idnits 2.17.1 

draft-ietf-clue-protocol-05.txt:

  Checking boilerplate required by RFC 5378 and the IETF Trust (see
  https://trustee.ietf.org/license-info):
  ----------------------------------------------------------------------------

     No issues found here.

  Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt:
  ----------------------------------------------------------------------------

     No issues found here.

  Checking nits according to https://www.ietf.org/id-info/checklist :
  ----------------------------------------------------------------------------

  ** There are 115 instances of too long lines in the document, the longest
     one being 10 characters in excess of 72.

  ** The abstract seems to contain references ([I-D.ietf-clue-signaling],
     [I-D.ietf-clue-framework], [I-D.ietf-clue-datachannel], [RFC7262]), which
     it shouldn't.  Please replace those with straight textual mentions of the
     documents in question.

  ** The document seems to lack a both a reference to RFC 2119 and the
     recommended RFC 2119 boilerplate, even if it appears to use RFC 2119
     keywords. 

     RFC 2119 keyword, line 225: '...a CLUE dialogue, the involved CPs MUST...'
     RFC 2119 keyword, line 422: '....43).  Only one <version> element MUST...'
     RFC 2119 keyword, line 433: '...   <version> tag MUST be included....'
     RFC 2119 keyword, line 449: '...ype 2xx the response MUST also include...'
     RFC 2119 keyword, line 451: '...   elements; it MAY include them for a...'
     (8 more instances...)


  Miscellaneous warnings:
  ----------------------------------------------------------------------------

  == The copyright year in the IETF Trust and authors Copyright Line does not
     match the current year

  == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD',
     or 'RECOMMENDED' is not an accepted usage according to RFC 2119.  Please
     use uppercase 'NOT' together with RFC 2119 keywords (if that is what you
     mean).
     
     Found 'MUST not' in this paragraph:
     
     The optional boolean <ack> element, set to "true", if present,
     indicates that the CONF message also acknowledges the referred
     advertisement, by applying in that way a piggybacking mechanism for
     simultaneously acknowledging and replying to the ADV message.  In the
     above case, the CONF message MUST carry a 200 (Success) response code. 
     The <ack> element MUST not be present if an ACK message has been already
     sent back to the MP.

  -- The document date (October 19, 2015) is 3111 days in the past.  Is this
     intentional?


  Checking references for intended status: Proposed Standard
  ----------------------------------------------------------------------------

     (See RFCs 3967 and 4897 for information about using normative references
     to lower-maturity documents in RFCs)

  == Missing Reference: '0-9' is mentioned on line 1183, but not defined

  == Missing Reference: '1-9' is mentioned on line 1183, but not defined

  == Unused Reference: 'RFC6502' is defined on line 2292, but no explicit
     reference was found in the text

  == Unused Reference: 'RFC6503' is defined on line 2301, but no explicit
     reference was found in the text

  == Outdated reference: A later version (-18) exists of
     draft-ietf-clue-datachannel-10

  ** Downref: Normative reference to an Experimental draft:
     draft-ietf-clue-datachannel (ref. 'I-D.ietf-clue-datachannel')

  == Outdated reference: A later version (-25) exists of
     draft-ietf-clue-framework-23

  == Outdated reference: A later version (-15) exists of
     draft-ietf-clue-signaling-06

  ** Downref: Normative reference to an Experimental draft:
     draft-ietf-clue-signaling (ref. 'I-D.ietf-clue-signaling')

  ** Obsolete normative reference: RFC 3023 (Obsoleted by RFC 7303)

  ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126)

  -- Obsolete informational reference (is this intentional?): RFC 5117
     (Obsoleted by RFC 7667)


     Summary: 7 errors (**), 0 flaws (~~), 9 warnings (==), 2 comments (--).

     Run idnits with the --verbose option for more detailed information about
     the items above.

--------------------------------------------------------------------------------


2	CLUE Working Group                                             R. Presta
3	Internet-Draft                                                 S. Romano
4	Intended status: Standards Track                    University of Napoli
5	Expires: April 21, 2016                                 October 19, 2015

7	                             CLUE protocol
8	                      draft-ietf-clue-protocol-05

10	Abstract

12	   The CLUE protocol is an application protocol conceived for the
13	   description and negotiation of a CLUE telepresence session.  The
14	   design of the CLUE protocol takes into account the requirements and
15	   the framework defined, respectively, in [I-D.ietf-clue-framework] and
16	   [RFC7262].  The companion document [I-D.ietf-clue-signaling] delves
17	   into CLUE signaling details, as well as on the SIP/SDP session
18	   establishment phase.  CLUE messages flow upon the CLUE data channel,
19	   based on reliable and ordered SCTP over DTLS transport, as described
20	   in [I-D.ietf-clue-datachannel].  Message details, together with the
21	   behavior of CLUE Participants acting as Media Providers and/or Media
22	   Consumers, are herein discussed.

24	Status of This Memo

26	   This Internet-Draft is submitted in full conformance with the
27	   provisions of BCP 78 and BCP 79.

29	   Internet-Drafts are working documents of the Internet Engineering
30	   Task Force (IETF).  Note that other groups may also distribute
31	   working documents as Internet-Drafts.  The list of current Internet-
32	   Drafts is at http://datatracker.ietf.org/drafts/current/.

34	   Internet-Drafts are draft documents valid for a maximum of six months
35	   and may be updated, replaced, or obsoleted by other documents at any
36	   time.  It is inappropriate to use Internet-Drafts as reference
37	   material or to cite them other than as "work in progress."

39	   This Internet-Draft will expire on April 21, 2016.

41	Copyright Notice

43	   Copyright (c) 2015 IETF Trust and the persons identified as the
44	   document authors.  All rights reserved.

46	   This document is subject to BCP 78 and the IETF Trust's Legal
47	   Provisions Relating to IETF Documents
48	   (http://trustee.ietf.org/license-info) in effect on the date of
49	   publication of this document.  Please review these documents
50	   carefully, as they describe your rights and restrictions with respect
51	   to this document.  Code Components extracted from this document must
52	   include Simplified BSD License text as described in Section 4.e of
53	   the Trust Legal Provisions and are provided without warranty as
54	   described in the Simplified BSD License.

56	Table of Contents

58	   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
59	   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
60	   3.  Overview of the CLUE protocol  . . . . . . . . . . . . . . . .  5
61	   4.  Protocol messages  . . . . . . . . . . . . . . . . . . . . . .  7
62	     4.1.  OPTIONS  . . . . . . . . . . . . . . . . . . . . . . . . .  9
63	     4.2.  OPTIONS RESPONSE . . . . . . . . . . . . . . . . . . . . . 11
64	     4.3.  ADVERTISEMENT  . . . . . . . . . . . . . . . . . . . . . . 12
65	     4.4.  ADVERTISEMENT ACKNOWLEDGEMENT  . . . . . . . . . . . . . . 13
66	     4.5.  CONFIGURE  . . . . . . . . . . . . . . . . . . . . . . . . 14
67	     4.6.  CONFIGURE RESPONSE . . . . . . . . . . . . . . . . . . . . 15
68	     4.7.  Response codes and reason strings  . . . . . . . . . . . . 15
69	   5.  Protocol state machines  . . . . . . . . . . . . . . . . . . . 17
70	   6.  CLUE Participant's state machine . . . . . . . . . . . . . . . 17
71	     6.1.  Media Provider's state machine . . . . . . . . . . . . . . 19
72	     6.2.  Media Consumer's state machine . . . . . . . . . . . . . . 22
73	   7.  Versioning . . . . . . . . . . . . . . . . . . . . . . . . . . 25
74	   8.  Extensions and options . . . . . . . . . . . . . . . . . . . . 26
75	   9.  XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 27
76	   10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
77	     10.1. Simple ADV . . . . . . . . . . . . . . . . . . . . . . . . 31
78	     10.2. ADV with MCCs  . . . . . . . . . . . . . . . . . . . . . . 37
79	   11. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 44
80	     11.1. URN Sub-Namespace Registration . . . . . . . . . . . . . . 44
81	     11.2. XML Schema registration  . . . . . . . . . . . . . . . . . 45
82	     11.3. MIME Media Type Registration for 'application/clue+xml'  . 45
83	     11.4. DNS Registrations  . . . . . . . . . . . . . . . . . . . . 46
84	       11.4.1.  Application Service tag . . . . . . . . . . . . . . . 46
85	       11.4.2.  Application Protocol tag  . . . . . . . . . . . . . . 46
86	     11.5. CLUE Protocol Registry . . . . . . . . . . . . . . . . . . 47
87	       11.5.1.  CLUE Message Types  . . . . . . . . . . . . . . . . . 47
88	       11.5.2.  CLUE Response Codes . . . . . . . . . . . . . . . . . 47
89	   12. Diff with draft-ietf-clue-protocol-04  . . . . . . . . . . . . 48
90	   13. Diff with draft-ietf-clue-protocol-03  . . . . . . . . . . . . 48
91	   14. Diff with draft-ietf-clue-protocol-02  . . . . . . . . . . . . 48
92	   15. Diff with draft-ietf-clue-protocol-01  . . . . . . . . . . . . 48
93	   16. Diff with draft-ietf-clue-protocol-00  . . . . . . . . . . . . 49
94	   17. Diff with draft-presta-clue-protocol-04  . . . . . . . . . . . 49
95	   18. Diff with draft-presta-clue-protocol-03  . . . . . . . . . . . 49
96	   19. Diff with draft-presta-clue-protocol-02  . . . . . . . . . . . 50
97	   20. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 50
98	   21. References . . . . . . . . . . . . . . . . . . . . . . . . . . 50
99	     21.1. Normative References . . . . . . . . . . . . . . . . . . . 50
100	     21.2. Informative References . . . . . . . . . . . . . . . . . . 51

102	1.  Introduction

104	   The CLUE protocol is an application protocol used by two CLUE
105	   Participants to enhance the experience of a multimedia telepresence
106	   session.  The main goals of the CLUE protocol are:

108	   1.  enabling a Media Provider (MP) to properly announce its current
109	       telepresence capabilities to a Media COnsumer (MC) in terms of
110	       available media captures, groups of encodings, simultaneity
111	       constraints and other information envisioned in
112	       [I-D.ietf-clue-framework];

114	   2.  enabling an MC to request the desired multimedia streams from the
115	       offering MP.

117	   CLUE-capable endpoints are connected by means of the CLUE data
118	   channel, an SCTP over DTLS channel which is opened and established as
119	   described in [I-D.ietf-clue-signaling] and
120	   [I-D.ietf-clue-datachannel].  CLUE protocol messages flowing upon
121	   such a channel are detailed in this document, both syntactically and
122	   semantically.

124	   In Section 3 we provide a general overview of the CLUE protocol.
125	   CLUE protocol messages are detailed in Section 4.  The CLUE
126	   Participant state machine is introduced in Section 5.  Versioning and
127	   extensions are discussed in Section 7 and Section 8, respectively.
128	   The XML schema defining the CLUE messages is reported in Section 9.

130	2.  Terminology

132	   This document refers to the same terminology used in
133	   [I-D.ietf-clue-framework] and in [RFC7262].  We briefly recall herein
134	   some of the main terms used in the document.  The definition of "CLUE
135	   Participant" herein proposed is not imported from any of the above
136	   documents.

138	   CLUE Participant (CP):  An entity able to use the CLUE protocol
139	      within a telepresence session.  It can be an endpoint or an MCU
140	      able to use the CLUE protocol.

142	   CLUE-capable device:  A device that supports the CLUE data channel
143	      [I-D.ietf-clue-datachannel], the CLUE protocol and the principles
144	      of CLUE negotiation, and seeks CLUE-enabled calls.

146	   Endpoint:  The logical point of final termination through receiving,
147	      decoding and rendering, and/or initiation through capturing,
148	      encoding, and sending of media streams.  An endpoint consists of
149	      one or more physical devices which source and sink media streams,
150	      and exactly one [RFC4353] Participant (which, in turn, includes
151	      exactly one SIP User Agent).  Endpoints can be anything from
152	      multiscreen/multicamera room controllers to handheld devices.

154	   MCU:  Multipoint Control Unit (MCU) - a device that connects two or
155	      more endpoints together into one single multimedia conference
156	      [RFC5117].  An MCU may include a Mixer [RFC4353].

158	   Media:  Any data that, after suitable encoding, can be conveyed over
159	      RTP, including audio, video or timed text.

161	   Media Capture:  A "Media Capture", or simply "Capture", is a source
162	      of Media.

164	   Media Consumer (MC):  A CLUE Participant (i.e., an Endpoint or an
165	      MCU) able to receive Media Streams.

167	   Capture Encoding:  A specific encoding of a Media Capture, to be sent
168	      via RTP [RFC3550].

170	   Media Provider (MP):  A CLUE Participant (i.e., an Endpoint or an
171	      MCU) able to send Media Streams.

173	   Media Stream:  The term "Media Stream", or simply "Stream", is used
174	      as a synonym of Capture Encoding.

176	3.  Overview of the CLUE protocol

178	   The CLUE protocol is conceived to enable CLUE telepresence sessions.
179	   It is designed in order to address SDP limitations in terms of the
180	   description of some information about the multimedia streams that are
181	   involved in a real-time multimedia conference.  Indeed, by simply
182	   using SDP we are not able to convey information about the features of
183	   the flowing multimedia streams that are needed to enable a "being
184	   there" rendering experience.  Such information is designed in the
185	   CLUE framework document and formally defined and described in the
186	   CLUE data model document.  The CLUE protocol represents the mechanism
187	   for the exchange of CLUE information between CLUE Participants.  It
188	   mainly provides the messages to enable a Media Provider to advertise
189	   its telepresence capabilities and to enable a Media Consumer to
190	   select the desired telepresence options.

192	   The CLUE protocol, as defined in the following, is a stateful,
193	   client-server, XML-based application protocol.  CLUE protocol
194	   messages flow on a reliable and ordered SCTP over DTLS transport
195	   channel connecting two CLUE Participants.  Messages carry information
196	   taken from the XML-based CLUE data model
197	   ([I-D.ietf-clue-data-model-schema]).  Three main communication layers
198	   can be identified:

200	   1.  Establishment of the CLUE data channel: in this phase, the CLUE
201	       data channel setup takes place.  If it completes successfully,
202	       the CPs are able to communicate and start the initiation phase.

