XML in WebDAV or, a Tale of Two Standards

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XML in WebDAV or, a Tale of Two Standards

• Rohit Khare
• (with Jim Whitehead)
• UC Irvine
• November 15, 1998 CSCW'98
• Originally for XML98 Dev Day

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XML in WebDAV

• Distributed Authoring and Versioning
• WebDAV Abstract Model
• Why WebDAV Used XML
• The WebDAV Protocol DTD
• PROPFIND Example ( 7.1.1)
• Standards Process Update
• Call to Arms

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Distributed Authoring

• Very first Web tools edited, too
• ... but didnt have collaboration support
• WebDAV founded to prevent lost-update
• HTTP extensions to update documents
• Metadata to describe sites and pages
• Implemented with XML
• ... about 1/3 of the spec (by volume)

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WebDAV Abstract Model

• Resources
• Properties
• create, remove, and query metadata links
• Collections
• Locks
• exclusive or shared write access
• Namespace Operations
• atomic copy and move commands

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Why WebDAV Used XML

• Used XML in headers and entity-bodies
• to add extra XML elements to existing data
• to support internationalization
• Used whenever arguments
• are unbounded length
• are shown to humans
• Decentralized Extensibility
• e.g. new locktypes beyond write access

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The WebDAV Protocol DTD

• Protocol elements
• activelock, multistatus, link, propfind
• Property elements
• creationdate, displayname, getcontentlength
• The DAV Namespace
• Reference-by-copy of a previous draft (24.4)
• About to be updated by the new one!
• as about to be replaced by xmlns

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PROPFIND Example ( 7.1.1)
HTTP/1.1 207 Multi-Status Content-Type
text/xml Content-Length xxxxx lt?xml
version"1.0"?gt lt?xmlnamespace ns"DAV"
prefix"D"?gt lt?xmlnamespace ns"http//www.foo.ba
r/boxschema/" prefix"R"?gt ltDmultistatusgt ltDresp
onsegt ltDhrefgthttp//www.foo.bar/files/lt/Dhrefgt
ltDpropstatgt ltDpropgt ltRbigboxgt ltRBoxTyp
egtBox type Alt/RBoxTypegt lt/Rbigboxgt ltRau
thorgt ltRNamegtJ.J. Johnsonlt/RNamegt lt/Rauthor
gt lt/Dpropgt ltDstatusgtHTTP/1.1 200
OKlt/Dstatusgt lt/Dpropstatgt ltDpropstatgt ltD
propgtltRDingALing/gtltRRandom/gtlt/Dpropgt ltDstat
usgtHTTP/1.1 403 Forbiddenlt/Dstatusgt ltDrespons
edescriptiongt The user does not have access
to the DingALing
property. lt/Dresponsedescriptiongt lt/Dpropst
atgt lt/Dresponsegt ltDresponsedescriptiongt An
access violation error. lt/Dresponsedescriptiongt lt
/Dmultistatusgt
PROPFIND /files/ HTTP/1.1 Host
www.foo.bar Depth 0 Content-type
text/xml Content-Length xyz lt?xml
version"1.0"?gt lt?xmlnamespace ns"DAV"
prefix"D"?gt lt?xmlnamespace ns"http//www.foo.ba
r/boxschema/" prefix"R"?gt ltDpropfindgt ltDpropgt
ltRbigbox/gt ltRauthor/gt ltRDingALing/gt ltR
Random/gt lt/Dpropgt lt/Dpropfindgt
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Standards Process Update

• Imminent IETF Proposed Standard
• Next steps IESG Approval, Implementations
• Launching DAV Searching Location (DASL) WG
  Access Control Lists (ACL) to come
• Support from several vendors
• Microsoft, Netscape prototype servers
• Workflow vendors
• More announcements on the way...

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Call to Arms

• WebDAV uses XML
• ... for its protocol commands
• ... for its properties/ metadata
• WebDAV can manage XML
• ... ideal for versioning
• ... manages source and derived editions
• Protocols can be built atop XML
• ... though it was tough to coordinate maturity

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For More Information...

• WebDAV Working Group
• w3c-dist-auth_at_w3.org mailing list
• Meeting _at_ LA IETF
• Chair E. James Whitehead
• ejw_at_ics.uci.edu
• http//www.ics.uci.edu/ejw/authoring
• (this talk will be available at that url)
• Acknowledgments to many, many others