Network Working Group C. Daboo Internet-Draft Apple Computer Intended status: Informational October 22, 2006 Expires: April 25, 2007 vCard Extensions to WebDAV (CardDAV) draft-daboo-carddav-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 25, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document specifies a set of methods, headers and resource types that define an extension to the WebDAV protocol to support vCard data stored as address books on the server. The new protocol elements are intended to make WebDAV-based address book management an interoperable standard that supports address book access, address book sharing, and address book publishing. Daboo Expires April 25, 2007 [Page 1] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Change History (to be removed prior to publication as an RFC) Changes from -00 1. Fixed various incorrect references and typos. 2. Major changes to sync with latest CalDAV spec behaviors. Table of Contents 1. Introduction and Overview . . . . . . . . . . . . . . . . . . 4 1.1. IMSP . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. ACAP . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3. LDAP . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.4. WebDAV for Address Books . . . . . . . . . . . . . . . . . 6 1.5. vCard . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1. Notational Conventions . . . . . . . . . . . . . . . . . . 7 2.2. XML Namespaces and Processing . . . . . . . . . . . . . . 8 2.3. Method Preconditions and Postconditions . . . . . . . . . 8 3. Requirements Overview . . . . . . . . . . . . . . . . . . . . 9 4. Address Book Data Model . . . . . . . . . . . . . . . . . . . 9 4.1. Address Book Server . . . . . . . . . . . . . . . . . . . 10 5. Address Book Resources . . . . . . . . . . . . . . . . . . . . 10 5.1. vCard Object Resources . . . . . . . . . . . . . . . . . . 10 5.2. Address Book Collection . . . . . . . . . . . . . . . . . 11 6. Address Book Feature . . . . . . . . . . . . . . . . . . . . . 12 6.1. Address Book Support . . . . . . . . . . . . . . . . . . . 12 6.1.1. Example: Using OPTIONS for the Discovery of Support for CardDAV . . . . . . . . . . . . . . . . . 12 6.2. Address Book Properties . . . . . . . . . . . . . . . . . 13 6.2.1. CARDDAV:adbk-description Property . . . . . . . . . . 13 6.2.2. CARDDAV:supported-adbk-data Property . . . . . . . . . 13 6.2.3. CARDDAV:max-resource-size Property . . . . . . . . . . 14 6.3. Creating Resources . . . . . . . . . . . . . . . . . . . . 15 6.3.1. MKADBK Method . . . . . . . . . . . . . . . . . . . . 15 6.3.1.1. Status Codes . . . . . . . . . . . . . . . . . . . 17 6.3.1.2. Example - Successful MKADBK request . . . . . . . 18 6.3.2. Creating vCard Object Resources . . . . . . . . . . . 18 6.3.2.1. Additional Preconditions for PUT, COPY and MOVE . 20 7. Address Book Access Control . . . . . . . . . . . . . . . . . 21 7.1. Additional Principal Property . . . . . . . . . . . . . . 21 7.1.1. CARDDAV:adbk-home-set Property . . . . . . . . . . . . 21 8. Address Book Reports . . . . . . . . . . . . . . . . . . . . . 22 8.1. REPORT Method . . . . . . . . . . . . . . . . . . . . . . 22 8.2. Ordinary collections . . . . . . . . . . . . . . . . . . . 22 8.3. Searching Text: Collations . . . . . . . . . . . . . . . . 22 Daboo Expires April 25, 2007 [Page 2] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 8.3.1. CARDDAV:supported-collation-set Property . . . . . . . 23 8.4. Partial Retrieval . . . . . . . . . . . . . . . . . . . . 24 8.5. Non-standard properties and parameters . . . . . . . . . . 24 8.6. CARDDAV:adbk-query Report . . . . . . . . . . . . . . . . 25 8.6.1. Example: Partial retrieval of vCards matching a NICKNAME . . . . . . . . . . . . . . . . . . . . . . . 26 8.6.2. Example: Partial retrieval of vCards matching a full name . . . . . . . . . . . . . . . . . . . . . . 28 8.7. CARDDAV:adbk-multiget Report . . . . . . . . . . . . . . . 31 8.7.1. Example: CARDDAV:adbk-multiget Report . . . . . . . . 32 8.8. CARDDAV:adbk-sync Report . . . . . . . . . . . . . . . . . 33 8.8.1. Example: Initial CARDDAV:adbk-sync Report . . . . . . 35 8.8.2. Example: CARDDAV:adbk-sync Report with token . . . . . 36 9. Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 38 9.1. Restrict the Properties Returned . . . . . . . . . . . . . 38 9.2. Use of Locking . . . . . . . . . . . . . . . . . . . . . . 38 9.3. Finding address books . . . . . . . . . . . . . . . . . . 38 10. XML Element Definitions . . . . . . . . . . . . . . . . . . . 40 10.1. CARDDAV:adbk XML Element . . . . . . . . . . . . . . . . . 40 10.2. CARDDAV:mkadbk XML Element . . . . . . . . . . . . . . . . 40 10.3. CARDDAV:mkadbk-response XML Element . . . . . . . . . . . 41 10.4. CARDDAV:supported-collation XML Element . . . . . . . . . 41 10.5. CARDDAV:adbk-query XML Element . . . . . . . . . . . . . . 41 10.6. CARDDAV:adbk-data XML Element . . . . . . . . . . . . . . 42 10.6.1. CARDDAV:allprop XML Element . . . . . . . . . . . . . 43 10.6.2. CARDDAV:prop XML Element . . . . . . . . . . . . . . . 43 10.7. CARDDAV:filter XML Element . . . . . . . . . . . . . . . . 44 10.7.1. CARDDAV:prop-filter XML Element . . . . . . . . . . . 44 10.7.2. CARDDAV:param-filter XML Element . . . . . . . . . . . 45 10.7.3. CARDDAV:is-not-defined XML Element . . . . . . . . . . 46 10.7.4. CARDDAV:text-match XML Element . . . . . . . . . . . . 46 10.8. CARDDAV:adbk-multiget XML Element . . . . . . . . . . . . 47 10.9. CARDDAV:adbk-sync XML Element . . . . . . . . . . . . . . 47 10.9.1. CARDDAV:sync-token XML Element . . . . . . . . . . . . 47 11. Internationalization Considerations . . . . . . . . . . . . . 48 12. Security Considerations . . . . . . . . . . . . . . . . . . . 48 13. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 49 13.1. Namespace Registration . . . . . . . . . . . . . . . . . . 49 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 49 14.1. Normative References . . . . . . . . . . . . . . . . . . . 49 14.2. Informative References . . . . . . . . . . . . . . . . . . 50 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 50 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 51 Intellectual Property and Copyright Statements . . . . . . . . . . 52 Daboo Expires April 25, 2007 [Page 3] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 1. Introduction and Overview Address books are a key component of personal information management tools, such as email or calendaring and scheduling clients. To date several protocols have been used for remote access to address data, including LDAP [RFC2251], IMSP and ACAP [RFC2244]. 