. Fielding <fielding@kiwi.ics.uci.edu>
Date: Fri, 21 Aug 1998 15:27:40 -0700
To: Larry Masinter <masinter@parc.xerox.com>
cc: WebDAV working group <w3c-dist-auth@w3.org>
Message-ID: <9808211527.aa13244@paris.ics.uci.edu>
>|I have a resource called http://a/b/c. I delete http://a/b. Is http://a/b/c
>Is this a trick question?
>   DELETE instructs that the collection specified in the request-URI
>   and all its internal member resources are to be deleted.
>So whether deleting http://a/b deletes http://a/b/c by dint of this
>rule depends on whether http://a/b/c is or isn't an internal member
>resource of http://a/b.
>For the most part, WebDAV works fine without the assumption that
>resource membership hierarchy is mapped onto URL syntax.

For the most part, WebDAV doesn't define things in terms of the
URL syntax.  The only thing it does is internal members, and that's
because people did want to require that http://a/b/c be deleted whenever
http://a/b/ is deleted.

>Of course, if we allow a resource to be an 'internal member' of multiple
>collections, why, we might have to resort to reference counting! Or even
>garbage collection!

I am all for a member of a collection that may appear in multiple
collections and does not act like an external reference.  However, that
thing is called a direct reference (or alias) and not 'internal member'.
And yes, you might need reference counting and garbage collection to
keep track of aliased resource disposal, but not for internal members.

Calling both things an 'internal member' makes it impossible to describe
the requirements of internal resources that do not exist independent
of the collection.

Received on Friday, 21 August 1998 18:43:16 UTC

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