Network Working Group J. Reschke Internet-Draft greenbytes Expires: February 28, 2005 August 30, 2004 Datatypes for WebDAV properties draft-reschke-webdav-property-datatypes-07 Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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 February 28, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This specification extends the Web Distributed Authoring Protocol (WebDAV) to support datatyping. Protocol elements are defined to let clients and servers specify the datatype, and to instruct the WebDAV method PROPFIND to return datatype information. Editorial Note *(To be removed before publication as RFC):* Reschke Expires February 28, 2005 [Page 1]
Internet-Draft Datatypes for WebDAV properties August 2004 Please send comments to the Distributed Authoring and Versioning (WebDAV) working group at w3c-dist-auth@w3.org [1], which may be joined by sending a message with subject "subscribe" to w3c-dist-auth-request@w3.org [2]. Discussions of the WEBDAV working group are archived at . Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1 Data types . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Changes for PROPPATCH method . . . . . . . . . . . . . . . . . 4 4.1 Marshalling type information . . . . . . . . . . . . . . . 4 4.1.1 Example for successful PROPPATCH . . . . . . . . . . . 5 4.1.2 Example for failed PROPPATCH . . . . . . . . . . . . . 6 4.1.3 Example for succesful PROPPATCH where type information was not preserved . . . . . . . . . . . . 7 5. Changes for PROPFIND method . . . . . . . . . . . . . . . . . 8 5.1 Marshalling of datatype information . . . . . . . . . . . 8 5.1.1 Example for PROPFIND/prop . . . . . . . . . . . . . . 8 6. Compatibility Considerations . . . . . . . . . . . . . . . . . 9 6.1 Datatype marshalling . . . . . . . . . . . . . . . . . . . 9 7. Internationalization Considerations . . . . . . . . . . . . . 10 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 10.1 Normative References . . . . . . . . . . . . . . . . . . . . 10 10.2 Informative References . . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 11 A. Example: marshalling of array-typed properties . . . . . . . . 11 A.1 Setting of array-typed property . . . . . . . . . . . . . 12 A.2 Getting an array-typed property . . . . . . . . . . . . . 13 B. Change Log (to be removed by RFC Editor before publication) . 14 B.1 Since 'draft-reschke-webdav-property-datatypes-00' . . . . 14 B.2 Since 'draft-reschke-webdav-property-datatypes-01' . . . . 14 B.3 Since 'draft-reschke-webdav-property-datatypes-02' . . . . 14 B.4 Since 'draft-reschke-webdav-property-datatypes-03' . . . . 15 B.5 Since 'draft-reschke-webdav-property-datatypes-04' . . . . 15 B.6 Since 'draft-reschke-webdav-property-datatypes-05' . . . . 15 B.7 Since 'draft-reschke-webdav-property-datatypes-06' . . . . 15 C. Resolved issues (to be removed by RFC Editor before publication) . . . . . . . . . . . . . . . . . . . . . . . . . 15 C.1 strip-flags-and-displaynames . . . . . . . . . . . . . . . 15 D. Open issues (to be removed by RFC Editor prior to publication) . . . . . . . . . . . . . . . . . . . . . . . . . 15 D.1 edit . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . 17 Reschke Expires February 28, 2005 [Page 2]
Internet-Draft Datatypes for WebDAV properties August 2004 1. Introduction This specification builds on the infrastructure provided by the WebDAV Distributed Authoring Protocol, adding support for data-typed properties. Although servers must support XML content in property values, it may be desirable to persist values as scalar values when possible, and to expose the data's type when the property value is returned to the client. The client is free to ignore this information, but it may be able to take advantage of it when modifying a property. On the other hand, when setting new properties, it can be desirable to pass data type information along with the value. A server can take advantage of this information to optimize storage and to perform additional parsing (for instance of dates). Servers that support searching can also take advantage of known data types when doing comparisons and sorting. 