1.1. IMSP IMSP, which was the predecessor to ACAP [RFC2244], received limited support from vendors, but those that did implement solutions based on it, found it to be a useful feature for large deployments of email clients at sites where users may roam from machine to machine. IMSP provided for multiple personal, shared or public address books, organized in a hierarchy, and gave individual users the ability to control access to their address books so that they could grant read or write access rights to other specific users or groups. This provided an easy and convenient way for users or workgroups to quickly setup and manage shared address information. Address book support in IMSP suffers from a number of problems, including a limited format for the address data itself, and scalability issues with large address books. The key features of address book support in IMSP are: 1. Ability to use multiple address books with hierarchical layout. 2. Ability to control access to individual address books. 3. 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. 4. Ability to download/upload an individual address in an address book. The key disadvantages of address book support in IMSP are: 1. Limited schema for address data. 2. Does not scale to large address books (e.g. no way to page through the list of addresses in an address book). 3. Does not provide any type of synchronization capability, which easily leads to 'lost update' problems when multiple users are editing the same address book entries. Daboo Expires April 25, 2007 [Page 4] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 4. Lack of internationalization support. 5. Does not provide per-address access control 6. Does not provide a simple way to lookup users on the system. 1.2. ACAP ACAP [RFC2244] was meant as the successor to IMSP and as such was designed to be a more 'generic' data access protocol for general application use. ACAP defined specific 'datasets' (basically formal schema definitions) for different anticipated areas of use, including address books, email accounts, application preferences, mime types etc. The use of such formal schema definitions was intended to enhance interoperability between clients. However, ACAP proved difficult to implement due to over complexity in the protocol itself, and this lead to few implementations. The key features of address book support in ACAP are: 1. Ability to use multiple address books with hierarchical layout. 2. Ability to control access to individual address books and address entries. 3. 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. 4. Ability to inherit address book data from others. 5. Ability to watch changes in address book data through use of 'contexts'. 6. Ability to page through address book data through use of 'contexts'. 7. Internationalization support through use of UTF-8 for all data. 8. Well defined address schema to enhance client interoperability. 9. Compatibility with vCard data format. 10. Users and groups dataset can be used to enumerate and find other users on the system. The key disadvantages of address book support in ACAP are: Daboo Expires April 25, 2007 [Page 5] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 1. Inheritance, access control and contexts all together is hard, and ultimately proved one of the major hurdles to implementations. 1.3. LDAP LDAP [RFC2251] is a generic directory access protocol that is specifically targeted at management applications and browser applications that provide read/write interactive access to directories. Often such directories contain information about people, including contact/address data. The key features of address book support in LDAP are: 1. To do The key disadvantages of address book support in LDAP are: 1. Lack of schemas require overly complex client configuration to map expected fields in the client to directory entries in the server. 2. General reluctance to give 'ordinary' users write access to even a small portion of the directory as often sensitive information is included in directory entries and a small mistake in configuring access control can lead to a major security breach. 1.4. WebDAV for Address Books WebDAV [RFC2518] 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. Daboo Expires April 25, 2007 [Page 6] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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. 2. Stateless nature of protocol can result in more data being sent with each transaction to maintain per-user session across requests. 1.5. vCard 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. 2. Conventions 2.1. Notational Conventions The augmented BNF used by this document to describe protocol elements is described in Section 2.1 of [RFC2616]. Because this augmented BNF uses the basic production rules provided in Section 2.2 of [RFC2616], those rules apply to this document as well. 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 1.4.2 of [RFC3253]. 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. Daboo Expires April 25, 2007 [Page 7] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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 [RFC2518] which use the "DAV:" namespace. Wherever such XML elements appear, they are explicitly prefixed with "DAV:" to avoid confusion. 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 [RFC2518], in particular Section 14, and Appendix 3 of that specification. 2.3. Method Preconditions and Postconditions A "precondition" of a method describes the state of the server that must be true for that method to be performed. A "postcondition" of a method describes the state of the server that must be true after that method has been completed. If a method precondition or postcondition for a request is not satisfied, the response status of the request MUST be either 403 (Forbidden) if the request should not be repeated because it will always fail, or 409 (Conflict) if it is expected that the user might be able to resolve the conflict and resubmit the request. In order to allow better client handling of 403 and 409 responses, a distinct XML element type is associated with each method precondition and postcondition of a request. When a particular precondition is not satisfied or a particular postcondition cannot be achieved, the appropriate XML element MUST be returned as the child of a top-level DAV:error element in the response body, unless otherwise negotiated by the request. In a 207 Multi-Status response, the DAV:error element would appear in the appropriate DAV:responsedescription Daboo Expires April 25, 2007 [Page 8] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 element. 