204	   2.  Negotiation of the CLUE protocol version and options (initiation
205	       phase): the CPs connected via the CLUE data channel agree on the
206	       version and on the options to be used during the telepresence
207	       session.  Special CLUE messages are used for such a task (OPTIONS
208	       and OPTIONS RESPONSE).  The version and options negotiation can
209	       be performed once and only at this stage.  At the end of that
210	       basic negotiation, each CP starts its activity as a CLUE MP
211	       and/or CLUE MC.

213	   3.  CLUE telepresence capabilities description and negotiation: in
214	       this phase, the MP-MC dialogues take place on the data channel by
215	       means of the CLUE protocol messages.

217	   As soon as the channel is ready, the CLUE Participants must agree on
218	   the protocol version and extensions to be used within the
219	   telepresence session.  CLUE protocol version numbers are
220	   characterized by a major version number and a minor version number,
221	   both unsigned integers, separated by a dot.  While minor version
222	   numbers denote backward compatible changes in the context of a given
223	   major version, different major version numbers generally indicate a
224	   lack of interoperability between the protocol implementations.  In
225	   order to correctly establish a CLUE dialogue, the involved CPs MUST
226	   have in common a major version number (see Section 7 for further
227	   details).  The subset of the protocol options and extensions that are
228	   allowed within the CLUE session is also determined in the initiation
229	   phase, such subset being the one including only the options that are
230	   supported by both parties.  A mechanism for the negotiation of the
231	   CLUE protocol version and extensions is is part of the initial phase.
232	   According to such a solution, the CP which is the CLUE Channel
233	   initiator (CI) issues a proper CLUE message (OPTIONS) to the CP which
234	   is the Channel Receiver (CR) specifying the supported version and
235	   extensions.  The CR then answers by selecting the subset of the CI
236	   extensions that it is able to support and determines the protocol
237	   version to be used.

239	   After that negotiation phase is completed, CLUE Participants describe
240	   and agree on the media flows to be exchanged.  In many cases CPs will
241	   seek to both transmit and receive media.  Hence in a call between two
242	   CPs, A and B, there would be two seperate dialogs, as follows:

244	   1.  the one needed to describe and set up the media streams sent from
245	       A to B, i.e., the dialogue between A's Media Provider side and
246	       B's Media Consumer side

248	   2.  the one needed to describe and set up the media streams sent from
249	       B to A, i.e., the dialogue between B's Media Provider side and
250	       A's Media Consumer side

252	   CLUE messages for the media session description and negotiation are
253	   designed by considering the MP side as the server side of the
254	   protocol, since it produces and provides media streams, and the MC
255	   side as the client side of the protocol, since it requests and
256	   receives media streams.  The messages that are exchanged to set up
257	   the telepresence media session are described by focusing on a single
258	   MP-MC dialogue.

260	   The MP first advertises its available media captures and encoding
261	   capabilities to the MC, as well as its simultaneity constraints,
262	   according to the information model defined in
263	   [I-D.ietf-clue-framework].  The CLUE message conveying the MP's
264	   multimedia offer is the ADVERTISEMENT message.  Such message
265	   leverages the XML data model definitions provided in
266	   [I-D.ietf-clue-data-model-schema].

268	   The MC selects the desired streams of the MP by using the CONFIGURE
269	   message, which makes reference to the information carried in the
270	   previously received ADVERTISEMENT.

272	   Besides ADVERTISEMENT and CONFIGURE, other messages have been
273	   conceived in order to provide all the needed mechanisms and
274	   operations.  Such messages will be detailed in the following
275	   sections.

277	4.  Protocol messages

279	   CLUE protocol messages are textual, XML-based messages that enable
280	   the configuration of the telepresence session.  The formal definition
281	   of such messages is provided in the XML Schema provided at the end of
282	   this document (Section 9).

284	   The XML definitions of the CLUE information provided in
285	   [I-D.ietf-clue-data-model-schema] are included within some CLUE
286	   protocol messages (namely the ADVERTISEMENT and the CONFIGURE
287	   messages), in order to use the concepts defined in
288	   [I-D.ietf-clue-framework].

290	   The CLUE protocol messages are the following:

292	   o  OPTIONS

294	   o  OPTIONS RESPONSE

296	   o  ADVERTISEMENT (ADV)

298	   o  ADVERTISEMENT ACKNOWLEDGEMENT (ACK)

300	   o  CONFIGURE (CONF)

302	   o  CONFIGURE RESPONSE (CONF RESPONSE)

304	   While the OPTIONS and OPTIONS RESPONSE messages are exchanged in the
305	   initiation phase between the CPs, the other messages are involved in
306	   MP-MC dialogues.

308	   Each CLUE message inherits a basic structure depicted in the
309	   following excerpt:

311	<!-- CLUE MESSAGE TYPE -->
312	<xs:complexType name="clueMessageType" abstract="true">
313	<xs:sequence>
314	<xs:element name="clueId" type="xs:string"/>
315	<xs:element name="sequenceNr" type="xs:positiveInteger"/>
316	</xs:sequence>
317	<xs:attribute name="protocol" type="xs:string" fixed="CLUE" use="required"/>
318	<xs:attribute name="v" type="versionType" use="required"/>
319	</xs:complexType>

321	<!-- VERSION TYPE -->
322	<xs:simpleType name="versionType">
323	<xs:restriction base="xs:string">
324	<xs:pattern value="([0-9])+\.([0-9]+)"></xs:pattern>
325	</xs:restriction>
326	</xs:simpleType>

328	   The basic structure determines the mandatory information that is
329	   carried within each CLUE message.  Such an information is made by:

331	   o  clueId: an XML element containing the identifier (in the form of a
332	      generic string) of the CP within the telepresence system;

334	   o  sequenceNr: an XML element containing the local message sequence
335	      number.  The sender must increment the sequence numbers by one for
336	      each new message sent, the receiver must remember the most recent
337	      sequence number received and send back a 401 error if it receives
338	      a message with an unexpected sequence number;

340	   o  protocol: a mandatory attribute set to "CLUE", identifying the
341	      procotol the messages refer to;

343	   o  v: a mandatory attribute carrying the version of the protocol.
344	      The content of the "v" attribute is composed by the major version
345	      number followed by a dot and then by the minor version number of
346	      the CLUE protocol in use.  Allowed values are of this kind: "1.3",
347	      "2.45", etc.

349	   Each CP should manage up to three (independent) streams of sequence
350	   numbers: (i) one for the messages exchanged in the initiation phase,
351	   (ii) one for the messages exchanged as MP, and (iii) one for the
352	   messages exchanged as MC.

354	4.1.  OPTIONS

356	   The OPTIONS message is sent by the CP which is the CI to the CP which
357	   is the CR as soon as the CLUE data channel is ready.  Besides the
358	   information envisioned in the basic structure, it specifies:

360	   o  mediaProvider: a mandatory boolean field set to "true" if the CP
361	      is able to act as a MP

363	   o  mediaConsumer: a mandatory boolean field set to "true" if the CP
364	      is able to act as a MC

366	   o  supportedVersions: the list of the supported versions

368	   o  supportedOptions: the list of the supported options

370	   The XML Schema of such a message is reported below:

372	<!-- CLUE OPTIONS -->
373	<xs:complexType name="optionsMessageType">
374	<xs:complexContent>
375	<xs:extension base="clueMessageType">
376	<xs:sequence>
377	<xs:element name="mediaProvider" type="xs:boolean"/>
378	<xs:element name="mediaConsumer" type="xs:boolean"/>
379	<xs:element name="supportedVersions" type="versionsListType" minOccurs="0"/>
380	<xs:element name="supportedOptions" type="optionsListType" minOccurs="0"/>
381	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
382	</xs:sequence>
383	<xs:anyAttribute namespace="##other" processContents="lax"/>
384	</xs:extension>
385	</xs:complexContent>
386	</xs:complexType>

388	<!-- VERSIONS LIST TYPE -->
389	<xs:complexType name="versionsListType">
390	<xs:sequence>
391	<xs:element name="version" type="versionType" minOccurs="1"
392	 maxOccurs="unbounded"/>
393	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
394	</xs:sequence>
395	<xs:anyAttribute namespace="##other" processContents="lax"/>
396	</xs:complexType>

398	<!-- OPTIONS LIST TYPE -->
399	<xs:complexType name="optionsListType">
400	<xs:sequence>
401	<xs:element name="option" type="optionType" minOccurs="1"
402	 maxOccurs="unbounded"/>
403	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
404	</xs:sequence>
405	<xs:anyAttribute namespace="##other" processContents="lax"/>
406	</xs:complexType>

408	<!-- OPTION TYPE -->
409	<xs:complexType name="optionType">
410	<xs:sequence>
411	<xs:element name="name" type="xs:string" />
412	<xs:element name="schemaRef" type="xs:anyURI" minOccurs="0"/>
413	<xs:element name="version" type="versionType" minOccurs="0"/>
414	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
415	</xs:sequence>
416	<xs:anyAttribute namespace="##other" processContents="lax"/>
417	</xs:complexType>
418	   <supportedVersions> contains the list of the versions that are
419	   supported by the CI, each one represented in a child <version>
420	   element.  The content of each <version> element is a string made by
421	   the major version number followed by a dot and then by the minor
422	   version number (e.g., 1.3 or 2.43).  Only one <version> element MUST
423	   be provided for each major version supported, containing the maximum
424	   minor version number of such a version, since all minor versions are
425	   backward compatible.  If no <supportedVersions> is carried within the
426	   OPTIONS message, the CI supports only the version declared in the "v"
427	   attribute and all the versions having the same major version number
428	   and lower minor version number.  For example, if the "v" attribute
429	   has a value of "3.4" and there is no <supportedVersions> tag in the
430	   OPTIONS message, it means the CI supports only major version 3 with
431	   all the minor versions comprised between 3.0 and 3.4, with version
432	   3.4 included.  If a <supportedVersion> is provided, at least one
433	   <version> tag MUST be included.

435	   The <supportedOptions> element specifies the list of options
436	   supported by the CI.  If there is no <supportedOptions> in the
437	   OPTIONS message, the CI does not support anything other than what is
438	   envisioned in the versions it supports.  For each option, an <option>
439	   element is provided.  An option is characterized by a name, an XML
440	   schema of reference where the option is defined, and the version of
441	   the protocol which the option refers to.

443	4.2.  OPTIONS RESPONSE

445	   The OPTIONS RESPONSE is sent by a CR to a CI as a reply to the
446	   OPTIONS message.  As depicted in the figure below, the OPTIONS
447	   RESPONSE contains mandatorily a response code and a reason string
448	   indicating the processing result of the OPTIONS message.  If the
449	   responseCode is of the type 2xx the response MUST also include
450	   <mediaProvider>, <mediaConsumer>, <version> and <commonOptions>
451	   elements; it MAY include them for any other response code.
452	   <mediaProvider> and <mediaConsumer> elements are associated with the
453	   supported roles (in terms of, respectively MP and MC), similarly to
454	   what the CI does in the OPTIONS message.  The <version> field
455	   indicates the highest commonly supported version number.  The content
456	   of the <version> element MUST be a string made of the major version
457	   number followed by a dot and then by the minor version number (e.g.,
458	   1.3 or 2.43).  Finally, the commonly supported options are copied in
459	   the the <commonOptions> field.

461	 <!-- CLUE OPTIONS RESPONSE -->
462	 <xs:complexType name="optionsResponseMessageType">
463	 <xs:complexContent>
464	 <xs:extension base="clueMessageType">
465	 <xs:sequence>
466	 <xs:element name="responseCode" type="xs:short"/>
467	 <xs:element name="reasonString" type="xs:string"/>
468	 <xs:element name="mediaProvider" type="xs:boolean" minOccurs="0"/>
469	 <xs:element name="mediaConsumer" type="xs:boolean" minOccurs="0"/>
470	 <xs:element name="version" type="versionType" minOccurs="0"/>
471	 <xs:element name="commonOptions" type="optionsListType" minOccurs="0"/>
472	 <xs:any namespace="##other"
473	 processContents="lax" minOccurs="0"/>
474	 </xs:sequence>
475	 <xs:anyAttribute namespace="##other" processContents="lax"/>
476	 </xs:extension>
477	 </xs:complexContent>
478	 </xs:complexType>

480	   After the reception of such a message, the version to be used is
481	   determined by each part of the conversation.  Indeed, it is the one
482	   provided in the <version> tag of the OPTIONS RESPONSE message.  The
483	   following CLUE messages MUST use such a version number in the "v"
484	   attribute.  The allowed options in the CLUE dialogue will be those
485	   indicated in the <commonOptions> of the OPTIONS RESPONSE message.

487	4.3.  ADVERTISEMENT

489	   The ADVERTISEMENT message (ADV) is used by the MP to advertise the
490	   available media captures and related information to the MC.  The MP
491	   sends to the MC an ADV as soon as it is ready after the successful
492	   completion of the initiation phase, i.e., as soon as the version and
493	   the options of the CLUE protocol are agreed between the CPs.  During
494	   a single CLUE session, an MP may send new ADV messages to replace the
495	   previously advertised options, if, for instance, its media CLUE
496	   telepresence capabilities change mid-call.  A new ADV completely
497	   invalidates the previous ADV.

499	   The ADV structure is defined in the picture below.  The ADV contains
500	   elements compliant with the CLUE data model that characterize the
501	   MP's telepresence offer.  Namely, such elements are: the list of the
502	   media captures (<mediaCaptures>), of the encoding groups
503	   (<encodingGroups>), of the capture scenes (<captureScenes>), of the
504	   simultaneous sets (<simultaneousSets>), of the global views
505	   (<globalViews>), and of the represented participants (<people>).
506	   Each of them is fully described in the CLUE framework document and
507	   formally defined in the CLUE data model document.

