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Versions: 00 01 02 03 04 05 06 07 08 09 10 RFC 6352

Network Working Group                                           C. Daboo
Internet-Draft                                                     Apple
Intended status: Standards Track                       February 10, 2009
Expires: August 14, 2009


                  vCard Extensions to WebDAV (CardDAV)
                     draft-ietf-vcarddav-carddav-05

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 14, 2009.

Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Abstract

   This document defines extensions to the Web Distributed Authoring and
   Versioning (WebDAV) protocol to specify a standard way of accessing,



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   managing, and sharing contact information based on the vCard format.


Table of Contents

   1.  Introduction and Overview  . . . . . . . . . . . . . . . . . .  4
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  5
     2.2.  XML Namespaces and Processing  . . . . . . . . . . . . . .  5
   3.  Requirements Overview  . . . . . . . . . . . . . . . . . . . .  6
   4.  Address Book Data Model  . . . . . . . . . . . . . . . . . . .  7
     4.1.  Address Book Server  . . . . . . . . . . . . . . . . . . .  7
   5.  Address Book Resources . . . . . . . . . . . . . . . . . . . .  7
     5.1.  Address Object Resources . . . . . . . . . . . . . . . . .  7
     5.2.  Address Book Collections . . . . . . . . . . . . . . . . .  8
   6.  Address Book Feature . . . . . . . . . . . . . . . . . . . . .  9
     6.1.  Address Book Support . . . . . . . . . . . . . . . . . . .  9
       6.1.1.  Example: Using OPTIONS for the Discovery of
               Support for CardDAV  . . . . . . . . . . . . . . . . .  9
     6.2.  Address Book Properties  . . . . . . . . . . . . . . . . .  9
       6.2.1.  CARDDAV:addressbook-description Property . . . . . . . 10
       6.2.2.  CARDDAV:supported-address-data Property  . . . . . . . 10
       6.2.3.  CARDDAV:max-resource-size Property . . . . . . . . . . 11
     6.3.  Creating Resources . . . . . . . . . . . . . . . . . . . . 12
       6.3.1.  Extended MKCOL Method  . . . . . . . . . . . . . . . . 12
         6.3.1.1.  Example - Successful MKCOL request . . . . . . . . 13
       6.3.2.  Creating Address Object Resources  . . . . . . . . . . 14
         6.3.2.1.  Additional Preconditions for PUT, COPY and MOVE  . 15
         6.3.2.2.  Non-Standard vCard Properties, and Parameters  . . 16
         6.3.2.3.  Address Object Resource Entity Tag . . . . . . . . 17
   7.  Address Book Access Control  . . . . . . . . . . . . . . . . . 17
     7.1.  Additional Principal Properties  . . . . . . . . . . . . . 17
       7.1.1.  CARDDAV:addressbook-home-set Property  . . . . . . . . 17
       7.1.2.  CARDDAV:principal-address Property . . . . . . . . . . 18
   8.  Address Book Reports . . . . . . . . . . . . . . . . . . . . . 19
     8.1.  REPORT Method  . . . . . . . . . . . . . . . . . . . . . . 19
     8.2.  Ordinary Collections . . . . . . . . . . . . . . . . . . . 20
     8.3.  Searching Text: Collations . . . . . . . . . . . . . . . . 20
       8.3.1.  CARDDAV:supported-collation-set Property . . . . . . . 21
     8.4.  Partial Retrieval  . . . . . . . . . . . . . . . . . . . . 22
     8.5.  Non-standard Properties and Parameters . . . . . . . . . . 22
     8.6.  CARDDAV:addressbook-query Report . . . . . . . . . . . . . 22
       8.6.1.  Limiting Results . . . . . . . . . . . . . . . . . . . 24
       8.6.2.  Truncation of Results  . . . . . . . . . . . . . . . . 24
       8.6.3.  Example: Partial Retrieval of vCards Matching
               NICKNAME . . . . . . . . . . . . . . . . . . . . . . . 24
       8.6.4.  Example: Partial Retrieval of vCards Matching a
               Full Name or Email Address . . . . . . . . . . . . . . 26



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       8.6.5.  Example: Truncated Results . . . . . . . . . . . . . . 29
     8.7.  CARDDAV:addressbook-multiget Report  . . . . . . . . . . . 30
       8.7.1.  Example: CARDDAV:addressbook-multiget Report . . . . . 32
   9.  Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 33
     9.1.  Restrict the Properties Returned . . . . . . . . . . . . . 33
     9.2.  Use of Locking . . . . . . . . . . . . . . . . . . . . . . 34
     9.3.  Finding Address Books  . . . . . . . . . . . . . . . . . . 34
   10. XML Element Definitions  . . . . . . . . . . . . . . . . . . . 36
     10.1. CARDDAV:addressbook XML Element  . . . . . . . . . . . . . 36
     10.2. CARDDAV:supported-collation XML Element  . . . . . . . . . 36
     10.3. CARDDAV:addressbook-query XML Element  . . . . . . . . . . 36
     10.4. CARDDAV:address-data XML Element . . . . . . . . . . . . . 37
       10.4.1. CARDDAV:allprop XML Element  . . . . . . . . . . . . . 38
       10.4.2. CARDDAV:prop XML Element . . . . . . . . . . . . . . . 39
     10.5. CARDDAV:filter XML Element . . . . . . . . . . . . . . . . 40
       10.5.1. CARDDAV:prop-filter XML Element  . . . . . . . . . . . 40
       10.5.2. CARDDAV:param-filter XML Element . . . . . . . . . . . 41
       10.5.3. CARDDAV:is-not-defined XML Element . . . . . . . . . . 42
       10.5.4. CARDDAV:text-match XML Element . . . . . . . . . . . . 42
     10.6. CARDDAV:limit XML Element  . . . . . . . . . . . . . . . . 44
       10.6.1. CARDDAV:nresults XML Element . . . . . . . . . . . . . 44
     10.7. CARDDAV:addressbook-multiget XML Element . . . . . . . . . 44
   11. Service Discovery via SRV Records  . . . . . . . . . . . . . . 45
   12. Internationalization Considerations  . . . . . . . . . . . . . 45
   13. Security Considerations  . . . . . . . . . . . . . . . . . . . 45
   14. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 46
     14.1. Namespace Registration . . . . . . . . . . . . . . . . . . 46
   15. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 47
   16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 47
     16.1. Normative References . . . . . . . . . . . . . . . . . . . 47
     16.2. Informative References . . . . . . . . . . . . . . . . . . 48
   Appendix A.  Change History (to be removed prior to
                publication as an RFC)  . . . . . . . . . . . . . . . 48
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 51

















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1.  Introduction and Overview

   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 [RFC4511], Internet
   Message Support Protocol IMSP [IMSP] and Application Configuration
   Access Protocol ACAP [RFC2244], together with SyncML used for
   synchronization of such data.

   WebDAV [RFC4918] offers a number of advantages as a framework or
   basis for address book access and management.  Most of these
   advantages boil down to a significant reduction in design costs,
   implementation costs, interoperability test costs and deployment
   costs.

   The key features of address book support with WebDAV are:

   1.  Ability to use multiple address books with hierarchical layout.

   2.  Ability to control access to individual address books and address
       entries.

   3.  Principal namespace can be used to enumerate and find other users
       on the system.

   4.  Server-side searching of address data, avoiding the need for
       clients to download an entire address book in order to do a quick
       address 'expansion' operation.

   5.  Well-defined internationalization support through standard HTTP.

   6.  Use of vCards for well defined address schema to enhance client
       interoperability.

   7.  Many limited clients (e.g. mobile devices) contain an HTTP stack
       which makes implementing WebDAV much easier than other protocols.

   The key disadvantages of address book support in WebDAV are:

   1.  Lack of change notification.  Many of the alternative protocols
       also lack this ability.  However, an extension for push
       notifications could easily be developed.

   2.  Stateless nature of protocol can result in more data being sent
       with each transaction to maintain per-user session across
       requests.



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   vCard [RFC2426] is a MIME directory profile aimed at encapsulating
   personal addressing and contact information about people.  The
   specification of vCard was originally done by the Versit consortium,
   with a subsequent 3.0 version standardized by the IETF [RFC2426].
   vCard is in wide spread use in email clients and mobile devices as a
   means of encapsulating address information for transport via email,
   or for import/export and synchronization operations.

   An update to vCard is currently being developed
   [I-D.ietf-vcarddav-vcardrev] and is compatible with this
   specification.


2.  Conventions

2.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The term "protected" is used in the Conformance field of property
   definitions as defined in Section 15 of [RFC4918].

   When XML element types in the namespaces "DAV:" and
   "urn:ietf:params:xml:ns:carddav" are referenced in this document
   outside of the context of an XML fragment, the string "DAV:" and
   "CARDDAV:" will be prefixed to the element type names, respectively.

2.2.  XML Namespaces and Processing

   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 [W3C.REC-xml-20060816].

   The namespace "urn:ietf:params:xml:ns:carddav" is reserved for the
   XML elements defined in this specification, its revisions, and
   related CardDAV specifications.  XML elements defined by individual
   implementations MUST NOT use the "urn:ietf:params:xml:ns:carddav"
   namespace, and instead should use a namespace that they control.