3. Requirements Overview This section lists what functionality is required of a CardDAV server. To advertise support for the 'adbk-access' features of CardDAV, a server: o MUST support WebDAV Class 1 [RFC2518] (note that [I-D.ietf-webdav-rfc2518bis] describes clarifications to [RFC2518] that aid interoperability); o MUST support WebDAV ACLs [RFC3744]. o MUST support transport over TLS [RFC2246] as defined in [RFC2818] (note that [RFC2246] has been obsoleted by [RFC4346]); o MUST support strong ETags to support disconnected operations. o MUST support address book REPORTs as described in this document. o MUST support the MKADBK method. To advertise support for the 'adbk-sync' features of CardDAV, a server: o MUST support the 'adbk-access' features described above. o MUST support the 'adbk-sync' REPORT on address book collections. 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 vCard objects as their direct child resources. Each resource representing a vCard object is called a "vCard object resource". Each vCard 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. Daboo Expires April 25, 2007 [Page 9] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 4.1. Address Book Server A CardDAV server is a vCard-aware engine combined with a WebDAV repository. A WebDAV repository is a set of WebDAV collections, containing other WebDAV resources, within a unified URL namespace. For example, the repository "http://example.org/webdav/" may contain WebDAV collections and resources, all of which have URLs beginning with "http://example.org/webdav/". Note that the root URL "http://example.org/" may not itself be a WebDAV repository (for example, if the WebDAV support is implemented through a servlet or other Web server extension). A WebDAV repository MAY include address book data in some parts of its URL namespace, and non-address book data in other parts. A WebDAV repository can advertise itself as a CardDAV server if it supports the functionality defined in this specification at any point within the root of the repository. That might mean that vCard data is spread throughout the repository and mixed with non-vCard data in nearby collections (e.g. vCard data may be found in /lisa/ addressbook/ as well as in /bernard/addressbook/, and non-vCard data in /lisa/calendars/). Or, it might mean that vCard 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 vCard objects. So a repository confining vCard data to the /carddav/ collection would only need to support the CardDAV required features within that collection. The CardDAV server or repository is the canonical location for vCard data and state information. Clients may submit requests to change data or download data. Clients may store vCard objects offline and attempt to synchronize at a later time. However, clients MUST be prepared for vCard 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. vCard Object Resources vCard 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. Daboo Expires April 25, 2007 [Page 10] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 5.2. Address Book Collection CardDAV defines the following new resource type for use in WebDAV repositories holding vCard data. 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:adbk XML elements in the value of the DAV:resourcetype property. The element type declaration for CARDDAV:adbk is: 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 MKADBK method (see Section 6.3.1). This method can be useful for 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:adbk-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 vCard 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 vCard object resources. This ensures that address book clients do not have to deal with non-vCard data in an address book collection, though they do have to distinguish between vCard 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 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 vCard object resources contained in the address book collection. Multiple address book collections MAY be children of the same Daboo Expires April 25, 2007 [Page 11] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 collection. 6. Address Book Feature 6.1. Address Book Support If the server supports the CardDAV features described in this document, it MUST include "adbk-access" 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 "adbk- access" in the DAV header MUST indicate that the server supports all MUST level requirements and REQUIRED features specified in this document, with the exception of the CARDDAV:adbk-sync REPORT. CardDAV includes a special report to allow better client/server synchronization performance. Support for this feature is OPTIONAL, though RECOMMENDED. If a server supports this feature then it MUST include "adbk-sync" as a field in the DAV response header from an OPTIONS request on any address book collection resource that supports the report. 6.1.1. Example: Using OPTIONS for the Discovery of Support for CardDAV >> Request << OPTIONS /addressbooks/users/ HTTP/1.1 Host: adbk.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 Allow: MKADBK, ACL DAV: 1, 2, access-control, adbk-access 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 MKADBK method is available, and as a possible target for REPORT requests for address book reports. Daboo Expires April 25, 2007 [Page 12] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 6.2. Address Book Properties 6.2.1. CARDDAV:adbk-description Property Name: adbk-description Namespace: urn:ietf:params:xml:ns:carddav Purpose: Provides a human-readable description of the address book collection. Conformance: This property MAY be defined on any address book collection. If defined, it MAY be protected and SHOULD NOT be returned by a PROPFIND DAV:allprop request (as defined in Section 12.14.1 of [RFC2518]). An xml:lang attribute indicating the human language of the description SHOULD be set for this property by clients or through server provisioning. Servers MUST return any xml:lang attribute if set for the property. Description: If present, the property contains a description of the address book collection that is suitable for presentation to a user. If not present, the client should assume no description for the address book collection. PCDATA value: string Address de Oliver Daboo 6.2.2. CARDDAV:supported-adbk-data Property Name: supported-adbk-data Namespace: urn:ietf:params:xml:ns:carddav Purpose: Specifies what media types are allowed for address book object resources in an address book collection. Conformance: This property MAY be defined on any address book collection. If defined, it MUST be protected and SHOULD NOT be returned by a PROPFIND DAV:allprop request (as defined in Section 12.14.1 of [RFC2518] ). Daboo Expires April 25, 2007 [Page 13] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Description: The CARDDAV:supported-adbk-data property is used to specify the media type supported for the address (vCard) object resources contained in a given address book collection (e.g., vCard version 3.0). Any attempt by the client to store vCard object resources with a media type not listed in this property MUST result in an error, with the CARDDAV:supported-adbk-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: Example: 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 a vCard object resource is stored in an address book collection. Conformance: This property MAY be defined on any address book collection. If defined, it MUST be protected and SHOULD NOT be returned by a PROPFIND DAV:allprop request (as defined in Section 12.14.1 of [RFC2518] ). 