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Versions: (draft-camarillo-sipping-pending-additions) 00 01 02 03 04 05 RFC 5362

SIPPING                                                     G. Camarillo
Internet-Draft                                                  Ericsson
Intended status: Standards Track                           April 2, 2007
Expires: October 4, 2007


 The Session Initiation Protocol (SIP) Pending Additions Event Package
              draft-ietf-sipping-pending-additions-02.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
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   This Internet-Draft will expire on October 4, 2007.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines the SIP Pending Additions event package.  This
   event package is used by SIP relays to inform user agents about the
   consent-related status of the entries to be added to a resource list.








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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of Operation  . . . . . . . . . . . . . . . . . . . .  3
   4.  XML Schema Definition  . . . . . . . . . . . . . . . . . . . .  3
   5.  Pending Additions Event Package Definition . . . . . . . . . .  5
     5.1.  Event Package Name . . . . . . . . . . . . . . . . . . . .  5
       5.1.1.  Event Package Parameters . . . . . . . . . . . . . . .  5
       5.1.2.  SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . .  5
       5.1.3.  Subscription Duration  . . . . . . . . . . . . . . . .  5
       5.1.4.  NOTIFY Bodies  . . . . . . . . . . . . . . . . . . . .  5
       5.1.5.  Notifier Processing of SUBSCRIBE Requests  . . . . . .  6
       5.1.6.  Notifier Generation of NOTIFY Requests . . . . . . . .  6
       5.1.7.  Subscriber Processing of NOTIFY Requests . . . . . . .  6
       5.1.8.  Handling of Forked Requests  . . . . . . . . . . . . .  6
       5.1.9.  Rate of Notifications  . . . . . . . . . . . . . . . .  7
       5.1.10. State Agents . . . . . . . . . . . . . . . . . . . . .  7
       5.1.11. Example  . . . . . . . . . . . . . . . . . . . . . . .  7
   6.  Usage of the Pending Additions Event Package with the XCAP
       Diff Format  . . . . . . . . . . . . . . . . . . . . . . . . .  7
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
     7.1.  SIP Event Package Registration . . . . . . . . . . . . . .  9
     7.2.  URN Sub-Namespace Registration . . . . . . . . . . . . . .  9
     7.3.  XML Schema Registration  . . . . . . . . . . . . . . . . . 10
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 11
     10.2. Informative References . . . . . . . . . . . . . . . . . . 11
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
   Intellectual Property and Copyright Statements . . . . . . . . . . 12



















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1.  Introduction

   The framework for consent-based communications in SIP [8] identifies
   the need for users manipulating the translation logic at a relay
   (e.g., adding a new recipient) to be informed about the consent-
   related status of the recipients of a given translation.  That is,
   the user manipulating the translation logic needs to know which
   recipients have given the relay permission to send them SIP requests.

   This document defines a SIP event package whereby user agents can
   subscribe to the consent-related state of the resources that are
   being added to a resource list that defines a translation.


2.  Terminology

   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 RFC 2119 [1].

   Relay:  Any SIP server, be it a proxy, B2BUA (Back-to-Back User
      Agent), or some hybrid, that receives a request, translates its
      Request-URI into one or more next-hop URIs (i.e., recipient URIs),
      and delivers the request to those URIs.


3.  Overview of Operation

   A user agent subscribes to a relay using the Pending Additions event
   package.  NOTIFY requests within this event package can carry an XML
   document in the "application/resource-lists+xml" format [6] or in the
   "application/xcap-diff+xml" format [7].

   A document in the "application/resource-lists+xml" format provides
   the user agent with the whole list of resources being added to a
   resource list along with the consent-related status of those
   resources.

   A document in the "application/xcap-diff+xml" format informs the user
   agent that the document that describes the resources being added to
   the resource list has changed.  The user agent can then download the
   document in the "application/resource-lists+xml" format from the
   relay using XCAP [5].


4.  XML Schema Definition

   This section defines the <consent-status> element, which provides



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   consent-related information about a resource to be added to a relay's
   translation logic.

