1、 International Telecommunication Union ITU-T T.135TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2007) SERIES T: TERMINALS FOR TELEMATIC SERVICES Data protocols for multimedia conferencing User-to-reservation system transactions within T.120 conferences ITU-T Recommendation T.135 ITU-T T-SERIES
2、 RECOMMENDATIONS TERMINALS FOR TELEMATIC SERVICES Facsimile Framework T.0T.19 Still-image compression Test charts T.20T.29 Facsimile Group 3 protocols T.30T.39 Colour representation T.40T.49 Character coding T.50T.59 Facsimile Group 4 protocols T.60T.69 Telematic services Framework T.70T.79 Still-im
3、age compression JPEG-1, Bi-level and JBIG T.80T.89 Telematic services ISDN Terminals and protocols T.90T.99 Videotext Framework T.100T.109 Data protocols for multimedia conferencing T.120T.149 Telewriting T.150T.159 Multimedia and hypermedia framework T.170T.189 Cooperative document handling T.190T.
4、199 Telematic services Interworking T.300T.399 Open document architecture T.400T.429Document transfer and manipulation T.430T.449 Document application profile T.500T.509 Communication application profile T.510T.559 Telematic services Equipment characteristics T.560T.649 Still-image compression JPEG
5、2000 T.800T.849 Still-image compression JPEG-1 extensions T.850T.899 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. T.135 (08/2007) i ITU-T Recommendation T.135 User-to-reservation system transactions within T.120 conferences Summary ITU-T Recommendation T.135 int
6、roduces a protocol that enables a reservation application in a user terminal to communicate electronically with the reservation system a service provider, in order to reserve resources for multimedia conferences, modify or cancel previous reservations, and perform other related transactions. The arc
7、hitecture model defined by this Recommendation is designed for in-band transactions that is, transactions taking place between a reservation system and a T.120 compliant user terminal joined to an ongoing conference. This revised version of T.135 introduces a number of clarifications to the previous
8、 version. Source ITU-T Recommendation T.135 was approved on 29 August 2007 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. T.135 (08/2007) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of
9、 telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World T
10、elecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In som
11、e areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognize
12、d operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words
13、“shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that th
14、e practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation
15、development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are t
16、herefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. T.135 (08/2007) iii CONTENTS Page 1 Scope 1 2 Refe
17、rences. 1 3 Definitions 2 4 Abbreviations 3 5 Conventions 4 6 Introduction 5 7 T.135 model 5 7.1 System model . 5 7.2 Mode of operation 7 8 Service description 17 8.1 Service summary 17 8.2 Service description . 18 9 Protocol specification . 49 9.1 Encoding of URST PDUs. 49 9.2 URST ASN.1 Module 50
18、ITU-T Rec. T.135 (08/2007) 1 ITU-T Recommendation T.135 User-to-reservation system transactions within T.120 conferences 1 Scope This Recommendation provides a standard protocol for multimedia conference reservation transactions between users and service providers, whilst users are utilizing a T.120
19、-based terminal. Its primary intent is to enable conferencing users to perform operations such as reserving resources for their next conference, or directly interacting from the conference they are participating in to modify the conferences resource use. The architecture model and the protocol speci
20、fied in this Recommendation make provision of a collection of parameters which allow conferencing users to deal with multiple service providers simultaneously. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute p
21、rovisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommend
22、ations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. ITU-T H.231 ITU-T Recommendation H.231 (1997), Multipoint control units for audiovisual systems using digital channels up to 1920 kbit/s. ITU-T H.242 ITU-T Recommendation H.242 (2004
23、), System for establishing communication between audiovisual terminals using digital channels up to 2 Mbit/s. ITU-T H.243 ITU-T Recommendation H.243 (2005), Procedures for establishing communication between three or more audiovisual terminals using digital channels up to 1920 kbit/s. ITU-T H.261 ITU
24、-T Recommendation H.261 (1993), Video codec for audiovisual services at p 64 kbit/s. ITU-T H.262 ITU-T Recommendation H.262 (2000), Information technology Generic coding of moving pictures and associated audio information: Video. ITU-T H.320 ITU-T Recommendation H.320 (2004), Narrow-band visual tele
25、phone systems and terminal equipment. ITU-T Q.931 ITU-T Recommendation Q.931 (1998), ISDN user-network interface layer 3 specification for basic call control. ITU-T T.50 ITU-T Recommendation T.50 (1992), International Reference Alphabet (IRA) (Formerly International Alphabet No. 5 or IA5) Informatio
26、n technology 7-bit coded character set for information interchange. ITU-T T.120 ITU-T Recommendation T.120 (2007), Data protocols for multimedia conferencing. ITU-T T.122 ITU-T Recommendation T.122 (1998), Multipoint communication service Service definition. 2 ITU-T Rec. T.135 (08/2007) ITU-T T.123
27、ITU-T Recommendation T.123 (2007), Network specific data protocol stacks for multimedia conferencing. ITU-T T.124 ITU-T Recommendation T.124 (2007), Generic Conference Control. ITU-T T.125 ITU-T Recommendation T.125 (1998), Multipoint communication service protocol specification. 3 Definitions This
28、Recommendation defines the following terms: 3.1 application protocol: Any standard or non-standard protocol utilized by an application. 3.2 application protocol entity: The name given to any instance of an application protocol within the frame of the T.120 communication infrastructure. 3.3 conferenc
29、e resource: Some part of a multimedia conferencing device that can be used in a conference. 3.4 multimedia conference: A number of multimedia conferencing devices that are joined together and that are capable of exchanging audiographic and audiovisual information across various communication network
