1、STD-ITU-T RECMN T*LBO-ENGL 399B E 48b2593 Ob58343 b7T I INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TA80 (06/98) SERIES T: TERMINALS FOR TELEMATIC SERVICES Homogeneous access mechanism to communication services ITU-T Recommendation T. 180 (Previously C
2、CIlT Recommendation) STD-ITU-T RECNN f-L8O-ENGL 3998 II 4862593 Ob58342 50b ITU-T T-SERIES RECOMMENDATIONS TERMINALS FOR TELEMATIC SERVICES For further details, please refer IO ITU-T List of Recommendations. STDmITU-T RECMN T-380-ENGL 3978 4862573 Ob58LY3 442 I ITU-T RECOMMENDATION T.180 HOMOGENEOUS
3、 ACCESS MECHANISM TO COMMUNICATION SERVICES Summary This Recommendation specifies a homogenous access mechanism to communication services (called XAPI). The XAPI, which is an abbreviation for extensive Application Programming Interface, is an operating system and language-independent programming int
4、erface to general communication services. This Recommendation specifies a set of functions which allow XAPI users to have access to the services of an underlying provider. These functions apply to all providers which are specified in this Recommendation. A model of communication is introduced which
5、defines the semantics of those XAPI functions which are communication related. Making available appropriate providers, the communication system can be tailored to specific requirements, and all communication services are accessible via one homogenous access mechanism. Source ITU-T Recommendation T.1
6、80 was prepared by ITU-T Study Group 8 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 1 8* of June 1998. STD-ITU-T RECMN T-LBO-ENGL 1998 = 4b2573 Ob58344 387 111 FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field
7、of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The 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. T
8、he World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedur
9、e laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-T?s purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation the term recognized operating agency (ROA) includes any individual, company, co
10、rporation or governmental organization that operates a public correspondence service. The terms Administration, ROA and public correspondence are defined in the Constitution of the ITU (Geneva, 1992). INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implem
11、entation of this Recommendation may involve the use of a claimed Intellectual Property Right. The 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 development proc
12、ess. As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore str
13、ongly urged to consult the TSB patent database. O ITU 1999 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. STD-ITU-T RECMN T-LBO-ENG
14、L 1998 E 4Bb259L 0658145 215 CONTENTS 1 2 3 4 5 6 6.1 6.2 6.3 7 7.1 7.2 8 8.1 8.2 9 9.1 9.2 Scope References Definitions Abbreviations . Structure of this Recommendation . Introduction to the XAPI Location of the XAPI . Phases of communication . Applications that are supported by XAPI . A Model of c
15、ommunication Classes of communication 7.1.1 Peer-to-peer communication . The state transition diagram as part of the model . 7.1.2 Multipeer communication . Description of the XAPI . XAPI in point-to-point and in multipoint environments XAPI functions and the corresponding state transition diagram X
16、API functions . Conventions Communication-related functions 9.2.1 9.2.2 9.2.3 9.2.4 9.2.5 9.2.6 9.2.7 9.2.8 9.2.9 9.2.10 9.2.1 1 9.2.12 9.2.13 9.2.14 X-CONCONF/x-concon f X-CONIND/x conind . X-CONREQ/x-conreq x-coNRsP/xconrsp . - X.RCVDATNx-rcvdata . X-RCVDIS/xrcvdis . X-RCVINFO/xrcvinfo X-RCVSP/x r
17、cvsp - X-RELCONF/x-relconf X.RELND/xrelind X-RELREQ/x relreq . X-RELRSP/x-relrsp X-SNDDIS/x snddis . - X-SNDD ATA/x-snddata - Page 1 1 2 3 4 5 5 7 9 12 12 12 14 18 22 22 25 31 34 35 35 36 36 37 38 39 40 40 41 41 42 42 42 43 STDmITU-T RECMN T-140-ENGL 1776 4862571 0658146 151 113 9.2.15 X-SNDINFO/x-s
18、ndinfo 9.2.16 X-SNDSP/x-sndsp 9.3 Not communication-related functions Functions for the initialization and de-initialization phase . 9.3.1 9.3.2 Utility functions . Annex A . Interface definition language description Annex B . Error codes . Appendix I . Examples of XAPI access to service providers .