   A consent-status document is an XML document that MUST be well-formed
   and SHOULD be valid.  Consent-status documents MUST be based on XML
   1.0 and MUST be encoded using UTF-8.  This specification makes use of
   XML namespaces for identifying consent-status documents.  The
   namespace URI for elements defined for this purpose is a URN, using
   the namespace identifier 'ietf'.  This URN is:


       urn:ietf:params:xml:ns:consent-status



   <?xml version="1.0" encoding="UTF-8"?>
   <xs:schema targetNamespace="urn:ietf:params:xml:ns:consent-status"
     elementFormDefault="qualified"
     attributeFormDefault="unqualified"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     xmlns:tns="urn:ietf:params:xml:ns:consent-status">
      <xs:element name="consent-status">
         <xs:simpleType>
           <xs:restriction base="xs:string">
             <xs:enumeration value="pending"/>
             <xs:enumeration value="waiting"/>
             <xs:enumeration value="error"/>
             <xs:enumeration value="denied"/>
             <xs:enumeration value="granted"/>
           </xs:restriction>
         </xs:simpleType>
      </xs:element>
   </xs:schema>

   The <consent-status> element can take on the following values:

   Pending:  the relay has received a request to add a resource to its
      translation logic and will ask for permission to do so.

   Waiting:  the relay has requested permission to add the resource to
      its translation logic but has not gotten any answer from the
      resource yet.

   Error:  the relay has requested permission to add the resource to its
      translation logic and has received an error response (e.g., a SIP
      error response to the MESSAGE request send to request permission).
      That is, the permission document requesting permission could not
      be delivered to the resource.



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   Denied:  the resource has denied the relay permission to add the
      resource to the relay's translation logic.

   Granted:  the resource has granted the relay permission to add the
      resource to the relay's translation logic.


5.  Pending Additions Event Package Definition

   This section provides the details for defining a SIP [2] event
   notification package, as specified by RFC 3265 [3].

5.1.  Event Package Name

   The name of this event package is "consent-pending-additions".  This
   package name is carried in the Event and Allow-Events header, as
   defined in RFC 3265 [3].

5.1.1.  Event Package Parameters

   This package does not define any event package parameters.

5.1.2.  SUBSCRIBE Bodies

   A SUBSCRIBE for Pending Additions events MAY contain a body.  This
   body would serve the purpose of filtering the subscription.  The
   definition of such a body is outside the scope of this specification.

   A SUBSCRIBE for the Pending Additions event package MAY be sent
   without a body.  This implies that the default session policy
   filtering policy has been requested.  The default policy is that
   notifications are generated every time there is any change in the
   state of a resource in the list.

5.1.3.  Subscription Duration

   The default expiration time for a subscription is one hour (3600
   seconds).

5.1.4.  NOTIFY Bodies

   In this event package, the body of the notifications contains a
   resource list document.  This document describes the resources being
   added as recipients to a translation operation.  All subscribers and
   notifiers MUST support the "application/resource-lists+xml" data
   format [6] and its extension to carry consent-related state
   information, which is specified in Section 4.  The SUBSCRIBE request



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   MAY contain an Accept header field.  If no such header field is
   present, it has a default value of "application/resource-lists+xml".
   If the header field is present, it MUST include "application/
   resource-lists+xml", and MAY include any other types capable of
   representing consent-related state.

   Additionally, all subscribers and notifiers SHOULD support the
   "application/xcap-diff+xml" format [7].  Section 6 discusses the
   usage of the Pending Additions event package with this format.

5.1.5.  Notifier Processing of SUBSCRIBE Requests

   The state of the resources to be added to a relay's translation logic
   can reveal sensitive information.  Therefore, all subscriptions
   SHOULD be authenticated and then authorized before approval.
   Authorization policy is at the discretion of the administrator.

5.1.6.  Notifier Generation of NOTIFY Requests

   A notifier for the Pending Additions event package SHOULD include the
   <consent-status> element, which is defined in Section 4.  The
   <consent-status> element MUST be positioned as an instance of the
   <any> element within the <entry> element.

