SIMPLE WG M. Lonnfors
Internet-Draft E. Leppanen
Expires: April 25, 2005 H. Khartabil
Nokia
J. Urpalainen
Nokia Research Center
October 25, 2004
Presence Information Data format (PIDF) Extension for Partial
Presence
draft-ietf-simple-partial-pidf-format-02
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 April 25, 2005.
Copyright Notice
Copyright (C) The Internet Society (2004).
Abstract
The Presence Information Document Format (PIDF) specifies the
baseline XML based format for describing presence information. One
of the characteristic of the PIDF is that document always needs to
Lonnfors, et al. Expires April 25, 2005 [Page 1]
Internet-Draft Partial PIDF October 2004
carry all presence information available for the presentity. In some
environments where low bandwidth and high latency links can exist it
is often beneficial to limit the amount of information that is
transported over the network. This document introduces a new MIME
type which enables transporting of only changed parts of the PIDF
based presence information.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Structure of partial PIDF documents . . . . . . . . . . . . . 3
3.1 "version" attribute . . . . . . . . . . . . . . . . . . . 4
3.2 "entity" attribute . . . . . . . . . . . . . . . . . . . . 5
3.3 <add> element . . . . . . . . . . . . . . . . . . . . . . 5
3.4 <replace> element . . . . . . . . . . . . . . . . . . . . 5
3.5 <remove> element . . . . . . . . . . . . . . . . . . . . . 5
4. Usage of 'application/pidf-diff+xml' . . . . . . . . . . . . . 5
5. Node Selector . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1 Content-type registration for
'application/pidf-diff+xml' . . . . . . . . . . . . . . . 6
6.2 URN sub-namespace registration for
'urn:ietf:params:xml:ns:pidf-diff' . . . . . . . . . . . . 7
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9. Interoperability Considerations . . . . . . . . . . . . . . . 13
10. Security Considerations . . . . . . . . . . . . . . . . . . 14
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 14
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
12.1 Normative references . . . . . . . . . . . . . . . . . . . . 14
12.2 Informative references . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . . . 17
Lonnfors, et al. Expires April 25, 2005 [Page 2]
Internet-Draft Partial PIDF October 2004
1. Introduction
The Presence Information Document Format (PIDF) specifies the
baseline XML based format for describing presence information. One
of the characteristic of the PIDF is that document always needs to
carry all presence information available for the presentity. In some
environments where low bandwidth and high latency links can exist it
is often beneficial to limit the amount of information that is
transported over the network.
This document introduces a new MIME-Type 'application/pidf-diff+xml'
which enables transporting of only changed parts of the PIDF based
presence information.
2. Conventions
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
indicate requirement levels for compliant implementations.
This memo makes use of the vocabulary defined in RFC2778 [2]. In
addition, the following terms are defined:
Full presence document: A presence document that contains all the
presentity's presence information that is available to a
particular watcher.
Partial presence document: A presence document that represents a
fragment of the full presence document. A partial presence
documents can only be understood in the context of the full
presence document, i.e., a partial presence document modifies a
local copy of the full presence document. A document with MIME
type 'application/pidf-diff+xml' represents a partial presence
document.
3. Structure of partial PIDF documents
The mechanism for implementing the partial PIDF requires defining a
new MIME type which is named as 'application/pidf-diff+xml'.
The data format is in principle similar to XCAP package [12] except
that instead of the ETag a "version" attribute is used to ensure
consistent updates. The "version" attribute contains a sequence
number that is progressively incremented by one between subsequent
document updates i.e. a more recent document update has a higher
"version" value than the previous one. The recipient of the document
Lonnfors, et al. Expires April 25, 2005 [Page 3]
Internet-Draft Partial PIDF October 2004
can use the "version" attribute to properly order received documents.
The partial PIDF document contains a collection of add, remove or
replace operations which will be applied one-by-one in the given
order to the current local composition presence document. Each of
the operations contains at least one XPath [15] compatible selector
which is used to select a specific part within the local document.
Furthermore, also the changed or added data content is given. For
example, when an add operation is being requested, the element onto
which new data is going to be appended is searched first and then the
new content is added.
It is an error condition if any of the given operations can not be
unambiguously fulfilled.
