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Versions: 00 02 03 04 05                                                
SIPPING                                                        D. Petrie
Internet-Draft                                                SIPez LLC.
Intended status: Standards Track                        S. Channabasappa
Expires: May 20, 2008                                          CableLabs
                                                              S. Ganesan
                                                                Motorola
                                                       November 17, 2007


 A Schema and Guidelines for Defining Session Initiation Protocol User
                         Agent Profile Datasets
              draft-petrie-sipping-profile-datasets-05.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
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   This Internet-Draft will expire on May 20, 2008.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines the requirements and a format for SIP user
   agent profile data.  An overall schema is specified for the
   definition of profile datasets.  The schema also provides for
   expressing constraints for how multiple sources of profile data are



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   to be combined.  This document provides a guide to considerations,
   policies and syntax for defining datasets to be included in profile
   data.  It also explores some specific datasets to test the
   requirements, assumptions and syntax.


Table of Contents

   1.  Motivation . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Requirements Terminology . . . . . . . . . . . . . . . . .  5
     2.2.  Profile Data Terminology . . . . . . . . . . . . . . . . .  5
     2.3.  Overview . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Design Considerations  . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . .  6
       3.1.1.  Outbound Proxy Setting . . . . . . . . . . . . . . . .  7
       3.1.2.  Codec Settings . . . . . . . . . . . . . . . . . . . .  8
       3.1.3.  Transport Protocol Setting . . . . . . . . . . . . . . 11
     3.2.  Requirement Descriptions . . . . . . . . . . . . . . . . . 13
       3.2.1.  Implementer Extensibility  . . . . . . . . . . . . . . 13
       3.2.2.  Flexible Capabilities  . . . . . . . . . . . . . . . . 13
       3.2.3.  XML  . . . . . . . . . . . . . . . . . . . . . . . . . 14
       3.2.4.  Access Control . . . . . . . . . . . . . . . . . . . . 14
       3.2.5.  Data Constraints and Range Definition  . . . . . . . . 15
       3.2.6.  Support of User, Application, Device, Local
               Network Sources  . . . . . . . . . . . . . . . . . . . 15
       3.2.7.  The Ability to Specify Policy  . . . . . . . . . . . . 16
   4.  Overall Dataset Schema . . . . . . . . . . . . . . . . . . . . 17
     4.1.  Data Primitives  . . . . . . . . . . . . . . . . . . . . . 17
     4.2.  Use of Namespaces  . . . . . . . . . . . . . . . . . . . . 18
     4.3.  The 'propertySet' Element  . . . . . . . . . . . . . . . . 18
     4.4.  The Abstract 'setting_container' Element . . . . . . . . . 18
     4.5.  The Abstract 'setting' Element . . . . . . . . . . . . . . 18
       4.5.1.  The 'visibility' Attribute . . . . . . . . . . . . . . 19
       4.5.2.  The 'policy' Attributes  . . . . . . . . . . . . . . . 19
       4.5.3.  The 'excludedPolicy' Attributes  . . . . . . . . . . . 20
       4.5.4.  The 'direction' Attribute  . . . . . . . . . . . . . . 20
       4.5.5.  The 'q' Attribute  . . . . . . . . . . . . . . . . . . 20
     4.6.  The 'profileUri' Element . . . . . . . . . . . . . . . . . 21
     4.7.  The 'profileCredential' Element  . . . . . . . . . . . . . 21
       4.7.1.  realm Element  . . . . . . . . . . . . . . . . . . . . 21
       4.7.2.  authUser Element . . . . . . . . . . . . . . . . . . . 22
       4.7.3.  a1Digest Element . . . . . . . . . . . . . . . . . . . 22
       4.7.4.  password Element . . . . . . . . . . . . . . . . . . . 22
     4.8.  The 'profileContactUri' Element  . . . . . . . . . . . . . 22
     4.9.  The 'profileInfo' Element  . . . . . . . . . . . . . . . . 23
     4.10. Example Profile Dataset  . . . . . . . . . . . . . . . . . 23
     4.11. Merging Property Sets  . . . . . . . . . . . . . . . . . . 24



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       4.11.1. Single Numeric Value Merging Algorithm . . . . . . . . 25
       4.11.2. Multiple Enumerated Value Merging Algorithm  . . . . . 25
       4.11.3. Closest Value First Merging Algorithm  . . . . . . . . 26
     4.12. Common Types . . . . . . . . . . . . . . . . . . . . . . . 27
   5.  Defining Data Sets . . . . . . . . . . . . . . . . . . . . . . 27
     5.1.  Namespace  . . . . . . . . . . . . . . . . . . . . . . . . 27
     5.2.  Property Definitions . . . . . . . . . . . . . . . . . . . 27
     5.3.  Merging Data Sets  . . . . . . . . . . . . . . . . . . . . 28
   6.  Candidate Data Sets  . . . . . . . . . . . . . . . . . . . . . 28
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 29
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 29
     8.1.  Content-type registration for
           'application/uaprofile+xml'  . . . . . . . . . . . . . . . 29
   9.  Change History . . . . . . . . . . . . . . . . . . . . . . . . 30
     9.1.  Changes from draft-petrie-sipping-profile-datasets-04  . . 30
     9.2.  Changes from draft-petrie-sipping-profile-datasets-03  . . 30
     9.3.  Changes from draft-petrie-sipping-profile-datasets-02  . . 31
     9.4.  Changes from draft-petrie-sipping-profile-datasets-01  . . 31
     9.5.  Changes from draft-petrie-sipping-profile-datasets-00  . . 31
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 32
     10.2. Informative References . . . . . . . . . . . . . . . . . . 33
   Appendix A.  Relax NG SIP UA Profile Schema  . . . . . . . . . . . 33
   Appendix B.  Acknowledgments . . . . . . . . . . . . . . . . . . . 38
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38
   Intellectual Property and Copyright Statements . . . . . . . . . . 40

























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1.  Motivation

   Today all SIP user agent implementers use proprietary means of
   expressing and delivering user, device, and local network profile
   information to the user agent.  The SIP User Agent Profile Delivery
   Framework [I-D.ietf-sipping-config-framework] and the Framework for
   Session SIP Session Policies
   [I-D.hilt-sipping-session-policy-framework] specify how SIP user
   agents locate and retrieve profile data specific to the user, the
   device, and the local network.  It is important for SIP User Agents
   to be able to obtain and use these multiple sources of profile data
   in order to support a wide range of applications without undue
   complexity.

   While these frameworks define the mechanisms for transmitting profile
   data, they do not define a format for the actual profile data.  This
   document defines the requirements, the default/manditory to support
   content type for [I-D.ietf-sipping-config-framework], a high level
   schema for, and guide to how these datasets can be defined.  The goal
   is to enable any SIP user agent to obtain profile data and be
   functional in a new environment independent of the implementation or
   model of user agent.  The nature of having profile data from four
   potential sources requires the definition of policies on how to apply
   the data in an interoperable way across implementations which may
   have widely varying capabilities.

   The ultimate objective of the framework described in the SIP User
   Agent Profile Delivery Framework and this document is to provide a
   start up experience similar to that of users of an analog telephone.
   From the point of view of a user, you just plug in an analog
   telephone and it works (assuming that you have made the right
   arrangements with your local phone company).  There is no end user
   setup required to make an analog phone work, at least in a basic
   sense.  So the objective here is to be able to take a new SIP user
   agent out of the box, plug it in or install the software and have it
   get its profiles without human intervention other than security
   measures.  This is necessary for cost effective deployment of large
   numbers of user agents.  All user agents do not provide telephone
   capabilities, but the user set up experience goal is applicable to
   most of the range of user agent capabilities.


2.  Introduction








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2.1.  Requirements Terminology

   Keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT" and
   "MAY" that appear in this document are to be interpreted as described
   in RFC 2119[RFC2119].

