$Id: xrd-1.0.xml 214 2010年11月01日 12:25:27Z willnorris $ &document-id; &this-file;.xml &this-file;.html &this-file;.pdf &previous-file;.xml &previous-file;.html &previous-file;.pdf &latest-file;.xml &latest-file;.html &latest-file;.pdf OASIS Extensible Resource Identifier (XRI) TC PeterDavis NeuStar Inc. DrummondReed XDI.org EranHammer-Lahav WillNorris Google &pubdate; 2010 OASIS Open, Inc. All Rights Reserved. This specification replaces or supersedes: Extensible Resource Identifier (XRI) Resolution Version 2.0, Committee Specification 01, April 2008 This document defines XRD, a simple generic format for describing and discovering resources. This document was last revised or approved by the OASIS Membership on the above date. The level of approval is also listed above. Check the current location noted above for possible later revisions of this document. This document is updated periodically on no particular schedule. Technical Committee members should send comments on this specification to the Technical Committee's email list. Others should send comments to the Technical Committee by using the "Send A Comment" button on the Technical Committee's web page at . For information on whether any patents have been disclosed that may be essential to implementing this specification, and any offers of patent licensing terms, please refer to the Intellectual Property Rights section of the Technical Committee web page (). The non-normative errata page for this specification is located at . Copyright © OASIS Open 2010. All Rights Reserved. All capitalized terms in the following text have the meanings assigned to them in the OASIS Intellectual Property Rights Policy (the "OASIS IPR Policy"). The full Policy may be found at the OASIS website. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published, and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this section are included on all such copies and derivative works. However, this document itself may not be modified in any way, including by removing the copyright notice or references to OASIS, except as needed for the purpose of developing any document or deliverable produced by an OASIS Technical Committee (in which case the rules applicable to copyrights, as set forth in the OASIS IPR Policy, must be followed) or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by OASIS or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and OASIS DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. OASIS requests that any OASIS Party or any other party that believes it has patent claims that would necessarily be infringed by implementations of this OASIS Final Deliverable, to notify OASIS TC Administrator and provide an indication of its willingness to grant patent licenses to such patent claims in a manner consistent with the IPR Mode of the OASIS Technical Committee that produced this deliverable. OASIS invites any party to contact the OASIS TC Administrator if it is aware of a claim of ownership of any patent claims that would necessarily be infringed by implementations of this OASIS Final Deliverable by a patent holder that is not willing to provide a license to such patent claims in a manner consistent with the IPR Mode of the OASIS Technical Committee that produced this OASIS Final Deliverable. OASIS may include such claims on its website, but disclaims any obligation to do so. OASIS takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this OASIS Final Deliverable or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on OASIS' procedures with respect to rights in any document or deliverable produced by an OASIS Technical Committee can be found on the OASIS website. Copies of claims of rights made available for publication 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 OASIS Final Deliverable, can be obtained from the OASIS TC Administrator. OASIS makes no representation that any information or list of intellectual property rights will at any time be complete, or that any claims in such list are, in fact, Essential Claims. The names "OASIS" and "XRD" are trademarks of OASIS, the owner and developer of this specification, and should be used only to refer to the organization and its official outputs. OASIS welcomes reference to, and implementation and use of, specifications, while reserving the right to enforce its marks against misleading uses. Please see for above guidance.

This document defines XRD (Extensible Resource Descriptor), a simple generic format for describing resources. Resource descriptor documents provide machine-readable information about resources (resource metadata) for the purpose of promoting interoperability. They also assist in interacting with unknown resources that support known interfaces. For example, a web page about an upcoming meeting can provide in its descriptor document the location of the meeting organizer's free/busy information to potentially negotiate a different time. The descriptor for a social network profile page can identify the location of the user's address book as well as accounts on other sites. A web service implementing an API protocol can advertise which of the protocol's optional components are supported.

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 .

The XRD document structure is defined in a schema associated with the following XML namespace: http://docs.oasis-open.org/ns/xri/xrd-1.0 The schema for (the "xml:" namespace), which is associated with the following XML namespace, is imported into the XRD schema: http://www.w3.org/XML/1998/namespace The following fragment defines the XML namespaces and other header information for the XRD schema: Document identifier: xrd-schema-1.0 Location: http://docs.oasis-open.org/xri/xrd/v1.0/ ... ]]> The location of the normative XML Schema file for an XRD document as defined by this specification is: . The following URI will always reference the latest version of this file: &latest-file;.xsd.