509	   <!-- CLUE ADVERTISEMENT MESSAGE TYPE -->
510	   <xs:complexType name="advertisementMessageType">
511	   <xs:complexContent>
512	   <xs:extension base="clueMessageType">
513	   <xs:sequence>
514	   <!-- mandatory -->
515	   <xs:element name="mediaCaptures" type="dm:mediaCapturesType"/>
516	   <xs:element name="encodingGroups" type="dm:encodingGroupsType"/>
517	   <xs:element name="captureScenes" type="dm:captureScenesType"/>
518	   <!-- optional -->
519	   <xs:element name="simultaneousSets" type="dm:simultaneousSetsType"
520	    minOccurs="0"/>
521	   <xs:element name="globalViews" type="dm:globalViewsType"
522	    minOccurs="0"/>
523	   <xs:element name="people" type="dm:peopleType" minOccurs="0"/>
524	   <xs:any namespace="##other" processContents="lax" minOccurs="0"/>
525	   </xs:sequence>
526	   <xs:anyAttribute namespace="##other" processContents="lax"/>
527	   </xs:extension>
528	   </xs:complexContent>
529	   </xs:complexType>

531	4.4.  ADVERTISEMENT ACKNOWLEDGEMENT

533	   The ADVERTISEMENT ACKNOWLEDGEMENT message (ACK) is sent by a MC to a
534	   MP to acknowledge an ADV message.  As it can be seen from the message
535	   schema provided in the following, the ACK contains a response code
536	   and a reason string for describing the processing result of the ADV.
537	   The <advSequenceNr> carries the sequence number of the ADV the ACK
538	   refers to.

540	   <!-- ADV ACK MESSAGE TYPE -->
541	   <xs:complexType name="advAcknowledgementMessageType">
542	   <xs:complexContent>
543	   <xs:extension base="clueMessageType">
544	   <xs:sequence>
545	   <xs:element name="responseCode" type="xs:short"/>
546	   <xs:element name="reasonString" type="xs:string"/>
547	   <xs:element name="advSequenceNr" type="xs:positiveInteger"/>
548	   <xs:any namespace="##other" processContents="lax" minOccurs="0"/>
549	   </xs:sequence>
550	   <xs:anyAttribute namespace="##other" processContents="lax"/>
551	   </xs:extension>
552	   </xs:complexContent>
553	   </xs:complexType>

555	4.5.  CONFIGURE

557	   The CONFIGURE message (CONF) is sent from a MC to a MP to list the
558	   advertised captures the MC wants to receive.  [ToDo: check this after
559	   signaling review - the CP must wait for the sdp offer to arrive? only
560	   for the first time?]  The MC can send a CONF after the reception of
561	   an ADV or each time it wants to request other captures that have been
562	   previously advertised by the MP.  The content of the CONF message is
563	   shown below.

565	    <!-- CLUE CONFIGURE MESSAGE TYPE -->
566	   <xs:complexType name="configureMessageType">
567	   <xs:complexContent>
568	   <xs:extension base="clueMessageType">
569	   <xs:sequence>
570	   <!-- mandatory fields -->
571	   <xs:element name="advSequenceNr" type="xs:positiveInteger"/>
572	   <xs:element name="ack" type="xs:boolean" minOccurs="0" fixed="true"/>
573	   <xs:element name="captureEncodings" type="dm:captureEncodingsType"
574	    minOccurs="0"/>
575	   <xs:any namespace="##other" processContents="lax" minOccurs="0"/>
576	   </xs:sequence>
577	   <xs:anyAttribute namespace="##other" processContents="lax"/>
578	   </xs:extension>
579	   </xs:complexContent>
580	   </xs:complexType>

582	   The <advSequenceNr> element contains the sequence number of the ADV
583	   message the CONF refers to.

585	   The optional boolean <ack> element, set to "true", if present,
586	   indicates that the CONF message also acknowledges the referred
587	   advertisement, by applying in that way a piggybacking mechanism for
588	   simultaneously acknowledging and replying to the ADV message.  In the
589	   above case, the CONF message MUST carry a 200 (Success) response
590	   code.  The <ack> element MUST not be present if an ACK message has
591	   been already sent back to the MP.

593	   The most important content of the CONFIGURE message is the list of
594	   the capture encodings provided in the <captureEncodings> element.
595	   Such an element contains a sequence of capture encodings,
596	   representing the streams to be instantiated.

598	4.6.  CONFIGURE RESPONSE

600	   <!-- CONFIGURE RESPONSE MESSAGE TYPE -->
601	   <xs:complexType name="configureResponseMessageType">
602	   <xs:complexContent>
603	   <xs:extension base="clueMessageType">
604	   <xs:sequence>
605	   <xs:element name="responseCode" type="xs:short"/>
606	   <xs:element name="reasonString" type="xs:string"/>
607	   <xs:element name="confSequenceNr" type="xs:positiveInteger"/>
608	   <xs:any namespace="##other" processContents="lax" minOccurs="0"/>
609	   </xs:sequence>
610	   <xs:anyAttribute namespace="##other" processContents="lax"/>
611	   </xs:extension>
612	   </xs:complexContent>
613	   </xs:complexType>

615	   The CONFIGURE RESPONSE message (CONF RESPONSE) is sent from the MP to
616	   the MC to communicate the processing result of requests carried in
617	   the previously received CONF message.  It contains a response code
618	   with a reason string indicating either the success or the failure
619	   (along with failure details) of a CONF request processing.
620	   Following, the <confSequenceNr> field contains the sequence number of
621	   the CONF message the response refers to.

623	4.7.  Response codes and reason strings

625	   The response codes and strings defined for use with CLUE are as
626	   follows:

628	   +-----------------+----------------------+--------------------------+
629	   |                 |                      |                          |
630	   |  Response code  |  Reason string       |       Description        |
631	   |                 |                      |                          |
632	   +-----------------+----------------------+--------------------------+
633	   |                 |                      |                          |
634	   |   200           |  Success             |  The request has been    |
635	   |                 |                      |  successfully processed. |
636	   |                 |                      |                          |
637	   +-----------------+----------------------+--------------------------+
638	   |                 |                      |                          |
639	   |   300           |  Bad syntax          |  The XML syntax of the   |
640	   |                 |                      |  message is not          |
641	   |                 |                      |  correct.                |
642	   +-----------------+----------------------+--------------------------+
643	   |                 |                      |                          |
644	   |   301           |  Invalid value       |  The message             |
645	   |                 |                      |  contains an invalid     |
646	   |                 |                      |  parameter value.        |
647	   +-----------------+----------------------+--------------------------+
648	   |                 |                      |                          |
649	   |   302           |  Conflicting values  |  The message             |
650	   |                 |                      |  contains values that    |
651	   |                 |                      |  cannot be used together.|
652	   +-----------------+----------------------+--------------------------+
653	   |                 |                      |                          |
654	   |   400           | Version not supported|  The protocol version    |
655	   |                 |                      |  used in the message     |
656	   |                 |                      |  is not supported.       |
657	   |                 |                      |                          |
658	   +-----------------+----------------------+--------------------------+
659	   |                 |                      |                          |
660	   |   401           |  Invalid sequencing  |  The sequence number of  |
661	   |                 |                      |  the message is out      |
662	   |                 |                      |  of date.                |
663	   +-----------------+----------------------+--------------------------+
664	   |                 |                      |                          |
665	   |   402           |  Invalid identifier  |  The identifier used in  |
666	   |                 |                      |  the message is          |
667	   |                 |                      |  not valid or unknown.   |
668	   +-----------------+----------------------+--------------------------+
669	   |                 |                      |                          |
670	   |   403           |  ADV Expired         |  The number of the ADV   |
671	   |                 |                      |  the CONF refers to is   |
672	   |                 |                      |  out of date.            |
673	   +-----------------+----------------------+--------------------------+
674	   |                 |                      |                          |
675	   |   404           |  Subset choice not   |  The subset choice is not|
676	   |                 |  allowed             | allowed for the specified|
677	   |                 |                      |  MCC                     |
678	   +-----------------+----------------------+--------------------------+

680	   Response codes are defined as a sequence of three digits.  A well-
681	   defined meaning is associated with the first digit.  Response codes
682	   beginning with "2" are associated with successful responses.
683	   Response codes beginning with "1" will represent a delayed or
684	   incomplete response.  Response codes that do not begin with either
685	   "2" or "1" indicate an error response, i.e., that an error occurred
686	   while processing a CLUE request.  In particular, response codes
687	   beginning with "3" indicate problems with the XML content of the
688	   message ("Bad syntax", "Invalid value", etc.), while response codes
689	   beginning with "4" refer to problems related to CLUE protocol
690	   semantics ("Invalid sequencing", "Version not supported", etc.).
691	   Further response codes can be designed in future versions of the
692	   protocol, provided they do not overwrite the ones here defined and
693	   they respect the semantics of the first code digit.

695	5.  Protocol state machines

697	   The CLUE protocol is an application protocol used between two CPs in
698	   order to properly configure a multimedia telepresence session.  CLUE
699	   protocol messages flow upon the CLUE Data Channel, a DTLS/SCTP
700	   channel established as depicted in [I-D.ietf-clue-datachannel].  We
701	   herein discuss the state machines associated, respectively, with the
702	   CLUE Participant, with the MC process and with the MP process.
703	   Endpoints often wish to both send a receive media, i.e., act as both
704	   MP and MC.  As such there will often be two sets of messages flowing
705	   in opposite directions; the state machines of these two flows do not
706	   interact with each other.  Only the CLUE application logic is
707	   considered.  The interaction of CLUE protocol and SDP negotiations
708	   for the media streams exchanged is treated in
709	   [I-D.ietf-clue-signaling].

711	6.  CLUE Participant's state machine

713	   The main state machines focus on the behavior of the CLUE Participant
714	   (CP) acting as a CLUE channel initiator/receiver (CI/CR).

716	   The initial state is the IDLE one.  When in the IDLE state, the CLUE
717	   data channel is not established and no CLUE-controlled media are
718	   exchanged between the two considered CLUE-capable devices (if there
719	   is an ongoing exchange of media streams, such media streams are not
720	   currently CLUE-controlled).

722	   When the CLUE data channel set up starts ("start channel"), the CP
723	   moves from the IDLE state to the CHANNEL SETUP state.

725	   If the CLUE data channel is successfully set up ("channel
726	   established"), the CP moves from the CHANNEL SETUP state to the
727	   OPTIONS state.  Otherwise ("channel error"), it moves back to the
728	   IDLE state.  The same transition happens if the CLUE-enabled
729	   telepresence session ends ("session ends"), i.e., when an SDP
730	   negotiation for removing the CLUE channel is performed.

732	   When in the OPTIONS state, the CP addresses the initiation phase
733	   where both parts agree on the version and on the options to be used
734	   in the subsequent CLUE messages exchange phase.  If the CP is the
735	   Channel Initiator (CI), it sends an OPTIONS message and waits for the
736	   OPTIONS RESPONSE message.  If the CP is the Channel Receiver (CR), it
737	   waits for the OPTIONS message and, as soon as it arrives, replies
738	   with the OPTIONS RESPONSE message.  If the negotiation is
739	   successfully completed ("OPTIONS phase success"), the CP moves from
740	   the OPTIONS state to the ACTIVE state.  If the initiation phase fails
741	   ("OPTIONS phase failure"), the CP moves from the OPTIONS state to the
742	   IDLE state.  The initiation phase might fail because of one of the
743	   following reasons:

745	   1.  the CI receives an OPTIONS RESPONSE with an error response code

747	   2.  the CI does not receive any OPTIONS RESPONSE and a timeout error
748	       is raised

750	   3.  the CR does not receive any OPTIONS and a timeout error is raised

752	   When in the ACTIVE state, the CP starts the envisioned sub-state
753	   machines (i.e., the MP state machine and the MC state machine)
754	   according to the roles it plays in the telepresence sessions.  Such
755	   roles have been previously declared in the OPTIONS and OPTIONS
756	   RESPONSE messages involved in the initiation phase (see OPTIONS
757	   sections Section 4.1 and Section 4.2 for the details).  When in the
758	   ACTIVE state, the CP delegates the sending and the processing of the
759	   CLUE messages to the appropriate MP/MC sub-state machines.  If the CP
760	   receives a further OPTIONS/OPTIONS RESPONSE message, it MUST ignore
761	   the message and stay in the ACTIVE state.

763	   The CP moves from the ACTIVE state to the IDLE one when the sub-state
764	   machines that have been activated are (both) in the relative
765	   TERMINATED state (see sections Section 6.1 and Section 6.2).

767	                                  +----+
768	          +---------------------->|IDLE|<----------------------------+
769	          |                       +-+--+                             |
770	          |                         |                                |
771	          |                         |  start                         |
772	          |                         |  channel                       |
773	          |                         v                                |
774	          |  channel error/      +--------+                          |
775	          |  session ends        | CHANNEL|                          |
776	          +----------------------+ SETUP  |                          |
777	          |                      +--+-----+                          |
778	          |                         |                                |
779	          |                         |  channel                       |
780	          |                         |  established                   |
781	          |  channel error/         v                 OPTIONS phase  |
782	          |  session ends         +-------+           failure        |
783	          +-----------------------+OPTIONS+--------------------------+
784	          |                       +-+-----+                          |
785	          |                         |                                |
786	          |                         |  OPTIONS phase                 |
787	          |                         |  success                       |
788	          |                         v                                |
789	          |   channel error/     +---------+                         |
790	          |   session ends       | ACTIVE  |                         |
791	          +----------------------+         |                         |
792	                                 | +----+  +------------------+      |
793	                                 | | MP |  |    send/receive  |      |
794	                                 | +----+  |    CLUE messages |      |
795	                                 |         |<-----------------+      |
796	                                 | +----+  |                         |
797	                                 | | MC |  |both sub state machines  |
798	                                 | +----+  |terminated               |
799	                                 |         |                         |
800	                                 +---------+-------------------------+

802	6.1.  Media Provider's state machine

804	   As soon as the sub-state machine of the MP is activated, it is in the
805	   ADV state.  In the ADV state, the MP is preparing the ADV message
806	   reflecting its actual telepresence capabilities.