2.2.  Profile Data Terminology

   property -  a named configurable characteristic of a user agent.  A
      given property has a well-defined range of possible values.  A
      given property may be defined to have a range of values, allow for
      simultaneous use of many values (as in a list of allowed
      possibilities), or a set of related values that collectively form
      a single profile information item.
   setting -  the binding of a specific value or set of values to a
      given property.
   profile -  a collection of settings to be applied for a specific
      user, device, or local network.
   device -  SIP user agent, either software or hardware appliance.
      This is a logical concept, as there may be no physical dedicated
      device or it may be part of an assembly of devices.  In this
      document, the terms "user agent" and "device" are interchangeable.
   user profile -  the profile that applies to a specific user.  This is
      best illustrated by the "hotelling" use case - a user has an
      association for some period of time with a particular device.  The
      user profile is that set of profile data the user wants to
      associate with that device (e.g. ringtones used when someone calls
      them, the user's shortcuts).
   device profile -  data profile that applies to a specific device.  In
      the "hotelling" use case, this is the data that is bound to the
      device itself independent of the user.  It relates to specific
      capabilities of the device and/or preferences of the owner of the
      device.
   local network profile -  data that applies to the user agent in the
      context of the local network.  This is best illustrated by roaming
      applications; a new device appears in the local network (or a
      device appears in a new network, depending on the point of view).
      The local network profile includes settings and perhaps policies
      that allow the user agent to function in the local network (e.g.
      how to traverse NAT or firewall, bandwidth constraints).
   dataset -  a collection of properties.
   working profile -  the set of property values actually set in a SIP
      User Agent as a result of merging the profiles from all sources;
      the actual effective profile for the user agent .







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   merging -  the operation of resolving overlapping settings from
      multiple profiles.  Overlap occurs when the same property occurs
      in multiple profiles (e.g. device, user, application, local
      network).

2.3.  Overview

   In this document requirements are specified for containing and
   expressing profile data for use on SIP user agents.  Though much of
   this can be considered independent of SIP there is one primary
   requirement that is not well satisfied through more generic profile
   data mechanisms.  SIP User Agent set up requires the agent to merge
   settings, which may overlap, from potentially four different sources
   (see [I-D.ietf-sipping-config-framework]); each source must not only
   be able to provide profile information, but also express policies
   regarding how the profile settings may be combined with that from
   other sources.

   A schema and syntax is defined in this document to specify properties
   that may be aggregated to construct profiles.  The general design
   philosophy is that many small datasets provide flexibility to the
   implementer to support the aggregated set that best matches the
   capability of the user agent.  The actual properties are not defined
   in this document (see [I-D.ietf-sipping-media-policy-dataset] and
   [reference: Core SIP Dataset]).  However, some examples are explored
   here to illustrate the proposed mechanisms and to validate the
   requirements.

   This document defines a set of considerations, syntax and policies
   that must be specified when defining datasets.  These are to help
   authors of dataset specifications to define datasets that will work
   in the overall schema defined in this document.  The actual
   specification of these datasets is outside the scope of this
   document.


3.  Design Considerations

   The following section defines some of the design considerations that
   were taken into account when defining the schema, syntax and policies
   for generating and applying profile data.  Section 3.2.6 describes
   need for merging of the four dataset sources provided in
   [I-D.ietf-sipping-config-framework].

3.1.  Use Cases

   In the following use case scenarios the device profile is provided by
   the device owner/manager.  The owner/manager may be a service



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   provider, an enterprise or a user administering the device setup.
   The user is assumed to be the end user operating the user agent to
   perform SIP functions such as telephony, IM etc.  In the scenarios
   that the user profile is provided, the user profile contains user
   specific properties that the end user has set directly or indirectly
   through an administration process.  The local network profiles
   represent the suggested policy behavior that the local network
   operator would like user agents to adhere to
   [I-D.hilt-sipping-session-policy-framework].  From a security
   perspective, the local network operator cannot trust the user agent
   to follow the local network profile policy.  The local network
   operator must use a means external to the user agent to enforce these
   policies.  The local network profile is intended to express to the
   user agent, the policies that the user agent should follow if the
   user agent wants to function properly in the local network.

3.1.1.  Outbound Proxy Setting

   First consider the use cases for a simple user agent property: the
   outbound proxy.  It is not likely that the user would want to
   influence the outbound proxy for SIP signaling.  Conceptually an
   application might wish to use a specific outbound proxy for signaling
   related to that application.  For this use case, assume that the only
   the device owner/manager or the local network operator are likely to
   want to set the outbound proxy property.  The device profile defines
   an outbound proxy perhaps so that the device owner/manager can
   monitor all signaling.  The local network operator also defines an
   outbound proxy because the proxy allows the SIP signaling to get
   through a NAT or firewall.

   It seems there are few possible solutions to this conflict resolution
   problem:
   o  The simple solution is to define a policy where the local network
      profile overrides the device profile.  In this approach the local
      network profile wins.
   o  A comprehensive solution is to allow the aggregation of the
      outbound proxies.  In this scenario SIP messages would be sent
      with a pre-populated route set that had two hops.  First the
      outbound proxy set in the local network profile, then the outbound
      proxy set in the device profile.

   The aggregation approach is closest to solving the requirements to
   the use case above.  By aggregating the two outbound proxies, the
   local network provided outbound proxy allows the signaling to get out
   of the local network and the device profile provided outbound proxy
   is able to monitor all SIP signaling from the user agent.





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3.1.2.  Codec Settings

   Use cases for the codec properties are illustrated here as they are
   likely one of the more complicated sets of properties with respect to
   merging and constraining across more than one profile.  There are
   reasonable scenarios where requirements can be rationalized that the
   device, user and local network profiles may each wish to express
   preferences and constrains of the codec properties.  Without getting
   into details or syntax of the codec properties, it is assumed that
   codec properties will need to express a codec definition and a
   preference order.  This is the order that these codecs will be put in
   SDP for codec negotiation purposes.

   The following scenarios illustrate some possible combinations of
   sources of codec properties from the device, user and local network
   profiles.  The scenarios identify rationale for providing codec
   properties in each of the profiles.

3.1.2.1.  Codec Setting Not Set

   In the scenario where a device has no profiles or the profiles
   contain no codec properties, the device will enable a default set and
   preference order of codecs.  The default set and preference order of
   codecs is a implementer specific choice.  In some implementations it
   is s subset of the codecs supported by the device.

3.1.2.2.  Codec Set in Device Profile

   Let us assume a scenario where user agents providing telephony
   capabilities are deployed.  The deployment has very simple
   requirements such that the user agents have fixed locations and are
   always associated with the same user.  This scenario does not need
   the separation between the user, device and local network profiles.
   A single profile would suffice.  Another scenario having similar
   requirements is one where the user and local network profiles do not
   provide any codec related properties.  This might be because the user
   does not care what codecs are used and the local network does not
   wish to impose any constraints on the codes used in the network.  In
   the following use case, the device profile is the only source of
   codec properties.

   The codecs in the device profile may differ from the set of codecs
   supported by the device, due to the administrator of the device
   profile wanting:
   o  To have a uniform set of codecs used across all device types
   o  To exclude the use of a specific codec due to performance issues/
      concerns




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   The resulting device profile data further will constrain the list of
   codecs that get applied.  In addition, the administrator may want to
   list the order of which the codecs are to be applied.  In this
   scenario the device profile data will dictate the ordered list of
   codecs to be applied.  The use agent will ignore codec types included
   in the profile that the user agent does not support.

3.1.2.3.  Set in Device and User Profiles

   In the following scenario users are allowed to express a preference
   over codecs.  Users are probably not likely to express specific codes
   in the form of G.7XX, etc.  They are likely to want to express a
   preference in the form of wideband, normal and low bandwidth.  In the
   following use case, device and user profiles contain codec
   properties.

   The user may prefer a higher quality codec to be used, if available.
   Thereby the user profile data may provide an ordered list of codecs
   to be applied.  The device profile also specifies a list of codecs
   and a default preference order.

   The merging of the data sources is as follows:
   o  The ordering of the codecs will be determined from the user
      profile data, which overrides the codec preference ordering from
      the device profile data.
   o  The set of codecs that may be applied, are the codecs listed in
      the user data constrained by the list of codecs from the device
      profile data.

   The case in which none of the codecs in the resulting merged profile
   datasets are supported by the device, the profile data constitutes a
   misconfiguration between device and user profiles.  It may not be
   possible to successfully establish a session in this case.  It is
   suggested that the user agent provide feedback to the user indicating
   the misconfiguration.  The user agent may also attempt to function in
   the network by ignoring one or more of the profile constraints.