   The XML declarations used in this document do not include namespace
   information.  Thus, implementers must not use these declarations as
   the only way to create valid CardDAV properties or to validate
   CardDAV XML element type.  Some of the declarations refer to XML
   elements defined by WebDAV [RFC4918] which use the "DAV:" namespace.
   Wherever such XML elements appear, they are explicitly prefixed with
   "DAV:" to avoid confusion.



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   Also note that some CardDAV XML element names are identical to WebDAV
   XML element names, though their namespace differs.  Care must be
   taken not to confuse the two sets of names.

   Processing of XML by CardDAV clients and servers MUST follow the
   rules described in Section 17 of [RFC4918].


3.  Requirements Overview

   This section lists what functionality is required of a CardDAV
   server.  To advertise support for CardDAV, a server:

   o  MUST support vCard [RFC2426] as a media type for the address
      object resource format;

   o  MUST support WebDAV Class 3 [RFC4918];

   o  MUST support WebDAV ACL [RFC3744];

   o  MUST support secure transport as defined in [RFC2818] using TLS
      [RFC5246];

   o  MUST support ETags [RFC2616] with additional requirements
      specified in Section 6.3.2.3 of this document;

   o  MUST support all address book REPORTs defined in Section 8 of this
      document; and

   o  MUST advertise support on all addressbook collections and address
      object resources for the addressbook reports in the DAV:supported-
      report-set property, as defined in Versioning Extensions to WebDAV
      [RFC3253].

   In addition, a server:

   o  SHOULD support the extended MKCOL method
      [I-D.ietf-vcarddav-webdav-mkcol] to create address book
      collections as defined in Section 6.3.1 of this document.

   o  SHOULD support the DAV:current-user-principal-URL property as
      defined in [RFC5397] to give clients a fast way to locate user
      principals.








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4.  Address Book Data Model

   As a brief overview, a 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.
   Requirements derived from this model are provided in Section 5.1 and
   Section 5.2.

4.1.  Address Book Server

   A CardDAV server is an address-aware engine combined with a WebDAV
   server.  The server may include address data in some parts of its URL
   namespace, and non-address data in other parts.

   A WebDAV server can advertise itself as a CardDAV server if it
   supports the functionality defined in this specification at any point
   within the root of its repository.  That might mean that address data
   is spread throughout the repository and mixed with non-address data
   in nearby collections (e.g. address data may be found in /lisa/
   addressbook/ as well as in /bernard/addressbook/, and non-address
   data in /lisa/calendars/).  Or, it might mean that address data can
   be found only in certain sections of the repository (e.g.
   /addressbooks/user/).  Address book features are only required in the
   repository sections that are or contain address objects.  So a
   repository confining address data to the /carddav/ collection would
   only need to support the CardDAV required features within that
   collection.

   The CardDAV server is the canonical location for address data and
   state information.  Clients may submit requests to change data or
   download data.  Clients may store address objects offline and attempt
   to synchronize at a later time.  However, clients MUST be prepared
   for address data on the server to change between the time of last
   synchronization and when attempting an update, as address book
   collections may be shared and accessible via multiple clients.
   Entity tags and other features help this work.


5.  Address Book Resources

5.1.  Address Object Resources

   This specification uses vCard as the default format for address or
   contact information being stored on the server.  However, this



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   specification does allow other formats for address data provided that
   the server advertises support for those additional formats as
   described below.  The requirements in this section pertain to vCard
   address data, or formats that follow the semantics of vCard data.

   Address object resources contained in address book collections MUST
   contain a single vCard component only.

   vCard components in an address book collection MUST have a UID
   property value that MUST be unique in the scope of the address book
   collection in which it is contained.

5.2.  Address Book Collections

   Address book collections appear to clients as a WebDAV collection
   resource, identified by a URL.  An address book collection MUST
   report the DAV:collection and CARDDAV:addressbook XML elements in the
   value of the DAV:resourcetype property.  The element type declaration
   for CARDDAV:addressbook is:

       <!ELEMENT addressbook EMPTY>

   An address book collection can be created through provisioning (e.g.,
   automatically created when a user's account is provisioned), or it
   can be created with the extended MKCOL method (see Section 6.3.1).
   This can be used by a user to create additional address books (e.g.,
   "soccer team members") or for users to share an address book (e.g.,
   "sales team contacts").  Note however that this document doesn't
   define what extra address book collections are for.  Users must rely
   on non-standard cues to find out what an address book collection is
   for, or use the CARDDAV:addressbook-description property defined in
   Section 6.2.1 to provide such a cue.

   The following restrictions are applied to the resources within an
   address book collection:

   a.  Address book collections MUST only contain address object
       resources and collections that are not address book collections.
       i.e., the only "top-level" non-collection resources allowed in an
       address book collection are address object resources.  This
       ensures that address book clients do not have to deal with non-
       address data in an address book collection, though they do have
       to distinguish between address object resources and collections
       when using standard WebDAV techniques to examine the contents of
       a collection.

   b.  Collections contained in address book collections MUST NOT
       contain address book collections at any depth. i.e., "nesting" of



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       address book collections within other address book collections at
       any depth is not allowed.  This specification does not define how
       collections contained in an address book collection are used or
       how they relate to any address object resources contained in the
       address book collection.

   Multiple address book collections MAY be children of the same
   collection.


6.  Address Book Feature

6.1.  Address Book Support

   A server supporting the features described in this document, MUST
   include "addressbook" as a field in the DAV response header from an
   OPTIONS request on any resource that supports any address book
   properties, reports, or methods.  A value of "addressbook" in the DAV
   response header MUST indicate that the server supports all MUST level
   requirements and REQUIRED features specified in this document.

6.1.1.  Example: Using OPTIONS for the Discovery of Support for CardDAV

   >> Request <<

   OPTIONS /addressbooks/users/ HTTP/1.1
   Host: addressbook.example.com

   >> Response <<

   HTTP/1.1 200 OK
   Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
   Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, REPORT, ACL
   DAV: 1, 2, 3, access-control, addressbook
   DAV: extended-mkcol
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Length: 0

   In this example, the OPTIONS response indicates that the server
   supports CardDAV in this namespace, therefore the '/addressbooks/
   users/' collection may be used as a parent for address book
   collections as the extended MKCOL method is available, and as a
   possible target for REPORT requests for address book reports.

6.2.  Address Book Properties






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6.2.1.  CARDDAV:addressbook-description Property

   Name:  addressbook-description

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Provides a human-readable description of the address book
      collection.

   Value:  Any text.

   Protected:  SHOULD NOT be protected so that users can specify a
      description.

   COPY/MOVE behavior:  This property value SHOULD be preserved in COPY
      and MOVE operations.

   allprop behavior:  SHOULD be returned by a PROPFIND DAV:allprop
      request.

   Description:  This property contains a description of the address
      book collection that is suitable for presentation to a user.

   Definition:

       <!ELEMENT addressbook-description (#PCDATA)>
       <!-- PCDATA value: string -->

   Example:

       <C:addressbook-description xml:lang="fr-CA"
          xmlns:C="urn:ietf:params:xml:ns:carddav"
       >Adresses de Oliver Daboo</C:addressbook-description>

6.2.2.  CARDDAV:supported-address-data Property

   Name:  supported-address-data

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies what media types are allowed for address object
      resources in an address book collection.

   Protected:  MUST be protected as it indicates the level of support
      provided by the server.






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   COPY/MOVE behavior:  This property value MUST be preserved in COPY
      and MOVE operations.

   allprop behavior:  SHOULD be returned by a PROPFIND DAV:allprop
      request.

   Description:  The CARDDAV:supported-address-data property is used to
      specify the media type supported for the address object resources
      contained in a given address book collection (e.g., vCard version
      3.0).  Any attempt by the client to store address object resources
      with a media type not listed in this property MUST result in an
      error, with the CARDDAV:supported-address-data precondition
      (Section 6.3.2.1) being violated.  In the absence of this property
      the server MUST only accept data with the media type "text/vcard"
      and vCard version 3.0, and clients can assume that.

   Definition:

       <!ELEMENT supported-address-data (address-data+)>

   Example:

       <C:supported-address-data
          xmlns:C="urn:ietf:params:xml:ns:carddav">
         <C:address-data content-type="text/vcard" version="3.0"/>
       </C:supported-address-data>

6.2.3.  CARDDAV:max-resource-size Property

   Name:  max-resource-size

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Provides a numeric value indicating the maximum size of a
      resource in octets that the server is willing to accept when an
      address object resource is stored in an address book collection.

   Value:  Any text representing a numeric value.

   Protected:  MUST be protected as it indicates limits provided by the
      server.

   COPY/MOVE behavior:  This property value MUST be preserved in COPY
      and MOVE operations.







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   allprop behavior:  SHOULD be returned by a PROPFIND DAV:allprop
      request.

   Description:  The CARDDAV:max-resource-size is used to specify a
      numeric value that represents the maximum size in octets that the
      server is willing to accept when an address object resource is
      stored in an address book collection.  Any attempt to store an
      address book object resource exceeding this size MUST result in an
      error, with the CARDDAV:max-resource-size precondition
      (Section 6.3.2.1) being violated.  In the absence of this property
      the client can assume that the server will allow storing a
      resource of any reasonable size.