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 a vCard 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 Daboo Expires April 25, 2007 [Page 14] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 reasonable size. Definition: PCDATA value: a numeric value (positive integer) Example: 102400 6.3. Creating Resources The creation of address book collections and vCard object resources may be initiated by either a CardDAV client or by the CardDAV server. For example, a server might come pre-configured with a user's address book collection, or the CardDAV client might request the server to create a new address book collection for a given user. Servers might populate vCard objects inside an address book collection, or clients might request the server to create vCards. Either way, both client and server MUST comply with the requirements in this document, and MUST understand objects appearing in address book collections or according to the data model defined here. 6.3.1. MKADBK Method An HTTP request using the MKADBK method creates a new address book collection resource. A server MAY restrict address book collection creation to particular collections. 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 MKADBK request, or alternatively issue a PROPPATCH request to change the DAV:displayname property to the appropriate value immediately after using the MKADBK 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 empty, 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 Daboo Expires April 25, 2007 [Page 15] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 human-readable text. If a MKADBK request fails, the server state preceding the request MUST be restored. Marshalling: If a request body is included, it MUST be a CARDDAV:mkadbk XML element. Instruction processing MUST occur in the order instructions are received (i.e., from top to bottom). Instructions MUST either all be executed or none executed. Thus if any error occurs during processing all executed instructions MUST be undone and a proper error result returned. Instruction processing details can be found in the definition of the DAV:set instruction in section 12.13 of [RFC2518]. If a response body for a successful request is included, it MUST be a CARDDAV:mkadbk-response XML element. The response MUST include a Cache-Control:no-cache header. Preconditions: (DAV:resource-must-be-null): A resource MUST NOT exist at the Request-URI. (CARDDAV:adbk-collection-location-bad): The Request-URI MUST identify a location where an address book collection can be created. (DAV:needs-privilege): The DAV:bind privilege MUST be granted to the current user. Postconditions: (CARDDAV:initialize-adbk-collection): A new address book collection exists at the Request-URI. The DAV:resourcetype of the address book collection MUST contain both DAV:collection and CARDDAV:adbk XML elements. Daboo Expires April 25, 2007 [Page 16] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 6.3.1.1. Status Codes The following are examples of response codes one would expect to get in a response to a MKADBK request. Note that this list is by no means exhaustive. 201 (Created) - The address book collection resource was created in its entirety. 207 (Multi-Status) - The address book collection resource was not created since one or more DAV:set instructions specified in the request body could not be processed successfully. The following are examples of response codes one would expect to be used in a 207 (Multi-Status) response: 403 (Forbidden) - The client, for reasons the server chooses not to specify, cannot alter one of the properties. 409 (Conflict) - The client has provided a value whose semantics are not appropriate for the property. This includes trying to set read-only properties. 424 (Failed Dependency) - The DAV:set instruction on the specified resource would have succeeded if it were not for the failure of another DAV:set instruction specified in the request body. 423 (Locked) - The specified resource is locked and the client either is not a lock owner or the lock type requires a lock token to be submitted and the client did not submit it. 507 (Insufficient Storage) - The server did not have sufficient space to record the property. 403 (Forbidden) - This indicates at least one of two conditions: 1) the server does not allow the creation of address book collections at the given location in its namespace, or 2) the parent collection of the Request-URI exists but cannot accept members. 405 (Method Not Allowed) - MKADBK can only be executed on a null resource. 409 (Conflict) - A collection cannot be made at the Request-URI until one or more intermediate collections have been created. 415 (Unsupported Media Type) - The server does not support the request type of the body. Daboo Expires April 25, 2007 [Page 17] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 507 (Insufficient Storage) - The resource does not have sufficient space to record the state of the resource after the execution of this method. 6.3.1.2. Example - Successful MKADBK request This example creates an address book collection called /home/lisa/ addressbook/ on the server adbk.example.com with specific values for the properties DAV:displayname and CARDDAV:adbk-description. >> Request << MKADBK /home/lisa/addressbook/ HTTP/1.1 Host: adbk.example.com Content-Type: text/xml; charset="utf-8" Content-Length: xxx Lisa's Address Book My primary address book. >> Response << HTTP/1.1 201 Created Date: Fri, 22 Oct 2004 12:17:08 GMT Content-Length: 0 Cache-Control: no-cache 6.3.2. Creating vCard Object Resources Clients populate address book collections with vCard object resources. The URL for each vCard object resource is entirely arbitrary, and does not need to bear a specific relationship (but might) to the vCard object resource's vCard properties or other metadata. New vCard 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 vCard object resource. Daboo Expires April 25, 2007 [Page 18] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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 vCard 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. >> Request << PUT /lisa/addressbook/newvcard.vcf HTTP/1.1 If-None-Match: * Host: adbk.