2. Notational Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. The term "property element" refers to the XML element that identifies a particular property, for instance <getcontentlength xmlns="DAV:" /> The term "prop element" is used for the WebDAV "prop" element as defined in section 12.11 of [RFC2518]. The XML representation of schema components uses a vocabulary identified by the namespace name "http://www.w3.org/2001/XMLSchema". For brevity, the text and examples in this specification use the prefix "xs:" to stand for this namespace; in practice, any prefix can be used. "XML Schema: Structures" ([XS1]) also defines several attributes for direct use in any XML documents. These attributes are in a different namespace named "http://www.w3.org/2001/XMLSchema-instance". For brevity, the text and examples in this specification use the prefix "xsi:" to stand for this latter namespace; in practice, any prefix can be used. 3. Overview 3.1 Data types Although WebDAV property types can be anything that can be marshalled Reschke Expires February 28, 2005 [Page 3]
Internet-Draft Datatypes for WebDAV properties August 2004 as content of an XML element, in many cases they actually are simple types like integers, booleans or dates. "XML Schema Part 2: Datatypes" [XS2] defines a set of simple types which can be used as a basis for supplying type information to attributes. Data type information is represented using the attribute "type" from the XML Schema namespace "http://www.w3.org/2001/XMLSchema-instance". In XML Schema, data types are qualified names, and the XML Schema recommendation defines a set of built-in datatypes (section 3 of [XS2]), defined in the namespace "http://www.w3.org/2001/XMLSchema". To avoid unnecessary verbosity, data type information should only be supplied if it adds usable information to the protocol. In particular, type information is not required for live properties defined in WebDAV [RFC2518] and for properties of type "xs:string". A server may implement any combination of datatypes, both from the XML Schema recommendation and possibly from other namespaces. Note that a particular property can be typed for a number of reasons: o The property is a live property with server-defined semantics and value space. o The property may have been set using a non-WebDAV protocol that the server understands in addition to WebDAV. o The type may have been specified in an extended PROPPATCH method as defined in Section 4. 4. Changes for PROPPATCH method 4.1 Marshalling type information If the property element has an XML attribute named "xsi:type", the server may use this information to select an optimized representation for storing the property value. For instance, by specifying a type as "xs:boolean", the client declares the property value to be of type boolean (as defined in [XS2]). The server may choose any suitable internal format for persisting this property, and in particular is allowed to fail the request if the format given does not fit the format defined for this type. The server should indicate successful detection and parsing of the typed value by setting the xsi:type attribute on the property element in the response body (this implies that it should return a MULTISTATUS status code and a <multistatus> response body). Reschke Expires February 28, 2005 [Page 4]
Internet-Draft Datatypes for WebDAV properties August 2004 4.1.1 Example for successful PROPPATCH >>Request PROPPATCH /bar.html HTTP/1.1 Host: example.org Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:propertyupdate xmlns:D="DAV:" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:set> <D:prop> <Z:released xsi:type="xs:boolean">false</Z:released> </D:prop> </D:set> </D:propertyupdate> >>Response HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:multistatus xmlns:D="DAV:" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:response> <D:href>http://example.org/bar.html</D:href> <D:propstat> <D:prop><Z:released xsi:type="xs:boolean" /></D:prop> <D:status>HTTP/1.1 200 OK</D:status> </D:propstat> </D:response> </D:multistatus> In this cases, the xsi:type attribute on the element "Z:released" indicates that the server indeed has understood the submitted data type information. Reschke Expires February 28, 2005 [Page 5]