   Definition:

       <!ELEMENT max-resource-size (#PCDATA)>
       <!-- PCDATA value: a numeric value (positive integer) -->

   Example:

       <C:max-resource-size xmlns:C="urn:ietf:params:xml:ns:carddav"
       >102400</C:max-resource-size>

6.3.  Creating Resources

   Address book collections and address object resources may be created
   by either a CardDAV client or by the CardDAV server.  This
   specification defines restrictions and a data model that both clients
   and servers MUST adhere to when manipulating such address data.

6.3.1.  Extended MKCOL Method

   An HTTP request using the extended MKCOL method
   [I-D.ietf-vcarddav-webdav-mkcol] can be used to create a new address
   book collection resource.  A server MAY restrict address book
   collection creation to particular collections.

   To create an address book, the client sends an extended MKCOL request
   to the server and in the body of the request sets the DAV:
   resourcetype property to the resource type for an address book
   collection as defined in Section 5.2.

   Support for creating address books on the server is only RECOMMENDED
   and not REQUIRED because some address book stores only support one
   address book per user (or principal), and those are typically pre-
   created for each account.  However, servers and clients are strongly
   encouraged to support address book creation whenever possible to
   allow users to create multiple address book collections to help



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   organize their data better.

   Clients SHOULD use the DAV:displayname property for a human-readable
   name of the address book.  Clients can either specify the value of
   the DAV:displayname property in the request body of the extended
   MKCOL request, or alternatively issue a PROPPATCH request to change
   the DAV:displayname property to the appropriate value immediately
   after using the extended MKCOL request.  Clients SHOULD NOT set the
   DAV:displayname property to be the same as any other address book
   collection at the same URI "level".  When displaying address book
   collections to users, clients SHOULD check the DAV:displayname
   property and use that value as the name of the address book.  In the
   event that the DAV:displayname property is not set, the client MAY
   use the last part of the address book collection URI as the name,
   however that path segment may be "opaque" and not represent any
   meaningful human-readable text.

6.3.1.1.  Example - Successful MKCOL request

   This example creates an address book collection called /home/lisa/
   addressbook/ on the server addressbook.example.com with specific
   values for the properties DAV:resourcetype, DAV:displayname and
   CARDDAV:addressbook-description.

   >> Request <<

   MKCOL /home/lisa/addressbook/ HTTP/1.1
   Host: addressbook.example.com
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:mkcol xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:set>
       <D:prop>
         <D:resourcetype>
           <D:collection/>
           <C:addressbook/>
         </D:resourcetype>
         <D:displayname>Lisa's Contacts</D:displayname>
         <C:addressbook-description xml:lang="en"
   >My primary address book.</C:addressbook-description>
       </D:prop>
     </D:set>
   </D:mkcol>





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   >> Response <<

   HTTP/1.1 201 Created
   Cache-Control: no-cache
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: application/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:mkcol-response xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:propstat>
       <D:prop>
         <D:resourcetype/>
         <D:displayname/>
         <C:addressbook-description/>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:mkcol-response>

6.3.2.  Creating Address Object Resources

   Clients populate address book collections with address object
   resources.  The URL for each address object resource is entirely
   arbitrary, and does not need to bear a specific relationship (but
   might) to the address object resource's vCard properties or other
   metadata.  New address object resources MUST be created with a PUT
   request targeted at an unmapped URI.  A PUT request targeted at a
   mapped URI updates an existing address object resource.

   When servers create new resources, it's not hard for the server to
   choose a unique URL.  It's slightly tougher for clients, because a
   client might not want to examine all resources in the collection, and
   might not want to lock the entire collection to ensure that a new one
   isn't created with a name collision.  However, there is an HTTP
   feature to mitigate this.  If the client intends to create a new
   address resource the client SHOULD use the HTTP header "If-None-
   Match: *" on the PUT request.  The Request-URI on the PUT request
   MUST include the target collection, where the resource is to be
   created, plus the name of the resource in the last path segment.  The
   "If-None-Match" header ensures that the client will not inadvertently
   overwrite an existing resource even, if the last path segment turned
   out to already be used.







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   >> Request <<

   PUT /lisa/addressbook/newvcard.vcf HTTP/1.1
   If-None-Match: *
   Host: addressbook.example.com
   Content-Type: text/vcard
   Content-Length: xxx

   BEGIN:VCARD
   VERSION:3.0
   FN:Cyrus Daboo
   N:Daboo;Cyrus
   ADR;TYPE=POSTAL:;2822 Email HQ;Suite 2821;RFCVille;PA;15213;USA
   EMAIL;TYPE=INTERNET,PREF:cyrus@example.com
   NICKNAME:me
   NOTE:Example VCard.
   ORG:Self Employed
   TEL;TYPE=WORK,VOICE:412 605 0499
   TEL;TYPE=FAX:412 605 0705
   URL:http://www.example.com
   UID:1234-5678-9000-1
   END:VCARD

   >> Response <<

   HTTP/1.1 201 Created
   Date: Thu, 02 Sep 2004 16:53:32 GMT
   Content-Length: 0
   ETag: "123456789-000-111"

   The request to change an existing address object resource is the
   same, but with a specific ETag in the "If-Match" header, rather than
   the "If-None-Match" header.

   File names for vCards are commonly suffixed by ".vcf", and clients
   may choose to use the same convention for URLs.

6.3.2.1.  Additional Preconditions for PUT, COPY and MOVE

   This specification creates additional Preconditions for PUT, COPY and
   MOVE methods.  These preconditions apply:

   o  When a PUT operation of an address object resource into an address
      book collection occurs.

   o  When a COPY or MOVE operation of an address object resource into
      an address book collection occurs.




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   The new preconditions are:

      (CARDDAV:supported-address-data): The resource submitted in the
      PUT request, or targeted by a COPY or MOVE request MUST be a
      supported media type (i.e., vCard) for address object resources;

      (CARDDAV:valid-address-data): The resource submitted in the PUT
      request, or targeted by a COPY or MOVE request MUST be valid data
      for the media type being specified (i.e., MUST contain valid vCard
      data);

      (CARDDAV:no-uid-conflict): The resource submitted in the PUT
      request, or targeted by a COPY or MOVE request MUST NOT specify a
      vCard UID property value already in use in the targeted address
      book collection or overwrite an existing address object resource
      with one that has a different UID property value.  Servers SHOULD
      report the URL of the resource that is already making use of the
      same UID property value in the DAV:href element;

          <!ELEMENT no-uid-conflict (DAV:href)>

      (CARDDAV:addressbook-collection-location-ok): In a COPY or MOVE
      request, when the Request-URI is an address book collection, the
      URI targeted by the Destination HTTP Request header MUST identify
      a location where an address book collection can be created;

      (CARDDAV:max-resource-size): The resource submitted in the PUT
      request, or targeted by a COPY or MOVE request MUST have an octet
      size less than or equal to the value of the CARDDAV:max-resource-
      size property value (Section 6.2.3) on the address book collection
      where the resource will be stored;

6.3.2.2.  Non-Standard vCard Properties, and Parameters

   vCard provides a "standard mechanism for doing non-standard things".
   This extension support allows implementers to make use of non-
   standard properties and parameters whose names are prefixed with the
   text "X-".

   Servers MUST support the use of non-standard properties and
   parameters in address object resources stored via the PUT method.

   Servers may need to enforce rules for their own "private" properties
   or parameters, so servers MAY reject any attempt by the client to
   change those or use values for those outside of any restrictions the
   server may have.  Servers SHOULD ensure that any "private" properties
   or parameters it uses follow the convention of including a vendor id
   in the "X-" name, as described in Section 3.8 of [RFC2426], e.g.,



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   "X-ABC-PRIVATE".

6.3.2.3.  Address Object Resource Entity Tag

   The DAV:getetag property MUST be defined and set to a strong entity
   tag on all address object resources.

   A response to a GET request targeted at an address object resource
   MUST contain an ETag response header field indicating the current
   value of the strong entity tag of the address object resource.

   Servers SHOULD return a strong entity tag (ETag header) in a PUT
   response when the stored address object resource is equivalent by
   octet equality to the address object resource submitted in the body
   of the PUT request.  This allows clients to reliably use the returned
   strong entity tag for data synchronization purposes.  For instance,
   the client can do a PROPFIND request on the stored address object
   resource and have the DAV:getetag property returned, and compare that
   value with the strong entity tag it received on the PUT response, and
   know that if they are equal, then the address object resource on the
   server has not been changed.

   In the case where the data stored by a server as a result of a PUT
   request is not equivalent by octet equality to the submitted address
   object resource, the behavior of the ETag response header is not
   specified here, with the exception that a strong entity tag MUST NOT
   be returned in the response.  As a result, clients may need to
   retrieve the modified address object resource (and ETag) as a basis
   for further changes, rather than use the address object resource it
   had sent with the PUT request.


7.  Address Book Access Control

   CardDAV servers MUST support and adhere to the requirements of WebDAV
   ACL [RFC3744].  WebDAV ACL provides a framework for an extensible set
   of privileges that can be applied to WebDAV collections and ordinary
   resources.

7.1.  Additional Principal Properties

   This section defines additional properties for WebDAV principal
   resources as defined in [RFC3744].

