Title: Representing vCard v3.0 in RDF Author: Renato Iannella From: http://www.dstc.edu.au/RDU/RDF/draft-iannella-vcard-rdf-00.txt Date: 1999-01-19 --------------------------------------------------------------------------- Title: Representing vCard v3.0 in RDF Creator: Renato Iannella Date: 1999-01-14 1. Introduction This memo specifies a Resource Description Format (RDF) [RDF] encoding that corresponds to the vCard electronic business card profile defined by RFC 2425 [VCARD]. This specification provides equivalent functionality to the standard format defined by [VCARD]. RDF is an application of the eXtensible Markup Language [XML]. Documents structured in accordance with this RDF encoding may also be known as 'RDF vCard' documents. This specification is in no way intended to create a separate definition for the vCard schema. The sole purpose for this memo is to define an alternative RDF encoding for the format defined by [VCARD]. The RDF vCard does not introduce any capability not expressible in the format defined by [VCARD]. However, an attempt has been made to leverage the capabilities of the XML and RDF syntax to better articulate the original intent of the vCard authors. This memo attempts to be consistent with other XML-based vCard formats, such as the XML DTD [VCDTD]. 2. RDF vCard Namespace RDF uses the XML Namespace [NAMESPACE] to uniquely identify the metadata schema and version. For vCard, the following URI [URI] is defined to be vCard Namespace: http://imc.org/vCard/3.0# The explicit use of this XML Namespace in RDF means that there is no need to support the VCARD Profile and VERSION type. Examples used in this memo will use "vCard" as the XML Namespace prefix. 3. RDF vCard Specifications 3.1 Basic Properties The RDF vCard equally promotes all vCard types into RDF property types. Some of the vCard types, for example BEGIN, END, PROFILE, and VERSION, are not required to be expressed as these are implicitly provided by RDF. With RDF, statements are made about a resource. The resource in question is identified with a URI. This has similar semantics to the vCard UID type. Hence, RDF descriptions should use the vCard UID as the RDF "about" value when the UID is expressed as a machine-resolvable URI. The majority of the vCard property types have strings as their values (objects of statements) and are simply represented by their property type name and value as specified in the vCard specification [VCARD]. These include: FN NICKNAME BDAY MAILER GEO TITLE ROLE CATEGORIES NAME SOURCE NOTE PRODID REV SORT-STRING CLASS For example, the following shows sample RDF vCard encodings: Corky Crystal 1980-01-01 Computer Officer Class 3 Programmer There are special cases to be noted for the SOURCE and NAME property types. SOURCE maps to the RDF "about" URI and should be used to indicate the unique identifier for the person object. NAME is a human-displayable text about the vCard record itself (not the person). If NAME is required, then it should be represented as a Statement about Statements (see Section 4 of the RDF specification [RDF].) 3.2 Grouping and Ordering To have multiple values of a vCard property type, RDF provides three mechanisms; Bags, Sequences, and Alternatives. An RDF Bag is used when there are more than one value and the order is not important. For example: Programmer Fire Warden If order is important, then an RDF Sequence can be used. For example: Principal Research Scientist Visiting Professor An RDF Alternative is used when there is a choice of values available for a property, with each value being valid but dependent on some other externally defined factor. The first value is the default. For example, a vCard resource may have a number of aliases for their email address. In essence, these are all different representations of the same email addresses. This would be encoded as: corky@qqq.com info@qqq.com corky@hotmail.com The vCard also allows properties to be arbitrarily grouped. For RDF to support this, we need to define a new vCard property to capture this. We call this new vCard property "GROUP". For example, to group two NICKNAME and NOTE properties: Corky Porky Only used by close friends Princess Corky Only used by my Mother Note: The "rdf:parseType=Resource" indicates that the content should be treated as if it were the content of an element. Some of these grouping and ordering features are unique to RDF, so it is important to realise that the conversion from RDF to native vCard format may result in some lose of information. However, it should not be a critical lose of semantics. 3.3 Properties with Attributes A number of vCard properties include the ability to indicate one or more "type parameters" of a value. For example, to indicate that a Telephone number is a Fax number, or that a particular email address is the preferred value. To represent this in RDF, we utilise the property which allows us to specify the type of a resource by indicating a URI that represents this type. The URI will be: http://imc.org/vCard/3.0# where will be one of the officially defined vCard type parameters. Also, the property value must now be given by using the property. For example: +61 7 555 5555 Note: The "rdf:parseType=Resource" simply indicates properties within the two tags, should be considered as the entire value for the property. The vCard properties that have a type parameter are listed here with their possible values: vCard Property Type Parameter Values -------------- ----------------------------------------------- TEL home, msg, work, pref, voice, fax, cell, video, pager, bbs, modem, car, isdn, pcs EMAIL internet, x400, pref ADR dom, intl, postal, parcel, home, work, pref LABEL dom, intl, postal, parcel, home, work, pref TZ text In cases where the type parameter has been defined by an external body (ie: not defined by the vCard specification), we must use a "vCard:TYPE" attribute in the property since we have no control over the potential size of this list. For example, to indicate that the value for the UID property is of type "United States Social Security Number": 555-555-555-555 The vCard properties that have uncontrolled type parameters are listed here: vCard Property Type Parameter Values -------------- ----------------------------------------------- UID Any IANA registered or non-standard identifier formats LOGO Any IANA registered or non-standard image formats PHOTO Any IANA registered or non-standard image formats SOUND Any IANA registered or non-standard sound formats There are two special cases to be noted. 