3.1.2.4.  Set in Device and Local Profiles

   In another scenario the user is not allowed or does not care to
   express codec preferences.  The owner/manager of the device defines
   the set of codecs which may be used on the device along with a
   preference ordering of codecs.  There is no user profile or the user
   profile contains no codec properties.  The local network wishes to
   define a policy over codec usage in the network.  It is not clear
   there is a requirement that the local network be able to express a
   preference order.  However the network operator is very likely to
   want to express a set of codecs that can or should not be used.  The



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   constraints that the local network operator wishes suggest may relate
   to the goal of controlling bandwidth or conveying what will work over
   the available WAN connection.  In the following use case, device and
   local network profiles provide codec properties.  The local network
   may limit the type of codecs that can be applied due to resources
   available.

   The merging of the data sources is as follows:
   o  The set of codecs that may be used is the ordered list of codecs
      from the device profile data, further constrained by the local
      network profile data.

   The case in which none of the codecs in the resulting merged profile
   datasets are supported by the device, the profile data constitutes a
   misconfiguration between local network and device.  It may not be
   possible to successfully establish a session in this case.  It is
   suggested that the user agent provide feedback to the user indicating
   the misconfiguration.  The user agent may also attempt to function in
   the network by ignoring one or more of the profile constraints.

3.1.2.5.  Set in Device, User and Local Profiles

   In this scenario everyone has an opinion on the codecs to be used.
   The device owner/manager wishes to define a set of codes based upon
   best interoperability of known end points in the environment.  The
   user wishes to express preferences in the codecs (e.g. prefers
   wideband audio).  The local network wishes to constrain the codecs
   based upon bandwidth (e.g. a wireless network with limited local
   network bandwidth, a SOHO network with dialup connectivity, a small
   office with shared 256kbps WAN connectivity).  In the following
   scenario, device, user and local network profiles provide codec
   properties.

   The merging of the data sources is as follows:
   o  The ordering of the codecs will be determined from the user
      profile data, which overrides the ordering from the device profile
      data.
   o  The set of codecs that may be used are the codecs listed in the
      device profile data, constrained by the list of codecs from the
      user profile data and further constrained by the list of codecs
      from the local network profile data.

   The case in which none of the codecs in the resulting merged profile
   datasets are supported by the device, the profile data constitutes a
   misconfiguration between device, user and local network profiles.  It
   may not be possible to successfully establish a session in this case.
   It is suggested that the user agent provide feedback to the user
   indicating the misconfiguration.  The user agent may also attempt to



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   function in the network by ignoring one or more of the profile
   constraints.

3.1.2.6.  Derived Requirements

   1.  A device will have a set of codecs supported, that may be
       offered.  The list of codecs supported by a device may differ
       from the list of codecs in the device profile data.  The list of
       codecs in the device profile data that get applied is the subset
       of the codecs supported by the device.  Codecs listed in profiles
       that are not supported by the device are ignored.
   2.  The device profile data will have a default ordered list of
       codecs, which implies a preference order that may be offered.
   3.  The user profile data may provide an ordered list of user
       preferred codecs.  The ordering of the codecs in the user profile
       data will override the ordering of the codecs in the device
       profile data.  The user list of codecs may further constrain the
       list of codecs to be used.
   4.  The local network profile data may provide a list of codecs
       supported.  This list will further constrain the list of codecs
       that may be offered.
   5.  The application profile data containing codec data will be
       ignored.
   6.  The profiles need the ability to express codecs that may be used
       and codecs that should not be used.

3.1.3.  Transport Protocol Setting

   This section describes use cases related to the use of the SIP
   transport protocol settings for a user agent.  It is assumed that
   user agents are configurable to define what transport protocols (e.g.
   UDP, TCP, TLS) are to be used for the SIP signaling as well as the
   default order in which to attempt each of the protocol.

3.1.3.1.  Setting Not Set

   When none of the profiles are available or the profiles do not
   specify the SIP transport protocol setting, the device's default
   signaling transport(s) will be used.

3.1.3.2.  Set in Device Profile

   In the following scenario, the device profile is the only source of
   profile data.  The signaling transports contained in the device
   profile may differ from the set of signaling transports supported by
   the device.  This may be due to the administrator of the device
   profile wanting:




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   o  To have a uniform use of signaling transports used across all
      device types.
   o  To mandate TLS for security reasons.
   o  To exclude the use of a specific signaling transport due to
      performance issues/concerns.
   o  To indicate the preferred, default order in which to attempt using
      each of the transport protocols.

   This will result in the device profile data further constraining the
   list of signaling transports that could be used.  The highest
   preference ordered signaling transport from the device profile
   dataset will be used first.

3.1.3.3.  Set in Device and User Profiles

   The following scenario extends the prior case described above.  SIP
   transport protocol properties are provided in both the device and
   user profiles.  Consider that SIP user agents, like email agents, may
   want to provide the user with options to:
   o  Mandate that secure transport must be used.  If secure transport
      is not possible the user does not want to use the user agent.
   o  Prefer secure transport.  Attempt to use secure transport.  If
      secure transport will not work, use which ever transport protocol
      will make communication work.

   When the user mandates the use of secure signaling transports only,
   the user wishes to constrain the available signaling transports to
   TLS.  When indicating a preference to secure transport, the use is
   specifying a preference order for the use of transport protocols
   where TLS is the highest priority.

   Now consider the merging strategy required to accomplish the goals of
   this use case scenario where the device and user profiles both
   contain SIP transport protocol properties.  The merging of the data
   sources is as follows:
   o  The set of signaling transports that are allowed to be used is
      constrained by the device profile data.  This is further
      constrained by the user profile data.
   o  The signaling transports attempted will be those from the merged,
      constrained list in order of highest to lowest priority.

3.1.3.4.  Set in Device and Local Profiles

   In the following scenario, device and local network profile data is
   available.  The local network may have a limited set of signaling
   transports that it supports due to NAT or firewall constraints.

   The merging of the data sources is as follows:



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   o  The set of signaling transports that may be used is the ordered
      list of signaling transports from the device profile data, further
      constrained by the local network profile data.

   The case in which none of the local network data signaling transports
   are supported by the device profile data constitutes a
   misconfiguration between local network and device.  The device might
   not be able to successfully establish a session in this case.

3.1.3.5.  Derived Requirements

   1.  A device will have a set of signaling transports that it supports
       (note: one can be a set), with a default signaling transport.
   2.  The set of signaling transports supported by a device may differ
       from the set of signaling transports in the device profile data.
       The set of signaling transports in the device profile data is an
       ordered list, that is a subset of the set of signaling transports
       supported by the device.  This may be due to performance issues
       associated with one of the signaling transport(s).
   3.  The user profile data may provide a list of preferred signaling
       transports to be used (e.g., TLS for securing the signaling).
   4.  The local network profile data provides a list of signaling
       transports supported, and will constrain the set of signaling
       transports that could be used.

3.2.  Requirement Descriptions

3.2.1.  Implementer Extensibility

   Implementers must be able to differentiate each implementation.  In
   addition, it does not serve user agent owners and administrators well
   to require an orchestrated upgrade for all user agent implementations
   and profile delivery servers before a new capability or feature can
   be supported with the required profile data.  Hence one of the most
   important requirements is to support the ability of implementers to
   extend specified standard datasets to include additional related
   features and flexibility.  It MUST be possible to extend a dataset
   without breaking user agents that support that dataset.  This may
   require that user agents ignore parts of a dataset that it does not
   implement or extensions that it does support.

3.2.2.  Flexible Capabilities

   User agents vary quite widely in their capabilities.  Some user
   agents function like traditional telephones.  Some user agents
   support only text messaging.  Some user agents support many media
   types such as video.  Some user agents that function like a telephone
   have a single line, some have large numbers of lines.  There is no



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   such thing as one size fits all.  It MUST be possible for an
   implementer to choose which datasets to support based upon the
   capabilities that are supported by the user agent.  The schema for
   containing the profile data MUST support a profile that contains only
   the data sets that a user agent supports.  This allows the profile
   delivery server to create small profiles for specific devices.
   However a user agent SHOULD ignore properties for capabilities that
   it does not support.  This allows the profile delivery server to be
   ignorant of the capabilities of the device.  The degree to which the
   profile delivery server has intelligence of the user agent
   capabilities is an implementation choice.