7.1.1.  CARDDAV:addressbook-home-set Property






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   Name:  addressbook-home-set

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Identifies the URL of any WebDAV collections that contain
      address book collections owned by the associated principal
      resource.

   Protected:  MAY be protected if the server has fixed locations in
      which address books are created.

   COPY/MOVE behavior:  This property value MUST be preserved in COPY
      and MOVE operations.

   allprop behavior:  SHOULD be returned by a PROPFIND DAV:allprop
      request.

   Description:  The CARDDAV:addressbook-home-set property is meant to
      allow users to easily find the address book collections owned by
      the principal.  Typically, users will group all the address book
      collections that they own under a common collection.  This
      property specifies the URL of collections that either are address
      book collections or ordinary collections that have child or
      descendant address book collections owned by the principal.

   Definition:

       <!ELEMENT addressbook-home-set (DAV:href*)>

   Example:

       <C:addressbook-home-set xmlns:D="DAV:"
          xmlns:C="urn:ietf:params:xml:ns:carddav">
         <D:href>http://addressbook.example.com/bernard/addresses/<
         /D:href>
       </C:addressbook-home-set>

7.1.2.  CARDDAV:principal-address Property

   Name:  principal-address

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Identifies the URL of an address object resource that
      corresponds to the user represented by the principal.






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   Protected:  MAY be protected if the server provides a fixed location
      for principal addresses.

   COPY/MOVE behavior:  This property value MUST be preserved in COPY
      and MOVE operations.

   allprop behavior:  SHOULD be returned by a PROPFIND DAV:allprop
      request.

   Description:  The CARDDAV:principal-address property is meant to
      allow users to easily find contact information for users
      represented by principals on the system.  This property specifies
      the URL of the address object resource containing the
      corresponding contact information.

   Definition:

       <!ELEMENT principal-address (DAV:href)>

   Example:

       <C:principal-address xmlns:D="DAV:"
          xmlns:C="urn:ietf:params:xml:ns:carddav">
          <D:href>http://addressbook.example.com/system/cyrus.vcf<
          /D:href>
       </C:principal-address>


8.  Address Book Reports

   This section defines the reports that CardDAV servers MUST support on
   address book collections and address object resources.

   CardDAV servers MUST advertise support for these REPORTs on all
   address book collections and address object resources with the DAV:
   supported-report-set property defined in Section 3.1.5 of [RFC3253].
   CardDAV servers MAY also advertise support for these REPORTs on
   ordinary collections.

   Some of these REPORTs allow address data (from possibly multiple
   resources) to be returned.

8.1.  REPORT Method

   The REPORT method (defined in Section 3.6 of [RFC3253]) provides an
   extensible mechanism for obtaining information about a resource.
   Unlike the PROPFIND method, which returns the value of one or more
   named properties, the REPORT method can involve more complex



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   processing.  REPORT is valuable in cases where the server has access
   to all of the information needed to perform the complex request (such
   as a query), and where it would require multiple requests for the
   client to retrieve the information needed to perform the same
   request.

   A server that supports this specification MUST support the DAV:
   expand-property report (defined in Section 3.8 of [RFC3253]).

8.2.  Ordinary Collections

   Servers MAY support the REPORTs defined in this document on ordinary
   collections (collections that are not address book collections) in
   addition to address book collections or address object resources.  In
   computing responses to the REPORTs on ordinary collections, servers
   MUST only consider address object resources contained in address book
   collections that are targeted by the REPORT based on the value of the
   Depth request header.

8.3.  Searching Text: Collations

   Some of the reports defined in this section do text matches of
   character strings provided by the client and compared to stored
   address data.  Since vCard data is by default encoded in the UTF-8
   charset and may include characters outside of the US-ASCII charset
   range in some property and parameter values, there is a need to
   ensure that text matching follows well-defined rules.

   To deal with this, this specification makes use of the IANA Collation
   Registry defined in [RFC4790] to specify collations that may be used
   to carry out the text comparison operations with a well-defined rule.

   Collations supported by the server MUST support "equality" and
   "substring" match operations as per [RFC4790] Section 4.2, including
   the "prefix" and "suffix" options for "substring" matching.  CardDAV
   uses these match options for "equals", "contains", "starts-with" and
   "ends-with" match operations.

   CardDAV servers are REQUIRED to support the "i;ascii-casemap"
   [RFC4790] and "i;unicode-casemap" [RFC5051] collations, and MAY
   support other collations.

   Servers MUST advertise the set of collations that they support via
   the CARDDAV:supported-collation-set property defined on any resource
   that supports reports that use collations.

   In the absence of a collation explicitly specified by the client, or
   if the client specifies the "default" collation identifier (as



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   defined in [RFC4790] Section 3.1), the server MUST default to using
   "i;unicode-casemap" as the collation.

   Wildcards (as defined in [RFC4790] Section 3.2) MUST NOT be used in
   the collation identifier.

   If the client chooses a collation not supported by the server, the
   server MUST respond with a CARDDAV:supported-collation precondition
   error response.

8.3.1.  CARDDAV:supported-collation-set Property

   Name:  supported-collation-set

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Identifies the set of collations supported by the server
      for text matching operations.

   Protected:  MUST be protected as it indicates support provided by the
      server.

   COPY/MOVE behavior:  This property value MUST be preserved in COPY
      and MOVE operations.

   allprop behavior:  SHOULD be returned by a PROPFIND DAV:allprop
      request.

   Description:  The CARDDAV:supported-collation-set property contains
      zero or more CARDDAV:supported-collation elements which specify
      the collection identifiers of the collations supported by the
      server.

   Definition:

         <!ELEMENT supported-collation-set (supported-collation*)>

         <!ELEMENT supported-collation (#PCDATA)>

   Example:

      <C:supported-collation-set
        xmlns:C="urn:ietf:params:xml:ns:carddav">
        <C:supported-collation>i;ascii-casemap</C:supported-collation>
        <C:supported-collation>i;octet</C:supported-collation>
        <C:supported-collation>i;unicode-casemap</C:supported-collation>
      </C:supported-collation-set>




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8.4.  Partial Retrieval

   Some address book REPORTs defined in this document allow partial
   retrieval of address object resources.  A CardDAV client can specify
   what information to return in the body of an address book REPORT
   request.

   A CardDAV client can request particular WebDAV property values, all
   WebDAV property values, or a list of the names of the resource's
   WebDAV properties.  A CardDAV client can also request address data to
   be returned and whether all vCard properties should be returned or
   only particular ones.  See CARDDAV:address-data in Section 10.4.

8.5.  Non-standard Properties and Parameters

   Servers MUST support the use of non-standard property or parameter
   names in the CARDDAV:address-data XML element in address book REPORT
   requests to allow clients to request that non-standard properties and
   parameters be returned in the address data provided in the response.

   Servers MAY support the use of non-standard property or parameter
   names in the CARDDAV:prop-filter and CARDDAV:param-filter XML
   elements specified in the CARDDAV:filter XML element of address book
   REPORT requests.

   Servers MUST fail with the CARDDAV:supported-filter precondition if
   an address book REPORT request uses a CARDDAV:prop-filter or CARDDAV:
   param-filter XML element that makes reference to a non-standard
   property or parameter name which the server does not support queries
   on.

8.6.  CARDDAV:addressbook-query Report

   The CARDDAV:addressbook-query REPORT performs a search for all
   address object resources that match a specified filter.  The response
   of this REPORT will contain all the WebDAV properties and address
   object resource data specified in the request.  In the case of the
   CARDDAV:address-data XML element, one can explicitly specify the
   vCard properties that should be returned in the address object
   resource data that matches the filter.

   The format of this report is modeled on the PROPFIND method.  The
   request and response bodies of the CARDAV:addressbook-query report
   use XML elements that are also used by PROPFIND.  In particular the
   request can include XML elements to request WebDAV properties to be
   returned.  When that occurs the response should follow the same
   behavior as PROPFIND with respect to the DAV:multistatus response
   elements used to return specific property results.  For instance, a



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   request to retrieve the value of a property which does not exist is
   an error and MUST be noted with a response XML element which contains
   a 404 (Not Found) status value.

   Support for the CARDDAV:addressbook-query REPORT is REQUIRED.

   Marshalling:

      The request body MUST be a CARDDAV:addressbook-query XML element
      as defined in Section 10.3.

      The request MAY include a Depth header.  If no Depth header is
      included, Depth:0 is assumed.

      The response body for a successful request MUST be a DAV:
      multistatus XML element (i.e., the response uses the same format
      as the response for PROPFIND).  In the case where there are no
      response elements, the returned DAV:multistatus XML element is
      empty.

      The response body for a successful CARDDAV:addressbook-query
      REPORT request MUST contain a DAV:response element for each
      address object that matched the search filter. address data is
      returned in the CARDDAV:address-data XML element inside the DAV:
      propstat XML element.

   Preconditions:

      (CARDDAV:supported-address-data): The attributes "content-type"
      and "version" of the CARDDAV:address-data XML element (see
      Section 10.4) specify a media type supported by the server for
      address object resources.