30、s. In this Recommendation, a multimedia conference is assumed to be T.120-based for some or all of its data part. 3.5 multimedia conferencing device: A device used in a multimedia conference which may include terminals, multiport terminals, MCUs and other machines. 3.6 multipoint: The ability to exc
31、hange any or all of audio, video or data among multiple multimedia conferencing devices simultaneously as opposed to point-to-point where audio, video and/or data is exchanged between two directly connected nodes. 3.7 multipoint control unit: Commonly referred to as an MCU or bridge; a multiport dev
32、ice that serves to connect terminals and other MCUs in a multipoint fashion. An MCU is not primarily intended as an end-point for user communication. 3.8 multiport terminal: A user terminal also capable of bridging T.120 information. Refer to clause 3 of ITU-T T.124 for the full definition of a mult
33、iport terminal. 3.9 registered site: Given a particular reservation system, a registered site is a site which is known by the reservation system (its description is stored in (one of) the reservation system database(s), and that can be unambiguously identified by it by the means of its Site ID. 3.10
34、 reservation application: An application utilizing a T.135 APE. 3.11 reservation connection: A data point-to-point connection established between a client and a server reservation application and by the means of which a user has logged into a reservation system. 3.12 reservation device: Generic name
35、 given to components of a reservation system when it is designed as a distributed architecture. 3.13 reservation domain: The set of multimedia conferencing devices managed by a reservation system. The term “management“ is used in the sense of direct control of scheduling resources and, for some case
36、s, real-time control of conferencing devices. 3.14 reservation server node: A special reservation device that is capable of representing the service provider which device is a component in a multimedia conference. 3.15 reservation system: A system capable of managing the entire related reservation d
37、omain. 3.16 reservation transaction: An interaction between two reservation applications which is globally based on a query/response model. ITU-T Rec. T.135 (08/2007) 3 3.17 service provider: An organization owning or controlling one or more reservation systems and using them to provide multimedia c
38、onference bridging services. 3.18 service subscriber: A person, an organization or any intermediate entity known i.e., recorded in (one of) the database(s) by a reservation system and recognized by it as a registered user of the service provider. The subscriber is unambiguously identified within the
39、 reservation system of the service provider reservation system by means of its Subscriber ID. 3.19 service user: A person, an organization or any intermediate entity using the services provided by a service provider. 3.20 site: A global piece of information describing a member of a multimedia confer
40、ence. Site information includes information relative to the multimedia conferencing device used, to the network to which the device is directly connected including the device network address(es), to the physical location of the device, and to the human participants using this device. 3.21 site ID: A
41、n unambiguous identification by which a site is recognized as a registered site by a reservation system. 3.22 subscriber ID: An unambiguous identification by which a user is recognized as a service subscriber by a reservation system. 3.23 user terminal: The terminal that a user actually utilizes to
42、participate into multimedia conferences. 4 Abbreviations This Recommendation uses the following abbreviations: APE Application Protocol Entity API Application Programming Interface ATM Asynchronous Transfer Mode CSDN Circuit Switched Digital Network GCC General Conference Control GSTN Global Switche
43、d Telephone Network GUI Graphical User Interface ISDN Integrated Services Digital Network LAN Local Area Network MCE Multimedia Conferencing Equipment MCS Multipoint Communication Service MCU Multipoint Control Unit PDU Protocol Data Unit PSTN Public Switched Telephone Network RD Reservation Device
44、RSN Reservation Server Node RSN-RA Reservation Server Node Reservation Application URST User-to-Reservation System Transactions 4 ITU-T Rec. T.135 (08/2007) UT User Terminal UT-RA User Terminal Reservation Application 5 Conventions The primitive parameters of the abstract services defined in this Re
45、commendation use the following key: M Parameter is mandatory. C Parameter is conditional. O Parameter is optional. Blank Parameter is absent. (=) Value of the parameter is identical to the value of the corresponding parameter of the preceding primitive, where preceding is defined relative to the ord
46、er: request, indication, response, confirm. (=RQ) Value of the parameter is identical to the value of the corresponding parameter in a preceding primitive, where RQ = request, IN = indication, RS = response, and CF = confirm. Service primitives are categorized in up to four types: Request, Indicatio
47、n, Response, and Confirm. Some primitives support all of these types, while others do not. These four types are defined as follows: Request primitives: Those that are sourced from a Reservation Application to a URST APE to initiate a URST transaction or command a specific service. Indication primiti
48、ves: Those that are sourced from a URST APE to a Reservation Application either as a result of a received Request or Indication PDU or a URST APE initiated action. Response primitives: Those that are sourced from a Reservation Application to a URST APE in response to an Indication primitive which re
49、quires a response. Confirm primitives: Those that are sourced from a URST APE to a Reservation Application as a result of a received Response PDU or directly in response to a Request primitive. PDUs are categorized into three types. PDU names all include the words “Request“, “Indication“, or “Response“ to indicate the intended use of the PDU. These are defined as follows: Request PDUs: Those that require a Response PDU in return. A URST APE receiving a Request PDU from the peer side generates an Ind