3.2.3.  XML

   XML is perhaps not really a requirement, but a solution base upon
   requirements.  However it is hard to ignore the desire to utilize
   readily available tools to manage and manipulate profile data such as
   XSLT, XPATH and XCAP.  The requirement that should be considered when
   defining the schema and syntax is that many user agents have limited
   resources for supporting advanced XML operation.  The simplest XML
   construct possible should be used, that support the required
   functionality.  It is not a requirement that user agents validate the
   profile XML document.  This relieves the requirement that the Relax
   NG schema defined in this and other datasets documents be enforced on
   the user agent.  The Relax NG schema should not be used to strictly
   validate profile XML documents.  Unknown elements and attributes
   should be ignored to allow extensions to be supported.  Strict
   enforcement of the Relax NG schema would make it very difficult to
   deploy new user agents without lock step upgrades of the profile
   delivery server.  Guidelines for the Use of Extensible Markup
   Language (XML) within IETF Protocols [RFC3470] provides useful
   information in this regard.

3.2.4.  Access Control

   Many user agents (e.g. appliances and softphones running on PCs)
   provide user interfaces that permit the user to edit properties that
   are logically part of user, application, device or local network
   profiles.  Operators and administrators would like to be able to
   specify what an end user can change in those profiles and what an end
   user is not allowed to change.  There may also be sensitive data the
   user agent requires to function, but that the operator of the system
   does not want the end user to see.  For some properties the system
   operator may allow the user a fixed set of choices among the
   supported set of possible values.  It MUST be possible to express
   whether an end user may change a dataset property.  It MUST be
   possible to express that a property should not be made visible to the
   end user.  It MUST be possible to express allowable values or ranges



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   that the end user may change a property to.  The access control
   information SHOULD be optional to the dataset.  It might be useful if
   it was possible to express the access control independent of the
   properties themselves.  The access control specification by itself
   might be useful to express a general policy that the device owner or
   local network operator wish to impose.

3.2.5.  Data Constraints and Range Definition

   There is a need for property value types such as free form text,
   token/enumerations, integers, real numbers, etc.  Many of these
   properties will have constrained values as opposed to the range of
   all possible values.  These constrains may be due to protocol
   definitions, implementation limitations, and/or the desire (e.g. by
   the user, device owner, local network operator) to impose policy on
   the user agent.  The ability to express the property constraints is
   useful from the perspective of access control as described in the
   above section.  It is also useful to parameterize a user interface
   (e.g. on the user agent itself or on the profile delivery server)
   which provides a facility to modify profile data.  It MUST be
   possible for the schema to specify property constraints as ranges or
   discrete sets of possible values.  These constrains SHOULD be
   optional to the dataset.  It might be useful if it was possible to
   express the constraints independent of the properties themselves.
   The constraints without the property values might be used to specify
   the capabilities of a particular user agent implementation.

3.2.6.  Support of User, Application, Device, Local Network Sources

   [I-D.ietf-sipping-config-framework] specifies a mechanism where the
   user agent retrieves profile data from as many as four different
   sources.  The separation of the user profile facilitates a hotelling
   capability and the ability to easily re-assign a user to a different
   device.  The separation of the local network profile facilitates
   properties specific to operating in the local network in a roaming
   scenario (e.g. outbound proxy or NAT traversal properties).  The
   local network profile may also impose policy as describe in the next
   section.  The device profile facilitates device capability based
   properties as well as a means for the device owner or manager (e.g.
   enterprise or service provider) to impose policy.

   The multiple potential sources of profile data add some complexity to
   the user agent that must consolidate these separate profiles into a
   single working profile.  It would be simpler if we could define each
   property as only allowed in one of the profiles.  However it overly
   constrains the profiles and takes away desired functionality such as
   hotelling, roaming and shared profile management.  It would also be
   simpler if we could define one rule for all profile datasets and



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   properties by which we merge the profile (e.g. local network profile
   overwrites user profile which overwrites device profile for all
   data).  However this too is overly restrictive and eliminates some
   very useful functionality.

   The rules to merge profile datasets needs to be defined for each
   dataset.  In some cases an entire dataset must be considered atomic
   when merging one profile source with another.  In other cases it
   makes sense to merge profile datasets, aggregating properties from
   the dataset provided in each of the profiles.  It may also be
   desirable to have the effect of filtering of dataset properties.  The
   desired effect might be for the owner of the device or the local
   network operator to constrain what values are allowed for properties
   in the profiles.  This may also be the mechanism to facilitate
   imposing of policy as described in the next section.  The operation
   of resolving overlapping datasets from multiple profiles, regardless
   of the means or net result, will be referred to as "merging" in this
   document.

   A profile must have the means to constrain the merging algorithm.
   Due to the differences in the desired outcome for each data setting,
   the merging algorithm is specific to the setting.  When defining a
   property setting, the merging algorithm must also be defined.  A few
   of the more commonly used merging algorithms are defined in this
   document.  Most settings are likely to use the common set defined in
   this document.  However authors of profile datasets may define new
   algorithms for merging dataset properties (see Section 4.11 and
   Section 5.3).

3.2.7.  The Ability to Specify Policy

   Local network operators would like to impose policy on users and
   devices operating in their network.  There is a need to constrain the
   operation and require specific behavior in the network.  This might
   be as simple as to get access to the Internet, user agents must use a
   specified outbound proxy and NAT traversal mechanism.  The network
   might have limited bandwidth such that the operator would like to
   constrain codecs or media streams to keep the network functional.
   The local network may provide emergency service behavior or
   functionality properties that are more specific than those provided
   by the device or user profile.  The examples here focus on
   constraints to impose policy from the local network.  However the
   facility to impose policy may be equally useful to the user and
   device profiles.

   It MUST be possible to impose policy in any of the profile sources
   that constrains, overwrites or modifies properties provided in
   datasets from other sources.



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4.  Overall Dataset Schema

   Notifiers and Subscribers of the event package defined in
   [I-D.ietf-sipping-config-framework] SHOULD support the content-type:
   application/uaprofile+xml.  The Notifier SHOULD indicate all of the
   dataset schemas that is supports by listing all of the MIME types for
   the supported datasets in the SUBSCRIBE request header: Accept.  This
   document defines an Relax NG Schema for that content-type with the
   namespace: urn:ietf:params:xml:ns:uaprof, for SIP Profile Datasets
   that provides:
   o  a base element type "setting" from which all settings in other
      schema definitions inherit (this allows other definitions to
      specify the content models for ways of combining settings; it is
      analogous to a C++ virtual base class).
   o  Attributes to the "setting" element that define constraints and
      other properties used to impose policy that apply to the element
      value.  These attributes are inherited by elements that are
      derived from the abstract settings element.
   o  A root element for all property sets (the outermost container).

   The full text of the schema is in Appendix A; the following describes
   the usage of the schema in defining properties and combining them to
   construct the working profile of a User Agent.

4.1.  Data Primitives

   Each property in a profile data set is defined using XML Schema
   Datatypes [W3C.REC-xmlschema-2] and Relax NG Schema.  A property is
   modeled by an XML element derived from the "setting" element in the
   SIP Profile Data Set Schema.  The element content is the setting
   value.

   Properties consisting of one single value can be expressed using a
   single XML element.  Properties that may consist of multiple values
   require the use of container elements.  A container element is
   defined for such a property.  This container can contain multiple XML
   elements, which each defines a possible value for that property (see
   examples in Section 4.5.2).

   When constructing a property set, the creator of a profile may not be
   able to know all of the capabilities of the User Agent that will
   receive that property set.  The creator of profile constraints or
   policies should be aware that a user agent may ignore properties that
   are unsupported or do not apply to its capabilities.







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4.2.  Use of Namespaces

   XML namespaces [W3C.REC-xml-names-19990114] provide a means to
   uniquely identify the elements and datatypes defined in a data set.
   It is therefore RECOMMENDED that each data set specifies its own
   namespace.  The namespace URIs SHOULD be URNs [RFC2141], using the
   namespace identifier 'ietf' defined by [RFC2648] and extended by
   [I-D.mealling-iana-xmlns-registry].  The core schema defined in this
   document defines the namespace: "urn:ietf:params:xml:ns:uaprof".
   Profile datasets that extend this schema SHOULD define a new
   namespace by appending a ":" and a unique name to the
   "urn:ietf:params:xml:ns:uaprof" namespace.  These namespaces MUST be
   registered with IANA.