      (CARDDAV:supported-filter): The CARDDAV:prop-filter (see
      Section 10.5.1) and CARDDAV:param-filter (see Section 10.5.2) XML
      elements used in the CARDDAV:filter XML element (see Section 10.5)
      in the REPORT request only make reference to properties and
      parameters for which queries are supported by the server. i.e., if
      the CARDDAV:filter element attempts to reference an unsupported
      property or parameter, this precondition is violated.  Servers
      SHOULD report the CARDDAV:prop-filter or CARDDAV:param-filter for
      which it does not provide support.

          <!ELEMENT supported-filter (prop-filter*,
                                      param-filter*)>






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      (CARDDAV:supported-collation): Any XML attribute specifying a
      collation MUST specify a collation supported by the server as
      described in Section 8.3.

   Postconditions:

      (DAV:number-of-matches-within-limits): The number of matching
      address object resources must fall within server-specific,
      predefined limits.  For example, this condition might be triggered
      if a search specification would cause the return of an extremely
      large number of responses.

8.6.1.  Limiting Results

   A client can limit the number of results returned by the server
   through use of the CARDDAV:limit element in the request body.  This
   is useful when clients are only interested in a few matches, or only
   have limited space to display results to users and thus don't need
   the overhead of receiving more than that.  When the results are
   truncated by the server, the server MUST follow the rules below for
   indicating a result set truncation to the client.

8.6.2.  Truncation of Results

   A server MAY limit the number of resources in a response, for
   example, to limit the amount of work expended in processing a query,
   or as the result of an explicit limit set by the client.  If it does
   so, the response MUST use status code 207, return a DAV:multistatus
   response body, and indicate a status of 507 (Insufficient Storage)
   for the request URI.  That DAV:response element SHOULD include a DAV:
   error element with the DAV:number-of-matches-within-limits pre-
   condition, as defined in [RFC3744] (Section 9.2).

   The server SHOULD also include the partial results in additional DAV:
   response elements.  If a client requested limit is being applied, the
   507 response for the request URI MUST NOT be included in calculating
   the limit (e.g., if the client requests that only a single result be
   returned, and multiple matches are present, then the DAV:multistatus
   response will include one DAV:response for the matching resource and
   one DAV:response for the 507 status on the request URI).

8.6.3.  Example: Partial Retrieval of vCards Matching NICKNAME

   In this example, the client requests the server to search for address
   object resources that contain a NICKNAME property whose value equals
   some specific text, and to return specific vCard properties for those
   vCards found.  In addition the DAV:getetag property is also requested
   and returned as part of the response.



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   >> Request <<


   REPORT /home/bernard/addressbook/ HTTP/1.1
   Host: addressbook.example.com
   Depth: 1
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <C:addressbook-query xmlns:D="DAV:"
                     xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:prop>
       <D:getetag/>
       <C:address-data>
         <C:prop name="VERSION"/>
         <C:prop name="UID"/>
         <C:prop name="NICKNAME"/>
         <C:prop name="EMAIL"/>
         <C:prop name="FN"/>
       </C:address-data>
     </D:prop>
     <C:filter>
       <C:prop-filter name="NICKNAME">
         <C:text-match collation="i;unicode-casemap"
                       match-type="equals"
         >me</C:text-match>
       </C:prop-filter>
     </C:filter>
   </C:addressbook-query>





















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   >> Response <<


   HTTP/1.1 207 Multi-Status
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:"
                  xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:response>
       <D:href>/home/bernard/addressbook/v102.vcf</D:href>
       <D:propstat>
         <D:prop>
           <D:getetag>"23ba4d-ff11fb"</D:getetag>
           <C:address-data>BEGIN:VCARD
   VERSION:3.0
   NICKNAME:me
   UID:34222-232@example.com
   FN:Cyrus Daboo
   EMAIL:daboo@example.com
   END:VCARD
   </C:address-data>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>


8.6.4.  Example: Partial Retrieval of vCards Matching a Full Name or
        Email Address

   In this example, the client requests the server to search for address
   object resources that contain a FN property whose value contains some
   specific text or that contain an EMAIL property whose value contains
   other text, and to return specific vCard properties for those vCards
   found.  In addition the DAV:getetag property is also requested and
   returned as part of the response.











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   >> Request <<


   REPORT /home/bernard/addressbook/ HTTP/1.1
   Host: addressbook.example.com
   Depth: 1
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <C:addressbook-query xmlns:D="DAV:"
                     xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:prop>
       <D:getetag/>
       <C:address-data>
         <C:prop name="VERSION"/>
         <C:prop name="UID"/>
         <C:prop name="NICKNAME"/>
         <C:prop name="EMAIL"/>
         <C:prop name="FN"/>
       </C:address-data>
     </D:prop>
     <C:filter test="anyof">
       <C:prop-filter name="FN">
         <C:text-match collation="i;unicode-casemap"
                       match-type="contains"
         >daboo</C:text-match>
       </C:prop-filter>
       <C:prop-filter name="EMAIL">
         <C:text-match collation="i;unicode-casemap"
                       match-type="contains"
         >daboo</C:text-match>
       </C:prop-filter>
     </C:filter>
   </C:addressbook-query>
















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   >> Response <<


   HTTP/1.1 207 Multi-Status
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:"
                  xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:response>
       <D:href>/home/bernard/addressbook/v102.vcf</D:href>
       <D:propstat>
         <D:prop>
           <D:getetag>"23ba4d-ff11fb"</D:getetag>
           <C:address-data>BEGIN:VCARD
   VERSION:3.0
   NICKNAME:me
   UID:34222-232@example.com
   FN:David Boo
   EMAIL:daboo@example.com
   END:VCARD
   </C:address-data>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
     <D:response>
       <D:href>/home/bernard/addressbook/v104.vcf</D:href>
       <D:propstat>
         <D:prop>
           <D:getetag>"23ba4d-ff11fc"</D:getetag>
           <C:address-data>BEGIN:VCARD
   VERSION:3.0
   NICKNAME:oliver
   UID:34222-23222@example.com
   FN:Oliver Daboo
   EMAIL:oliver@example.com
   END:VCARD
   </C:address-data>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>





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8.6.5.  Example: Truncated Results

   In this example, the client requests the server to search for address
   object resources that contain a FN property whose value contains some
   specific text, and to return the DAV:getetag property for two results
   only.  The server response includes a 507 status for the request URI
   indicating that there were more than two resources that matched the
   query, but that the server truncated the result set as requested by
   the client.

   >> Request <<


   REPORT /home/bernard/addressbook/ HTTP/1.1
   Host: addressbook.example.com
   Depth: 1
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <C:addressbook-query xmlns:D="DAV:"
                     xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:prop>
       <D:getetag/>
     </D:prop>
     <C:filter test="anyof">
       <C:prop-filter name="FN">
         <C:text-match collation="i;unicode-casemap"
                       match-type="contains"
         >daboo</C:text-match>
       </C:prop-filter>
     </C:filter>
     <C:limit>
       <C:nresults>2</C:nresults>
     </C:limit>
   </C:addressbook-query>















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   >> Response <<


   HTTP/1.1 207 Multi-Status
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:"
                  xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:response>
       <D:href>/home/bernard/addressbook/</D:href>
       <D:status>HTTP/1.1 507 OK</D:status>
       <D:error><D:number-of-matches-within-limits/></D:error>
       <D:responsedescription xml:lang="en">
         Only two matching records were returned
       </D:responsedescription>
     </D:response>
     <D:response>
       <D:href>/home/bernard/addressbook/v102.vcf</D:href>
       <D:propstat>
         <D:prop>
           <D:getetag>"23ba4d-ff11fb"</D:getetag>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
     <D:response>
       <D:href>/home/bernard/addressbook/v104.vcf</D:href>
       <D:propstat>
         <D:prop>
           <D:getetag>"23ba4d-ff11fc"</D:getetag>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>


8.7.  CARDDAV:addressbook-multiget Report

   The CARDDAV:addressbook-multiget REPORT is used to retrieve specific
   address object resources from within a collection, if the Request-URI
   is a collection, or to retrieve a specific address object resource,
   if the Request-URI is a address object resource.  This report is
   similar to the CARDDAV:addressbook-query REPORT (see Section 8.6),
   except that it takes a list of DAV:href elements instead of a



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   CARDDAV:filter element to determine which address object resources to
   return.

   Support for the addressbook-multiget REPORT is REQUIRED.

   Marshalling:

      The request body MUST be a CARDDAV:addressbook-multiget XML
      element (see Section 10.7, which MUST contain at least one DAV:
      href XML element, and one optional CARDDAV:address-data element as
      defined in Section 10.4.  If the Request-URI is a collection
      resource, then the DAV:href elements MUST refer to resources
      within that collection, and they MAY refer to resources at any
      depth within the collection.  As a result the "Depth" header MUST
      be ignored by the server and SHOULD NOT be sent by the client.  If
      the Request-URI refers to a non-collection resource, then there
      MUST be a single DAV:href element that is equivalent to the
      Request-URI.

      The response body for a successful request MUST be a DAV:
      multistatus XML element.

      The response body for a successful CARDDAV:addressbook-multiget
      REPORT request MUST contain a DAV:response element for each
      address object resource referenced by the provided set of DAV:href
      elements.  Address data is returned in the CARDDAV:address-data
      element inside the DAV:prop element.