In order to keep the update document as small as possible, the
defined namespace prefixes and uri's within the current local
document are used to expand location step prefixes just like in XCAP
[11]. Given the full presence document is using a "pres" prefixed
namespace definition and there's a selector "pres:presence" that has
to be interpreted, the namespace definition has to be found from the
local composition document. As <presence> node happens to be the
root node the definition for the namespace uri must be within that
node. As default namespaces can also be used, a selector like
"presence" is interpreted as if it had an implicit default namespace
uri attached. It should be noted that when using add operation it is
also possible that the namespace definition can be within the content
of corresponding <add> element.
Implementations using this document format must follow guidelines
specified in the PIDF [4]. Specifically, the XML document MUST be
well formed and SHOULD be valid. Presence documents MUST be based on
XML 1.0 and MUST be encoded using UTF-8. This specification makes
use of XML namespaces for identifying presence documents and document
fragments. The namespace URI for elements defined by this
specification is a URN [5], using the namespace identifier 'ietf'
specified in RFC 2648 [6] and extended by RFC3688 [7]. This URN is:
urn:ietf:params:xml:ns:pidf-diff
3.1 "version" attribute
Every presence document compliant with this specification contains a
"version" attribute in the <pidf-diff> element.
Implementations MUST support a 32 bit integer in the version number.
Lonnfors, et al. Expires April 25, 2005 [Page 4]
Internet-Draft Partial PIDF October 2004
3.2 "entity" attribute
Every presence document compliant with this specification may contain
an "entity" attribute in <pidf-diff> element. It's content MUST then
be the same than that of the full presence document.
3.3 <add> element
The <add> element has two selection attributes: "parent" and "sel".
The content of the "parent" attribute is used to select a single
element from the local composition document onto which new data will
be appended. The second selector "sel" is a relative location step
that will uniquely point after the append to the newly created
element, text-node content or attribute within the "parent" selection
context. If there are several sibling elements in the new document
the "sel" selector MUST include a position constraint to fulfill an
unambiguous request. The content of the <add> element is text for
attributes and elements which have only text-content i.e. XPath
text() function is being used in the last location step. For other
elements the content of <add> element is enclosed with CDATA section
and it inludes all the attributes and child elements and e.g.
possible namespace definitions.
3.4 <replace> element
The <replace> element has only one attribute: "sel" the content of
which is used to select an element, a text-node content or an
attribute that is going to be replaced with the new content. The
content of the <replace> element is the same as with <add> operation.
3.5 <remove> element
The <remove> element has only one attribute: "sel" the content of
which is used to select an element, text-node content or an attribute
that is going to be removed.
4. Usage of 'application/pidf-diff+xml'
The partial presence document SHOULD only contain those elements or
attributes that have changed. However, when there are a lot of
queued changes it may be desirable to send the full presence document
content instead. How this will be done in practice is beyond the
scope of this document. This document format allows to use the root
node selector i.e. "presence" which actually contains the full
content of the presence document as there can only be one root node
in any valid XML document. It should be noted that it is still
impossible to create a new document with this format, i.e. first the
full presence document has to be sent with the PIDF format and then
Lonnfors, et al. Expires April 25, 2005 [Page 5]
Internet-Draft Partial PIDF October 2004
only patches are sent with this format.
5. Node Selector
The ABNF [14] is used to describe the syntax for the node selector
expressions. The node selector syntax is defined to be XPath [15]
compatible, but has a more restricted set of capabilities. Each
element selection has to point to a single node. As the document
root is always the starting point for selections relative location
paths can be used.
node-sel = element-sel ["/" (attribute-sel / "text()")]
element-sel = element-step *("/" element-step)
element-step = ("*" / node-name) [conditions]
conditions = *("[" condition "]")
condition = 1*DIGIT / ; positional
cond-name "=" <"> value <"> ; value comparison
cond-name = "@" node-name / ; attribute selection
node-name / ; element selection
"." ; current node selection
node-name = [prefix ":"] string
prefix = <any sequence of data supported by XML for namespace
prefixes>
string = <any sequence of data supported by XML for element or
attribute names>
value = <any sequence of data supported by XML for element or
attribute values>
attribute-sel = "@" node-name
6. IANA Considerations
This memo calls for IANA to:
o register a new XML namespace URN per [7].
o register a new content type 'application/pidf-diff+xml' per
RFC2048 [10].