4.3.  The 'propertySet' Element

   The root element of a property set is "propertySet"; it is the
   container that is provided to the user agent.  The elements contained
   within a propertySet contain the specific properties which are to be
   applied to the user agent.  The properties may be simple types with a
   single value, complex types or container elements with a list of
   properties.

4.4.  The Abstract 'setting_container' Element

   The "setting_container" element is the abstract element in which a
   list of properties which allow mutliple values may be contained.
   Elements derived from the "setting_container" element may contain
   zero or more elements derived from the "setting" element.  The
   "setting_container" element has an "excludedPolicy" attribute.

4.5.  The Abstract 'setting' Element

   The setting element is the abstract element from which all profile
   properties or settings shall inherit.

   The setting element has a number of attributes that provide
   functionalities, which are generally useful for many properties.
   These attributes are inherited by properties that are derived from
   the settings element.  This enables the re-use of common
   functionalities and ensures a common syntax for these elements across
   different data sets.  The following functionalities are provided by
   attributes of the settings element:

   o  Property Access Control: 'visibility' attribute
   o  Policies: 'policy' attribute

   Additional attributes are defined in the schema that may used in



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   elements derived from "setting".  By default these attributes cannot
   be set.  These attribute must be explicitly added to elements derived
   from the "setting" element:

   o  Unidirectional Properties: 'direction' attribute
   o  Preferences: 'q' attribute

4.5.1.  The 'visibility' Attribute

   The attribute "visibility" is defined on the "setting" element to
   specify whether or not the user agent is permitted to display the
   property value to the user.  This is used to hide setting values that
   the profile administrator may not want the user to see or know.  The
   "visibility" attribute has two possible values:

   o  visible: specifies that display of the property value is not
      restricted.  This is the default value of the attribute if it is
      not specified.
   o  hidden: Specifies that the user agent SHOULD NOT display the
      property value.  Display of the property value may be allowed
      using special administrative interfaces, but is not appropriate to
      the ordinary user.

4.5.2.  The 'policy' Attributes

   The setting element has an optional 'policy' attribute.  The policy
   attribute is used to define the constraining properties of an
   element.  It defines how the element value is used by an endpoint
   (e.g. whether it can or can not be used in a session).  The following
   values are defined for the 'policy' attribute:

   o  allow: the value contained in the element is allowed and SHOULD be
      used in sessions.  This is the default value that is used if the
      'policy' attribute is omitted.
   o  disallow: the value contained in the element is forbidden and
      SHOULD NOT be used in sessions.

   The policy attribute can be omitted if the default policy 'allow'
   applies.

      OPEN ISSUE: The policy attribute may not be needed for elements
      outside of a settings_container.  Further clarification is needed
      on this.  Using the policy attribute only inside containers would
      further simplify the specification of profile data.







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4.5.3.  The 'excludedPolicy' Attributes

   The "setting_container" element has an optional 'excludedPolicy'
   attribute.  This attribute specifies the default policy for all
   values that are not in the container.  Elements that are present in
   the container have their own 'policy' attribute, which defines the
   policy for that element.  The following values are defined for the
   'excludedPolicy' attribute:

   o  allow: values not listed in the container are allowed and MAY be
      used in sessions.  This is the default value that is used if the
      'excludedPolicy' attribute is omitted.
   o  disallow: values not listed in the container are forbidden and
      MUST NOT be used in sessions.

   The excludedPolicy attribute can be omitted if the default policy
   'allow' applies.  The following example shows a policy that allows
   the media type audio and disallows all other media types in sessions
   (effectively, this construct requires the use of audio):


   <media-types excludedPolicy="disallow">
     <media-type policy="allow">audio</media-type>
   </media-types>

4.5.4.  The 'direction' Attribute

   Some properties are unidirectional and only apply to messages or data
   streams transmitted into one direction.  For example, a property for
   media streams can be restricted to outgoing media streams only.
   Unidirectional properties can be expressed by adding a 'direction'
   attribute to the respective element.

   The 'direction' attribute can have the following values:

   o  recvonly: the property only applies to incoming messages/streams.
   o  sendonly: the property only applies to outgoing messages/streams.
   o  sendrecv: the property applies to messages/streams in both
      directions.  This is the default value that is used if the
      'direction' attribute is omitted.

4.5.5.  The 'q' Attribute

   It should be possible to express a preference for a certain value, if
   multiple values are allowed within a property.  For example, it
   should be possible to express that the codecs G.711 and G.729 are
   allowed, but G.711 is preferred.  Preferences can be expressed by
   adding a 'q' attribute to a property element.  Elements derived from



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   the "setting" element for which multiple occurrences and values are
   allowed SHOULD have a "q" attribute if the order is significant.
   Typically these elements are contained in an element derived from the
   "setting_container" element.  The 'q' attribute is only meaningful if
   the 'policy' attribute set to 'allowed'.  It must be ignored in all
   other cases.

   An element with a higher 'q' value is preferred over one with a lower
   'q' value. 'q' attribute values range from 0 to 1.  The default value
   is 0.5.

4.6.  The 'profileUri' Element

   The <profileUri> element contains the URI of this profile on the
   profile server.  The value contained in the profileUri element may be
   different than the URI subscribe to when retrieving this profile.
   When the user agent retrieves a profile where the profileUri is
   different than the subscribe to URI, the user agent SHOULD
   unsubscribe to the current URI and then subscribe to the new URI.

   The <profileUri> element is optional and MAY occur only once inside a
   <propertySet> element.  The profileUri element is specific to the
   local-network, device, user or application profile in which it
   occurs.  It has no meaning outside of the profile in which it occurs
   and SHOULD NOT be merged.

4.7.  The 'profileCredential' Element

   The <profileCredential> element contains the digest authentication
   information that SHOULD be used for authentication for the profile
   subscription via SIP or profile retrieval via HTTP, HTTPS, etc.  The
   profileCredential element is optional and MAY occur only once inside
   a propertySet element.  The profileCredential element is specific to
   the local-network, device, user or application profile in which it
   occurs.  It has no meaning outside of the profile in which it occurs
   and SHOULD NOT be merged.  The profileCredential element MUST contain
   exactly one of each of the elements: realm, authUser and one of
   either a1Digest or password.

4.7.1.  realm Element

   The realm element contains the string that defines the realm to which
   this credential pertains.  The value of the realm element is the same
   as the realm parameter in the [RFC2617] headers: WWW-Authenticate,
   Authorization and the SIP [RFC3261] headers: Proxy-Authenticate and
   Proxy-Authorization.  If a match of the realm value is found, the
   user agent uses the values in the authUser and a1Digest elements
   contained in the profileCredential element.  Exactly one realm



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   element MUST be contained in a profileCredential element.  A wildcard
   of "*" MAY be used as the realm value in which case the user agent
   MUST calculate the A1 DIGEST for the realm given in the
   authentication challenge.  If the wildcard is given for the realm,
   the clear text form of the password contained in the password element
   MUST also be used.

4.7.2.  authUser Element

   The authUser element contains the string value of the "username"
   parameter which SHOULD be used in Authorization and Proxy-
   Authorization request headers when retrying a request that was
   challenged for authentication.  Exactly one authUser element SHOULD
   be contained in a profileCredential element.

4.7.3.  a1Digest Element

   The a1Digest element contains a string with the value of the A1
   digest of the username, realm and password as defined in [RFC2617].
   At most one a1Digest element MUST be contained in a profileCredential
   element.  The a1Digest element MUST NOT exist in a profileCredential
   element containing a password element.  The username and realm used
   to construct the value of the a1Digest element MUST match the values
   of the realm and authUser elements contained in the profileCredential
   element with the a1Digest element.

4.7.4.  password Element

   The password element contains the clear text password for use with
   DIGEST Authentication [RFC2617].  At most one password MUST be
   contained in a profileCredential element.  The password element MUST
   NOT exist in a profileCredential element containing a a1Digest
   element.  The user agent uses this password along with the realm and
   authUser elements to calculate the A1 digest used for DIGEST
   Authentication.

4.8.  The 'profileContactUri' Element

   The <profileContactUri> element contains a contact URI (e.g. a SIP,
   HTTP URI or email address) under which the issuer of this profile can
   be reached.  The contact element may, for example, contain the
   address of a support hotline.

