1. WebDAV Collections December 10, 1998 Judy Slein jslein@crt.xerox.com

2. WebDAV Advanced Collections2 Issues n Properties of Direct References n Optional Backpointers n Hiding the Target n Definition of “Weak Reference”

3. WebDAV Advanced Collections3 Properties of Direct References n Re-Direct header overrides default behavior for any method on a direct reference n Makes direct references behave like redirect references for that request n Makes it possible to access and update the properties of the reference

4. WebDAV Advanced Collections4 Rationale n Be able to access the properties of the reference –DAV:resourcetype, DAV:reftype, etc. –creator, create date, comment n Be able to modify properties of the reference that were set via headers at creation time –DAV:hidetarget, DAV:refintegrity n For versioning –Specifying different default revisions when accessed from different collections?

5. WebDAV Advanced Collections5 Optional Backpointers n DAV:references property on a target resource lists all references to it n Read-only property for security reasons

6. WebDAV Advanced Collections6 Rationale n Scenario: Server declines to delete target because there are references to it. Client must discover the references in order to delete them so that the target can be deleted. n Scenario: Server does not maintain referential integrity. Client wants to be a good citizen by checking for references before deleting a resource. n Scenario: DMS client wants to display a list of all collections that a target belongs to by reference, so that users can navigate to those collections to find related documents or see how the target resource is being used.

7. WebDAV Advanced Collections7 Proposal: Hiding the Target n Drop this requirement: “When creating a direct reference, it is possible to request that the location of its target be hidden.”

8. WebDAV Advanced Collections8 Rationale n The constraint really belongs at the target, not at the reference n Added test for the server for every request on a direct reference

9. WebDAV Advanced Collections9 Proposal: Weak References n Values for Ref-Integrity header are –DAV:weak –DAV:serverdefault n Values for DAV:refintegrity property are –DAV:weak –DAV:serverdefault

10. WebDAV Advanced Collections10 Rationale: Weak References n Requirement: It is possible when creating a reference to request that the server not enforce referential integrity for that reference –Populate a directory with references before their targets are created –Temporarily remove targets without having to destroy / recreate references to them