6.1 Content-type registration for 'application/pidf-diff+xml'
MIME media type name: application
MIME subtype name: pidf-diff+xml
Lonnfors, et al. Expires April 25, 2005 [Page 6]
Internet-Draft Partial PIDF October 2004
Mandatory parameters: none
Optional parameters: charset
Indicates the character encoding of enclosed XML. Default is
UTF-8.
Encoding considerations:
Uses XML, which can employ 8-bit characters, depending on the
character encoding used. See RFC 3023 [8], section 3.2.
Security considerations:
This content type is designed to carry presence data, which may be
considered private information. Appropriate precautions should be
adopted to limit disclosure of this information. Please refer to
[[[RFCXXXX]]] security considerations section for more
information.
Interoperability considerations: none
Published specification: [[[RFCXXXX]]]
Applications which use this media type: SIP-based presence systems
Additional information:
Magic Number: None
File Extension: .xml
Macintosh file type code: "TEXT"
Personal and email address for further information: Mikko
Lonnfors, mikko.lonnfors@nokia.com
Intended usage: LIMITED USE
Author/Change controller:
This specification is a work item of the IETF SIMPLE working
group, with mailing list address <simple@ietf.org>.
6.2 URN sub-namespace registration for
'urn:ietf:params:xml:ns:pidf-diff'
URI:
urn:ietf:params:xml:ns:pidf-diff
Description:
Lonnfors, et al. Expires April 25, 2005 [Page 7]
Internet-Draft Partial PIDF October 2004
This is the XML namespace for XML elements defined by
[[[RFCXXXX]]] to describe the 'application/pidf-diff+xml' content
type for partial PIDF.
Registrant Contact:
IETF, SIMPLE working group, <simple@ietf.org>
Mikko Lonnfors, <mikko.lonnfors@nokia.com>
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>PIDF extension for partial PIDF</title>
</head>
<body>
<h1>Namespace for PIDF extension for partial
notifications</h1>
<h2>urn:ietf:params:xml:ns:pidf-diff</h2>
<p>See <a href="[[[URL of published RFC]]]">
RFCXXXX</a>.</p>
</body>
</html>
END
7. Examples
An 'application/pidf+xml' document that contains full state
information:
<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:pe="urn:ietf:params:xml:ns:pidf:person"
xmlns:de="urn:ietf:params:xml:ns:pidf:device"
xmlns:rs="urn:ietf:params:xml:ns:pidf:status:rpid-status"
xmlns:rt="urn:ietf:params:xml:ns:pidf:rpid-tuple"
xmlns:ci="urn:ietf:params:xml:ns:pidf:cipid"
xmlns:sc="urn:ietf:params:xml:ns:pidf:status:servcaps"
xmlns:dc="urn:ietf:params:xml:ns:pidf:status:devcaps"
entity="pres:someone@example.com">
<tuple id="sg89ae">
Lonnfors, et al. Expires April 25, 2005 [Page 8]
Internet-Draft Partial PIDF October 2004
<status>
<basic>open</basic>
<rs:relationship>assistant</rs:relationship>
</status>
<sc:servcaps>
<sc:video>false</sc:video>
<sc:audio>true</sc:audio>
<sc:message>true</sc:message>
</sc:servcaps>
<contact priority="0.8">tel:09012345678</contact>
</tuple>
<tuple id="cg231jcr">
<status>
<basic>open</basic>
</status>
<contact priority="1.0">im:pep@example.com</contact>
</tuple>
<tuple id="r1230d">
<status>
<basic>closed</basic>
<rs:activity>meeting</rs:activity>
</status>
<ci:homepage>http://example.com/~pep/</ci:homepage>
<ci:icon>http://example.com/~pep/icon.gif</ci:icon>
<ci:card>http://example.com/~pep/card.vcd</ci:card>
<contact priority="0.9">sip:pep@example.com</contact>
</tuple>
<pe:person>
<pe:status>
<rs:activities>
<rs:activity>on-the-phone</rs:activity>
<rs:activity>busy</rs:activity>
</rs:activities>
</pe:status>
</pe:person>
<de:device device-id="urn:esn:600b40c7">
<de:status>
<dc:devcaps>
<dc:supported>
<dc:fixed/>
</dc:supported>
</dc:prescaps>
</de:status>
</de:device>
Lonnfors, et al. Expires April 25, 2005 [Page 9]
Internet-Draft Partial PIDF October 2004
<note xml:lang="en">Full state presence document</note>
</presence>
An 'application/pidf-diff+xml' document that contains partial
updates:
<?xml version="1.0" encoding="UTF-8"?>
<pidf-diff xmlns="urn:ietf:params:xml:ns:pidf-diff"
entity="pres:someone@example.com"
version="1">
<add parent="presence" sel="*[4]">