808	   After the ADV has been sent ("ADV sent"), the MP moves from the ADV
809	   state to the WAIT FOR ACK state.  If an ACK message with a successful
810	   response code arrives ("ACK received"), the MP moves to the WAIT FOR
811	   CONF state.  If a NACK arrives (i.e., an ACK message with an error
812	   response code), and the number of NACKs for the issued ADV is under
813	   the retry threshold ("NACK received && retry not expired"), the MP
814	   moves back to the ADV state for preparing a new ADV.  The same
815	   happens if the waiting time for the ACK is fired a number of times
816	   under the retry threshold ("timeout && retry not expired"): also in
817	   this case, the MP goes back to the ADV state to send a new copy of
818	   the ADV.  If the number of retries overcomes the threshold ("timeout
819	   && retry expired"), the MP moves from the WAIT FOR ACK state to the
820	   MP-TERMINATED state.  When in the WAIT FOR ACK state, if a CONFIGURE
821	   message with the <ack> element set to TRUE arrives ("CONF+ACK
822	   received"), the MP goes directly to the CONF RESPONSE state.  CONF+
823	   ACK messages referring to out-of-date (i.e., having a sequence number
824	   equal to or less than the highest seen so far) ADVs MUST be ignored,
825	   i.e., they do not trigger any state transition.  If the telepresence
826	   settings of the MP change while in the WAIT FOR ACK state ("changed
827	   telepresence settings"), the MP switches from the WAIT FOR ACK state
828	   to the ADV state to create a new ADV.

830	   When in the WAIT FOR CONF state, the MP listens to the channel for a
831	   CONF request coming from the MC.  If a CONF arrives ("CONF
832	   received"), the MP switches to the CONF RESPONSE state.  If the CONF
833	   does not arrive within the timeout interval and the retry threshold
834	   has not been overcome ("timeout && retry not expired"), the MP moves
835	   back to the ADV state.  When the retry expires ("timeout && retry
836	   expired") the MP moves to the MP TERMINATED state.  If the
837	   telepresence settings change in the meanwhile ("changed telepresence
838	   settings"), the MP moves from the WAIT FOR CONF back to the ADV state
839	   to create the new ADV to be sent to the MC.

841	   The MP in the CONF RESPONSE state processes the received CONF in
842	   order to produce a CONF RESPONSE message.  If the MP successfully
843	   processes the MC's configuration, then it sends a 200 CONF RESPONSE
844	   ("success CONF RESPONSE sent") and moves to the ESTABLISHED state.
845	   If there are errors in the CONF processing, then the MP issues a CONF
846	   RESPONSE carrying an error response code and, if under the retry
847	   treshold ("error CONF RESPONSE sent && retry not expired"), it goes
848	   back to the WAIT FOR CONF state to wait for a new configuration
849	   request.  If the number of trials exceeds the retry threshold ("error
850	   CONF RESPONSE sent && retry expired"), the state MP TERMINATED is
851	   reached.  Finally, if there are changes in the MP's telepresence
852	   settings ("changed telepresence settings"), the MP switches to the
853	   ADV state.

855	   The MP in the ESTABLISHED state has successfully negotiated the media
856	   streams with the MC by means of the CLUE messages.  If there are
857	   changes in the MP's telepresence settings ("changed telepresence
858	   settings"), the MP moves back to the ADV state.  In the ESTABLISHED
859	   state, the CLUE-controlled media streams of the session are those
860	   described in the last successfully processed CONF message.

862	+------------------------->+-----+<---------------------------+
863	|            +------------>| ADV |<-------------------+       |
864	|            |             +-+---+                    |       |timeout
865	|            |               |       NACK received    |       |&&
866	|            |       ADV sent|             &&         |       |retry
867	|            |               v       retry not expired|       |not
868	|     changed|             +--------+                 |       |expired
869	|telepresence+-------------+WAIT FOR+-----------------+       |
870	|    settings|   +---------+  ACK   +-------------------------+
871	|            |   |CONF+ACK +-+------+------------------------------------+
872	|            |   |received   |                                 timeout &&|
873	|            |   |           |ACK received                        retry  |
874	|            |   |           v                                    expired|
875	+------------|-------------+--------+                                    |
876	timeout      +-------------+WAIT FOR+------------------------------------+
877	&&           |   |         |  CONF  |<-------------------------------+   |
878	retry        |   |         +-+------+                                |   |
879	not expired  |   |           |                                       |   |
880	             |   |           |CONF received                          |   |
881	             |   |           v               error CONF RESPONSE sent|   |
882	             |   +-------->+---------+        && retry not expired   |   |
883	             +-------------+CONF     |-------------------------------+   |
884	    +--------------------->|RESPONSE +-----------------------------------+
885	    |        |             +-+-------+           error CONF RESPONSE sent|
886	    |        |               |                           && retry expired|
887	    |        |               |  success                                  |
888	    |        |               |  CONF RESPONSE                            |
889	    |        |               |  sent                                     |
890	    |        |               |                                           |
891	    |        |               |                                           |
892	    |CONF    |               |                                           |
893	    |received|               v                                           |
894	    |        |             +------------+                                |
895	    |        +-------------+ESTABLISHED |                                |
896	    +----------------------+------------+                                |
897	                                                                         |
898	                                                                         |
899	                                                                         |
900	                           +-----------+                                 |
901	                           !    MP     |                                 |
902	                           |TERMINATED |                                 |
903	                           +-----------+<--------------------------------+

905	6.2.  Media Consumer's state machine

907	   As soon as the sub-state machine of the MC is activated, it is in the
908	   WAIT FOR ADV state.  An MC in the WAIT FOR ADV state is waiting for
909	   an ADV coming from the MP.  If the ADV arrives ("ADV received"), the
910	   MC reaches the ADV PROCESSING state.  Otherwise, the MC is stuck in
911	   the WAIT FOR ADV state.

913	   In the ADV PROCESSING state, the ADV is parsed by the MC.  If the ADV
914	   is successfully processed, there are two possibilities.  According to
915	   the first one, the MC issues a successful ACK message to the MP ("ACK
916	   sent") and moves to the CONF state.  In the second one, the MC
917	   prepares and sends a CONF message with the <ack> field set to "true"
918	   ("CONF+ACK sent") and goes directly to the WAIT FOR CONF RESPONSE
919	   state.

921	   If the ADV elaboration is unsuccessful (bad syntax, missing XML
922	   elements, etc.), and the number of times this has happened is under
923	   the retry treshold, the MC sends a NACK message (i.e., an ACK with an
924	   error response code) to the MP describing the problem via a proper
925	   reason phrase.  By this way ("NACK sent && retry not expired"), the
926	   MC switches back to the WAIT FOR ADV state, waiting for a new ADV.
927	   If the NACK retry expires ("retry expired"), the MC moves to the MC
928	   TERMINATED state.

930	   When in the CONF state, the MC is preparing the CONF request to be
931	   issued to the MP on the basis of the previously ACK-ed ADV.  When the
932	   CONF has been sent ("CONF sent"), the MC moves to the WAIT FOR CONF
933	   RESPONSE state.  If a new ADV arrives in the meanwhile ("ADV
934	   received"), the MC goes back to the ADV PROCESSING state.

936	   In the WAIT FOR CONF RESPONSE state, the MC is waiting for the MP's
937	   response to the issued CONF or CONF+ACK.  If a 200 CONF RESPONSE
938	   message is received ("successful CONF RESPONSE received"), it means
939	   that the MP and the MC have successfully agreed on the media streams
940	   to be shared.  Then, the MC can move to the ESTABLISHED state.  On
941	   the other hand, if an error response is received and the associated
942	   retry counter does not overcome the threshold ("error CONF RESPONSE
943	   received && retry not expired"), the MC moves back to the CONF state
944	   to prepare a new CONF request.  In case of "retry expired", the MC
945	   moves to the MC TERMINATED state.  If no CONF RESPONSE arrives at
946	   all, and the number of timeouts is under the threshold ("timeout &&
947	   retry not expired"), the MC moves to the WAIT FOR ADV state, waiting
948	   for a new ADV.  If a new ADV is received in the WAIT FOR CONF
949	   RESPONSE state, the MC switches to the ADV PROCESSING state.

951	   When the MC is in the ESTABLISHED state, the telepresence session
952	   configuration has been set up at the CLUE application level according
953	   to the MC's preferences.  Both the MP and the MC have agreed on (and
954	   are aware of) the CLUE-controlled media streams to be exchanged
955	   within the call.  While in the ESTABLISHED state, it might happen
956	   that the MC decides to change something in the call settings.  The MC
957	   then issues a new CONF ("CONF sent") and goes to wait for the new
958	   CONF RESPONSE in the WAIT FOR CONF RESPONSE state.  On the other
959	   hand, in the ESTABLISHED state, if a new ADV arrives from the MP
960	   ("ADV received"), it means that something has changed on the MP's
961	   side.  The MC then moves to the ADV PROCESSING state.

963	                           +----------+
964	                           | WAIT FOR |
965	                           |   ADV    |<-------------------------------+
966	                           +----+-----+<--------+                      |
967	                                |               |           timeout&&  |
968	                        ADV     |      NACK sent|             retry    |
969	                        received|      && retry |           not expired|
970	                                v    not expired|                      |
971	                           +-----------+--------+    retry expired     |
972	                           |  ADV      +-------------------------------|--+
973	                           | PROCESSING|<-----------------------+      |  |
974	                           +-+-----+---+                        |      |  |
975	                             |     |                            |      |  |
976	                   CONF+ACK  |     |  ACK                       |      |  |
977	                     sent    |     |  sent                      |      |  |
978	                             |     v                            |      |  |
979	                             |  +-----+                         |      |  |
980	                             |  |CONF |            ADV received |      |  |
981	            +------------------>|     +-------------------------+      |  |
982	            |                |  +--+--+                         |      |  |
983	            |error           |     |                            |      |  |
984	            |CONF RESPONSE   |     | CONF                       |      |  |
985	            |received&&      |     | sent      retry expired    |      |  |
986	            |retry           |     |      +-------------------------------+
987	            |not expired     v     v      |                     |      |  |
988	            +-------------+---------------+        ADV received |      |  |
989	               +--------->|   WAIT FOR    +---------------------+      |  |
990	               |          |  CONF RESPONSE+----------------------------+  |
991	               |          +-------+-------+                     |         |
992	               |                  |                             |         |
993	               |                  |                             |         |
994	               |                  |successful                   |         |
995	               |                  |CONF RESPONSE                |         |
996	               |                  |received                     |         |
997	               |                  v                             |         |
998	               |CONF sent   +-----------+           ADV received|         |
999	               +------------+ESTABLISHED+-----------------------+         |
1000	                            +-----------+                                 |
1001	                                                                          |
1002	                                                                          |
1003	                                                                          |
1004	                             +-----------+                                |
1005	                             |   MC      |<-------------------------------+
1006	                             |TERMINATED |
1007	                             +-----------+

1009	7.  Versioning

1011	   CLUE protocol messages are XML messages compliant to the CLUE
1012	   protocol XML schema [I-D.ietf-clue-data-model-schema].  The version
1013	   of the protocol corresponds to the version of the schema.  Both
1014	   client and server have to test the compliance of the received
1015	   messages with the XML schema of the CLUE protocol.  If the compliance
1016	   is not verified, the message cannot be processed further.

1018	   Obviously, client and server cannot communicate if they do not share
1019	   exactly the same XML schema.  Such a schema associated with the CLUE
1020	   URN "urn:ietf:params:xml:ns:clue-protocol".  If all CLUE-enabled
1021	   devices use that schema there will be no interoperability problems
1022	   due to schema issues.

1024	   The version of the XML schema contained in the standard document
1025	   deriving from this draft will be 1.0.  The version usage is similar
1026	   in philosophy to XMPP ([RFC6120]).  A version number has major and
1027	   minor components, each a non-negative integer.  Major version changes
1028	   denote non-interoperable changes.  Minor version changes denote
1029	   schema changes that are backward compatible by ignoring unknown XML
1030	   elements, or other backward compatible changes.

1032	   The minor versions of the XML schema MUST be backward compatible, not
1033	   only in terms of schema but also semantically and procedurally as
1034	   well.  This means that they should define further features and
1035	   functionality besides those defined in the previous versions, in an
1036	   incremental way, without impacting the basic rules defined in the
1037	   previous version of the schema.  In this way, if a MP is able to
1038	   speak, e.g., version 1.5 of the protocol while the MC only
1039	   understands version 1.4, the MP should have no problem in reverting
1040	   the dialogue back to version 1.4 without exploiting 1.5 features and
1041	   functionality.

1043	   It is expected that, before the CLUE protocol XML schema reaches a
1044	   steady state, prototypes developed by different organizations will
1045	   conduct interoperability testing.  In that case, in order to
1046	   interoperate, they have to be compliant to the current version of the
1047	   XML schema, i.e., the one copied in the most up-to-date version of
1048	   the draft defining the CLUE protocol.  The versions of the non-
1049	   standard XML schema will be numbered as 0.01, 0.02, and so on.
1050	   During the standard development phase, the versions of the XML schema
1051	   will probably not be backward compatible so it is left to prototype
1052	   implementers the responsibility of keeping their products up to date.

1054	8.  Extensions and options

1056	   Although the standard version of the CLUE protocol XML schema is
1057	   designed to thoroughly cope with the requirements emerging from the
1058	   application domain, new needs might arise and extensions can be
1059	   designed.  Extensions specify information and behaviors that are not
1060	   described in a certain version of the protocol.  They can relate to:

1062	   1.  new information, to be carried in the existing messages.  For
1063	       example, we may want to add more fields within an existing
1064	       message;

1066	   2.  new messages.  This is the case if there is no proper message for
1067	       a certain task, so a brand new CLUE message needs to be defined.

1069	   As to the first type of extensions, it is possible to distinguish
1070	   between protocol-specific and data model information.  Indeed, CLUE
1071	   messages are envelopes carrying both:

1073	   o  (i) XML elements defined within the CLUE protocol XML schema
1074	      itself (protocol-specific information)

1076	   o  (ii) other XML elements compliant to the CLUE data model schema
1077	      (data model information)

1079	   When new protocol-specific information is needed somewhere in the
1080	   protocol messages, it can be added in place of the <any> elements and
1081	   <anyAttribute> elements envisioned by the protocol schema.  The
1082	   policy currently defined in the protocol schema for handling <any>
1083	   and <anyAttribute> elements is:

1085	   o  elementFormDefault="qualified"

1087	   o  attributeFormDefault="unqualified"

1089	   In that case, the new information must be qualified by namespaces
1090	   other than "urn:ietf:params:xml:ns:clue-protocol" (the protocol URN)
1091	   and "urn:ietf:params:xml:ns:clue-info" (the data model URN).
1092	   Elements or attributes from unknown namespaces MUST be ignored.

