Extensible Markup Language (XML) Format Extension for Representing Copy Control Attributes in Resource Lists
RFC 5364

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• IESG evaluation record
• IESG writeups
• Email expansions
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• 07

Network Working Group                                   M. Garcia-Martin
Request for Comments: 5364                                  G. Camarillo
Category: Standards Track                                       Ericsson
                                                            October 2008

  Extensible Markup Language (XML) Format Extension for Representing
               Copy Control Attributes in Resource Lists

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   In certain types of multimedia communications, a Session Initiation
   Protocol (SIP) request is distributed to a group of SIP User Agents
   (UAs).  The sender sends a single SIP request to a server which
   further distributes the request to the group.  This SIP request
   contains a list of Uniform Resource Identifiers (URIs), which
   identify the recipients of the SIP request.  This URI list is
   expressed as a resource list XML document.  This specification
   defines an XML extension to the XML resource list format that allows
   the sender of the request to qualify a recipient with a copy control
   level similar to the copy control level of existing email systems.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of Operation  . . . . . . . . . . . . . . . . . . . .  3
   4.  Extension to the Resource List Data Format . . . . . . . . . .  6
   5.  XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  Carrying URI Lists in SIP  . . . . . . . . . . . . . . . . . . 10
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
     9.1.  Disposition Type Registration  . . . . . . . . . . . . . . 13
     9.2.  XML Namespace Registration . . . . . . . . . . . . . . . . 13
     9.3.  XML Schema Registration  . . . . . . . . . . . . . . . . . 14
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 14
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 14
     11.2. Informative References . . . . . . . . . . . . . . . . . . 15

Garcia-Martin & Camarillo   Standards Track                     [Page 1]
RFC 5364        Copy Control Attribute in Resource Lists    October 2008

1.  Introduction

   RFC 5363 [RFC5363] describes a generic framework for carrying Uniform
   Resource Identifier (URI) lists in SIP [RFC3261] messages.
   Specifically, the document provides a common framework for specific
   implementations of URI-list services, such as conferences initiated
   with INVITE requests [RFC5366] or Multiple-recipient MESSAGE requests
   [RFC5365].

   Common to all URI-list services is the presence of a SIP request that
   contains a collection of resources, typically expressed as an XML
   resource list [RFC4826].  SIP requests carrying resource lists can
   appear either in requests received by the URI-list server, indicating
   the list of intended recipients, or in each of the requests that the
   URI-list server sends to recipients, indicating the list of
   recipients of the same SIP request.

   Although the XML resource list [RFC4826] provides a powerful
   mechanism for describing a list of resources, there is a need for a
   copy control attribute to determine whether a resource is receiving a
   SIP request as a primary recipient, a carbon copy, or a blind carbon
   copy.  This is similar to common email systems, where the sender can
   categorize each recipient as a "to", "cc", or "bcc" recipient.

   This document addresses this problem by providing an extension to the
   XML resource list [RFC4826] that enables the sender to supply a copy
   control attribute that labels each recipient as a "to", "cc", or
   "bcc" recipient.  This attribute indicates whether the recipient is
   receiving a primary copy of the SIP request, a carbon copy, or a
   blind carbon copy.  Additionally, we provide the sender with the
   capability of indicating in the URI list that one or more resources
   should be anonymized, so that some recipients' URIs are not disclosed
   to the other recipients.  Instead, these URIs are replaced with
   anonymous URIs.

   The remainder of this document is organized as follows: Section 2
   introduces the terminology used throughout this specification.
   Section 3 gives an overview of operation.  Section 4 formally defines
   an extension to URI lists.  The XML schema definition is provided in