All XRD string values have or extend the type xs:string, which is built in to the W3C specification. Unless otherwise noted in this specification or particular profiles, all strings in XRD documents must consist of at least one non-whitespace character (whitespace is defined in section 2.3 of ). The following schema fragment defines the xrd:string complex type, which extends xs:string to allow for arbitrary attributes (see ): ]]>

All XRD URI reference values have or extend the type xs:anyURI, which is built in to the W3C specification. Unless otherwise noted in this specification or particular profiles, all URIs in XRD documents must consist of at least one non-whitespace character (whitespace is defined in section 2.3 of ). The following schema fragment defines the xrd:anyURI complex type, which extends xs:anyURI to allow for arbitrary attributes (see ): ]]>

All XRD time values have the type xs:dateTime, which is built in to the W3C specification. Time values must be represented with the UTC designator 'Z'. XRD providers must not generate time instants that specify leap seconds.

XRD provides a simple and extensible XML format for describing a resource. An XRD document may describe the properties of the resource itself, as well as the relations the resource has with other resources. XRD builds directly on the typed link relations framework defined by , and used by , , and other protocols. An XRD document must (a) be a well-formed XML document as defined by with a root element of XRD, (b) validate against the normative XRD schema identified in , and (c) adhere to the additional syntactic constraints defined by and this section. The XRD schema defines only the elements necessary to support the most common use cases, with the explicit intention that applications will extend XRD as defined in to include other metadata about the resources and links they describe.

The XRD element encapsulates the entire resource descriptor. It contains the following attributes and elements: xml:id [Optional] This attribute, of type xs:ID, is defined by . It provides a unique identifier for this XRD, and is used as a signature reference. Expires [Zero or One] Specifies when this document expires. See . Subject [Zero or One] Provides the identifier of the resource described by this XRD. See . Alias [Zero or More] Provides an additional identifier for the resource described by this XRD. See . Property [Zero or More] Declares a property of the resource described by this XRD. See . Link [Zero or More] Identifies another resource which is related to the resource described by this XRD, and describes the semantics of that relation. See . ds:Signature [Zero or More] This XML Signature, included from the schema, protects the integrity of the document, as described in . Although allows a single document to contain multiple signatures, the signing profile described in requires only a single Signature element. Use of multiple Signature elements in an XRD document is therefore undefined. In order to aid certain types of XRD consumers, it is recommended that XRD providers place the Signature element of a signed XRD as near the beginning of the document as possible. The following schema fragment defines the XRD element and its XRDType complex type: ]]>

The Expires element contains a time value which specifies the instant at and after which the document has expired and should not be used. The value must be expressed in UTC form, as specified in , and must not use fractional seconds. The semantics of this element apply to the metadata available in the XRD document and are independent of the caching semantics of any transport protocol used to retrieve the document. If present, any cache expiration date specified by the transport protocol should not be later than the time instant indicated by the Expires element. The following schema fragment defines the Expires element and its ExpiresType complex type: ]]>

The Subject element contains a URI value which identifies the resource described by this XRD. This value must be an absolute URI. If Subject is not specified, it is expected that the resource described by the XRD will be identified by other means. Comparison of this value must be performed using the scheme-specific normalization rules for the URI, as specified in Section 6.2.3 of . The following schema fragment defines the Subject element: ]]>

The Alias element contains a URI value that is an additional identifier for the resource described by the XRD. This value must be an absolute URI. The Alias element does not identify additional resources the XRD is describing, but rather provides additional identifiers for the same resource. Comparison of this value must be performed using the scheme-specific normalization rules for the URI, as specified in Section 6.2.3 of . The following schema fragment defines the Alias element: ]]>