1094	   The other matter concerns data model information.  Data model
1095	   information is defined by the XML schema associated with the URN
1096	   "urn:ietf:params:xml:ns:clue-info".  Also for the XML elements
1097	   defined in such a schema there are extensibility issues.  Those
1098	   issues are overcome by using <any> and <anyAttribute> placeholders.
1099	   Similarly to what said before, new information within data model
1100	   elements can be added in place of <any> and <anyAttribute> schema
1101	   elements, as long as they are properly namespace qualified.

1103	   On the other hand (second type of extensions), "extra" CLUE protocol
1104	   messages, i.e., messages not envisioned in the latest standard
1105	   version of the schema, can be needed.  In that case, the messages and
1106	   the associated behavior should be defined in external documents that
1107	   both communication parties must be aware of.

1109	   Both types of extensions, i.e., new information and new messages, can
1110	   be characterized by:

1112	   o  a name;

1114	   o  an external XML Schema defining the XML information and/or the XML
1115	      messages representing the extension;

1117	   o  the standard version of the protocol the extension refers to.

1119	   For that reason, the extensions can be represented by means of the
1120	   <option> element as defined below, which is carried within the
1121	   OPTIONS and OPTIONS RESPONSE messages to represent the extensions
1122	   supported by the CI and by the CR.

1124	   <!-- OPTION TYPE -->
1125	   <xs:complexType name="optionType">
1126	   <xs:sequence>
1127	   <xs:element name="name" type="xs:string" />
1128	   <xs:element name="schemaRef" type="xs:anyURI" minOccurs="0"/>
1129	   <xs:element name="version" type="versionType" minOccurs="0"/>
1130	   <xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1131	   </xs:sequence>
1132	   <xs:anyAttribute namespace="##other" processContents="lax"/>
1133	   </xs:complexType>

1135	9.  XML Schema

1137	   In this section, the XML schema defining the CLUE messages is
1138	   provided.

1140	<?xml version="1.0" encoding="UTF-8" ?>
1141	<xs:schema
1142	version="0.5"
1143	targetNamespace="urn:ietf:params:xml:ns:clue-protocol"
1144	xmlns:tns="urn:ietf:params:xml:ns:clue-protocol"
1145	xmlns:xs="http://www.w3.org/2001/XMLSchema"
1146	xmlns:dm="urn:ietf:params:xml:ns:clue-info"
1147	xmlns="urn:ietf:params:xml:ns:clue-protocol"
1148	elementFormDefault="qualified"
1149	attributeFormDefault="unqualified">

1151	<!-- Import data model schema -->
1152	<xs:import namespace="urn:ietf:params:xml:ns:clue-info"
1153	schemaLocation="data-model-schema-09.xsd"/>

1155	<!-- ELEMENT DEFINITIONS -->
1156	<xs:element name="options" type="optionsMessageType"/>
1157	<xs:element name="optionsResponse" type="optionsResponseMessageType"/>
1158	<xs:element name="advertisement" type="advertisementMessageType"/>
1159	<xs:element name="ack" type="advAcknowledgementMessageType"/>
1160	<xs:element name="configure" type="configureMessageType"/>
1161	<xs:element name="configureResponse" type="configureResponseMessageType"/>

1163	<!-- CLUE MESSAGE TYPE -->
1164	<xs:complexType name="clueMessageType" abstract="true">
1165	<xs:sequence>
1166	<xs:element name="clueId" type="xs:string"/>
1167	<xs:element name="sequenceNr" type="xs:positiveInteger"/>
1168	</xs:sequence>
1169	<xs:attribute name="protocol" type="xs:string" fixed="CLUE" use="required"/>
1170	<xs:attribute name="v" type="versionType" use="required"/>
1171	</xs:complexType>

1173	<!-- VERSION TYPE -->
1174	<xs:simpleType name="versionType">
1175	<xs:restriction base="xs:string">
1176	<xs:pattern value="([0-9])+\.([0-9]+)"></xs:pattern>
1177	</xs:restriction>
1178	</xs:simpleType>

1180	<!-- RESPONSE CODE TYPE -->
1181	<xs:simpleType name="responseCodeType">
1182	  <xs:restriction base="xs:integer">
1183	   <xs:pattern value="[1-9][0-9][0-9]"/>
1184	  </xs:restriction>
1185	</xs:simpleType>

1187	<!-- CLUE OPTIONS -->
1188	<xs:complexType name="optionsMessageType">
1189	<xs:complexContent>
1190	<xs:extension base="clueMessageType">
1191	<xs:sequence>
1192	<xs:element name="mediaProvider" type="xs:boolean"/>
1193	<xs:element name="mediaConsumer" type="xs:boolean"/>
1194	<xs:element name="supportedVersions" type="versionsListType" minOccurs="0"/>
1195	<xs:element name="supportedOptions" type="optionsListType" minOccurs="0"/>
1196	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1197	</xs:sequence>
1198	<xs:anyAttribute namespace="##other" processContents="lax"/>
1199	</xs:extension>
1200	</xs:complexContent>
1201	</xs:complexType>

1203	<!-- VERSIONS LIST TYPE -->
1204	<xs:complexType name="versionsListType">
1205	<xs:sequence>
1206	<xs:element name="version" type="versionType" minOccurs="1"
1207	 maxOccurs="unbounded"/>
1208	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1209	</xs:sequence>
1210	<xs:anyAttribute namespace="##other" processContents="lax"/>
1211	</xs:complexType>

1213	<!-- OPTIONS LIST TYPE -->
1214	<xs:complexType name="optionsListType">
1215	<xs:sequence>
1216	<xs:element name="option" type="optionType" minOccurs="1"
1217	 maxOccurs="unbounded"/>
1218	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1219	</xs:sequence>
1220	<xs:anyAttribute namespace="##other" processContents="lax"/>
1221	</xs:complexType>

1223	<!-- OPTION TYPE -->
1224	<xs:complexType name="optionType">
1225	<xs:sequence>
1226	<xs:element name="name" type="xs:string" />
1227	<xs:element name="schemaRef" type="xs:anyURI" minOccurs="0"/>
1228	<xs:element name="version" type="versionType" minOccurs="0"/>
1229	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1230	</xs:sequence>
1231	<xs:anyAttribute namespace="##other" processContents="lax"/>
1232	</xs:complexType>

1234	<!-- CLUE OPTIONS RESPONSE -->
1235	<xs:complexType name="optionsResponseMessageType">
1236	<xs:complexContent>
1237	<xs:extension base="clueMessageType">
1238	<xs:sequence>
1239	<xs:element name="responseCode" type="responseCodeType"/>
1240	<xs:element name="reasonString" type="xs:string"/>
1241	<xs:element name="mediaProvider" type="xs:boolean" minOccurs="0"/>
1242	<xs:element name="mediaConsumer" type="xs:boolean" minOccurs="0"/>
1243	<xs:element name="version" type="versionType" minOccurs="0"/>
1244	<xs:element name="commonOptions" type="optionsListType" minOccurs="0"/>
1245	<xs:any namespace="##other"
1246	processContents="lax" minOccurs="0"/>
1247	</xs:sequence>
1248	<xs:anyAttribute namespace="##other" processContents="lax"/>
1249	</xs:extension>
1250	</xs:complexContent>
1251	</xs:complexType>

1253	<!-- CLUE ADVERTISEMENT MESSAGE TYPE -->
1254	<xs:complexType name="advertisementMessageType">
1255	<xs:complexContent>
1256	<xs:extension base="clueMessageType">
1257	<xs:sequence>
1258	<!-- mandatory -->
1259	<xs:element name="mediaCaptures" type="dm:mediaCapturesType"/>
1260	<xs:element name="encodingGroups" type="dm:encodingGroupsType"/>
1261	<xs:element name="captureScenes" type="dm:captureScenesType"/>
1262	<!-- optional -->
1263	<xs:element name="simultaneousSets" type="dm:simultaneousSetsType"
1264	 minOccurs="0"/>
1265	<xs:element name="globalViews" type="dm:globalViewsType"
1266	 minOccurs="0"/>
1267	<xs:element name="people" type="dm:peopleType" minOccurs="0"/>
1268	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1269	</xs:sequence>
1270	<xs:anyAttribute namespace="##other" processContents="lax"/>
1271	</xs:extension>
1272	</xs:complexContent>
1273	</xs:complexType>

1275	<!-- ACK MESSAGE TYPE -->
1276	<xs:complexType name="advAcknowledgementMessageType">
1277	<xs:complexContent>
1278	<xs:extension base="clueMessageType">
1279	<xs:sequence>
1280	<xs:element name="responseCode" type="responseCodeType"/>
1281	<xs:element name="reasonString" type="xs:string"/>
1282	<xs:element name="advSequenceNr" type="xs:positiveInteger"/>
1283	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1284	</xs:sequence>
1285	<xs:anyAttribute namespace="##other" processContents="lax"/>
1286	</xs:extension>
1287	</xs:complexContent>
1288	</xs:complexType>

1290	<!-- CLUE CONFIGURE MESSAGE TYPE -->
1291	<xs:complexType name="configureMessageType">
1292	<xs:complexContent>
1293	<xs:extension base="clueMessageType">
1294	<xs:sequence>
1295	<xs:element name="advSequenceNr" type="xs:positiveInteger"/>
1296	<xs:element name="ack" type="xs:boolean"
1297	 minOccurs="0" fixed="true"/>
1298	<xs:element name="captureEncodings" type="dm:captureEncodingsType"
1299	 minOccurs="0"/>
1300	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1301	</xs:sequence>
1302	<xs:anyAttribute namespace="##other" processContents="lax"/>
1303	</xs:extension>
1304	</xs:complexContent>
1305	</xs:complexType>

1307	<!-- CONFIGURE RESPONSE MESSAGE TYPE -->
1308	<xs:complexType name="configureResponseMessageType">
1309	<xs:complexContent>
1310	<xs:extension base="clueMessageType">
1311	<xs:sequence>
1312	<xs:element name="responseCode" type="responseCodeType"/>
1313	<xs:element name="reasonString" type="xs:string"/>
1314	<xs:element name="confSequenceNr" type="xs:positiveInteger"/>
1315	<xs:any namespace="##other" processContents="lax" minOccurs="0"/>
1316	</xs:sequence>
1317	<xs:anyAttribute namespace="##other" processContents="lax"/>
1318	</xs:extension>
1319	</xs:complexContent>
1320	</xs:complexType>

1322	</xs:schema>

1324	10.  Examples

1326	   In the following we provide an example of ADVERTISEMENT representing
1327	   the telepresence environment described in
1328	   [I-D.ietf-clue-data-model-schema], Section "Sample XML file" and
1329	   Section "MCC example" respectively.

1331	10.1.  Simple ADV

1333	   The associated Media Provider's telepresence capabilities are
1334	   described in [I-D.ietf-clue-data-model-schema], Section "Sample XML
1335	   file".