   Notifications SHOULD be generated for the Pending Additions package
   whenever there is a change in the consent-related state of a
   resource.  When a resource moves to the error, denied, or granted
   states, and once a NOTIFY request is sent, the resource is removed
   from further notifications.

5.1.7.  Subscriber Processing of NOTIFY Requests

   NOTIFY requests contain the full resource-list state.  The subscriber
   does not need to perform any type of information aggregation.

5.1.8.  Handling of Forked Requests

   The state of a given resource list is normally handled by a server
   and stored in a repository.  Therefore, there is usually a single
   place where the resource-list state is resident.  This implies that a
   subscription for this information is readily handled by a single
   element with access to this repository.  There is, therefore, no
   compelling need for a subscription to pending additions information
   to fork.  As a result, a subscriber MUST NOT create multiple dialogs
   as a result of a single subscription request.  The required
   processing to guarantee that only a single dialog is established is
   described in Section 4.4.9 of RFC 3265 [3].




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5.1.9.  Rate of Notifications

   For reasons of congestion control, it is important that the rate of
   notifications not become excessive.  As a result, it is RECOMMENDED
   that the server does not generate notifications for a single
   subscriber at a rate faster than once every 5 seconds.

5.1.10.  State Agents

   State agents have no role in the handling of this package.

5.1.11.  Example

   The following is an example of an "application/resource-lists+xml"
   document that carries consent-related state information using
   <consent-status> elements:


      <?xml version="1.0" encoding="UTF-8"?>
      <resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:cs="urn:ietf:params:xml:ns:consent-status">
       <list>
        <entry uri="sip:bill@example.com">
         <display-name>Bill Doe</display-name>
         <cs:consent-status>pending</cs:consent-status>
        </entry>
        <entry uri="sip:joe@example.com">
         <display-name>Joe Smith</display-name>
         <cs:consent-status>pending</cs:consent-status>
        </entry>
        <entry uri="sip:nancy@example.com">
         <display-name>Nancy Gross</display-name>
         <cs:consent-status>granted</cs:consent-status>
        </entry>
       </list>
      </resource-lists>


6.  Usage of the Pending Additions Event Package with the XCAP Diff
    Format

   As discussed in Section 5.1.4, if a client subscribing to the Pending
   Additions event package generates an Accept header field that
   includes the MIME type "application/xcap-diff+xml", the relay has the
   option of returning documents in this format (instead of in the
   'application/consent-pending-additions+xml' format).




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   Upon initial subscription, the relay does not know which instance of
   the resource list document for the user (where each instance is
   identified by an etag) the client currently possesses, if any.
   Indeed, upon startup, the client will not have any documents.

   The initial NOTIFY request in this case MUST include a <document>
   element for the resource list.  The "previous-etag" attribute MUST be
   absent, and the "new-etag" attribute MUST be present and contain the
   entity tag for the current version of the document.  An XCAP diff
   document structured this way is called a "reference" XCAP diff
   document.  It establishes the baseline etag and document URI for the
   document covered by the subscription.

   Upon receipt of this document, the client can determine whether its
   local instance document, if any, matches the etag in the XCAP diff
   document.  If they do not match, the client SHOULD perform a
   conditional GET for each document.  The document URI is constructed
   by appending the XCAP root in the "xcap-root" attribute of the <xcap-
   diff> element to the escape coded "doc-selector" from the <document>
   element.  The request is made conditional by including an If-Match
   header field, with the value of the etag from the <document> element.
   So long as the documents have not changed between the NOTIFY and the
   GET, the client will obtain the reference version that the server
   will use for subsequent notifications.

   If the conditional GET should fail, the client SHOULD generate a
   SUBSCRIBE refresh request to trigger a new NOTIFY.  The server will
   always generate a "reference" XML diff document on receipt of a
   SUBSCRIBE refresh.  This establishes a new baseline etag, and the
   client can then attempt to do another fetch.

   Once the client has obtained the version of the document identified
   in the reference XML diff, it can process NOTIFY requests on that
   subscription.  To process the NOTIFY requests, it makes sure that its
   current version matches the version in the "previous-etag" attribute
   of the <document> element.  If not, the client can then fetch the
   updated document from the server.  If they do match, the client has
   the most current version.