   The <profileContactUri> element is optional and MAY occur multiple
   times inside a <propertySet> element.  Multiple instances of the
   profileContactUri element allow multiple URI schemes to be provided
   for contact information.  The user agent MAY use the URI contained
   profile-contact-info element which has a URI scheme that the user



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   agent supports and can make work to provide support help for the
   profile.  The user agent MAY provide the URIs to the user to contact
   the creator of the profile through other communication channels.  The
   profileContactUri element is specific to the local-network, device,
   user or application profile in which it occurs.  It has no meaning
   outside of the profile in which it occurs and SHOULD NOT be merged.

4.9.  The 'profileInfo' Element

   The <profileInfo> element provides a short textual description of the
   property that should be intelligible to the human user.  This element
   may, for example, contain information about the nature of this
   profile, such as "Access Network Profile".  The text in the
   <profileInfo> element is in particular be helpful when a user needs
   to decide whether or not to use a newly downloaded profile or when
   problems with a profile (e.g. a policy conflict) occur.  A user agent
   MAY display this information in these cases.

   The <profileInfo> element is optional and MAY occur only once inside
   a <propertySet> element.  The profileInfo element is specific to the
   local-network, device, user or application profile in which it
   occurs.  It has not meaning outside of the profile in which it occurs
   and SHOULD NOT be merged.

4.10.  Example Profile Dataset

   The following XML example shows a SIP Profile Dataset with example
   extension setting elements: ddd, foo, bar, boo, containerElement and
   setting container elements: myContainer, myContainer1, myContainer2
   and container3.





















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   <?xml version="1.0" encoding="UTF-8"?>
   <propertySet xmlns="urn:ietf:params:xml:ns:uaprof">
       <profileUri>sip:a1b2c3d4e5f6@example.com</profileUri>
       <profileCredential>
            <realm>example.com</realm>
            <authUser>fred</authUser>
            <a1Digest>b6b577fd12aa7e1df8d60735ef56fc2e</a1Digest>
            <!-- <password>123</password> -->
       </profileCredential>
       <profileContactUri>tel:+16175551212</profileContactUri>
       <profileContactUri>sip:411@example.com</profileContactUri>
       <profileContactUri>
           http:example.com/sipProfile.html
       </profileContactUri>
       <profileInfo>
           This is an example profile from example.com
       </profileInfo>
       <ddd xmlns="blatz" policy="allow">fff</ddd>
       <foo xmlns="blatz" visibility="visible" policy="allow"
            direction="sendrecv" q="0">
       </foo>
       <bar xmlns="blatz" visibility="hidden" policy=""
            direction="sendonly" q="0.1000">
       </bar>
       <myContainer xmlns="blatz" excludedPolicy="disallow">
           <containerElement q="0.1">aaa</containerElement>
           <containerElement>bbb</containerElement>
           <containerElement q="0.8">ccc</containerElement>
       </myContainer>
       <boo xmlns="newns" q="1">ggg</boo>
       <myContainer1 xmlns="blatz" excludedPolicy="allow">
           <myContainer2 xmlns="newns" excludedPolicy="allow">
           </myContainer2>
       </myContainer1>
       <container3 xmlns="ns3">
           <containerElement q="0.1">111</containerElement>
           <containerElement>222</containerElement>
           <containerElement q="0.8">333</containerElement>
       </container3>
   </propertySet>

4.11.  Merging Property Sets

   A UA may receive property sets from multiple sources, which need to
   be merged into a single combined document the UA can work with.

   Properties that have a single value (e.g. the maximum bandwidth
   allowed) require that a common value is determined for this property



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   during the merging process.  The merging rules for determining this
   value need to be defined individually for each element in the schema
   definition.  Properties that allow multiple values (i.e. property
   containers) need to be merged by combining the values from the
   different data sets.  The following sections describe common merging
   algorithms.  A data set definition may refer to these algorithms.

4.11.1.  Single Numeric Value Merging Algorithm

   A general merging rule for elements with numeric values is to select
   the largest or the smallest value.  For example, a merging rule for a
   <max-bandwidth> element would be to select the smallest value from
   the values that are in the competing data sets.

4.11.2.  Multiple Enumerated Value Merging Algorithm

   Multiple values in property containers are merged by combining the
   values from each of the competing data sets.  This is accomplished by
   copying the elements from each property container into the merged
   container.  Elements with identical values are only copied once.  The
   'policy' attribute of two elements with the same value is adjusted
   during the merging process according to Table 1.  If an element
   exists only in one property container, then the default policy of the
   other container (i.e. the excludedPolicy) is used when accessing
   Table 1.  For example, if an element is disallowed in one data set
   and the element is not contained in the other data set but the
   default policy is allowed for that data set, then the values
   disallowed and allowed are used to access Table 1.  Consequently, the
   element will be disallowed in the merged data set.  Finally, the
   excludedPolicy attributes of the containers are also merged using
   Table 1.  In addition to these merging rules, each schema may define
   specific merging rules for each property container.


   set 1 \ set 2 |  allow   | disallow
   --------------+----------+----------
   allow         |  allow   | disallow
   disallow      | disallow | disallow

               Table 1: merging policies.

   The following example illustrates the merging process for two data
   sets.  All elements are merged into one container and the policy
   attributes are adjusted according to Table 1.  The merged container
   has the default policy disallow, which is determined using Table 1.
   The entry for PCMA in the merged data set is redundant since it has
   the default policy.




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   Data set 1:
   <codecs excludedPolicy='allow'>
     <codec policy='disallow'>PCMA</codec>
   </codecs>

   Data set 2:
   <codecs excludedPolicy='disallow'>
     <codec policy='allow'>PCMA</codec>
     <codec policy='allow'>G729</codec>
   </codecs>

   Merged data set:
   <codecs excludedPolicy='disallow'>
     <codec policy='disallow'>PCMA</codec>
     <codec policy='allow'>G729</codec>
   </codecs>

   Some constellations of policy attributes result in an illegal merged
   data set.  They constitute a conflict that can not be resolved
   automatically.  For example, two data sets may define two non-
   overlapping sets of allowed audio codecs and both disallow all other
   codes.  The resulting merged set of codecs would be empty, which is
   illegal according to the schema definition of the codecs element.  If
   the use of these properties is enforced by both networks, the UA may
   experience difficulties or may not be able to set up a session at
   all.

   The combined property set MUST again be valid and well-formed
   according to the schema definitions.  A conflict occurs if the
   combined property set is not a well-formed document after the merging
   process is completed.

4.11.3.  Closest Value First Merging Algorithm

   Some properties require that the values from different data sets are
   ordered based on the origin of the data set during the merging
   process.  Property values that come from a domain close to the user
   agent take precedence over values that were in a data set delivered
   by a remote domain.  This order can be used, for example, to select
   the property value from the closest domain.  In many cases, this is
   the local domain of the user agent.  For example, the URI of an
   outbound proxy could be merged this way.  This order can also be used
   to generate an ordered list of property values during the merging
   process.  For example, multiple values for media intermediaries can
   be ordered so that the closest media intermediary is traversed before
   the second closest intermediary and so on.

   This merging algorithm requires that the source of a data set is



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   considered.

   If property sets are delivered through the configuration framework
   [I-D.ietf-sipping-config-framework], the value received through a
   subscription using the "local-network" profile-type takes precedence
   over values received through other profile-type subscriptions.

      OPEN ISSUE: Can we define an order for 'device', 'user', and
      'application' profiles?

   The session-specific policy mechanism
   [I-D.hilt-sipping-session-policy-framework] provides an order among
   policy servers.  This order is based on the order, in which a SIP
   message traverses the network, starting with the closest domain.
   This order can directly be used to order property values as described
   above.

4.12.  Common Types

   The schema also defines a set of common types that are used in
   defining data sets (e.g.  DataIpPort).  [Need to document common
   types.]


5.  Defining Data Sets

   This section covers several issues that should be take into
   consideration when specifying new data set schemas.  This is intended
   to be a guide to authors writing specifications defining a new data
   set schema or extensions to existing ones.

5.1.  Namespace

   It is RECOMMENDED that a data set defines a new XML namespace
   [W3C.REC-xml-names-19990114] to scope all of the properties that are
   defined in the name space.

5.2.  Property Definitions

   The properties defined in a data set schema may be simple (i.e.
   having a single value) or they may be complex (i.e. a container with
   multiple values).  Each property in the data set SHOULD inherit from
   the "setting" element.  Complex properties and all of their child
   elements each should inherit from "setting" as well.