The Property element declares a property of a resource (when used as a child of the XRD element) or link relation (when used as a child of the Link element), expressed as a key-value pair. The key is identified by the type attribute, and the value expressed as the string content of the Property element. A property may have no value if the type identifier alone is sufficient. Property elements that contain no value must include the xsi:nil attribute with a value of true as defined in . Property has the following attributes: type [Required] The type attribute is a URI that identifies the property being declared. This value must be an absolute URI. This URI value is application-specific, and is used by the XRD provider to declare a property to consumers familiar with the type identifier. Comparison of this value must follow the same comparison rules used for comparing Link Relation Types as defined in . The following schema fragment defines the Property element and its PropertyType complex type: ]]>

The Link element serves as a container for metadata about a relation between the resource described by the XRD and a related resource. The semantics of this element are similar to the Link element, the Link element, and the HTTP Link Header. The one distinction is that the link relation described by the Link element is between the resource described by the XRD (referred to as the context resource by ) and the linked resource (referred to as the target resource by ), and not between the XRD document itself and the linked resource. The Link element contains the following attributes and elements: rel [Optional] This URI value defines the semantics of the relation between the resource described by the XRD and the linked resource. This value must be an absolute URI or a registered relation type, as defined in . Comparison of this value must follow the comparison rules for Link Relation Types defined in . With one exception, the rel attribute is semantically and syntactically equivalent to the Link Relation Types defined in . It differs in that it only allows for a single relation type and does not allow for multiple space delimited values. It is important to note that this value does not identify any property of the linked resource. Rather, it describes only how the linked resource is related to the resource described by the XRD. type [Optional] This string value identifies the media type of the linked resource, and must be of the form of a media type as defined in . The IANA media types registry can be found at . Comparison of this value must be done in accordance with . Note that this is only a hint and does not override the media type declared by the linked resource itself (e.g. the Content-Type header of a HTTP response obtained by following the link). href [Optional] The href attribute provides the URI of the linked resource. If no href attribute is defined, it is assumed the URI can be obtained from a template attribute or by application-specific means. A Link element may contain an href attribute or a template attribute, but must not contain both. template [Optional] The template attribute provides a URI template which can be used to obtain the URI of the linked resource. Templates provide a mechanism for URI construction, taking a list of variables as input, and producing a URI string as an output. The template syntax and vocabulary are determined by the application through which the XRD document is obtained and processed, and may be specific to the link relation type indicated by the rel attribute of the corresponding Link element. Applications utilizing the template mechanism must define the template syntax and processing rules (including error handling) as well as the variable vocabulary. A Link element may contain an href attribute or a template attribute, but must not contain both. Title [Zero or More] Provides a human-readable description of the linked resource. See . Property [Zero or More] Declares a property of this link relation, as described in . It is important to note that this value does not identify any property of the linked resource or the resource described by the XRD, but rather of the link relation between the linked resources. The following schema fragment defines the Link element and its LinkType complex type: ]]>

The Title element contains a string value that provides a human-readable description for the link. This value is intended only for human consumption and must not be used by an XRD consumer to affect the processing of the document. Title contains the following attributes: xml:lang [Optional] This attribute is defined by the specification, and is used to identify the natural language in which this element's content is written. The following schema fragment defines the Title element and its TitleType complex type: ]]>

The XRD schema defines only the elements necessary to support the most common use cases, with the explicit intention that applications will extend XRD to include other metadata about the resources they describe. XRD documents can be extended by providing custom, meaningful values for certain URI-based attributes and elements, as well as by extending the XML schema directly.

XRD uses URI-based identifiers for describing resources as well as for describing the relations between resources. Whenever possible, applications should use well-established URI identifiers for these purposes to promote interoperability and shared semantics. Only when absolutely necessary should new URI identifiers be defined. It is recommended that any new identifiers be defined in a formal specification of use. The meaning of a given URI used as such an identifier should not significantly change over time, and the identifier should not be used to mean two different things.

The XRD schema allows for the inclusion of attributes from arbitrary namespaces (except for the XRD namespace) in almost all XRD elements. Additionally, the XRD and Link elements allow for the inclusion of child elements from arbitrary namespaces (except for the XRD namespace). XML extensions must not require new interpretation of elements defined in this document. If an extension attribute or element is present, an XRD consumer must be able to ignore it and still correctly process the XRD document. This specification does not define generic rules for the comparison of string or URI values. Therefore, specifications that include XRD schema extensions must specify such comparison rules where necessary.