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@daboo.name NICKNAME:me NOTE:Example VCard. ORG:Self Employed TEL;TYPE=WORK,VOICE:412 605 0499 TEL;TYPE=FAX:412 605 0705 URL:http://www.daboo.name 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 vCard 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 Daboo Expires April 25, 2007 [Page 19] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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: When a PUT operation of a vCard object resource into an address book collection occurs. When a COPY or MOVE operation of a vCard object resource into an address book collection occurs. The new preconditions are: (CARDDAV:supported-adbk-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 vCard object resources; (CARDDAV:valid-adbk-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 vCard 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; (CARDDAV:adbk-collection-location-ok): In a COPY or MOVE request, when the Request-URI is an address book collection, the Destination-URI 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; Daboo Expires April 25, 2007 [Page 20] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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 Property This section defines an additional property for WebDAV principal resources as defined in [RFC3744]. 7.1.1. CARDDAV:adbk-home-set Property Name: adbk-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. Conformance: This property SHOULD be defined on a principal resource. If defined, it MAY be protected and SHOULD NOT be returned by a PROPFIND DAV:allprop request (as defined in Section 12.14.1 of [RFC2518]). Description: The CARDDAV:adbk-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: Example: http://adbk.example.com/bernard/addressbooks/ Daboo Expires April 25, 2007 [Page 21] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 8. Address Book Reports This section defines the reports that CardDAV servers MUST support on address book collections and vCard object resources. CardDAV servers MUST advertise support for these REPORTs on all address book collections and vCard 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 vCard 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 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 adbk-access 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 vCard object resources. In computing responses to the REPORTs on ordinary collections, servers MUST only consider vCard 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 vCard 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. Daboo Expires April 25, 2007 [Page 22] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 To deal with this, this specification makes use of the IANA Collation Registry defined in [I-D.newman-i18n-comparator] to specify collations that may be used to carry out the text comparison operations with a well-defined rule. The comparisons used in CardDAV are all "substring" matches as per [I-D.newman-i18n-comparator] Section 4.2. Collations supported by the server MUST support "substring" match operations. CardDAV servers are REQUIRED to support the "i;ascii-casemap" and "i;octet" collations as described in [I-D.newman-i18n-comparator], 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. Clients MUST only use collations from the list advertised by the server. In the absence of a collation explicitly specified by the client, or if the client specifies the "default" collation identifier (as defined in [I-D.newman-i18n-comparator] Section 3.1), the server MUST default to using "i;ascii-casemap" as the collation. Wildcards (as defined in [I-D.newman-i18n-comparator] 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. Conformance: This property MUST be defined on any resource that supports a REPORT that does text matching. If defined, it MUST be protected and SHOULD NOT be returned by a PROPFIND DAV:allprop request (as defined in Section 12.14.1 of [RFC2518]). Daboo Expires April 25, 2007 [Page 23] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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: Example: i;ascii-casemap i;octet 8.4. Partial Retrieval Some address book REPORTs defined in this document allow partial retrieval of vCard 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 vCard data to be returned and whether all vCard properties should be returned or only particular ones. See CARDDAV:abbk-data in Section 10.6. 8.5. Non-standard properties and parameters Servers MUST support the use of non-standard property or parameter names in the CARDDAV:adbk-data XML element in address book REPORT requests to allow clients to request that non-standard properties and parameters be returned in the vCard 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. Daboo Expires April 25, 2007 [Page 24] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 8.6. CARDDAV:adbk-query Report The CARDDAV:adbk-query REPORT performs a search for all vCard object resources that match a specified filter. The response of this REPORT will contain all the WebDAV properties and vCard object resource data specified in the request. In the case of the CARDDAV:adbk-data XML element, one can explicitly specify the vCard properties that should be returned in the vCard 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:adbk-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 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:adbk-query REPORT is REQUIRED. Marshalling: The request body MUST be a CARDDAV:adbk-query XML element as defined in Section 10.5. 