7.  IANA Considerations

   There are three IANA considerations associated with this
   specification.







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7.1.  SIP Event Package Registration

   This specification registers a SIP event package per the procedures
   in [3].

   Package name: consent-pending-additions

   Type: package

   Contact: Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com>

   Published Specification: RFC XXXX.  (Note to the RFC Editor: Please
   replace XXXX with the RFC Number of this specification.)

7.2.  URN Sub-Namespace Registration

   This section registers a new XML namespace per the procedures in [4].

   URI: The URI for this namespace is
   urn:ietf:params:xml:ns:consent-status

   Registrant Contact: IETF SIPPING working group, <sipping@ietf.org>,
   Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com>



   XML:

   <?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>Pending Additions Extension Namespace</title>
   </head>
   <body>
     <h1>Namespace for Consent-related Status Information Extension</h1>
     <h2>urn:ietf:params:xml:ns:consent-status</h2>
     <p>See <a href="[URL of published RFC]">RFCXXXX [[NOTE TO
   RFC-EDITOR/IANA: Please replace XXXX with the RFC Number of
   this specification]]</a>.</p>
    </body>
   </html>






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7.3.  XML Schema Registration

   This section registers an XML schema per the procedures in [4].

   URI: urn:ietf:params:xml:schema:consent-status.

   Registrant Contact: IETF SIPPING working group, <sipping@ietf.org>,
   Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com>

   The XML for this schema can be found in Section 4.


8.  Security Considerations

   Subscriptions to the Pending Additions even package can reveal
   sensitive information.  For this reason, it is RECOMMENDED that
   relays use strong means for authentication and information
   confidentiality.  Additionally, attackers may attempt to modify the
   contents of the notifications sent by a relay to its clients.
   Consequently, it is RECOMMENDED that relays use a strong means for
   information integrity protection.

   It is RECOMMENDED that relays authenticate subscribers using the
   normal SIP authentication mechanisms, such as Digest, as defined in
   RFC 3261 [2].

   The mechanism used for conveying information to clients SHOULD ensure
   the integrity and confidentially of the information.  In order to
   achieve these, an end-to-end SIP encryption mechanism, such as
   S/MIME, as described in RFC 3261 [2], SHOULD be used.

   If strong end-to-end security means (such as above) is not available,
   it is RECOMMENDED that hop-by-hop security based on TLS and SIPS
   URIs, as described in [2], is used.


9.  Acknowledgements

   Jonathan Rosenberg provided useful ideas on this document.  Ben
   Campbell and Mary Barnes performed a thorough review of this
   document.


10.  References







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10.1.  Normative References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [2]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
        Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
        Session Initiation Protocol", RFC 3261, June 2002.

   [3]  Roach, A., "Session Initiation Protocol (SIP)-Specific Event
        Notification", RFC 3265, June 2002.

   [4]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
        January 2004.

   [5]  Rosenberg, J., "The Extensible Markup Language (XML)
        Configuration Access Protocol (XCAP)", draft-ietf-simple-xcap-12
        (work in progress), October 2006.

   [6]  Rosenberg, J., "Extensible Markup Language (XML) Formats for
        Representing Resource Lists",
        draft-ietf-simple-xcap-list-usage-05 (work in progress),
        February 2005.

   [7]  Rosenberg, J., "An Extensible Markup Language (XML) Document
        Format for Indicating A Change  in XML Configuration Access
        Protocol (XCAP) Resources", draft-ietf-simple-xcap-diff-04 (work
        in progress), October 2006.

   [8]  Rosenberg, J., "A Framework for Consent-Based Communications in
        the Session Initiation  Protocol (SIP)",
        draft-ietf-sip-consent-framework-01 (work in progress),
        November 2006.

10.2.  Informative References


Author's Address

   Gonzalo Camarillo
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: Gonzalo.Camarillo@ericsson.com





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Full Copyright Statement

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   This document is subject to the rights, licenses and restrictions
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Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





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