1 - The URL property can only have a valid URI as its value. RDF provides a short-hand mechanism to encode this with the "rdf:resource" attribute. For example: 2 - The LABEL property has a value that is formatted text which may include XML statements. To indicate that the value should not be interpreted, we use the "rdf:parseType" attribute set to "Literal". For example: Corky Crystal
QQQ.COM Pty Ltd
PO Box 555
Coolville, AUSTRALIA 3.4 Structured Properties A number of vCard properties defines sub-structure. For example, the N property has Family Name, Given Names, and Honorific. It is important to preserve and express this structure and it is fully-supported in the RDF model. For example: Crystal Corky Jacky Dr III The properties that have defined sub-structure are listed here with the names of the property types. vCard Property Substructure Name Property Type Name -------------- -------------------- ------------------ N Family Name Family Given Name Given Additional Names Other Honorific Prefixes Prefix Honorific Suffixes Suffix ADR Post Office Box Pobox Extended Address Extadd Street Address Street Locality Locality Region Region Postal Code Pcode Country Country ORG Organisation Name Orgname Organisation Unit Orgunit There are two special cases to be noted. 1 - Even though the LABEL property has the same substructure defined by N and ADR, we do not use them in specifying its value. This is because the value of LABEL is formatted text that is not intended to be interpreted. 2 - There is an implied ordering for Organisational Units (higher to lower). This can be supported by using the mechanism. An example is given in Section 5. 3.5 Binary Values A number of vCard properties allow for inline binary values (encoded in BASE64) or external references via a URI. These include: PHOTO LOGO SOUND KEY In the case of binary values, we can represent the property with a "vCard:ENCODING" attribute indicating the content value ("b"). For example: MSJD9s99DS(S@W99329(#9.... In the case of an external reference, RDF provides a convenient encoding with the "rdf:resource" construct. For example: 3.6 Agent Property The Agent property allows the specification or identification of another vCard resource. RDF allows for the Agent vCard resource to be inline with an existing vCard resource. For example: Corky Crystal Research Director John Mutton Personal Assistant john@qqq.com To refer to an external identification (via a URI) of the Agent resource, RDF supports encoding with the "rdf:resource" construct. For example: Corky Crystal Research Director 4. vCard Language To express the language encoding of vCard property values, XML provides a convenient "xml:lang" attribute. The values are defined in RFC 1766. For example: Corky Crystal Computer Officer Class 3 Programmer In cases where a single vCard property is expressed with multiple language values, the RDF Alternative construct should be used. For example: Programmer Programmeur Programmatore 5. Complete Examples It is important to note that since XML is case-sensitive, the property and attribute names used in this specification and the below examples, should be taken literally. The following is a complete example of an RDF encoded vCard: Corky Crystal Crystal Corky Jacky Dr 1980-01-01 Computer Officer Class 3 Programmer +61 7 555 5555 corky@qqq.com 111 Lake Drive WonderCity 5555 Australia The following is an example of an RDF vCard that includes a photo element as inline binary content. Corky Crystal Crystal Corky corky@qqq.com MIICajCCAdOgAwIBAgICBEUwDQEEBQAwdzELMAkGA1UEBhMCVVMxLDA qBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25z.....W992WW329 This example shows how an RDF vCard objects can be integrated with other metadata standards and encoded with RDF. In this example, the Dublin Core [DC] metadata standard is used. Annual Report 1998/1999 Corky Crystal Crystal Corky corky@qqq.com 1998-01-01 Company Report, Outcomes, Objectives QQQ.COM Pty Ltd Copyright 1999 The following is an example of an RDF vCard that includes structured Organisation information: Corky Crystal Crystal Corky corky@qqq.com QQQ.COM Pty Ltd
  • Commercialisation Directorate
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    • 5. Acknowledgments Thanks to Dave Beckett (Uni Kent), Roland Schwaenzl (Uni Osnabrueck), Ron Daniel (DATAFUSION), Eric Miller (OCLC), and Hoylen Sue (DSTC) for their valuable feedback and comments on drafts of this document. The work reported in this paper has been funded in part by the Cooperative Research Centres Program through the Department of the Prime Minister and Cabinet of Australia. 6. Security Considerations Security issues are not currently discussed in this memo. 7. Bibliography [DC] Dublin Core Metadata for Resource Discovery, Internet RFC 2413. [NAMESPACE] Namespaces in XML, World Wide Web Consortium, November 1998. [RDF] Resource Description Framework (RDF) Model and Syntax Specification World Wide Web Consortium, October 1998. [URI] Uniform Resource Identifiers (URI): Generic Syntax, Berners-Lee, Fielding, Masinter, Internet Draft Standard, August 1998. [VCARD] vCard MIME Directory Profile, F. Dawson and T. Howes, Internet RFC 2426, September 1998. , September 1998. [VCDTD] The vCard v3.0 XML DTD, F. Dawson and P. Hoffman, Internet Draft Standard, November 1998. [XML] Extensible Markup Language (XML) 1.0, World Wide Web Consortium, February 1998.