<![CDATA[
<tuple id="ert4773">
<status>
<basic>open</basic>
</status>
<contact priority="0.4">mailto:pep@example.com</contact>
<note xml:lang="en">This is a new tuple inserted
between the last tuple and person element</note>
</tuple>
]] >
</add>
<replace
sel="presence/tuple[@id="r1230d"]/status/basic/text()"
>open</replace>
<remove sel="presence/tuple[@id="r1230d"]/status/
rs:activity"/>
<remove sel="presence/pe:person/pe:status/rs:activities/rs:activity
[.="busy"]"></remove>
<replace
sel="presence/tuple[@id="cg231jcr"]/contact/@priority"
>0.7</replace>
</pidf-diff>
An updated local composition presence document:
<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:pe="urn:ietf:params:xml:ns:pidf:person"
Lonnfors, et al. Expires April 25, 2005 [Page 10]
Internet-Draft Partial PIDF October 2004
xmlns:de="urn:ietf:params:xml:ns:pidf:device"
xmlns:rs="urn:ietf:params:xml:ns:pidf:status:rpid-status"
xmlns:rt="urn:ietf:params:xml:ns:pidf:rpid-tuple"
xmlns:ci="urn:ietf:params:xml:ns:pidf:cipid"
xmlns:sc="urn:ietf:params:xml:ns:pidf:status:servcaps"
xmlns:dc="urn:ietf:params:xml:ns:pidf:status:devcaps"
entity="pres:someone@example.com">
<tuple id="sg89ae">
<status>
<basic>open</basic>
<rs:relationship>assistant</rs:relationship>
</status>
<sc:servcaps>
<sc:video>false</sc:video>
<sc:audio>true</sc:audio>
<sc:message>true</sc:message>
</sc:servcaps>
<contact priority="0.8">tel:09012345678</contact>
</tuple>
<tuple id="cg231jcr">
<status>
<basic>open</basic>
</status>
<contact priority="0.7">im:pep@example.com</contact>
</tuple>
<tuple id="r1230d">
<status>
<basic>open</basic>
</status>
<ci:homepage>http://example.com/~pep/</ci:homepage>
<ci:icon>http://example.com/~pep/icon.gif</ci:icon>
<ci:card>http://example.com/~pep/card.vcd</ci:card>
<contact priority="0.9">sip:pep@example.com</contact>
</tuple>
<tuple id="ert4773">
<status>
<basic>open</basic>
</status>
<contact priority="0.4">mailto:pep@example.com</contact>
<note xml:lang="en">This is a new tuple inserted
between the last tuple and person element</note>
</tuple>
<pe:person>
Lonnfors, et al. Expires April 25, 2005 [Page 11]
Internet-Draft Partial PIDF October 2004
<pe:status>
<rs:activities>
<rs:activity>on-the-phone</rs:activity>
</rs:activities>
</pe:status>
</pe:person>
<de:device device-id="urn:esn:600b40c7">
<de:status>
<dc:devcaps>
<dc:supported>
<dc:fixed/>
</dc:supported>
</dc:prescaps>
</de:status>
</de:device>
<note xml:lang="en">Full state presence document</note>
</presence>
8. XML Schema
The XML schema for the 'application/pidf-diff+xml' data format.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:pidf-diff"
xmlns:tns="urn:ietf:params:xml:ns:pidf-diff"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xs:element name="pidf-diff">
<xs:complexType>
<xs:sequence minOccurs="0" maxOccurs="unbounded">
<xs:choice>
<xs:element name="add">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="parent" type="xs:string"
use="required"/>
<xs:attribute name="sel" type="xs:string"
use="required"/>
Lonnfors, et al. Expires April 25, 2005 [Page 12]
Internet-Draft Partial PIDF October 2004
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
<xs:element name="remove">
<xs:complexType>
<xs:attribute name="sel" type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
<xs:element name="replace">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="sel" type="xs:string" use="required"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:sequence>
<xs:attribute name="entity" type="xs:anyURI" use="optional"/>
<xs:attribute name="version" type="xs:nonNegativeInteger"
use="required"/>
</xs:complexType>
</xs:element>
</xs:schema>
9. Interoperability Considerations
Systems compliant with CPP [9] will not be by default able to use
this specification. However, this will not cause any
interoperability problems because all endpoints and gateways must
support the default MIME type (application/pidf+xml) regardless if
they support this specification. Thus if a gateway or another end
point does not understand this specification it will not be used.