      In the case of an error accessing any of the provided DAV:href
      resources, the server MUST return the appropriate error status
      code in the DAV:status element of the corresponding DAV:response
      element.

   Preconditions:

      (CARDAV:supported-address-data): The attributes "content-type" and
      "version" of the CARDDAV:address-data XML elements (see
      Section 10.4) specify a media type supported by the server for
      address object resources.

   Postconditions:

      None.








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8.7.1.  Example: CARDDAV:addressbook-multiget Report

   In this example, the client requests the server to return specific
   properties of the address components referenced by specific URIs.  In
   addition the DAV:getetag property is also requested and returned as
   part of the response.  Note that in this example, the resource at
   http://addressbook.example.com/home/bernard/addressbook/vcf1.vcf does
   not exist, resulting in an error status response.

   >> Request <<


   REPORT /home/bernard/addressbook/ HTTP/1.1
   Host: addressbook.example.com
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <C:addressbook-multiget xmlns:D="DAV:"
                        xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:prop>
       <D:getetag/>
       <C:address-data>
         <C:prop name="VERSION"/>
         <C:prop name="UID"/>
         <C:prop name="NICKNAME"/>
         <C:prop name="EMAIL"/>
         <C:prop name="FN"/>
       </C:address-data>
     </D:prop>
     <D:href>/home/bernard/addressbook/vcf102.vcf</D:href>
     <D:href>/home/bernard/addressbook/vcf1.vcf</D:href>
   </C:addressbook-multiget>


















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   >> Response <<


   HTTP/1.1 207 Multi-Status
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:multistatus xmlns:D="DAV:"
                  xmlns:C="urn:ietf:params:xml:ns:carddav">
     <D:response>
       <D:href>/home/bernard/addressbook/vcf102.vcf</D:href>
       <D:propstat>
         <D:prop>
           <D:getetag>"23ba4d-ff11fb"</D:getetag>
           <C:address-data>BEGIN:VCARD
   VERSION:3.0
   NICKNAME:me
   UID:34222-232@example.com
   FN:Cyrus Daboo
   EMAIL:daboo@example.com
   END:VCARD
   </C:address-data>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
     <D:response>
       <D:href>/home/bernard/addressbook/vcf1.vcf</D:href>
       <D:status>HTTP/1.1 404 Resource not found</D:status>
     </D:response>
   </D:multistatus>



9.  Guidelines

9.1.  Restrict the Properties Returned

   Clients may not need all the properties in a vCard object when
   presenting information to the user, or looking up specific items for
   their email address, for example.  Since some property data can be
   large (e.g., PHOTO or SOUND with inline content) clients can choose
   to ignore those by only requesting the specific items it knows it
   will use, through use of the CARDDAV:address-data XML element in the
   relevant reports.




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   However, if a client needs to make a change to a vCard, it can only
   change the entire vCard data via a PUT request.  There is no way to
   incrementally make a change to a set of properties within a vCard
   object resource.  As a result the client will have to cache the
   entire set of properties on a resource that is being changed.

9.2.  Use of Locking

   WebDAV locks can be used to prevent two clients modifying the same
   resource from either overwriting each others' changes (though that
   problem can also be solved by using ETags) and also to prevent the
   user from making changes that will conflict with another set of
   changes.  In a multi-user address book system, the address book
   client could lock an address object resource while the user is
   editing the vCard data, and unlock the address object resource when
   the user finishes or cancels.  Locks can also be used to prevent
   changes while data is being reorganized.  For example, an address
   book client might lock two address book collections prior to moving a
   bunch of address object resources from one to another.

   Clients may request a lock timeout period that is appropriate to the
   use case.  When the user explicitly decides to reserve a resource and
   prevent other changes, a long timeout might be appropriate, but in
   cases when the client automatically decides to lock the resource the
   timeout should be short (and the client can always refresh the lock
   should it need to).  A short lock timeout means that if the client is
   unable to remove the lock, the other address book users aren't
   prevented from making changes.

9.3.  Finding Address Books

   Much of the time an address book client (or agent) will discover a
   new address book's location by being provided directly with the URL.
   E.g. a user will type his or her own address book location into
   client configuration information, or cut and paste a URL from email
   into the address book application.  The client need only confirm that
   the URL points to a resource which is an address book.  The client
   may also be able to browse WebDAV collections to find address book
   collections.

   The choice of HTTP URLs means that address object resources are
   backward compatible with existing software, but does have the
   disadvantage that existing software does not usually know to look at
   the OPTIONS response to that URL to determine what can be done with
   it.  This is somewhat of a barrier for WebDAV usage as well as with
   CardDAV usage.  This specification does not offer a way through this
   other than making the information available in the OPTIONS response
   should this be requested.



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   For address book sharing use cases, one might wish to find the
   address book belonging to another user.  If the other user has an
   address book in the same repository, that address book can be found
   by using the principal namespace required by WebDAV ACL support.

   Because CardDAV requires servers to support WebDAV ACL [RFC3744]
   including principal namespaces, and with the addition of the CARDDAV:
   addressbook-home-set property, there are a couple options for CardDAV
   clients to find one's own address book or another user's address
   book.

   In this case, a DAV:principal-match REPORT is used to find a named
   property (the CARDDAV:addressbook-home-set) on the Principal-URL of
   the current user.  Using this, a WebDAV client can learn "who am I"
   and "where are my address books".  The REPORT request body looks like
   this:

   <?xml version="1.0" encoding="utf-8" ?>
   <D:principal-match xmlns:D="DAV:">
     <D:self/>
     <D:prop>
       <C:addressbook-home-set
          xmlns:C="urn:ietf:params:xml:ns:carddav"/>
     </D:prop>
   </D:principal-match>

   To find other users' address books, the DAV:principal-property-search
   REPORT can be used to filter on some properties and return others.
   To search for an address book owned by a user named "Laurie", the
   REPORT request body would look like this:

   <?xml version="1.0" encoding="utf-8" ?>
   <D:principal-property-search xmlns:D="DAV:">
     <D:property-search>
       <D:prop>
         <D:displayname/>
       </D:prop>
       <D:match>Laurie</D:match>
     </D:property-search>
     <D:prop>
       <C:addressbook-home-set
          xmlns:C="urn:ietf:params:xml:ns:carddav"/>
       <D:displayname/>
     </D:prop>
   </D:principal-property-search>

   The server performs a case-sensitive or caseless search for a
   matching string subset of "Laurie" within the DAV:displayname



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   property.  Thus, the server might return "Laurie Dusseault", "Laurier
   Desruisseaux" or "Wilfrid Laurier" all as matching DAV:displayname
   values, and the address books for each of these.


10.  XML Element Definitions

10.1.  CARDDAV:addressbook XML Element

   Name:  addressbook

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies the resource type of an address book collection.

   Description:  See Section 5.2.

   Definition:

       <!ELEMENT addressbook EMPTY>

10.2.  CARDDAV:supported-collation XML Element

   Name:  supported-collation

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Identifies a single collation via its collation identifier
      as defined by [RFC4790].

   Description:  The CARDDAV:supported-collation contains the text of a
      collation identifier as described in Section 8.3.1.

   Definition:

       <!ELEMENT supported-collation (#PCDATA)>
       <!-- PCDATA value: collation identifier -->

10.3.  CARDDAV:addressbook-query XML Element

   Name:  addressbook-query

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Defines a report for querying address book data






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   Description:  See Section 8.6.

   Definition:

       <!ELEMENT addressbook-query ((DAV:allprop |
                                     DAV:propname |
                                     DAV:prop)?, filter, limit?)>

10.4.  CARDDAV:address-data XML Element

   Name:  address-data

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies one of the following:

      1.  A supported media type for address object resources when
          nested in the CARDDAV:supported-address-data property;

      2.  The parts of an address object resource should be returned by
          a given address book REPORT;

      3.  The content of an address object resource in a response to an
          address book REPORT.

   Description:  When nested in the CARDDAV:supported-address-data
      property, the CARDDAV:address-data XML element specifies a media
      type supported by the CardDAV server for address object resources.

      When used in an address book REPORT request, the CARDDAV:address-
      data XML element specifies which parts of address object resources
      need to be returned in the response.  If the CARDDAV:address-data
      XML element doesn't contain any CARDDAV:prop elements, address
      object resources will be returned in their entirety.

      Finally, when used in an address book REPORT response, the
      CARDDAV:address-data XML element specifies the content of a
      address object resource.  Given that XML parsers normalize the
      two-character sequence CRLF (US-ASCII decimal 13 and US-ASCII
      decimal 10) to a single LF character (US-ASCII decimal 10), the CR
      character (US-ASCII decimal 13) MAY be omitted in address object
      resources specified in the CARDDAV:address-data XML element.
      Furthermore, address object resources specified in the CARDDAV:
      address-data XML element MAY be invalid per their media type
      specification if the CARDAV:address-data XML element part of the
      address book REPORT request did not specify required properties
      (e.g., UID, etc.) or specified a CARDDAV:prop XML element with the
      "novalue" attribute set to "yes".



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   Note:  The CARDDAV:address-data XML element is specified in requests
      and responses inside the DAV:prop XML element as if it were a
      WebDAV property.  However, the CARDDAV:address-data XML element is
      not a WebDAV property and as such it is not returned in PROPFIND
      responses nor used in PROPPATCH requests.