   A data set specification should contain a section which defines the
   meaning of all of the properties contained in the data set.  The
   objective is to define the property such that implementers have a



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   clear definition and semantics to interpret properties in a
   consistent way.  User agents not only need to use the same profile
   content, they need to apply the properties in a consistent way to
   achieve true interoperability.

   The following information should be defined for each property in a
   data set:
   o  description: describe the meaning and application of the property.
   o  cardinality: define how many instances of this property element
      may occur in a data set (e.g. zero, one or many) as well as its
      relationship to any other properties in this or other data sets.
   o  default value: define the default value of this property if it is
      not set.  Describe if the default is different if the property is
      present and not set vs. completely absent from the data set.
      Define if the default varies in relation to another property.

5.3.  Merging Data Sets

   User agents may receive data sets from multiple sources.  They need
   to merge these data sets in order to create an overall data set they
   can work with.  Collisions on data sets may occur if multiple sources
   provide different values for the same properties.  These collisions
   need to be resolved during the merging process.

   A data set schema MUST define rules for merging data sets from
   different sources for each property that is defined.  Considerations
   for merging data sets are discussed in Section 4.11.  A data set
   schema must define if and how these consideration apply and MAY
   define alternative merging rules for specific settings.  A data set
   schema must also identify combinations of properties that constitute
   a conflict that can't resolved.  It may provide additional guidelines
   for the behavior of a user agent in these cases.


6.  Candidate Data Sets

   The following sections name some of the candidate data sets that are
   or may be defined.  These data sets can be aggregated to form
   profiles appropriate to the capabilities of a user agent
   implementation.

   o  SIP Protocol Data Set: the lowest common denominator set of
      properties common to all SIP user agents of any capability.  A
      schema covering the elements of this data set can be found in
      [I-D.petrie-sipping-sip-dataset].
   o  Media Data Set: this data set contains media related policies.  A
      schema covering the elements of this data set can be found in
      [I-D.ietf-sipping-media-policy-dataset].



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   o  Identity Data Set: AORs and lines (see
      [I-D.petrie-sipping-identity-dataset])
   o  HTTP Protocol Data Set: server settings.  Proxy for clients.
   o  NAT Traversal Data Set: settings for STUN, TURN etc.
   o  SIP Digit Maps Data Set:
      [I-D.petrie-sipping-voip-features-dataset]
   o  VoIP Features: [I-D.petrie-sipping-voip-features-dataset]
   o  Address Book:
   o  Buddy List:


7.  Security Considerations

   Security is mostly a delivery problem.  The delivery framework SHOULD
   provide a secure means of delivering the profile data as it may
   contain sensitive data that would be undesirable if it were stolen or
   sniffed.  Storage of the profile on the profile delivery server and
   user agent is an implementation problem.  The profile delivery server
   and the user agent SHOULD provide protection that prevents
   unauthorized access of the profile data.  The profile delivery server
   and the user agent SHOULD enforce the access control policies defined
   in the profile data sets if present.
      [The point of the access control construct on the data set is to
      provide some security policy on the visibility and ability to
      change sensitive properties.  Does the access control mechanism
      also create a security problem where the local network can set or
      hide properties from the user?]

   Some transport mechanisms for delivery of the profile data do not
   provide a secure means of delivery.  In addition some user agents may
   not have the resources to support the secure mechanism used for
   delivery (e.g.  TLS).


8.  IANA Considerations

   XML name space registration: urn:ietf:params:xml:ns:uaprof

8.1.  Content-type registration for 'application/uaprofile+xml'

   To: ietf-types@iana.org
   Subject: Registration of MIME media type application/uaprofile+xml
   MIME media type name:  application
   MIME subtype name:     uaprofile+xml







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   Required 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 [RFC 3023], section 3.2.
   Security considerations:  This content type is designed to carry SIP
      user agent profile data, which may be considered private
      information.  Appropriate precautions should be adopted to limit
      disclosure of this information.
   Interoperability considerations:  This content type provides a common
      format for exchange of SIP user agent profile information.
   Published specification:  RFC XXXX (Note to RFC Editor: Please fill
      in XXXX with the RFC number of this specification)
   Applications which use this media type:  SIP user agents and profile
      delivery servers.
   Additional information:  Magic number(s): File extension(s):
      Macintosh File Type Code(s):
   Person & email address to contact for further information:  Daniel
      Petrie EMail: dan.ietf AT sipez DOT com
   Intended usage:  LIMITED USE
   Author/Change controller:  This specification is a proposed work item
      of the IETF SIPPING working group, with mailing list address:
      sipping@ietf.edu.
   Other information:  This media type is a specialization of
      application/xml [RFC 3023], and many of the considerations
      described there also apply to application/uaprof+xml.


9.  Change History

   [[RFC Editor: Please remove this entire section upon publication as
   an RFC.]]

9.1.  Changes from draft-petrie-sipping-profile-datasets-04

   Re-reved and activated draft

9.2.  Changes from draft-petrie-sipping-profile-datasets-03

   Converted the XML schema to use Relax NG and created a valid schema.

   Defined XML name space for schema: "urn:ietf:params:xml:ns:uaprof"

   Defined mime type: application/uaprofile+xml to be used as default
   content type for the configuration framework.

   Changed names of elements, attributes and other data types which



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   contained "-" or "_" to use camel case.

   Added password element so that credential can contain either A1
   digest or clear text password as the clear text password is required
   by the user agent in some cases (e.g. http GET) or to wildcard the
   realm.

9.3.  Changes from draft-petrie-sipping-profile-datasets-02

   Removed "mandatory" policy attribute value to simplify use and
   profile merging issues.

   Session Independent Policy draft was split into separate media
   dataset draft and policy drafts.  Fixed references and information in
   this draft to reflect the two drafts.

   Added concrete properties contained in elements: profileUri,
   profileCredential, profileContactUri and profileInfo.  Prior to this
   draft, there were only abstract elements defined in this draft.
   These elements have been added to contain information that is
   specific to the profile and are independent of the specific profile
   datasets contained in the profile.

   Split references into normative and informative sections.

   Numerous editorial changes

9.4.  Changes from draft-petrie-sipping-profile-datasets-01

   Split out the core SIP Protocol dataset into a separate draft.

   Schema changes: created setting_container, added q and direction
   attributes along with other tweaks to the schema.

   Better integration and coordination with
   [I-D.ietf-sipping-media-policy-dataset].  The media/codec dataset is
   now completely contained in the policy draft.

9.5.  Changes from draft-petrie-sipping-profile-datasets-00

   Added use case scenarios for codecs, SIP transport protocol and
   outbound proxy to better illustrate requirements.  Some of the
   derived requirements are listed with the use cases.

   Added settings element attributes "policy" and "visibility" to
   provide merging constraints and access control capability.  Removed
   the element based merging constraints using the: forbid, set_any,
   set_all and set_one elements.  This greatly simplifies the degree of



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   XML operations required to perform the request merging.

   Defined default merging policy and profile source precedence along
   with the option for different policies to be describe in specific
   settings definition documents.

   Added example merging with XML profiles from device and user for the
   SIP transport protocol.


10.  References

10.1.  Normative References

   [I-D.hilt-sipping-session-policy-framework]
              Hilt, V., "A Framework for Session Initiation Protocol
              (SIP) Session Policies",
              draft-hilt-sipping-session-policy-framework-01 (work in
              progress), March 2006.

   [I-D.ietf-sipping-config-framework]
              Channabasappa, S., "A Framework for Session Initiation
              Protocol User Agent Profile Delivery",
              draft-ietf-sipping-config-framework-14 (work in progress),
              November 2007.

   [I-D.mealling-iana-xmlns-registry]
              Mealling, M., "The IETF XML Registry",
              draft-mealling-iana-xmlns-registry-05 (work in progress),
              June 2003.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [RFC3261]  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.

   [W3C.REC-xml-names-19990114]
              Hollander, D., Bray, T., and A. Layman, "Namespaces in
              XML", W3C REC REC-xml-names-19990114, January 1999.




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   [W3C.REC-xmlschema-1]
              Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn,
              "XML Schema Part 1: Structures", W3C REC-xmlschema-1,
              May 2001, <http://www.w3.org/TR/xmlschema-1/>.