Other CPP compliant (other than SIP based) systems can also support
this specification if they have a mechanism to indicate support for
it. If they do it is possible to build a gateway which will preserve
end-to-end integrity with usage of partial PIDF.
Lonnfors, et al. Expires April 25, 2005 [Page 13]
Internet-Draft Partial PIDF October 2004
10. Security Considerations
Presence information may contain highly sensitive information about
the presentities. The protocol used to distribute it SHOULD ensure
privacy, message integrity and authentication. Furthermore, the
protocol should provide access controls which restrict who can see
who else's presence information. All security considerations
identified for PIDF [4] apply unchanged for this document.
11. Acknowledgments
The authors would like to thank Jose Costa-Requena, Jyrki Aarnos,
Jonathan Rosenberg, Dean Willis, Miguel Garcia, Kriztian Kiss, Ben
Cambell, Robert Sparks, Anders kristenssen and Aki Niemi for their
valuable comments and contributions.
12. References
12.1 Normative references
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
Instant Messaging", RFC 2778, February 2000.
[3] Rosenberg, J., "SIP Extensions for Presence",
draft-ietf-simple-presence-10 (work in progress), January 2003.
[4] Sugano, H., "CPIM presence information data format", RFC 3863,
May 2003.
[5] Moats, R., "URN syntax", RFC 2141, May 1997.
[6] Moats, R., "A URN namespace for IETF documents", RFC 2648, Aug.
1999.
12.2 Informative references
[7] Mealling, M., "The IETF XML Registry", RFC 3688, BCP 81,
January 2004.
[8] Murata, M., "XML media types", RFC 3023, January 2001.
[9] Peterson, J., "Common Profile for Presence (CPP)", RFC 3859.
[10] Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet
Mail Extensions (MIME) Part Four: Registration Procedures", RFC
Lonnfors, et al. Expires April 25, 2005 [Page 14]
Internet-Draft Partial PIDF October 2004
2048, November 1996.
[11] Rosenberg, J., "The Extensible Markup Language (XML)
Configuration Access Protoco (XCAP)",
draft-ietf-simple-xcap-04 (work in progress), October 2004.
[12] Rosenberg, J., "An Extensible Markup Language (XML) Document
Format For Indicating Changes in XML Configuration Access
Protocol (XCAP) Resources", draft-ietf-simple-xcap-package-02
(work in progress), July 2004.
[13] Rosenberg, J., "A Data Model for Presence",
draft-ietf-simple-presence-data-model-00 (work in progress),
September 2004.
[14] Crocker, D., "Augmented BNF for Syntax Specifications: ABNF",
RFC 2234, November 1997.
[15] "XML Path Language (XPath) Version 1.0", W3C REC
REC-xpath-19991116 , November 1999.
Authors' Addresses
Mikko Lonnfors
Nokia
Itamerenkatu 11-13 00180
Helsinki
Finland
Phone: +358 71 8008000
EMail: mikko.lonnfors@nokia.com
Eva Leppanen
Nokia
P.O BOX 785
Tampere
Finland
Phone: +358 7180 77066
EMail: eva-maria.leppanen@nokia.com
Lonnfors, et al. Expires April 25, 2005 [Page 15]
Internet-Draft Partial PIDF October 2004
Hisham Khartabil
Nokia
P.O. Box 321
Helsinki
Finland
Phone: +358 7180 76161
EMail: hisham.khartabil@nokia.com
Jari Urpalainen
Nokia Research Center
Itamerenkatu 11-13 00180
Helsinki
Finland
Phone: +358 7180 37686
EMail: jari.urpalainen@nokia.com
Lonnfors, et al. Expires April 25, 2005 [Page 16]
Internet-Draft Partial PIDF October 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.
Lonnfors, et al. Expires April 25, 2005 [Page 17]