1337	<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
1338	<advertisement xmlns="urn:ietf:params:xml:ns:clue-protocol"
1339	               xmlns:ns2="urn:ietf:params:xml:ns:clue-info"
1340	               xmlns:ns3="urn:ietf:params:xml:ns:vcard-4.0"
1341	               protocol="CLUE" v="0.4">
1342	    <clueId>Napoli</clueId>
1343	    <sequenceNr>45</sequenceNr>
1344	    <mediaCaptures>
1345	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1346	         xsi:type="ns2:videoCaptureType"  captureID="AC0" mediaType="video">
1347	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1348	            <ns2:encGroupIDREF>EG1</ns2:encGroupIDREF>
1349	            <ns2:spatialInformation>
1350	                <ns2:capturePoint>
1351	                    <ns2:x>0.5</ns2:x>
1352	                    <ns2:y>1.0</ns2:y>
1353	                    <ns2:z>0.5</ns2:z>
1354	                    <ns2:lineOfCapturePoint>
1355	                        <ns2:x>0.5</ns2:x>
1356	                        <ns2:y>0.0</ns2:y>
1357	                        <ns2:z>0.5</ns2:z>
1358	                    </ns2:lineOfCapturePoint>
1359	                </ns2:capturePoint>
1360	            </ns2:spatialInformation>
1361	            <ns2:individual>true</ns2:individual>
1362	            <ns2:description lang="en">main audio from the room</ns2:description>
1363	            <ns2:priority>1</ns2:priority>
1364	            <ns2:lang>it</ns2:lang>
1365	            <ns2:mobility>static</ns2:mobility>
1366	            <ns2:view>room</ns2:view>
1367	            <ns2:capturedPeople>
1368	                <ns2:personIDREF>alice</ns2:personIDREF>
1369	                <ns2:personIDREF>bob</ns2:personIDREF>
1370	                <ns2:personIDREF>ciccio</ns2:personIDREF>
1371	            </ns2:capturedPeople>
1372	        </ns2:mediaCapture>
1373	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1374	         xsi:type="ns2:videoCaptureType" mediaType="video" captureID="VC0">
1375	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1376	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1377	            <ns2:spatialInformation>
1378	                <ns2:capturePoint>
1379	                    <ns2:x>0.5</ns2:x>
1380	                    <ns2:y>1.0</ns2:y>
1381	                    <ns2:z>0.5</ns2:z>
1382	                    <ns2:lineOfCapturePoint>
1383	                        <ns2:x>0.5</ns2:x>
1384	                        <ns2:y>0.0</ns2:y>
1385	                        <ns2:z>0.5</ns2:z>
1386	                    </ns2:lineOfCapturePoint>
1387	                </ns2:capturePoint>
1388	            </ns2:spatialInformation>
1389	            <ns2:individual>true</ns2:individual>
1390	            <ns2:description lang="en">left camera video capture
1391	            </ns2:description>
1392	            <ns2:priority>1</ns2:priority>
1393	            <ns2:lang>it</ns2:lang>
1394	            <ns2:mobility>static</ns2:mobility>
1395	            <ns2:view>individual</ns2:view>
1396	            <ns2:capturedPeople>
1397	                <ns2:personIDREF>ciccio</ns2:personIDREF>
1398	            </ns2:capturedPeople>
1399	        </ns2:mediaCapture>
1400	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1401	         xsi:type="ns2:videoCaptureType" mediaType="video" captureID="VC1">
1402	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1403	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1404	            <ns2:spatialInformation>
1405	                <ns2:capturePoint>
1406	                    <ns2:x>0.5</ns2:x>
1407	                    <ns2:y>1.0</ns2:y>
1408	                    <ns2:z>0.5</ns2:z>
1409	                    <ns2:lineOfCapturePoint>
1410	                        <ns2:x>0.5</ns2:x>
1411	                        <ns2:y>0.0</ns2:y>
1412	                        <ns2:z>0.5</ns2:z>
1413	                    </ns2:lineOfCapturePoint>
1414	                </ns2:capturePoint>
1415	            </ns2:spatialInformation>
1416	            <ns2:individual>true</ns2:individual>
1417	            <ns2:description lang="en">central camera video capture
1418	            </ns2:description>
1419	            <ns2:priority>1</ns2:priority>
1420	            <ns2:lang>it</ns2:lang>
1421	            <ns2:mobility>static</ns2:mobility>
1422	            <ns2:view>individual</ns2:view>
1423	            <ns2:capturedPeople>
1424	                <ns2:personIDREF>alice</ns2:personIDREF>
1425	            </ns2:capturedPeople>
1426	        </ns2:mediaCapture>
1427	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1428	         xsi:type="ns2:videoCaptureType" mediaType="video" captureID="VC2">
1429	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1430	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1431	            <ns2:spatialInformation>
1432	                <ns2:capturePoint>
1433	                    <ns2:x>0.5</ns2:x>
1434	                    <ns2:y>1.0</ns2:y>
1435	                    <ns2:z>0.5</ns2:z>
1436	                    <ns2:lineOfCapturePoint>
1437	                        <ns2:x>0.5</ns2:x>
1438	                        <ns2:y>0.0</ns2:y>
1439	                        <ns2:z>0.5</ns2:z>
1440	                    </ns2:lineOfCapturePoint>
1441	                </ns2:capturePoint>
1442	            </ns2:spatialInformation>
1443	            <ns2:individual>true</ns2:individual>
1444	            <ns2:description lang="en">right camera video capture
1445	            </ns2:description>
1446	            <ns2:priority>1</ns2:priority>
1447	            <ns2:lang>it</ns2:lang>
1448	            <ns2:mobility>static</ns2:mobility>
1449	            <ns2:view>individual</ns2:view>
1450	            <ns2:capturedPeople>
1451	                <ns2:personIDREF>bob</ns2:personIDREF>
1452	            </ns2:capturedPeople>
1453	        </ns2:mediaCapture>
1454	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1455	         xsi:type="ns2:videoCaptureType" mediaType="video" captureID="VC3">
1456	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1457	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1458	            <ns2:nonSpatiallyDefinable>true</ns2:nonSpatiallyDefinable>
1459	            <ns2:composed>false</ns2:composed>
1460	            <ns2:switched>true</ns2:switched>
1461	            <ns2:policy>Soundlevel:0</ns2:policy>
1462	            <ns2:maxCaptures>1</ns2:maxCaptures>
1463	            <ns2:description lang="en">loudest room segment</ns2:description>
1464	            <ns2:priority>1</ns2:priority>
1465	            <ns2:lang>it</ns2:lang>
1466	            <ns2:mobility>static</ns2:mobility>
1467	            <ns2:view>individual</ns2:view>
1468	        </ns2:mediaCapture>
1469	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1470	         xsi:type="ns2:videoCaptureType" mediaType="video" captureID="VC4">
1471	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1472	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1473	            <ns2:spatialInformation>
1474	                <ns2:capturePoint>
1475	                    <ns2:x>0.5</ns2:x>
1476	                    <ns2:y>1.0</ns2:y>
1477	                    <ns2:z>0.5</ns2:z>
1478	                    <ns2:lineOfCapturePoint>
1479	                        <ns2:x>0.5</ns2:x>
1480	                        <ns2:y>0.0</ns2:y>
1481	                        <ns2:z>0.5</ns2:z>
1482	                    </ns2:lineOfCapturePoint>
1483	                </ns2:capturePoint>
1484	            </ns2:spatialInformation>
1485	            <ns2:individual>true</ns2:individual>
1486	            <ns2:description lang="en">zoomed out view of all people in
1487	            the room
1488	            </ns2:description>
1489	            <ns2:priority>1</ns2:priority>
1490	            <ns2:lang>it</ns2:lang>
1491	            <ns2:mobility>static</ns2:mobility>
1492	            <ns2:view>room</ns2:view>
1493	            <ns2:capturedPeople>
1494	                <ns2:personIDREF>alice</ns2:personIDREF>
1495	                <ns2:personIDREF>bob</ns2:personIDREF>
1496	                <ns2:personIDREF>ciccio</ns2:personIDREF>
1497	            </ns2:capturedPeople>
1498	        </ns2:mediaCapture>
1499	    </mediaCaptures>
1500	    <encodingGroups>
1501	        <ns2:encodingGroup encodingGroupID="EG0">
1502	            <ns2:maxGroupBandwidth>600000</ns2:maxGroupBandwidth>
1503	            <ns2:encodingIDList>
1504	                <ns2:encID>ENC1</ns2:encID>
1505	                <ns2:encID>ENC2</ns2:encID>
1506	                <ns2:encID>ENC3</ns2:encID>
1507	            </ns2:encodingIDList>
1508	        </ns2:encodingGroup>
1509	        <ns2:encodingGroup encodingGroupID="EG1">
1510	            <ns2:maxGroupBandwidth>300000</ns2:maxGroupBandwidth>
1511	            <ns2:encodingIDList>
1512	                <ns2:encID>ENC4</ns2:encID>
1513	                <ns2:encID>ENC5</ns2:encID>
1514	            </ns2:encodingIDList>
1515	        </ns2:encodingGroup>
1516	    </encodingGroups>
1517	    <captureScenes>
1518	        <ns2:captureScene scale="unknown" sceneID="CS1">
1519	            <ns2:sceneViews>
1520	                <ns2:sceneView sceneViewID="SE1">
1521	                    <ns2:mediaCaptureIDs>
1522	                        <ns2:captureIDREF>VC0</ns2:captureIDREF>
1523	                        <ns2:captureIDREF>VC1</ns2:captureIDREF>
1524	                        <ns2:captureIDREF>VC2</ns2:captureIDREF>

1526	                    </ns2:mediaCaptureIDs>
1527	                </ns2:sceneView>
1528	                <ns2:sceneView sceneViewID="SE2">
1529	                    <ns2:mediaCaptureIDs>
1530	                        <ns2:captureIDREF>VC3</ns2:captureIDREF>
1531	                    </ns2:mediaCaptureIDs>
1532	                </ns2:sceneView>
1533	                <ns2:sceneView sceneViewID="SE3">
1534	                    <ns2:mediaCaptureIDs>
1535	                        <ns2:captureIDREF>VC4</ns2:captureIDREF>
1536	                    </ns2:mediaCaptureIDs>
1537	                </ns2:sceneView>
1538	                <ns2:sceneView sceneViewID="SE4">
1539	                    <ns2:mediaCaptureIDs>
1540	                        <ns2:captureIDREF>VC4</ns2:captureIDREF>
1541	                    </ns2:mediaCaptureIDs>
1542	                </ns2:sceneView>
1543	            </ns2:sceneViews>
1544	        </ns2:captureScene>
1545	    </captureScenes>
1546	    <simultaneousSets>
1547	        <ns2:simultaneousSet setID="SS1">
1548	            <ns2:mediaCaptureIDREF>VC3</ns2:mediaCaptureIDREF>
1549	            <ns2:sceneViewIDREF>SE1</ns2:sceneViewIDREF>
1550	        </ns2:simultaneousSet>
1551	        <ns2:simultaneousSet setID="SS2">
1552	            <ns2:mediaCaptureIDREF>VC0</ns2:mediaCaptureIDREF>
1553	            <ns2:mediaCaptureIDREF>VC2</ns2:mediaCaptureIDREF>
1554	            <ns2:mediaCaptureIDREF>VC4</ns2:mediaCaptureIDREF>
1555	            <ns2:mediaCaptureIDREF>VC3</ns2:mediaCaptureIDREF>
1556	        </ns2:simultaneousSet>
1557	    </simultaneousSets>
1558	    <people>
1559	        <ns2:person personID="bob">
1560	            <ns2:personInfo>
1561	                <ns3:fn>
1562	                    <ns3:text>Bob</ns3:text>
1563	                </ns3:fn>
1564	            </ns2:personInfo>
1565	            <ns2:personType>minute taker</ns2:personType>
1566	        </ns2:person>
1567	        <ns2:person personID="alice">
1568	            <ns2:personInfo>
1569	                <ns3:fn>
1570	                    <ns3:text>Alice</ns3:text>
1571	                </ns3:fn>
1572	            </ns2:personInfo>
1573	            <ns2:personType>presenter</ns2:personType>

1575	        </ns2:person>
1576	        <ns2:person personID="ciccio">
1577	            <ns2:personInfo>
1578	                <ns3:fn>
1579	                    <ns3:text>Ciccio</ns3:text>
1580	                </ns3:fn>
1581	            </ns2:personInfo>
1582	            <ns2:personType>chairman</ns2:personType>
1583	            <ns2:personType>timekeeper</ns2:personType>
1584	        </ns2:person>
1585	    </people>
1586	</advertisement>

1588	10.2.  ADV with MCCs

1590	   The associated Media Provider's telepresence capabilities are
1591	   described in [I-D.ietf-clue-data-model-schema], Section "MCC
1592	   example".