   [W3C.REC-xmlschema-2]
              Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes",
              W3C REC-xmlschema-2, May 2001,
              <http://www.w3.org/TR/xmlschema-2/>.

10.2.  Informative References

   [I-D.ietf-sipping-media-policy-dataset]
              Hilt, V., "A User Agent Profile Data Set for Media
              Policy", draft-ietf-sipping-media-policy-dataset-04 (work
              in progress), May 2007.

   [I-D.petrie-sipping-identity-dataset]
              Petrie, D., "The Session Initiation Protocol User Agent
              Identity Profile Data Set",
              draft-petrie-sipping-identity-dataset-01 (work in
              progress), October 2006.

   [I-D.petrie-sipping-sip-dataset]
              Petrie, D., "The Core Session Initiation Protocol User
              Agent Protocol Data Set",
              draft-petrie-sipping-sip-dataset-02 (work in progress),
              October 2006.

   [I-D.petrie-sipping-voip-features-dataset]
              Petrie, D., "The Session Initiation Protocol User Agent
              VoIP Features Data Set",
              draft-petrie-sipping-voip-features-dataset-01 (work in
              progress), October 2006.

   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, May 1997.

   [RFC2648]  Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
              August 1999.

   [RFC3470]  Hollenbeck, S., Rose, M., and L. Masinter, "Guidelines for
              the Use of Extensible Markup Language (XML)
              within IETF Protocols", BCP 70, RFC 3470, January 2003.


Appendix A.  Relax NG SIP UA Profile Schema





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   <?xml version="1.0"?>
   <grammar xmlns="http://relaxng.org/ns/structure/1.0"
    ns="urn:ietf:params:xml:ns:uaprof"
    datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
       <start>
          <element name="propertySet">
              <optional>
                 <ref name="ElementProfileUri"/>
              </optional>
              <optional>
                 <ref name="ElementProfileCredential"/>
              </optional>
              <zeroOrMore>
                 <element name="profileContactUri">
                     <!-- who to contact for help with this profile -->
                     <data type="anyURI"/>
                 </element>
              </zeroOrMore>
              <optional>
                  <element name="profileInfo">
                      <text/>
                  </element>
              </optional>
              <zeroOrMore>
                  <choice>
                      <ref name="PropertySetExtension"/>
                      <ref name="ElementGenericSetting"/>
                      <ref name="ElementGenericSettingContainer"/>
                  </choice>
              </zeroOrMore>
          </element>
       </start>
       <!-- example setting with all setting attributes -->
       <!-- <define name="ElementFoo">
                <element name="foo">
                    <ref name="SettingAttributes"/>
                    <text/>
                 </element>
            </define>
        -->
       <define name="ElementProfileUri">
           <!-- URI to subscribe to for this profile -->
           <element name="profileUri">
               <ref name="DataSipUri"/>
           </element>
       </define>
       <define name="ElementProfileCredential">
           <!-- credentials for subscribing or getting profile -->



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           <element name="profileCredential">
               <ref name="DataCredential"/>
           </element>
       </define>
       <define name="PropertySetExtension">
           <!-- place to add new settings in other namespaces -->
           <empty/>
       </define>
       <define name="ElementGenericSettingContainer">
           <element>
               <anyName>
                   <except>
                       <nsName ns="urn:ietf:params:xml:ns:uaprof"/>
                       <nsName ns=""/>
                   </except>
               </anyName>
               <ref name="SettingContainerAttributes"/>
               <zeroOrMore>
                   <ref name="AttributeGeneric"/>
               </zeroOrMore>
             <!-- container can have containers or settings not both -->
               <choice>
                   <zeroOrMore>
                       <ref name="ElementGenericSetting"/>
                   </zeroOrMore>
                   <zeroOrMore>
                       <ref name="ElementGenericSettingContainer"/>
                   </zeroOrMore>
               </choice>
           </element>
       </define>
       <define name="ElementGenericSetting">
           <element>
               <anyName>
                   <except>
                       <nsName ns="urn:ietf:params:xml:ns:uaprof"/>
                       <nsName ns=""/>
                   </except>
               </anyName>
               <ref name="SettingAttributes"/>
               <zeroOrMore>
                   <ref name="AttributeGeneric"/>
               </zeroOrMore>
               <zeroOrMore>
                   <choice>
                       <text/>
                       <ref name="ElementGenericSetting"/>
                   </choice>



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               </zeroOrMore>
           </element>
       </define>
       <define name="AttributeGeneric">
           <attribute>
               <anyName>
                   <except>
                       <nsName ns="urn:ietf:params:xml:ns:uaprof"/>
                       <nsName ns=""/>
                   </except>
               </anyName>
           </attribute>
       </define>
       <define name="DataCredential">
           <element name="realm">
               <text/>
           </element>
           <element name="authUser">
               <text/>
           </element>
           <choice>
               <element name="a1Digest">
                   <data type="string">
                       <param name="pattern">[0-9,a-f]{32,32}</param>
                   </data>
               </element>
               <element name="password">
                   <text/>
               </element>
           </choice>
       </define>
       <define name="DataSipUri">
           <choice>
               <data type="anyURI">
                   <param name="pattern">sip:.*</param>
               </data>
               <data type="anyURI">
                   <param name="pattern">sips:.*</param>
               </data>
           </choice>
       </define>
       <define name="DataSipNameAddr">
           <choice>
               <data type="anyURI"><!-- need to tighten this up -->
                   <param name="pattern">"?.*"?&lt;?sip:.*</param>
               </data>
               <data type="anyURI">
                   <param name="pattern">"?.*"?&lt;?sips:.*</param>



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               </data>
           </choice>
       </define>
       <define name="SettingContainerAttributes">
           <optional>
               <attribute name="excludedPolicy">
                   <ref name="DataPolicies"/>
               </attribute>
           </optional>
       </define>
       <define name="SettingAttributes">
           <interleave>
              <optional>
                  <ref name="AttributePolicy"/>
              </optional>
              <optional>
                  <ref name="AttributeVisibility"/>
              </optional>
              <optional>
                  <ref name="AttributeDirection"/>
              </optional>
              <optional>
                  <ref name="AttributeQ"/>
              </optional>
           </interleave>
       </define>
       <define name="AttributePolicy">
          <attribute name="policy">
              <ref name="DataPolicies"/>
          </attribute>
       </define>
       <define name="DataPolicies">
           <choice>
               <value></value><!-- default of allow -->
               <value>allow</value>
               <value>disallow</value>
           </choice>
       </define>
       <define name="AttributeVisibility">
           <attribute name="visibility">
              <choice>
                  <value></value><!-- default of visible -->
                  <value>visible</value>
                  <value>hidden</value>
              </choice>
           </attribute>
       </define>
       <define name="AttributeDirection">



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           <attribute name="direction">
              <choice>
                  <value></value><!-- default of sendrecv -->
                  <value>sendrecv</value>
                  <value>sendonly</value>
                  <value>recvonly</value>
              </choice>
           </attribute>
       </define>
       <define name="AttributeQ">
           <attribute name="q">
              <data type="float">
                  <!-- default of 0.5 -->
                  <param name="minInclusive">0</param>
                  <param name="maxInclusive">1</param>
              </data>
           </attribute>
       </define>
       <define name="DataIpPort">
           <data type="integer">
               <param name="minInclusive">1</param>
               <param name="maxInclusive">65535</param>
           </data>
       </define>
       <define name="DataIpTransport">
           <choice>
               <value></value><!-- default of UDP -->
               <value>UDP</value>
               <value>TCP</value>
               <value>TLS</value>
               <value>DTLS</value>
               <value>SCTP</value>
           </choice>
       </define>
   </grammar>



Appendix B.  Acknowledgments












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Authors' Addresses

   Daniel Petrie
   SIPez LLC.
   34 Robbins Rd.
   Arlington, MA  02476
   US

   Phone: +1 617 273 4000
   Email: dan.ietf AT SIPez DOT com
   URI:   http://www.SIPez.com/


   Sumanth Channabasappa
   CableLabs
   858 Coal Creek Circle
   Louisville, CO  80027
   US

   Phone:
   Email: sumanth@cablelabs.com
   URI:


   Sam Ganesan
   Motorola
   80 Central Street
   Boxborough, MA  01719
   US

   Phone:
   Email: sam.ganesan@motorola.com
   URI:


















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Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   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.

   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, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


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   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.


Acknowledgment

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





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