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:adbk-query REPORT request MUST contain a DAV:response element for each vCard object that matched the search filter. vCard data is being returned in the CARDDAV:adbk-data XML element inside the DAV:propstat XML element. Preconditions: (CARDDAV:supported-adbk-data): The attributes "content-type" and "version" of the CARDDAV:adbk-data XML element (see Section 10.6) specify a media type supported by the server for vCard object Daboo Expires April 25, 2007 [Page 25] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 resources. (CARDDAV:supported-filter): The CARDDAV:prop-filter (see Section 10.7.1) and CARDDAV:param-filter (see Section 10.7.2) XML elements used in the CARDDAV:filter XML element (see Section 10.7) 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. (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 vCard 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. Example: Partial retrieval of vCards matching a NICKNAME In this example, the client requests the server to search for vCard 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. Daboo Expires April 25, 2007 [Page 26] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 >> Request << REPORT /home/bernard/addressbook/ HTTP/1.1 Host: adbk.example.com Depth: 1 Content-Type: text/xml; charset="utf-8" Content-Length: xxxx me Daboo Expires April 25, 2007 [Page 27] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 >> Response << HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx http://adbk.example.com/home/bernard/addressbook/v102.vcf "23ba4d-ff11fb" BEGIN:VCARD VERSION:3.0 NICKNAME:me UID:34222-232@example.com FN:Cyrus Daboo EMAIL:daboo@example.com END:VCARD HTTP/1.1 200 OK 8.6.2. Example: Partial retrieval of vCards matching a full name In this example, the client requests the server to search for vCard object resources that contain a FN property whose value contains 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. Daboo Expires April 25, 2007 [Page 28] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 >> Request << REPORT /home/bernard/addressbook/ HTTP/1.1 Host: adbk.example.com Depth: 1 Content-Type: text/xml; charset="utf-8" Content-Length: xxxx Daboo Daboo Expires April 25, 2007 [Page 29] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 >> Response << HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx http://adbk.example.com/home/bernard/addressbook/v102.vcf "23ba4d-ff11fb" BEGIN:VCARD VERSION:3.0 NICKNAME:me UID:34222-232@example.com FN:Cyrus Daboo EMAIL:daboo@example.com END:VCARD HTTP/1.1 200 OK http://adbk.example.com/home/bernard/addressbook/v104.vcf "23ba4d-ff11fc" BEGIN:VCARD VERSION:3.0 NICKNAME:oliver UID:34222-23222@example.com FN:Oliver Daboo EMAIL:oliver@example.com END:VCARD HTTP/1.1 200 OK Daboo Expires April 25, 2007 [Page 30] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 8.7. CARDDAV:adbk-multiget Report The CARDDAV:adbk-multiget REPORT is used to retrieve specific vCard object resources from within a collection, if the Request-URI is a collection, or to retrieve a specific vCard object resource, if the Request-URI is a vCard object resource. This report is similar to the CARDDAV:adbk-query REPORT (see Section 8.6), except that it takes a list of DAV:href elements instead of a CARDDAV:filter element to determine which vCard object resources to return. Support for the adbk-multiget REPORT is REQUIRED. Marshalling: The request body MUST be a CARDDAV:adbk-multiget XML element (see Section 10.8, which MUST contain at least one DAV:href XML element, and one optional CARDDAV:adbk-data element as defined in Section 10.6. 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:adbk-multiget REPORT request MUST contain a DAV:response element for each vCard object resource referenced by the provided set of DAV:href elements. vCard data is being returned in the CARDDAV:adbk-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-adbk-data): The attributes "content-type" and "version" of the CARDDAV:adbk-data XML elements (see Section 10.6 ) specify a media type supported by the server for vCard object resources. Postconditions: Daboo Expires April 25, 2007 [Page 31] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 None. 8.7.1. Example: CARDDAV:adbk-multiget Report In this example, the client requests the server to return specific properties of the vCards 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://adbk.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: adbk.example.com Content-Type: text/xml; charset="utf-8" Content-Length: xxxx http://adbk.example.com/home/bernard/addressbook/vcf102.vcf http://adbk.example.com/home/bernard/addressbook/vcf1.vcf Daboo Expires April 25, 2007 [Page 32] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 >> Response << HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx http://adbk.example.com/home/bernard/addressbook/vcf102.vcf "23ba4d-ff11fb" BEGIN:VCARD VERSION:3.0 NICKNAME:me UID:34222-232@example.com FN:Cyrus Daboo EMAIL:daboo@example.com END:VCARD HTTP/1.1 200 OK http://adbk.example.com/home/bernard/addressbook/vcf1.vcf HTTP/1.1 404 Resource not found 8.8. CARDDAV:adbk-sync Report Support for this report is OPTIONAL but RECOMMENDED. The CARDDAV:adbk-sync REPORT is used to provide an overview of what has changed on the server since a previous execution of this report. The primary purpose of this is to aid the client in synchronizing its local cache of data with the server, in an efficient manner with as few round trips as possible. Support for the adbk-sync REPORT is OPTIONAL. If this report is implemented by the CardDAV server, then the server MUST include Daboo Expires April 25, 2007 [Page 33] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 "adbk-sync" in any DAV: response header to an OPTIONS request as per Section 6.1 . If the report is not available, clients MUST NOT attempt to execute one. To implement the behaviour for this report a server needs to keep track of changes to vCard data in an address book collection. This includes noting the addition of new vCards, noting changes to vCards and noting removal of vCards (where "removal" could be the result of a DELETE or MOVE operation). The server will track each change and provide a synchronization "token" to the client that describes the state of the server at a specific point in time. This "token" is returned as part of the response to the "adbk-sync" report. Clients include the last token they got from the server in the next "adbk- sync" report that they execute and the server provides the changes from the previous state represented by the token to the current state, represented by the new token returned. The synchronization token itself is an "opaque" string - i.e., the actual string data has no specific meaning or syntax. A simple implementation of such a token would be a numeric counter that counts each change as it occurs and relates that change to the specific object that changed. The "adbk-sync" reports allows the client to specify whether it should receive vCard data for those objects that are new or have changed, and it uses the "adbk-data" element (also used in the "adbk- query" and "adbk-multiget" reports) for that purpose. Marshalling: The request URI MUST be an address book collection. The "Depth" header MUST be ignored by the server and SHOULD NOT be sent by the client. The request body MUST be a CARDDAV:adbk-sync XML element (see Section 10.9 , which MUST contain one CARDDAV:sync-token XML element, and one optional CARDDAV:adbk-data element as defined in Section 10.6 . The response body for a successful request MUST be a DAV: multistatus XML element, which