vCard Extensions to WebDAV (CardDAV)

Members of the IETF vCard and CardDAV (VCARDDAV) Working Group have
released an updated version of the specification "vCard Extensions to
WebDAV (CardDAV)." This IETF WG was chartered to produce: (1) A revision
of the vCard specification (RFC 2426) at proposed standard status; this
revision will include other vCard standardized extensions (RFC 2739,
4770) and extensions assisting synchronization technologies -- for
example, a per-entry UUID or per-attribute sequence number; other
extensions shall be considered either in the base specification or in
additional documents; (2) An address book access protocol leveraging
the vCard data format, for which the 'draft-daboo-carddav' I-D is the
starting point; (3) An XML schema which is semantically identical to
vCard in all ways and can be mechanically translated to and from vCard
format without loss of data. While vCard has deployed successfully and
will remain the preferred interchange format, a standard XML schema
which preserves vCard semantics might make vCard data more accessible
to XML-centric technologies such as AJAX and XSLT. Such a standard format
would be preferable to multiple proprietary XML schemas, particularly if
vCard semantics were lost by some of them and a lossy gateway problem
resulted. The draft "vCard Extensions to WebDAV (CardDAV)" defines
extensions to the Web Distributed Authoring and Versioning (WebDAV)
protocol to specify a standard way of accessing, managing, and sharing
contact information based on the vCard format. Address books containing
contact information are a key component of personal information management
tools, such as email, calendaring and scheduling, and instant messaging
clients. To date several protocols have been used for remote access to
contact data, including Lightweight Directory Access Protocol (LDAP),
Internet Message Support Protocol (IMSP) and Application Configuration
Access Protocol (ACAP - RFC 2244), together with SyncML used for
synchronization of such data. Each has key disadvantages... The proposed
CardDAV address book is modeled as a WebDAV collection with a well
defined structure; each of these address book collections contain a
number of resources representing address objects as their direct child
resources. Each resource representing an address object is called an
"address object resource". Each address object resource and each address
book collection can be individually locked and have individual WebDAV
properties. Definitions of XML elements in this document use XML element
type declarations (as found in XML Document Type Declarations), described
in Section 3.2 of the XML 1.0 Recommendation.