Link selection criteria is determined by the XRD consumer's needs, and should be based on the presence, absence, or value of the Link element attributes or child elements. The selection criteria is usually based on the value of the rel attribute with the value of the type attribute used as a hint (helping to determine if the linked resource uses a familiar media type). Selection based on multiple criteria should be handled by performing multiple selections. Each selection is assigned preference order based on the consumer's needs, and the selection results are compared to determine the most desired set. For example, an XRD consumer processing an XRD document describing an article may wish to select linked resources about the article's author. If that consumer prefers HTML documents over plain text, then the linked resource selection would occur in two steps. First, all links with the author relation type would be selected, and if more than one are found, then the most appropriate link would be selected based on its media type. If multiple Link elements are matched by a given selection criteria, they must be processed in the order in which they appear in the XRD document. Therefore, XRD providers may indicate element priority by placing them in a specific order. If the first Link is subsequently disqualified from the set of selected elements, the consumer should attempt to select the next matching element in document order. This process should be continued for all other matching Link elements until success is achieved or all elements are exhausted.

An XRD provider may digitally sign an XRD document in order to enable XRD consumers to verify the authenticity and integrity of the document. The specification defines a general XML syntax for signing data that includes many options for flexibility. This section details constraints on these options so that XRD consumers do not have to implement the full generality of XML Signature processing.

XRD documents must use enveloped signatures as defined by when signing. Any signature algorithm defined by may be used.

XRD documents must supply a value for the xml:id attribute on the root element of the XRD being signed. The XRD's root element may or may not be the root element of the actual XML document containing the signed XRD (e.g., it might be included within another document). Signatures must contain a single ds:Reference containing a same-document reference to the xml:id attribute value of the root element of the XRD being signed. For example, if the xml:id attribute value is foo, then the URI attribute in the ds:Reference element must be #foo.

XRD implementations must use without comments, both in the ds:CanonicalizationMethod element of ds:SignedInfo, and as a ds:Transform algorithm. Use of Exclusive Canonicalization facilitates the verification of signatures created over XRD instances when placed into a different XML context than present during signing. Note that use of this algorithm alone does not guarantee that a particular signed object can be moved from one context to another safely, nor is that a requirement of signed XRD instances in general, though it may be required by particular profiles.

Signatures in XRD documents must not contain transforms other than the enveloped signature transform (with the identifier http://www.w3.org/2000/09/xmldsig#enveloped-signature) or the exclusive canonicalization transform (with the identifier http://www.w3.org/2001/10/xml-exc-c14n#).

XML Signature defines usage of the ds:KeyInfo element. XRD does not require the use of ds:KeyInfo, nor does it impose any restrictions on its use. Therefore, ds:KeyInfo may be absent.

In cases where an application requires a sequence of XRD elements in a single XML document, this specification defines an alternate top-level element, XRDS. This element should contain either zero or more than one XRD elements. It has the following attributes and elements, and is not otherwise extensible: ref [Optional] This URI value identifies the resource described by the sequence of XRD elements. XRD [Zero or More] See . The following schema fragment defines the XRDS element and its XRDSType complex type: ]]>

An implementation is a conforming XRD Consumer if it meets the conditions in . An implementation is a conforming Signature-Capable XRD Consumer if it meets the conditions in . An implementation is a conforming XRD Provider if it meets the conditions in . An implementation is a conforming Signature-Capable XRD Provider if it meets the conditions in . An implementation may serve as both an XRD consumer and provider.

An implementation conforms to this specification as an XRD Consumer if it meets the following conditions: It must implement parsing of XRD documents as defined in . Support for XRDS documents, as defined in , is optional. It must conform to the processing rules as specified in .

An implementation conforms to this specification as a Signature-Capable XRD Consumer if it meets the following conditions: It must meet all conformance requirements of an XRD Consumer as defined by . It must support the verification of signed XRD documents as defined by , and must support the digital signature algorithm identified by http://www.w3.org/2000/09/xmldsig#rsa-sha256, as defined by .

An implementation conforms to this specification as an XRD Provider if it meets the following conditions: It must support the creation of XRD documents as defined in . Support for XRDS documents, as defined in , is optional.