1594	<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
1595	<advertisement xmlns="urn:ietf:params:xml:ns:clue-protocol"
1596	 xmlns:ns2="urn:ietf:params:xml:ns:clue-info"
1597	 xmlns:ns3="urn:ietf:params:xml:ns:vcard-4.0" protocol="CLUE" v="0.4">
1598	    <clueId>Napoli CLUE Endpoint</clueId>
1599	    <sequenceNr>34</sequenceNr>
1600	    <mediaCaptures>
1601	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1602	         xsi:type="ns2:videoCaptureType" mediaType="video" captureID="AC0">
1603	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1604	            <ns2:encGroupIDREF>EG1</ns2:encGroupIDREF>
1605	            <ns2:spatialInformation>
1606	                <ns2:capturePoint>
1607	                    <ns2:x>0.5</ns2:x>
1608	                    <ns2:y>1.0</ns2:y>
1609	                    <ns2:z>0.5</ns2:z>
1610	                    <ns2:lineOfCapturePoint>
1611	                        <ns2:x>0.5</ns2:x>
1612	                        <ns2:y>0.0</ns2:y>
1613	                        <ns2:z>0.5</ns2:z>
1614	                    </ns2:lineOfCapturePoint>
1615	                </ns2:capturePoint>
1616	            </ns2:spatialInformation>
1617	            <ns2:individual>true</ns2:individual>
1618	            <ns2:description lang="en">main audio from the room</ns2:description>
1619	            <ns2:priority>1</ns2:priority>
1620	            <ns2:lang>it</ns2:lang>
1621	            <ns2:mobility>static</ns2:mobility>
1622	            <ns2:view>room</ns2:view>
1623	            <ns2:capturedPeople>
1624	                <ns2:personIDREF>alice</ns2:personIDREF>
1625	                <ns2:personIDREF>bob</ns2:personIDREF>
1626	                <ns2:personIDREF>ciccio</ns2:personIDREF>
1627	            </ns2:capturedPeople>
1628	        </ns2:mediaCapture>
1629	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1630	         xsi:type="ns2:videoCaptureType" captureID="VC0" mediaType="video" >
1631	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1632	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1633	            <ns2:spatialInformation>
1634	                <ns2:capturePoint>
1635	                    <ns2:x>0.5</ns2:x>
1636	                    <ns2:y>1.0</ns2:y>
1637	                    <ns2:z>0.5</ns2:z>
1638	                    <ns2:lineOfCapturePoint>
1639	                        <ns2:x>0.5</ns2:x>
1640	                        <ns2:y>0.0</ns2:y>
1641	                        <ns2:z>0.5</ns2:z>
1642	                    </ns2:lineOfCapturePoint>
1643	                </ns2:capturePoint>
1644	            </ns2:spatialInformation>
1645	            <ns2:individual>true</ns2:individual>
1646	            <ns2:description lang="en">left camera video capture</ns2:description>
1647	            <ns2:priority>1</ns2:priority>
1648	            <ns2:lang>it</ns2:lang>
1649	            <ns2:mobility>static</ns2:mobility>
1650	            <ns2:view>individual</ns2:view>
1651	            <ns2:capturedPeople>
1652	                <ns2:personIDREF>ciccio</ns2:personIDREF>
1653	            </ns2:capturedPeople>
1654	        </ns2:mediaCapture>
1655	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1656	        xsi:type="ns2:videoCaptureType" captureID="VC1" mediaType="video">
1657	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1658	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1659	            <ns2:spatialInformation>
1660	                <ns2:capturePoint>
1661	                    <ns2:x>0.5</ns2:x>
1662	                    <ns2:y>1.0</ns2:y>
1663	                    <ns2:z>0.5</ns2:z>
1664	                    <ns2:lineOfCapturePoint>
1665	                        <ns2:x>0.5</ns2:x>
1666	                        <ns2:y>0.0</ns2:y>
1667	                        <ns2:z>0.5</ns2:z>
1668	                    </ns2:lineOfCapturePoint>
1669	                </ns2:capturePoint>
1670	            </ns2:spatialInformation>
1671	            <ns2:individual>true</ns2:individual>
1672	            <ns2:description lang="en">central camera video capture
1673	            </ns2:description>
1674	            <ns2:priority>1</ns2:priority>
1675	            <ns2:lang>it</ns2:lang>
1676	            <ns2:mobility>static</ns2:mobility>
1677	            <ns2:view>individual</ns2:view>
1678	            <ns2:capturedPeople>
1679	                <ns2:personIDREF>alice</ns2:personIDREF>
1680	            </ns2:capturedPeople>
1681	        </ns2:mediaCapture>
1682	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1683	        xsi:type="ns2:videoCaptureType" captureID="VC2" mediaType="video" >
1684	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1685	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1686	            <ns2:spatialInformation>
1687	                <ns2:capturePoint>
1688	                    <ns2:x>0.5</ns2:x>
1689	                    <ns2:y>1.0</ns2:y>
1690	                    <ns2:z>0.5</ns2:z>
1691	                    <ns2:lineOfCapturePoint>
1692	                        <ns2:x>0.5</ns2:x>
1693	                        <ns2:y>0.0</ns2:y>
1694	                        <ns2:z>0.5</ns2:z>
1695	                    </ns2:lineOfCapturePoint>
1696	                </ns2:capturePoint>
1697	            </ns2:spatialInformation>
1698	            <ns2:individual>true</ns2:individual>
1699	            <ns2:description lang="en">right camera video capture
1700	            </ns2:description>
1701	            <ns2:priority>1</ns2:priority>
1702	            <ns2:lang>it</ns2:lang>
1703	            <ns2:mobility>static</ns2:mobility>
1704	            <ns2:view>individual</ns2:view>
1705	            <ns2:capturedPeople>
1706	                <ns2:personIDREF>bob</ns2:personIDREF>
1707	            </ns2:capturedPeople>
1708	        </ns2:mediaCapture>
1709	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1710	        xsi:type="ns2:videoCaptureType" captureID="VC3" mediaType="video" >
1711	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1712	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1713	            <ns2:nonSpatiallyDefinable>true</ns2:nonSpatiallyDefinable>
1714	            <ns2:content>
1715	                <ns2:sceneViewIDREF>SE1</ns2:sceneViewIDREF>
1716	            </ns2:content>
1717	            <ns2:policy>Soundlevel:0</ns2:policy>
1718	            <ns2:maxCaptures>1</ns2:maxCaptures>
1719	            <ns2:allowSubsetChoice>false</ns2:allowSubsetChoice>
1720	            <ns2:description lang="en">loudest room segment</ns2:description>
1721	            <ns2:priority>1</ns2:priority>
1722	            <ns2:lang>it</ns2:lang>
1723	            <ns2:mobility>static</ns2:mobility>
1724	            <ns2:view>individual</ns2:view>
1725	        </ns2:mediaCapture>
1726	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1727	        xsi:type="ns2:videoCaptureType"  captureID="VC4" mediaType="video">
1728	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1729	            <ns2:encGroupIDREF>EG0</ns2:encGroupIDREF>
1730	            <ns2:spatialInformation>
1731	                <ns2:capturePoint>
1732	                    <ns2:x>0.5</ns2:x>
1733	                    <ns2:y>1.0</ns2:y>
1734	                    <ns2:z>0.5</ns2:z>
1735	                    <ns2:lineOfCapturePoint>
1736	                        <ns2:x>0.5</ns2:x>
1737	                        <ns2:y>0.0</ns2:y>
1738	                        <ns2:z>0.5</ns2:z>
1739	                    </ns2:lineOfCapturePoint>
1740	                </ns2:capturePoint>
1741	            </ns2:spatialInformation>
1742	            <ns2:individual>true</ns2:individual>
1743	            <ns2:description lang="en">zoomed out view of all people in the room
1744	            </ns2:description>
1745	            <ns2:priority>1</ns2:priority>
1746	            <ns2:lang>it</ns2:lang>
1747	            <ns2:mobility>static</ns2:mobility>
1748	            <ns2:view>room</ns2:view>
1749	            <ns2:capturedPeople>
1750	                <ns2:personIDREF>alice</ns2:personIDREF>
1751	                <ns2:personIDREF>bob</ns2:personIDREF>
1752	                <ns2:personIDREF>ciccio</ns2:personIDREF>
1753	            </ns2:capturedPeople>
1754	        </ns2:mediaCapture>
1755	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1756	        xsi:type="ns2:videoCaptureType"  captureID="VC5" mediaType="video">
1757	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1758	            <ns2:nonSpatiallyDefinable>true</ns2:nonSpatiallyDefinable>
1759	            <ns2:content>
1760	                <ns2:sceneViewIDREF>SE1</ns2:sceneViewIDREF>
1761	            </ns2:content>
1762	            <ns2:policy>Soundlevel:1</ns2:policy>
1763	            <ns2:maxCaptures>1</ns2:maxCaptures>
1764	            <ns2:allowSubsetChoice>false</ns2:allowSubsetChoice>
1765	            <ns2:description lang="en">penultimate loudest room segment
1766	            </ns2:description>
1767	            <ns2:priority>1</ns2:priority>
1768	            <ns2:lang>it</ns2:lang>
1769	            <ns2:mobility>static</ns2:mobility>
1770	            <ns2:view>individual</ns2:view>
1771	        </ns2:mediaCapture>
1772	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1773	        xsi:type="ns2:videoCaptureType"  captureID="VC6" mediaType="video">
1774	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1775	            <ns2:nonSpatiallyDefinable>true</ns2:nonSpatiallyDefinable>
1776	            <ns2:content>
1777	                <ns2:sceneViewIDREF>SE1</ns2:sceneViewIDREF>
1778	            </ns2:content>
1779	            <ns2:composed>false</ns2:composed>
1780	            <ns2:switched>true</ns2:switched>
1781	            <ns2:policy>Soundlevel:2</ns2:policy>
1782	            <ns2:maxCaptures>1</ns2:maxCaptures>
1783	            <ns2:allowSubsetChoice>false</ns2:allowSubsetChoice>
1784	            <ns2:description lang="en">last but two loudest room segment
1785	            </ns2:description>
1786	            <ns2:priority>1</ns2:priority>
1787	            <ns2:lang>it</ns2:lang>
1788	            <ns2:mobility>static</ns2:mobility>
1789	            <ns2:view>individual</ns2:view>
1790	        </ns2:mediaCapture>
1791	        <ns2:mediaCapture xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
1792	        xsi:type="ns2:videoCaptureType" captureID="VC7" mediaType="video">
1793	            <ns2:captureSceneIDREF>CS1</ns2:captureSceneIDREF>
1794	            <ns2:nonSpatiallyDefinable>true</ns2:nonSpatiallyDefinable>
1795	            <ns2:content>
1796	                <ns2:captureIDREF>VC3</ns2:captureIDREF>
1797	                <ns2:captureIDREF>VC5</ns2:captureIDREF>
1798	                <ns2:captureIDREF>VC6</ns2:captureIDREF>
1799	            </ns2:content>
1800	            <ns2:composed>true</ns2:composed>
1801	            <ns2:switched>true</ns2:switched>
1802	            <ns2:maxCaptures>1</ns2:maxCaptures>
1803	            <ns2:allowSubsetChoice>false</ns2:allowSubsetChoice>
1804	            <ns2:description lang="en">big picture of the current speaker +
1805	            pips about previous speakers</ns2:description>
1806	            <ns2:priority>1</ns2:priority>
1807	            <ns2:lang>it</ns2:lang>
1808	            <ns2:mobility>static</ns2:mobility>
1809	            <ns2:view>individual</ns2:view>
1810	        </ns2:mediaCapture>

1812	    </mediaCaptures>
1813	    <encodingGroups>
1814	        <ns2:encodingGroup encodingGroupID="EG0">
1815	            <ns2:maxGroupBandwidth>600000</ns2:maxGroupBandwidth>
1816	            <ns2:encodingIDList>
1817	                <ns2:encID>ENC1</ns2:encID>
1818	                <ns2:encID>ENC2</ns2:encID>
1819	                <ns2:encID>ENC3</ns2:encID>
1820	            </ns2:encodingIDList>
1821	        </ns2:encodingGroup>
1822	        <ns2:encodingGroup encodingGroupID="EG1">
1823	            <ns2:maxGroupBandwidth>300000</ns2:maxGroupBandwidth>
1824	            <ns2:encodingIDList>
1825	                <ns2:encID>ENC4</ns2:encID>
1826	                <ns2:encID>ENC5</ns2:encID>
1827	            </ns2:encodingIDList>
1828	        </ns2:encodingGroup>
1829	    </encodingGroups>
1830	    <captureScenes>
1831	        <ns2:captureScene scale="unknown" sceneID="CS1">
1832	            <ns2:sceneViews>
1833	                <ns2:sceneView sceneViewID="SE1">
1834	                    <ns2:description lang="en">participants' individual videos
1835	                    </ns2:description>
1836	                    <ns2:mediaCaptureIDs>
1837	                        <ns2:captureIDREF>VC0</ns2:captureIDREF>
1838	                        <ns2:captureIDREF>VC1</ns2:captureIDREF>
1839	                        <ns2:captureIDREF>VC2</ns2:captureIDREF>
1840	                    </ns2:mediaCaptureIDs>
1841	                </ns2:sceneView>
1842	                <ns2:sceneView sceneViewID="SE2">
1843	                    <ns2:description lang="en">loudest segment of the room
1844	                    </ns2:description>
1845	                    <ns2:mediaCaptureIDs>
1846	                        <ns2:captureIDREF>VC3</ns2:captureIDREF>
1847	                    </ns2:mediaCaptureIDs>
1848	                </ns2:sceneView>
1849	                <ns2:sceneView sceneViewID="SE5">
1850	                    <ns2:description lang="en">loudest segment
1851	                    of the room + pips</ns2:description>
1852	                    <ns2:mediaCaptureIDs>
1853	                        <ns2:captureIDREF>VC7</ns2:captureIDREF>
1854	                    </ns2:mediaCaptureIDs>
1855	                </ns2:sceneView>
1856	                <ns2:sceneView sceneViewID="SE4">
1857	                    <ns2:description lang="en">room audio</ns2:description>
1858	                    <ns2:mediaCaptureIDs>
1859	                        <ns2:captureIDREF>AC0</ns2:captureIDREF>

1861	                    </ns2:mediaCaptureIDs>
1862	                </ns2:sceneView>
1863	                <ns2:sceneView sceneViewID="SE3">
1864	                    <ns2:description lang="en">room video</ns2:description>
1865	                    <ns2:mediaCaptureIDs>
1866	                        <ns2:captureIDREF>VC4</ns2:captureIDREF>
1867	                    </ns2:mediaCaptureIDs>
1868	                </ns2:sceneView>
1869	            </ns2:sceneViews>
1870	        </ns2:captureScene>
1871	    </captureScenes>
1872	    <simultaneousSets>
1873	        <ns2:simultaneousSet setID="SS1">
1874	            <ns2:mediaCaptureIDREF>VC7</ns2:mediaCaptureIDREF>
1875	            <ns2:sceneViewIDREF>SE1</ns2:sceneViewIDREF>
1876	        </ns2:simultaneousSet>
1877	        <ns2:simultaneousSet setID="SS2">
1878	            <ns2:mediaCaptureIDREF>VC0</ns2:mediaCaptureIDREF>
1879	            <ns2:mediaCaptureIDREF>VC2</ns2:mediaCaptureIDREF>
1880	            <ns2:mediaCaptureIDREF>VC4</ns2:mediaCaptureIDREF>
1881	            <ns2:mediaCaptureIDREF>VC7</ns2:mediaCaptureIDREF>
1882	        </ns2:simultaneousSet>
1883	    </simultaneousSets>
1884	    <people>
1885	        <ns2:person personID="bob">
1886	            <ns2:personInfo>
1887	                <ns3:fn>
1888	                    <ns3:text>Bob</ns3:text>
1889	                </ns3:fn>
1890	            </ns2:personInfo>
1891	            <ns2:personType>minute taker</ns2:personType>
1892	        </ns2:person>
1893	        <ns2:person personID="alice">
1894	            <ns2:personInfo>
1895	                <ns3:fn>
1896	                    <ns3:text>Alice</ns3:text>
1897	                </ns3:fn>
1898	            </ns2:personInfo>
1899	            <ns2:personType>presenter</ns2:personType>
1900	        </ns2:person>
1901	        <ns2:person personID="ciccio">
1902	            <ns2:personInfo>
1903	                <ns3:fn>
1904	                    <ns3:text>Ciccio</ns3:text>
1905	                </ns3:fn>
1906	            </ns2:personInfo>
1907	            <ns2:personType>chairman</ns2:personType>
1908	            <ns2:personType>timekeeper</ns2:personType>

1910	        </ns2:person>
1911	    </people>
1912	</advertisement>

1914	11.  IANA Considerations

1916	   This document registers a new XML namespace, a new XML schema and the
1917	   MIME type for the schema.  This document also registers the "CLUE"
1918	   Application Service tag and the "CLUE" Application Protocol tag and
1919	   defines registries for the CLUE messages and response codes.

1921	11.1.  URN Sub-Namespace Registration

1923	   This section registers a new XML namespace,
1924	   ""urn:ietf:params:xml:ns:clue-protocol"".

1926	   URI: urn:ietf:params:xml:ns:clue-protocol

1928	   Registrant Contact: IETF CLUE working group (clue@ietf.org), Simon
1929	   Pietro Romano (spromano@unina.it).

1931	   XML:

1933	   BEGIN
1934	    <?xml version="1.0"?>
1935	    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
1936	      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
1937	    <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
1938	      <head>
1939	        <title>CLUE Messages</title>
1940	      </head>
1941	      <body>
1942	        <h1>Namespace for CLUE Messages</h1>
1943	        <h2>urn:ietf:params:xml:ns:clue-protocol</h2>
1944	   [[NOTE TO IANA/RFC-EDITOR: Please update RFC URL and replace XXXX
1945	       with the RFC number for this specification.]]
1946	        <p>See <a href="[[RFC URL]]">
1947	           RFCXXXX</a>.</p>
1948	      </body>
1949	    </html>
1950	   END

1952	11.2.  XML Schema registration

1954	   This section registers an XML schema per the guidelines in [RFC3688].

1956	   URI: urn:ietf:params:xml:schema:clue-protocol

1958	   Registrant Contact: CLUE working group (clue@ietf.org), Simon Pietro
1959	   Romano (spromano@unina.it).

1961	   Schema: The XML for this schema can be found as the entirety of
1962	   Section 9 of this document.

1964	11.3.  MIME Media Type Registration for 'application/clue+xml'

1966	   This section registers the " "application/clue+xml"" MIME type.

1968	   To: ietf-types@iana.org

1970	   Subject: Registration of MIME media type application/clue+xml

1972	   MIME media type name: application

1974	   MIME subtype name: clue+xml

1976	   Required parameters: (none)

1978	   Optional parameters: charset
1979	   Same as the charset parameter of "application/xml" as specified in
1980	   [RFC3023], Section 3.2.