   Note:  The address data embedded within the CARDDAV:address-data XML
      element MUST follow the standard XML character data encoding
      rules, including use of &lt;, &gt;, &amp; etc entity encoding or
      the use of a <![CDATA[ ... ]]> construct.  In the later case the
      vCard data cannot contain the character sequence "]]>" which is
      the end delimiter for the CDATA section.

   Definition:

       <!ELEMENT address-data EMPTY>

       when nested in the CARDDAV:supported-address-data property
       to specify a supported media type for address object
       resources;

       <!ELEMENT address-data (allprop | prop*)>

       when nested in the DAV:prop XML element in an addressbook
       REPORT request to specify which parts of address object
       resources should be returned in the response;

       <!ELEMENT address-data (#PCDATA)>
       <!-- PCDATA value: address data -->

       when nested in the DAV:prop XML element in an addressbook
       REPORT response to specify the content of a returned
       address object resource.

       <!ATTLIST address-data content-type CDATA "text/vcard"
                             version CDATA "3.0">
       <!-- content-type value: a MIME media type -->
       <!-- version value: a version string -->

       attributes can be used on all three variants of the
       CALDAV:address-data XML element.

10.4.1.  CARDDAV:allprop XML Element








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   Name:  allprop

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies that all properties shall be returned.

   Description:  This element can be used when the client wants all
      properties of components returned by a report.

   Definition:

       <!ELEMENT allprop EMPTY>

   NOTE: The CARDDAV:allprop element defined here has the same name as
   the DAV:allprop element defined in WebDAV.  However, the CARDDAV:
   allprop element defined here uses the
   "urn:ietf:params:xml:ns:carddav" namespace, as opposed to the "DAV:"
   namespace used for the DAV:allprop element defined in WebDAV.

10.4.2.  CARDDAV:prop XML Element

   Name:  prop

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Defines which properties to return in the response.

   Description:  The "name" attribute specifies the name of the vCard
      property to return (e.g., "NICKNAME").  The "novalue" attribute
      can be used by clients to request that the actual value of the
      property not be returned (if the "novalue" attribute is set to
      "yes").  In that case the server will return just the vCard
      property name and any vCard parameters and a trailing ":" without
      the subsequent value data.

      vCard allows a "group" prefix to appear before a property name in
      the vCard data.  When the "name" attribute does not specify a
      group prefix, it MUST match properties in the vCard data without a
      group prefix or with any group prefix.  When the "name" attribute
      includes a group prefix, it MUST match properties that have
      exactly the same group prefix and name. e.g.: a "name" set to
      "TEL" will match "TEL", "X-ABC.TEL", "X-ABC-1.TEL" vCard
      properties.  A "name" set to "X-ABC.TEL" will match an "X-ABC.TEL"
      vCard property only, it will not match "TEL" or "X-ABC-1.TEL".







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   Definition:

       <!ELEMENT prop EMPTY>

       <!ATTLIST prop name CDATA #REQUIRED
                  novalue (yes | no) "no">
       <!-- name value: a vCard property name -->
       <!-- novalue value: "yes" or "no" -->

   NOTE: The CARDDAV:prop element defined here has the same name as the
   DAV:prop element defined in WebDAV.  However, the CARDDAV:prop
   element defined here uses the "urn:ietf:params:xml:ns:carddav"
   namespace, as opposed to the "DAV:" namespace used for the DAV:prop
   element defined in WebDAV.

10.5.  CARDDAV:filter XML Element

   Name:  filter

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Determines which matching objects are returned.

   Description:  The "filter" element specifies the search filter used
      to match address objects that should be returned by a report.  The
      "test" attribute specifies whether any (logical OR) or all
      (logical AND) of the prop-filter tests needs to match in order for
      the overall filter to match.

   Definition:

       <!ELEMENT filter (prop-filter*)>

       <!ATTLIST filter test (anyof | allof) "anyof">
       <!-- test value:
                 anyof logical OR for prop-filter matches
                 allof logical AND for prop-filter matches -->

10.5.1.  CARDDAV:prop-filter XML Element

   Name:  prop-filter

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Limits the search to specific properties.






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   Description:  The CARDDAV:prop-filter XML element specifies a search
      criteria on a specific vCard property (e.g., NICKNAME).  An
      address object is said to match a CARDDAV:prop-filter if:

      *  A property of the type specified by the "name" attribute
         exists, and the CARDDAV:prop-filter is empty, or it matches any
         CARDDAV:text-match conditions if specified, and that CARDDAV:
         param-filter child elements also match.  The "test" attribute
         specifies whether any (logical OR) or all (logical AND) of the
         text-filter and param-filter tests need to match in order for
         the overall filter to match.

      or:

      *  A property of the type specified by the "name" attribute does
         not exist, and the CARDAV:is-not-defined element is specified.

      vCard allows a "group" prefix to appear before a property name in
      the vCard data.  When the "name" attribute does not specify a
      group prefix, it MUST match properties in the vCard data without a
      group prefix or with any group prefix.  When the "name" attribute
      includes a group prefix, it MUST match properties that have
      exactly the same group prefix and name. e.g.: a "name" set to
      "TEL" will match "TEL", "X-ABC.TEL", "X-ABC-1.TEL" vCard
      properties.  A "name" set to "X-ABC.TEL" will match an "X-ABC.TEL"
      vCard property only, it will not match "TEL" or "X-ABC-1.TEL".

   Definition:

       <!ELEMENT prop-filter (is-not-defined |
                              (text-match*, param-filter*))>

       <!ATTLIST prop-filter name CDATA #REQUIRED
                             test (anyof | allof) "anyof">
       <!-- name value: a vCard property name (e.g., "NICKNAME")
         test value:
             anyof logical OR for text-match/param-filter matches
             allof logical AND for text-match/param-filter matches -->

10.5.2.  CARDDAV:param-filter XML Element

   Name:  param-filter

   Namespace:  urn:ietf:params:xml:ns:carddav







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   Purpose:  Limits the search to specific parameter values.

   Description:  The CARDDAV:param-filter XML element specifies a search
      criteria on a specific vCard property parameter (e.g., TYPE) in
      the scope of a given CARDDAV:prop-filter.  A vCard property is
      said to match a CARDDAV:param-filter if:

      *  A parameter of the type specified by the "name" attribute
         exists, and the CARDDAV:param-filter is empty, or it matches
         the CARDDAV:text-match conditions if specified.

      or:

      *  A parameter of the type specified by the "name" attribute does
         not exist, and the CARDDAV:is-not-defined element is specified.

   Definition:

       <!ELEMENT param-filter (is-not-defined | text-match)?>

       <!ATTLIST param-filter name CDATA #REQUIRED>
       <!-- name value: a property parameter name (e.g., "TYPE") -->

10.5.3.  CARDDAV:is-not-defined XML Element

   Name:  is-not-defined

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies that a match should occur if the enclosing
      property or parameter does not exist.

   Description:  The CARDDAV:is-not-defined XML element specifies that a
      match occurs if the enclosing property or parameter value
      specified in an address book REPORT request does not exist in the
      address data being tested.

   Definition:

       <!ELEMENT is-not-defined EMPTY>

10.5.4.  CARDDAV:text-match XML Element

   Name:  text-match







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   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies a substring match on a property or parameter
      value.

   Description:  The CARDDAV:text-match XML element specifies text used
      for a substring match against the property or parameter value
      specified in an address book REPORT request.

      The "collation" attribute is used to select the collation that the
      server MUST use for character string matching.  In the absence of
      this attribute the server MUST use the "i;unicode-casemap"
      collation.

      The "negate-condition" attribute is used to indicate that this
      test returns a match if the text matches, when the attribute value
      is set to "no", or return a match if the text does not match, if
      the attribute value is set to "yes".  For example, this can be
      used to match components with a CATEGORIES property not set to
      PERSON.

      The "match-type" attribute is used to indicate the type of match
      operation to use.  Possible choices are:

         "equals" - an exact match to the target string

         "contains" - a substring match, matching anywhere within the
         target string

         "starts-with" - a substring match, matching only at the start
         of the target string

         "ends-with" - a substring match, matching only at the end of
         the target string

   Definition:

       <!ELEMENT text-match (#PCDATA)>
       <!-- PCDATA value: string -->

       <!ATTLIST text-match
          collation        CDATA "i;unicode-casemap"
          negate-condition (yes | no) "no"
          match-type (equals|contains|starts-with|ends-with) "contains">







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10.6.  CARDDAV:limit XML Element

   Name:  limit

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies different types of limits that can be applied to
      the results returned by the server.

   Description:  The CARDDAV:limit XML element can be used to specify
      different types of limits that the client can request the server
      to apply to the results returned by the server.  Currently only
      the CARDDAV:nresults limit can be used, other types of limit could
      be defined in the future.

   Definition:

       <!ELEMENT limit (nresults)>

10.6.1.  CARDDAV:nresults XML Element

   Name:  nresults

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  Specifies a limit on the number of results returned by the
      server.

   Description:  The CARDDAV:nresults XML element contains a requested
      maximum number of DAV:response elements to be returned in the
      response body of a query.  The server MAY disregard this limit.
      The value of this element is an unsigned integer.