An implementation conforms to this specification as a Signature-Capable XRD Provider if it meets the following conditions: It must meet all conformance requirements of an XRD Provider as defined by . It must support the creation of signed XRD documents as defined by , and must support the digital signature algorithm identified by http://www.w3.org/2000/09/xmldsig#rsa-sha256, as defined by .

The editors would like to thank the following current and former members of the OASIS XRI TC for their particular contributions to this and previous versions of this specification: Dirk Balfanz, Google Bill Barnhill, Booz Allen Hamilton John Bradley Scott Cantor, Internet2 Les Chasen, NeuStar Steven Churchill, XDI.org Brian Eaton, Google George Fletcher, AOL Victor Grey, Planetwork Joseph Holsten Nika Jones Breno de Medeiros, Google Bob Morgan, Internet2 Markus Sabadello, XDI.org Nat Sakimura, NRI Tatsuki Sakushima, NRI William Tan, NeuStar Gabe Wachob The editors would also like to acknowledge the contributions of the other members of the OASIS XRI Technical Committee, whose other voting members at the time of publication were: Giovanni Bartolomeo, University of Rome "Tor Vergata" Owen Davis, Planetwork Jeff Hodges Fen Labalme, Planetwork Ben Laurie, Google XiaoDong Lee, China Internet Network Information Center Nick Nicholas, Australian Department of Education Marty Schleiff, The Boeing Company Paul Trevithick 1970年01月01日T00:00:00Z http://example.com/gpburdell 1970年01月01日 ]]> Following is an example of a signed XRD document. The XML signature is valid, though the certificate is self-signed. 1970年01月01日T00:00:00Z http://example.com/gpburdell http://people.example.com/gpburdell acct:gpburdell@example.com 1.0 2.0 yi2N42KYR6b8dl6TCBKjs4duPuo= NGJ/tVRnK8O7FwTic3nQjrEw1do+SgWE/LKE/Q2bgE+k4b3Go6d9fLZq0/DX8nyr x0nYfpTgxzMUDVUVaDyvnp0MfnmTSJ/yL5bXAV2jW6+NWJH73DXjQoPKn0j1WY2G UoTdgnMiiNzKYY+QhWYogy4QXJOmjOF+6OE+uONKvQU= MIICsDCCAhmgAwIBAgIJAK6eiEXk2FoiMA0GCSqGSIb3DQEBBQUAMEUxCzAJBgNV BAYTAkFVMRMwEQYDVQQIEwpTb21lLVN0YXRlMSEwHwYDVQQKExhJbnRlcm5ldCBX aWRnaXRzIFB0eSBMdGQwHhcNMTAwNTA3MDQ1MDAzWhcNMzgwMTE5MDQ1MDAzWjBF MQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEhMB8GA1UEChMYSW50 ZXJuZXQgV2lkZ2l0cyBQdHkgTHRkMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB gQDVEftG6aMNrBRMu9hHaZUe4ZU5jrbtsaexNlh4OWnIOj9Tyyk2NfI9w1b2hp5f KQf5B9HYeZjowuYKVuc+NQMYgkN7V+YvcJ9ohAjCBZuo9Xcm5CiKeFnz5E6Ad0Fs BPnAHch9kZu2joz+iQOp6Av+A78Gvam9giG9ZT3rIj2LZQIDAQABo4GnMIGkMB0G A1UdDgQWBBR3yN91g2lEACpJ9WaKm3fM+PAPqTB1BgNVHSMEbjBsgBR3yN91g2lE ACpJ9WaKm3fM+PAPqaFJpEcwRTELMAkGA1UEBhMCQVUxEzARBgNVBAgTClNvbWUt U3RhdGUxITAfBgNVBAoTGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZIIJAK6eiEXk 2FoiMAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEFBQADgYEAc3cepBp8h2rwwc+f lFahLmJNVOePhw+uCyO8tLWu7Jcq9todVmeCNyqB9hGm2Rvt5yQ69tRpMxQ7Wmqs O6HbDYzW5APuCPHEtlXoafEq4oWZS8ICPNel68MX5mnXg+XkUOb8cjuY8CwRNtBf Ehs3jFzXUcMITIL1PmE7bb38Hug= ]]>