Internet-Draft Datatypes for WebDAV properties August 2004 4.1.2 Example for failed PROPPATCH >>Request PROPPATCH /bar.html HTTP/1.1 Host: example.org Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:propertyupdate xmlns:D="DAV:" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:set> <D:prop> <Z:released xsi:type="xs:boolean">t</Z:released> </D:prop> </D:set> </D:propertyupdate> >>Response HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:multistatus xmlns:D="DAV:" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:response> <D:href>http://example.org/bar.html</D:href> <D:propstat> <D:prop><Z:released/></D:prop> <D:status>HTTP/1.1 422 Unprocessable Entity</D:status> <D:responsedescription> Does not parse as xs:boolean </D:responsedescription> </D:propstat> </D:response> </D:multistatus> In this case the request failed because the supplied value "t" is not a valid representation for a boolean value. Note that similar error conditions can occur in the standard WebDAV protocol even though no data type was specified: for instance, when a client tries to set a live property for which only a certain value Reschke Expires February 28, 2005 [Page 6]
Internet-Draft Datatypes for WebDAV properties August 2004 space is allowed. 4.1.3 Example for succesful PROPPATCH where type information was not preserved >>Request PROPPATCH /bar.html HTTP/1.1 Host: example.org Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:propertyupdate xmlns:D="DAV:" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:set> <D:prop> <Z:released xsi:type="Z:custom">t</Z:released> </D:prop> </D:set> </D:propertyupdate> >>Response HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:multistatus xmlns:D="DAV:" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:response> <D:href>http://example.org/bar.html</D:href> <D:propstat> <D:prop><Z:released/></D:prop> <D:status>HTTP/1.1 200 OK</D:status> </D:propstat> </D:response> </D:multistatus> In this case the request succeeded, but the server did not know how to handle the data type "Z:custom". Therefore no data type information was returned in the response body. Reschke Expires February 28, 2005 [Page 7]
Internet-Draft Datatypes for WebDAV properties August 2004 5. Changes for PROPFIND method 5.1 Marshalling of datatype information PROPFIND is extended to return the data type information for properties unless one of the following conditions is met: o The data type MUST be different from "xs:string" (because this can be considered the default data type). o The property's data type MUST NOT be defined in [RFC2518] (because these types are already well-defined). 5.1.1 Example for PROPFIND/prop >>Request PROPFIND /bar.html HTTP/1.1 Host: example.org Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:propfind xmlns:D="DAV:" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:prop> <D:getcontenttype/> <Z:released/> </D:prop> </D:propfind> Reschke Expires February 28, 2005 [Page 8]
Internet-Draft Datatypes for WebDAV properties August 2004 >>Response HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:multistatus xmlns:D="DAV:" xmlns:Z="http://ns.example.org/standards/z39.50" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <D:response> <D:href>http://example.org/bar.html</D:href> <D:propstat> <D:prop> <D:getcontenttype>text/html</D:getcontenttype> <Z:released xsi:type="xs:boolean">1</Z:released> </D:prop> <D:status>HTTP/1.1 200 OK</D:status> </D:propstat> </D:response> </D:multistatus> This example shows that the property value "true" is returned with the correct data type information, and that the server chose one of the two possible representations defined in XML Schema. It also shows that data type information is not returned for "D:getcontenttype", as this property's data type is already defined in [RFC2518]. 6. Compatibility Considerations 6.1 Datatype marshalling This part of this specification does not introduce any new protocol elements, nor does it change the informal WebDAV DTD. It merely specifies additional server semantics for the case where clients submit additional data type information in an attribute on the property element (previously undefined), and adds an additional attribute on property elements upon PROPFIND. Clients not aware of datatype handling should not supply the "xsi:type" attribute on property elements (after all, this attribute belongs to the XML Schema-Instance namespace which has been defined for exactly this purpose). Old clients should also ignore additional attributes on property elements returned by PROPFIND (and similar methods), although the WebDAV specification only defines this behaviour for unknown elements (and is silent about unknown Reschke Expires February 28, 2005 [Page 9]
