WebDAV Collections

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WebDAV Collections

• March 17, 1999
• Judy Slein
• jslein_at_crt.xerox.com

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Reference Types

• Redirect
• Simple for servers to implement, never requires
  proxy behavior from server
• Requires client action before it can be resolved
• Client is aware of mediating reference
• Direct
• Server resolves automatically
• Client has the illusion that it is operating
  directly on the target resource

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Default Referencing Behavior Rules of Thumb

• Methods on Redirect References
• 302 response, Location header gives URI of target
• Client either resubmits to target or resubmits to
  reference with No-Passthrough
• Methods on Direct References
• Automatically passed through to target

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Default Referencing Behavior 4 Cases

• Redirect References
• Collections That Contain Redirect References
• Direct References
• Collections That Contain Direct References

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No-Passthrough

• No-Passthrough prevents the request from being
  passed through to the target resource

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Referencing Behavior Principles

• References should be usable by down-level clients
• Default behavior should be what makes sense to
  down-level clients
• Always be consistent between individual
  references and references encountered when
  processing a collection
• Never require a server to resolve a redirect
  reference
• Be consistent across operations as far as
  possible
• Be consistent with WebDAV and HTTP semantics for
  operations they define

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Default Referencing Behavior
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Default Referencing Behavior
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MOVE and DELETE

• Default Apply to reference
• Apply to target by sending request to the URI in
  the DAVreftarget property
• Rationale
• MOVE and DELETE affect membership in collections,
  not individual resources
• Should affect only the collection where the
  reference resides
• Should not affect the membership of the
  collection where the target resides
• Should not affect other collections that contain
  references to the target

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COPY

• Expect COPY to create a new, independent resource
  that can be modified without affecting the
  original resource
• Default COPY on direct reference applies to
  target
• The right result
• Default COPY on redirect reference applies to
  reference
• Intuitively wrong
• Avoids 302 responses when operating on a
  collection
• There is no way to get 302 response

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LOCK / UNLOCK

• Need lock on both reference and target to prevent
  surprises
• Default LOCK on direct reference locks target
• Rules of good citizenship prevent surprise
  changes to reference
• Consistent with typical behavior of methods on
  direct references
• Default LOCK on redirect reference locks
  reference
• Avoids 302 responses when operating on a
  collection
• 302 would make it impossible to lock collections
  that contain redirect references

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Other Referencing Issues

• YG-7 References to Collections
• YG-8, YG-11 Ref-Type and Ref-Target in Responses
• Instead of No-Passthrough, use a different URL
  for the reference

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Any Ordering Issues

• Server-maintained orderings

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Plan

• April 9 Publish revised protocol
• April 10-May 2 Working Group Last Call
• May 14 Publish revised protocol
• Second Working Group Last Call if necessary
• May 17 Submit to the IESG