MUST contain one CADRDDAV:sync- token element in addition to any DAV:response elements. The response body for a successful CARDDAV:adbk-multiget REPORT request MUST contain a DAV:response element for each vCard object resource that was created, has changed or been deleted since the last syncrhonization operation as specified by the CARDDAV:sync- token provided in the request. vCard data is returned in the CARDDAV:adbk-data element inside the DAV:prop element. Daboo Expires April 25, 2007 [Page 34] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 The DAV:status element in each DAV:response element is used to indicate how the vCard resource may have changed: A status code of '201 Created' is used to indicate vCards that are new. A status code of '200 OK' is used to indicate vCards that have changed. A status code of '404 Not Found' is used to indicate vCards that have been removed. If the synchronization token element is not empty and not recognized by the server, then the server MUST respond with 400 Bad Request response. Preconditions: None. Postconditions: None. 8.8.1. Example: Initial CARDDAV:adbk-sync Report In this example, the client is making its first synchronization request to the server, so the CARDDAV:sync-token element in the request is empty. The server responds with the items currently in the targetted address book collection (indicating that they are 'new' via the '201 Created' status code). The current synchronzation token is also returned. >> Request << REPORT /home/bernard/addressbook/ HTTP/1.1 Host: adbk.example.com Content-Type: text/xml; charset="utf-8" Content-Length: xxxx Daboo Expires April 25, 2007 [Page 35] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 >> Response << HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx http://adbk.example.com/home/bernard/addressbook/vcf100.vcf HTTP/1.1 201 Created http://adbk.example.com/home/bernard/addressbook/vcf105.vcf HTTP/1.1 201 Created http://adbk.example.com/home/bernard/addressbook/vcf106.vcf HTTP/1.1 201 Created 1234 8.8.2. Example: CARDDAV:adbk-sync Report with token In this example, the client is making a synchronization request to the server and is using the CARDDAV:sync-token element returned from the last report it ran on this address book collection. The server responds listing the items that have been added, changed or removed. The (new) current synchronzation token is also returned. Daboo Expires April 25, 2007 [Page 36] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 >> Request << REPORT /home/bernard/addressbook/ HTTP/1.1 Host: adbk.example.com Content-Type: text/xml; charset="utf-8" Content-Length: xxxx 1234 >> Response << HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx http://adbk.example.com/home/bernard/addressbook/vcf107.vcf HTTP/1.1 201 Created http://adbk.example.com/home/bernard/addressbook/vcf100.vcf HTTP/1.1 200 OK http://adbk.example.com/home/bernard/addressbook/vcf105.vcf HTTP/1.1 404 Not Found 1238 Daboo Expires April 25, 2007 [Page 37] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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:adbk-data XML element in the relevant reports. 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 a vCard while the user is editing the vCard data, and unlock the vCard 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 vCard 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 Daboo Expires April 25, 2007 [Page 38] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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 vCard 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. 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: adbk-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:adbk-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: 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: Daboo Expires April 25, 2007 [Page 39] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Laurie The server performs a case-sensitive or caseless search for a matching string subset of "Laurie" within the DAV:displayname 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:adbk XML Element Name: adbk Namespace: urn:ietf:params:xml:ns:carddav Purpose: Specifies the resource type of an address book collection. Description: See Section 5.2. Definition: 10.2. CARDDAV:mkadbk XML Element Name: mkadbk Namespace: urn:ietf:params:xml:ns:carddav Purpose: Specifies a request that includes the WebDAV property values to be set for an address book collection resource when it is created. Daboo Expires April 25, 2007 [Page 40] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Description: See Section 6.3.1 . Definition: 10.3. CARDDAV:mkadbk-response XML Element Name: mkadbk-response Namespace: urn:ietf:params:xml:ns:carddav Purpose: Specifies a response body for a successful MKADBK request. Description: See Section 6.3.1 . Definition: 10.4. 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 [I-D.newman-i18n-comparator]. Description: The CARDDAV:supported-collation contains the text of a collation identifier as described in Section 8.3.1. Definition: PCDATA value: collation identifier 10.5. CARDDAV:adbk-query XML Element Name: adbk-query Namespace: urn:ietf:params:xml:ns:carddav Purpose: Defines a report for querying address book data Daboo Expires April 25, 2007 [Page 41] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Description: See Section 8.6. Definition: 10.6. CARDDAV:adbk-data XML Element Name: adbk-data Namespace: urn:ietf:params:xml:ns:carddav Purpose: Used to (1) specify a supported media type for vCard object resources when nested in the CARDDAV:supported-adbk-data property; (2) specify which parts of a vCard object resource should be returned by a given address book REPORT; and (3) specify the content of a vCard object resource in a response to an address book REPORT. Description: When nested in the CARDDAV:supported-adbk-data property, the CARDDAV:adbk-data XML element specifies a media type supported by the CardDAV server for vCard object resources. When used in an address book REPORT request, the CARDDAV:adbk-data XML element specifies which parts of vCard object resources need to be returned in the response. If the CARDDAV:adbk-data XML element doesn't contain any CARDDAV:prop elements, vCard object resources will be returned in their entirety. Finally, when used in an address book REPORT response, the CARDDAV:adbk-data XML element specifies the content of a vCard 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 vCard object resources specified in the CARDDAV:adbk-data XML element. Furthermore, vCard object resources specified in the CARDDAV:adbk- data XML element MAY be invalid per their media type specification if the CARDAV:adbk-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". Note: The CARDDAV:adbk-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:adbk-data XML element is not a WebDAV property and as such it is not returned in PROPFIND Daboo Expires April 25, 2007 [Page 42] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 responses nor used in PROPPATCH requests. Note: The vCard data embedded within the CARDDAV:adbk-data XML element MUST follow the standard XML character data encoding rules, including use of <, >, & etc entity encoding or the use of a construct. In the later case the vCard data cannot contain the character sequence "]]>" which is the end delimiter for the CDATA section. Definition: PCDATA value: vCard object version CDATA "3.0"> content-type value: a MIME media type version value: a version string 10.6.1. CARDDAV:allprop XML Element 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: 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. 