1982	   Encoding considerations: Same as the encoding considerations of
1983	   "application/xml" as specified in [RFC3023], Section 3.2.

1985	   Security considerations: This content type is designed to carry
1986	   protocol data related to telepresence session control.  Some of the
1987	   data could be considered private.  This media type does not provide
1988	   any protection and thus other mechanisms such as those described in
1989	   Section Security are required to protect the data.  This media type
1990	   does not contain executable content.

1992	   Interoperability considerations: None.

1994	   Published specification: RFC XXXX [[NOTE TO IANA/RFC-EDITOR: Please
1995	   replace XXXX with the RFC number for this specification.]]

1997	   Applications that use this media type: CLUE participants.

1999	   Additional Information: Magic Number(s): (none),
2000	   File extension(s): .clue,
2001	   Macintosh File Type Code(s): TEXT.

2003	   Person & email address to contact for further information: Simon
2004	   Pietro Romano (spromano@unina.it).

2006	   Intended usage: LIMITED USE

2008	   Author/Change controller: The IETF

2010	   Other information: This media type is a specialization of
2011	   application/xml [RFC3023], and many of the considerations described
2012	   there also apply to application/clue+xml.

2014	11.4.  DNS Registrations

2016	   Section 11.4.1 defines an Application Service tag of "CLUE", which is
2017	   used to identify the CLUE service.  The Application Protocol tag
2018	   "CLUE", defined in Section 11.4.2, is used to identify a CLUE
2019	   Participant that understands CLUE.

2021	11.4.1.  Application Service tag

2023	   This section registers a new S-NAPTR/U-NAPTR Application Service tag
2024	   for CLUE, as mandated by [RFC3958].

2026	   Application Service Tag: CLUE

2028	   Intended usage: Identifies a server that supports CLUE telepresence
2029	   conferencing.

2031	   Defining publication: RFCXXXX [[NOTE TO IANA/RFC-EDITOR: Please
2032	   replace XXXX with the RFC number for this specification.]]

2034	   Contact information: The authors of this document

2036	   Author/Change controller: The IESG

2038	11.4.2.  Application Protocol tag

2040	   This section registers a new S-NAPTR/U-NAPTR Application Protocol tag
2041	   for CLUE, as mandated by [RFC3958].

2043	   Application Service Tag: CLUE

2045	   Intended Usage: Identifies the CLUE Protocol.

2047	   Applicable Service Tag(s): CLUE
2048	   Terminal NAPTR Record Type(s): U

2050	   Defining Publication: RFC XXXX [[NOTE TO IANA/RFC-EDITOR: Please
2051	   replace XXXX with the RFC number for this specification.]]

2053	   Contact Information: The authors of this document

2055	   Author/Change Controller: The IESG

2057	11.5.  CLUE Protocol Registry

2059	   The document requests that the IANA creates new registries for CLUE
2060	   messages and response codes.

2062	11.5.1.  CLUE Message Types

2064	   The following summarizes the registry for CLUE messages:

2066	   Related Registry: CLUE Message Types Registry

2068	   Defining RFC: RFC XXXX [[NOTE TO IANA/RFC-EDITOR: Please replace XXXX
2069	   with the RFC number for this specification.]]

2071	   Registration/Assignment Procedures: Following the policies outlined
2072	   in [RFC5226], the IANA policy for assigning new values for the CLUE
2073	   message types for the CLUE protocol is Specification Required.

2075	   Registrant Contact: IETF CLUE working group (clue@ietf.org), Simon
2076	   Pietro Romano (spromano@unina.it).

2078	   The initial Message table is populated using the CLUE messages
2079	   described in Section 4 and defined in the XML schema in Section 9.

2081	   ToDo: table: message description reference

2083	11.5.2.  CLUE Response Codes

2085	   The following summarizes the requested registry for CLUE response
2086	   codes:

2088	   Related Registry: CLUE Response Code Registry

2090	   Defining RFC: RFC XXXX [[NOTE TO IANA/RFC-EDITOR: Please replace XXXX
2091	   with the RFC number for this specification.]]

2093	   Registration/Assignment Procedures: Following the policies outlined
2094	   in [RFC5226], the IANA policy for assigning new values for the
2095	   Response codes for CLUE shall be Specification Required.

2097	   Registrant Contact: IETF CLUE working group (clue@ietf.org), Simon
2098	   Pietro Romano (spromano@unina.it).

2100	   The initial Response-code table is populated using the Response codes
2101	   defined in Section 4.7 as follows:

2103	   ToDo: table: number, default reason string, description, reference

2105	12.  Diff with draft-ietf-clue-protocol-04

2107	   o  The document has been revised based on feedback recevied on the
2108	      ML.  No major modification is included in this version.

2110	13.  Diff with draft-ietf-clue-protocol-03

2112	   o  Response codes section updated.

2114	   o  maxCaptureEncodings removed from examples, allowSubsetChoice
2115	      added.

2117	   o  State machines descriptions aligned with pictures.

2119	   o  Applied recommended updates indicated in Christian's review (2015-
2120	      03-19).

2122	14.  Diff with draft-ietf-clue-protocol-02

2124	   o  CLUE Participant state machine: TERMINATED state replaced with
2125	      IDLE.

2127	   o  MP and MC state machines: SDP O/A state removed.

2129	   o  Diff mechanism (and related example) removed.

2131	   o  Schema updates: versionType used as the data type for all versions
2132	      fields, xs:unsignedInt used as the data type for all sequence
2133	      number fields, diff support removed from the ADV definition.

2135	15.  Diff with draft-ietf-clue-protocol-01

2137	   o  The diff mechanism for the ADV message has been introduced.

2139	   o  READV and READV RESPONSE message have been both removed.

2141	   o  The state machines have been deeply reviewed and changed.

2143	   o  References: references have been updated and splitted into
2144	      Informative references and Normative references as in framework
2145	      v17.

2147	   o  Schema: <globalSceneEntries> changed in <globalViews>,
2148	      <participants> in <people>

2150	   o  Terminology: many definitions added.

2152	   o  Response codes updated.

2154	16.  Diff with draft-ietf-clue-protocol-00

2156	   1.  The XML schema of the ADVERTISEMENT and of the READV have been
2157	       aligned with the current definitions in
2158	       [I-D.ietf-clue-data-model-schema] (example of updates:
2159	       <participants> --> <people>, <globalCaptureEntries> -->
2160	       <globalSceneEntries>)

2162	   2.  Text has been added to clarify that, in the OPTIONS RESPONSE,
2163	       when the response code is not an error response code, both
2164	       <mediaProvider> and <mediaConsumer> are mandatory.

2166	   3.  The content of the "v" attribute and of the <version> elements
2167	       carried in the OPTIONS and OPTIONS RESPONSE messages has been
2168	       described more precisely.

2170	   4.  Advertisement examples have been added.

2172	17.  Diff with draft-presta-clue-protocol-04

2174	   1.  The response code type error in the OPTIONS response (and in
2175	       other parts) has been corrected.

2177	18.  Diff with draft-presta-clue-protocol-03

2179	   1.  The XML Schema has been deeply revised and completed.

2181	   2.  The descriptions of the CLUE messages have been added.

2183	   3.  The distinction between major version numbers and minor version
2184	       numbers has been cut and pasted from [I-D.ietf-clue-signaling].

2186	   4.  Besides the two way one, a three way mechanism for the options
2187	       negotiation has been proposed and provided to foster discussion.

2189	19.  Diff with draft-presta-clue-protocol-02

2191	   1.  "Terminology" section added.

2193	   2.  Introduced the concept of "CLUE Participant" - an Endpoint or a
2194	       MCU able to use the CLUE protocol within a telepresence session.
2195	       A CLUE Participant can act as a Media Provider and/or as a Media
2196	       Consumer.

2198	   3.  Introduced the ACK/NACK mechanism for the ADVERTISEMENT.

2200	   4.  MP and MC state machines have been updated.  The CP state machine
2201	       has been added.

2203	20.  Acknowledgments

2205	   The authors thank all the CLUErs for their precious feedbacks and
2206	   support, in particular Paul Kyzivat, Christian Groves and Scarlett
2207	   Liuyan.

2209	21.  References

2211	21.1.  Normative References

2213	   [I-D.ietf-clue-data-model-schema]  Presta, R. and S. Romano, "An XML
2214	                                      Schema for the CLUE data model", d
2215	                                      raft-ietf-clue-data-model-schema-
2216	                                      10 (work in progress), June 2015.

2218	   [I-D.ietf-clue-datachannel]        Holmberg, C., "CLUE Protocol data
2219	                                      channel",
2220	                                      draft-ietf-clue-datachannel-10
2221	                                      (work in progress),
2222	                                      September 2015.

2224	   [I-D.ietf-clue-framework]          Duckworth, M., Pepperell, A., and
2225	                                      S. Wenger, "Framework for
2226	                                      Telepresence Multi-Streams",
2227	                                      draft-ietf-clue-framework-23 (work
2228	                                      in progress), September 2015.

2230	   [I-D.ietf-clue-signaling]          Kyzivat, P., Xiao, L., Groves, C.,
2231	                                      and R. Hansen, "CLUE Signaling",
2232	                                      draft-ietf-clue-signaling-06 (work
2233	                                      in progress), August 2015.

2235	   [RFC3023]                          Murata, M., St. Laurent, S., and
2236	                                      D. Kohn, "XML Media Types",
2237	                                      RFC 3023, DOI 10.17487/RFC3023,
2238	                                      January 2001, <http://
2239	                                      www.rfc-editor.org/info/rfc3023>.

2241	   [RFC3550]                          Schulzrinne, H., Casner, S.,
2242	                                      Frederick, R., and V. Jacobson,
2243	                                      "RTP: A Transport Protocol for
2244	                                      Real-Time Applications", STD 64,
2245	                                      RFC 3550, DOI 10.17487/RFC3550,
2246	                                      July 2003, <http://
2247	                                      www.rfc-editor.org/info/rfc3550>.

2249	   [RFC3688]                          Mealling, M., "The IETF XML
2250	                                      Registry", BCP 81, RFC 3688,
2251	                                      DOI 10.17487/RFC3688,
2252	                                      January 2004, <http://
2253	                                      www.rfc-editor.org/info/rfc3688>.

2255	   [RFC3958]                          Daigle, L. and A. Newton, "Domain-
2256	                                      Based Application Service Location
2257	                                      Using SRV RRs and the Dynamic
2258	                                      Delegation Discovery Service
2259	                                      (DDDS)", RFC 3958, DOI 10.17487/
2260	                                      RFC3958, January 2005, <http://
2261	                                      www.rfc-editor.org/info/rfc3958>.

2263	   [RFC5226]                          Narten, T. and H. Alvestrand,
2264	                                      "Guidelines for Writing an IANA
2265	                                      Considerations Section in RFCs",
2266	                                      BCP 26, RFC 5226, DOI 10.17487/
2267	                                      RFC5226, May 2008, <http://
2268	                                      www.rfc-editor.org/info/rfc5226>.

2270	21.2.  Informative References

2272	   [RFC4353]                          Rosenberg, J., "A Framework for
2273	                                      Conferencing with the Session
2274	                                      Initiation Protocol (SIP)",
2275	                                      RFC 4353, DOI 10.17487/RFC4353,
2276	                                      February 2006, <http://
2277	                                      www.rfc-editor.org/info/rfc4353>.

2279	   [RFC5117]                          Westerlund, M. and S. Wenger, "RTP
2280	                                      Topologies", RFC 5117,
2281	                                      DOI 10.17487/RFC5117,
2282	                                      January 2008, <http://
2283	                                      www.rfc-editor.org/info/rfc5117>.

2285	   [RFC6120]                          Saint-Andre, P., "Extensible
2286	                                      Messaging and Presence Protocol
2287	                                      (XMPP): Core", RFC 6120,
2288	                                      DOI 10.17487/RFC6120, March 2011,
2289	                                      <http://www.rfc-editor.org/info/
2290	                                      rfc6120>.

2292	   [RFC6502]                          Camarillo, G., Srinivasan, S.,
2293	                                      Even, R., and J. Urpalainen,
2294	                                      "Conference Event Package Data
2295	                                      Format Extension for Centralized
2296	                                      Conferencing (XCON)", RFC 6502,
2297	                                      DOI 10.17487/RFC6502, March 2012,
2298	                                      <http://www.rfc-editor.org/info/
2299	                                      rfc6502>.

2301	   [RFC6503]                          Barnes, M., Boulton, C., Romano,
2302	                                      S., and H. Schulzrinne,
2303	                                      "Centralized Conferencing
2304	                                      Manipulation Protocol", RFC 6503,
2305	                                      DOI 10.17487/RFC6503, March 2012,
2306	                                      <http://www.rfc-editor.org/info/
2307	                                      rfc6503>.

2309	   [RFC7262]                          Romanow, A., Botzko, S., and M.
2310	                                      Barnes, "Requirements for
2311	                                      Telepresence Multistreams",
2312	                                      RFC 7262, DOI 10.17487/RFC7262,
2313	                                      June 2014, <http://
2314	                                      www.rfc-editor.org/info/rfc7262>.

2316	Authors' Addresses

2318	   Roberta Presta
2319	   University of Napoli
2320	   Via Claudio 21
2321	   Napoli  80125
2322	   Italy

2324	   EMail: roberta.presta@unina.it
2325	   Simon Pietro Romano
2326	   University of Napoli
2327	   Via Claudio 21
2328	   Napoli  80125
2329	   Italy

2331	   EMail: spromano@unina.it