Internet-Draft Datatypes for WebDAV properties August 2004 attributes). Servers not aware of datatype handling either drop the "xsi:type" attribute, or persist it along with the property value. However, they will never indicate successful parsing of the data type by returning back the type in the response to PROPPATCH. 7. Internationalization Considerations This proposal builds on [RFC2518], and inherits its internationalizability. 8. IANA Considerations This proposal does not introduce any new IANA considerations, since it does not specify any new namespaces (in the general sense), but merely uses existing ones. 9. Acknowledgements This draft has benefited from thoughtful discussion by Stefan Eissing, Eric Sedlar and Kevin Wiggen. 10. References 10.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S. and D. Jensen, "HTTP Extensions for Distributed Authoring -- WEBDAV", RFC 2518, February 1999. [XML] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E. and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Third Edition)", W3C REC-xml-20040204, February 2004, <http://www.w3.org/TR/2004/REC-xml-20040204>. [XS1] Thompson, H., Beech, D., Maloney, M., Mendelsohn, N. and World Wide Web Consortium, "XML Schema Part 1: Structures", W3C REC-xmlschema-1-20010502, May 2001, <http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/>. [XS2] Biron, P., Malhotra, A. and World Wide Web Consortium, "XML Schema Part 2: Datatypes", W3C REC-xmlschema-2-20010502, May 2001, <http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/>. Reschke Expires February 28, 2005 [Page 10]
Internet-Draft Datatypes for WebDAV properties August 2004 10.2 Informative References [SOAP11] Box, D., Ehnebuske, D., Kakivaya, G., Layman, A., Mendelsohn, N., Nielsen, H., Thatte, S., Winer, D. and World Wide Web Consortium, "Simple Object Access Protocol 1.1", W3C NOTE-SOAP-20000508, May 2000, <http://www.w3.org/TR/2000/NOTE-SOAP-20000508>. URIs [1] <mailto:w3c-dist-auth@w3.org> [2] <mailto:w3c-dist-auth-request@w3.org?subject=subscribe> Author's Address Julian F. Reschke greenbytes GmbH Salzmannstrasse 152 Muenster, NW 48159 Germany Phone: +49 251 2807760 Fax: +49 251 2807761 EMail: julian.reschke@greenbytes.de URI: http://greenbytes.de/tech/webdav/ Appendix A. Example: marshalling of array-typed properties As an example for more complex data types, this section shows marshalling of array-typed properties as implemented in the WebDAV protocol adapters of SAP Portal's Enterprise Portal System (release 5.0). As XML Schema [XS2] does not define simple types for arrays, it builds on the predefined array types used in [SOAP11]. These in turn can be based on the simple types defined in XML Schema. Note the following special properties of SOAP-encoded arrays: 1. They require an additional "arrayType" attribute to specify the array length and the base type. 2. The names of the individual children of the property element aren't relevant as the type information is already encoded on the property element itself. It is however recommended to use identical element names for all array members. Reschke Expires February 28, 2005 [Page 11]
Internet-Draft Datatypes for WebDAV properties August 2004 A.1 Setting of array-typed property >>Request PROPPATCH /bar.html HTTP/1.1 Host: example.org Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8"?> <propertyupdate xmlns="DAV:" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:Z="http://ns.example.org/standards/z39.50" xmlns:soap-enc="http://schemas.xmlsoap.org/soap/encoding/"> <set> <prop> <Z:refs xsi:type="soap-enc:Array" soap-enc:arrayType="xs:string[2]"> <xs:string>http://www.w3.org/TR/SOAP</xs:string> <xs:string>http://www.w3.org/TR/xmlschema-2</xs:string> </Z:refs> </prop> </set> </propertyupdate> Reschke Expires February 28, 2005 [Page 12]