10.6.2. CARDDAV:prop XML Element Name: prop Namespace: urn:ietf:params:xml:ns:carddav Daboo Expires April 25, 2007 [Page 43] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Purpose: Defines which properties to return in the response. Description: The "name" attribute specifies the name of the adbk 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. Definition: 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. 10.7. 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 vCard objects that should be returned by a report. Definition: 10.7.1. CARDDAV:prop-filter XML Element Name: prop-filter Namespace: urn:ietf:params:xml:ns:carddav Daboo Expires April 25, 2007 [Page 44] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Purpose: Limits the search to specific properties. Description: The CARDDAV:prop-filter XML element specifies a search criteria on a specific vCard property (e.g., NICKNAME). A vCard 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 the CARDDAV:text-match conditions if specified, and that any CARDDAV:param-filter child elements also match. or: * A property of the type specified by the "name" attribute does not exist, and the CARDAV:is-not-defined element is specified. Definition: name value: a vCard property name (e.g., "NICKNAME") 10.7.2. CARDDAV:param-filter XML Element Name: param-filter Namespace: urn:ietf:params:xml:ns:carddav 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. Daboo Expires April 25, 2007 [Page 45] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Definition: name value: a property parameter name (e.g., "TYPE") 10.7.3. 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 vCard data being tested. Definition: 10.7.4. CARDDAV:text-match XML Element Name: text-match 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;ascii-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 Daboo Expires April 25, 2007 [Page 46] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 PERSON. Definition: PCDATA value: string 10.8. CARDDAV:adbk-multiget XML Element Name: adbk-multiget Namespace: urn:ietf:params:xml:ns:carddav Purpose: CardDAV report used to retrieve specific vCard objects via their URIs. Description: See Section 8.7. Definition: 10.9. CARDDAV:adbk-sync XML Element Name: adbk-sync Namespace: urn:ietf:params:xml:ns:carddav Purpose: CardDAV report used to synchronize data between client and server. Description: See Section 8.8. Definition: 10.9.1. CARDDAV:sync-token XML Element Name: sync-token Daboo Expires April 25, 2007 [Page 47] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Namespace: urn:ietf:params:xml:ns:carddav Purpose: The synchronization token provided by the server and returned by the client. Description: See Section 8.8. Definition: 11. 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:adbk-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 10.7.4 ). 12. 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 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 webservers are often the target of automated indexing applications that gather data from the server, analyse it and extract 'interesting' parts, great care must be taken when allowing unauthenticated access to any address book or vCard object data. Clients MAY choose to warn users when they create vCard data in a public address book, copy or move vCard data into public address books, or change access privileges in such a way as to expose vCard Daboo Expires April 25, 2007 [Page 48] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 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. 13. IANA Consideration In addition to the namespaces defined by RFC2518 [RFC2518] 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 RFC2518 [RFC2518] also apply to this document. 13.1. 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. 14. References 14.1. Normative References [I-D.newman-i18n-comparator] Newman, C., "Internet Application Protocol Collation Registry", draft-newman-i18n-comparator-13 (work in progress), August 2006. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [RFC2426] Dawson, F. and T. Howes, "vCard MIME Directory Profile", RFC 2426, September 1998. [RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S., and D. Jensen, "HTTP Extensions for Distributed Authoring -- WEBDAV", RFC 2518, February 1999. Daboo Expires April 25, 2007 [Page 49] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 [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. [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 Distributed Authoring and Versioning (WebDAV) Access Control Protocol", RFC 3744, May 2004. [RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.1", RFC 4346, April 2006. [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 Recommendation REC-xml-20060816, August 2006, . 14.2. Informative References [I-D.ietf-webdav-rfc2518bis] Dusseault, L., "HTTP Extensions for Distributed Authoring - WebDAV", draft-ietf-webdav-rfc2518bis-15 (work in progress), May 2006. [RFC2244] Newman, C. and J. Myers, "ACAP -- Application Configuration Access Protocol", RFC 2244, November 1997. [RFC2251] Wahl, M., Howes, T., and S. Kille, "Lightweight Directory Access Protocol (v3)", RFC 2251, December 1997. Appendix A. Acknowledgments Thanks go to Lisa Dusseault and Bernard Desruisseaux for their work on CalDAV, on which CardDAV is heavily based. Daboo Expires April 25, 2007 [Page 50] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Author's Address Cyrus Daboo Apple Computer, Inc. 1 Infinite Loop Cupertino, CA 95014 USA Email: cyrus@daboo.name URI: http://www.apple.com/ Daboo Expires April 25, 2007 [Page 51] Internet-Draft vCard Extensions to WebDAV (CardDAV) October 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Daboo Expires April 25, 2007 [Page 52]