   Definition:

       <!ELEMENT nresults (#PCDATA)>
       <!-- nresults value: unsigned integer, must be digits -->

10.7.  CARDDAV:addressbook-multiget XML Element

   Name:  addressbook-multiget

   Namespace:  urn:ietf:params:xml:ns:carddav

   Purpose:  CardDAV report used to retrieve specific address objects
      via their URIs.





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   Description:  See Section 8.7.

   Definition:

       <!ELEMENT addressbook-multiget ((DAV:allprop |
                                        DAV:propname |
                                        DAV:prop)?,
                                        DAV:href+)>


11.  Service Discovery via SRV Records

   [RFC2782] defines a DNS-based service discovery protocol that has
   been widely adopted as a means of locating particular services within
   a local area network and beyond, using SRV RR records.

   This specification adds two service types for use with SRV records:

   carddav:  Identifies a CardDAV server that uses HTTP without SSL.

   carddavs:  Identifies a CardDAV server that uses HTTP with SSL.

   Example: non-SSL service record

       _carddav._tcp     SRV 0 1 80 addressbook.example.com.

   Example: SSL service

       _carddavs._tcp    SRV 0 1 443 addressbook.example.com.


12.  Internationalization Considerations

   CardDAV allows internationalized strings to be stored and retrieved
   for the description of address book collections (see Section 6.2.1).

   The CARDDAV:addressbook-query report (Section 8.6) includes a text
   searching option controlled by the CARDDAV:text-match element and
   details of character handling are covered in the description of that
   element (see Section 10.5.4).


13.  Security Considerations

   HTTP protocol transactions are sent in the clear over the network
   unless protection from snooping is negotiated.  This can be
   accomplished by use of TLS as defined in [RFC2818].  In particular,
   if HTTP Basic authentication is available, the server MUST allow TLS



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   to be used at the same time, and SHOULD prevent use of Basic
   authentication when TLS is not in use.

   With the ACL extension present, WebDAV allows control over who can
   access (read or write) any resource on the WebDAV server.  In
   addition, WebDAV ACL provides for an "inheritance" mechanism, whereby
   resources may inherit access privileges from other resources.  Often
   the "other" resource is a parent collection of the resource itself.
   Clients MUST take care to ensure users are aware of which address
   books may be "private" (i.e. only accessible to them) and which are
   "shared" (i.e. accessible to others).

   Since web servers are often the target of automated indexing
   applications that gather data from the server, analyze it and extract
   'interesting' parts, great care must be taken when allowing
   unauthenticated access to any address book or address object data.
   Clients MAY choose to warn users when they create address data in a
   public address book, copy or move address data into public address
   books, or change access privileges in such a way as to expose address
   data to unauthenticated users.

   This specification currently relies on standard HTTP authentication
   mechanisms for identifying users.  These comprise Basic and Digest
   authentication as well as SSL using client-side certificates.


14.  IANA Consideration

   In addition to the namespaces defined by RFC4918 [RFC4918] for XML
   elements, this document uses a URN to describe a new XML namespace
   conforming to a registry mechanism described in RFC3688 [RFC3688].
   All other IANA considerations mentioned in RFC4918 [RFC4918] also
   apply to this document.

14.1.  Namespace Registration

   Registration request for the carddav namespace:

   URI: urn:ietf:params:xml:ns:carddav

   Registrant Contact: See the "Author's Address" section of this
   document.

   XML: None.  Namespace URIs do not represent an XML specification.







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15.  Acknowledgments

   Thanks go to Lisa Dusseault and Bernard Desruisseaux for their work
   on CalDAV, on which CardDAV is heavily based.  The following
   individuals contributed their ideas and support for writing this
   specification: Stefan Eissing, Arnaud Quillaud, Julian Reschke, Elias
   Sinderson, Greg Stein, Wilfredo Sanchez.


16.  References

16.1.  Normative References

   [I-D.ietf-vcarddav-vcardrev]
              Perreault, S. and P. Resnick, "vCard Format
              Specification", draft-ietf-vcarddav-vcardrev-05 (work in
              progress), November 2008.

   [I-D.ietf-vcarddav-webdav-mkcol]
              Daboo, C., "Extended MKCOL for WebDAV",
              draft-ietf-vcarddav-webdav-mkcol-03 (work in progress),
              February 2009.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2426]  Dawson, F. and T. Howes, "vCard MIME Directory Profile",
              RFC 2426, September 1998.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2782]  Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", RFC 2782,
              February 2000.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [RFC3253]  Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J.
              Whitehead, "Versioning Extensions to WebDAV
              (Web Distributed Authoring and Versioning)", RFC 3253,
              March 2002.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC3744]  Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web



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              Distributed Authoring and Versioning (WebDAV)
              Access Control Protocol", RFC 3744, May 2004.

   [RFC4790]  Newman, C., Duerst, M., and A. Gulbrandsen, "Internet
              Application Protocol Collation Registry", RFC 4790,
              March 2007.

   [RFC4918]  Dusseault, L., "HTTP Extensions for Web Distributed
              Authoring and Versioning (WebDAV)", RFC 4918, June 2007.

   [RFC5051]  Crispin, M., "i;unicode-casemap - Simple Unicode Collation
              Algorithm", RFC 5051, October 2007.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5397]  Sanchez, W. and C. Daboo, "WebDAV Current Principal
              Extension", RFC 5397, December 2008.

   [W3C.REC-xml-20060816]
              Yergeau, F., Paoli, J., Bray, T., Sperberg-McQueen, C.,
              and E. Maler, "Extensible Markup Language (XML) 1.0
              (Fourth Edition)", World Wide Web Consortium
              FirstEdition REC-xml-20060816, August 2006,
              <http://www.w3.org/TR/2006/REC-xml-20060816>.

16.2.  Informative References

   [IMSP]     Myers, J., "IMSP - Internet Message Support Protocol",
              June 1995.

   [RFC2244]  Newman, C. and J. Myers, "ACAP -- Application
              Configuration Access Protocol", RFC 2244, November 1997.

   [RFC4511]  Sermersheim, J., "Lightweight Directory Access Protocol
              (LDAP): The Protocol", RFC 4511, June 2006.


Appendix A.  Change History (to be removed prior to publication as an
             RFC)

   Changes from -04

   1.  Removed mailing list discussion note from abstract.

   Changes from -03





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   1.  Tweaked limit element text to not imply any formal ordering of
       results.

   2.  Changed prop-filter element to allow zero or more text-match
       elements rather than zero or one.

   3.  Updated to RFC5397 reference.

   4.  Updated TLS reference to latest version RFC5246.

   5.  Boiler plate update.

   Changes from -02

   1.  Added limit element to addressbook-query.

   2.  Specified how a server signals that query results have been
       truncated.

   3.  Minor stylistic changes.

   Changes from -01

   1.  Added text to CARDDAV:prop and CARDDAV:prop-filter elements to
       explain how vCard "group" prefix on property names is handled.

   Changes from -00

   1.  Added section on SRV records.

   Changes from draft-daboo-carddav-04

   1.  Removed text describing other protocols.

   2.  Added comment about a new vcard spec being developed.

   3.  Added SHOULD support for the DAV:current-user-principal-URL
       property.

   4.  Added "anyof"/"allof" test attribute to query XML elements to
       support simple or/and combinations of tests.

   Changes from -03

   1.  Renamed addressbook-data to address-data for consistency.

   2.  Fixed address-data element definition.




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   Changes from -02

   1.  Replaced MKADDRESSBOOK with extended MKCOL.

   2.  Now require i;uncide-casemap as a supported collation and make it
       the default.

   3.  No longer require i;octet as a supported collation.

   4.  Allow different types of match operations via the "match-type"
       attribute on the "text-match" element.

   5.  Updated to 4918 reference and removed some text/sections
       duplicating 4918.

   6.  WebDAV Level 3 now required.

   7.  TLS requirement text tweaked to match latest text approved by
       IESG.

   8.  Added principal-address property to principal resources to allow
       a vcard to be associated with a principal.

   9.  XML definition clean-up.

   Changes from -01

   1.   Added commentary on SyncML.

   2.   Changed 'adbk' to 'addressbook'.

   3.   Support for MKADDRESSBOOK is now a SHOULD.

   4.   Updated to RFC4790 reference.

   5.   Removed synchronization report.

   6.   Removed BNF conventions section as we have no BNF.

   7.   Reworded and reformatted several items to match the final CalDAV
        spec.

   8.   Added section on use of nonstandard properties and parameters
        (as per CalDAV).

   9.   Added section of behavior of ETags (as per CalDAV).





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   10.  Generalized the text so that vCard need not be the only format
        supported by the server (i.e., allow xml version of vCard etc).

   11.  Renamed supported-addressbook-data to supported-address-data.

   12.  Renamed valid-addressbook-data to valid-address-data.

   13.  Now requires "i;unicasemao" collation.

   Changes from -00

   1.  Fixed various incorrect references and typos.

   2.  Major changes to sync with latest CalDAV spec behaviors.


Author's Address

   Cyrus Daboo
   Apple Inc.
   1 Infinite Loop
   Cupertino, CA  95014
   USA

   Email: cyrus@daboo.name
   URI:   http://www.apple.com/

























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