Internet-Draft Datatypes for WebDAV properties August 2004 >>Response HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <multistatus xmlns="DAV:" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:Z="http://ns.example.org/standards/z39.50" xmlns:soap-enc="http://schemas.xmlsoap.org/soap/encoding/"> <response> <href>http://example.org/bar.html</href> <propstat> <prop> <Z:refs xsi:type="soap-enc:Array" soap-enc:arrayType="xs:string[2]"/> </prop> <status>HTTP/1.1 200 OK</status> </propstat> </response> </multistatus> A.2 Getting an array-typed property >>Request PROPFIND /bar.html HTTP/1.1 Host: example.org Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:propfind xmlns:D="DAV:" xmlns:Z="http://ns.example.org/standards/z39.50"> <D:prop> <Z:refs/> </D:prop> </D:propfind> Reschke Expires February 28, 2005 [Page 13]
Internet-Draft Datatypes for WebDAV properties August 2004 >>Response HTTP/1.1 207 Multi-Status Content-Type: text/xml; charset="utf-8" Content-Length: xxxx <?xml version="1.0" encoding="utf-8" ?> <D:multistatus xmlns:D="DAV:" xmlns:Z="http://ns.example.org/standards/z39.50" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:soap-enc="http://schemas.xmlsoap.org/soap/encoding/"> <D:response> <D:href>http://example.org/bar.html</D:href> <D:propstat> <D:prop> <Z:refs xsi:type="soap-enc:Array" soap-enc:arrayType="xs:string[2]"> <xs:string>http://www.w3.org/TR/SOAP</xs:string> <xs:string>http://www.w3.org/TR/xmlschema-2</xs:string> </Z:refs> </D:prop> <D:status>HTTP/1.1 200 OK</D:status> </D:propstat> </D:response> </D:multistatus> Appendix B. Change Log (to be removed by RFC Editor before publication) B.1 Since 'draft-reschke-webdav-property-datatypes-00' Editorial fixes. Changed examples to explicitly use utf-8 encoding for HTTP content type and XML encoding. Added example for marshalling array-typed properties. B.2 Since 'draft-reschke-webdav-property-datatypes-01' Fix width of artwork for IETF compliance. "Non-normative references" -> "Informative references". B.3 Since 'draft-reschke-webdav-property-datatypes-02' Added marshalling for property flags such as "hidden" and "protected". Moved array marshalling example into back section. Added rational and description for pf:property-displayname-set. Reschke Expires February 28, 2005 [Page 14]
Internet-Draft Datatypes for WebDAV properties August 2004 Added acknowledgements section. B.4 Since 'draft-reschke-webdav-property-datatypes-03' Replaced domain names in examples according to RFC2606: "www.foo.com" by "example.org", "www.example.com" by "ns.example.org/standards/ z39.50/standards/z39.50" and "www.w3.com/standards/z39.50" by "ns.example.org/standards/z39.50". B.5 Since 'draft-reschke-webdav-property-datatypes-04' Remove superfluous IP and copyright sections. Moved "Introduction" section to front. B.6 Since 'draft-reschke-webdav-property-datatypes-05' Added proposal for DAV:basicsearch operators for array-typed properties. Update all references. B.7 Since 'draft-reschke-webdav-property-datatypes-06' Reformat abstract. Remove property flags, displayname support and DASL extensions. Appendix C. Resolved issues (to be removed by RFC Editor before publication) Issues that were either rejected or resolved in this version of this document. C.1 strip-flags-and-displaynames Type: edit julian.reschke@greenbytes.de (2004-08-28): Remove support for property flags and displaynames and move them into a separate spec (these will be defined in a separate document). Also remove DASL extensions. Resolution (2004-08-28): Done. Appendix D. Open issues (to be removed by RFC Editor prior to publication) D.1 edit Type: edit Reschke Expires February 28, 2005 [Page 15]
Internet-Draft Datatypes for WebDAV properties August 2004 julian.reschke@greenbytes.de (2004-07-08): Umbrella issue for editorial fixes/enhancements. Reschke Expires February 28, 2005 [Page 16]
Internet-Draft Datatypes for WebDAV properties August 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2004). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Reschke Expires February 28, 2005 [Page 17]