19、 1.1 XAPI access to the service provider for the ISDN B-channel 1.1.1 Scope . I . 1.2 References . I . 1.3 Definitions . I . 1.4 Abbreviations I . 1.5 Conventions . I . 1.6 Introduction to the ISDN physical service provider access . I . 1.7 Description of the access to the ISDN physical service prov
20、ider . XAPI access to the service provider for BFT over T.30 1.2.1 Scope . 1.2.2 References . 1.2.3 Definitions . 1.2.4 Abbreviations 1.2.5 Conventions . 1.2.6 Introduction to the BFT(T.30) provider access . 1.2.7 Description ofthe access to the BFT(T.30) provider XAPI access to the service provider
21、 for FAX4 and BFT . 1.2 1.3 1.3.1 Scope . 1.3.2 References . 1.3.3 Definitions . 1.3.4 Abbreviations 1.3.5 Conventions . 1.3.6 Introduction to the FAX4BFT service provider access 1.3.7 Description of the access to the FAX4BFT service provider . XAPI access to the service provider for ACSE and ROSE 1
22、.4.1 Scope . 1.4.2 References . 1.4.3 Definitions . 1.4.4 Abbreviations 1.4 Page 44 44 45 45 47 52 65 69 70 70 70 71 71 71 72 72 78 78 79 79 79 80 81 81 92 92 93 94 94 94 95 95 125 125 126 127 127 STD-ITU-T RECflN T.38O-ENGL 1998 1111 4862573 Ob58347 098 1111 1.5 1.6 1.7 1.4.5 Conventions . 1.4.6 In
23、troduction to the ACSEROSE provider access . 1.4.7 Description of the access to the ACSEROSE provider XAPI access to a Service Provider for Audio and Video (AV) Control 1.5.1 Scope . 1.5.2 References . 1.5.3 Definitions . 1.5.4 Abbreviations 1.5.5 Conventions . 1.5.6 Introduction to the video codec
24、service provider access . 1.5.7 Description of the access to the Video Codec Service Provider . XAPI access to the service provider for the T . 120 conference control 1.6.1 Scope . 1.6.2 References . 1.6.3 Definitions . 1.6.4 Abbreviations 1.6.5 Conventions . 1.6.6 1.6.7 Introduction to the conferen
25、ce control provider access . XAPI access to the service provider for T . 127 MBFT . Description of the access to the conference control provider 1.7.1 Scope . 1.7.2 References . 1.7.3 Definitions . 1.7.4 Abbreviations 1.7.5 Conventions . 1.7.6 Introduction to the MBFT service provider access . 1.7.7
26、 Description of the access to the MBFT service provider Appendix II . Tutorial: XAPI and selected providers . 11.1 XAPI and the ACSEROSE provider . 11.2 XAPI and the specific T.120 conference provider . 11.2.1 The T . 120 system model . 11.2.2 T.120 MBFT conferencing Page 127 128 131 163 163 163 164
27、 164 165 166 167 242 242 244 244 244 244 245 247 273 273 275 275 275 276 277 277 310 310 315 315 317 STD-ITU-T RECMN T-180-ENGL 1998 I 4862591 0658348 T24 SB Recommendation T.180 HOMOGENEOUS ACCESS MECHANISM TO COMMUNICATION SERVICES (Geneva, 1998) 1 Scope The MI, which is an abbreviation for extens
28、ive Application Programming Interface, is an operating system and language-independent homogenous access mechanism to general communication services. It is not dedicated to a certain layer, but allows access to all layers of the OS1 reference model and other layered communication models (e.g. confer
29、encing). The XAPI provides a framework of functions for the use in communication applications. All communication services are accessible through this set of functions. The XAPI does not impose any restrictions on the service interface of the underlying communication platform. Which services are made
30、 available via the XAPI depends on the installed service providers, and not on the XAPI, which only provides the access mechanism. New service providers can be added in the XAPI configuration. Thus, the communication system can be tailored to specific requirements and all communication services are
31、accessible via one homogeneous access mechanism. 2 References The following ITU-T Recommendations and other references contain provision which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendat
32、ions and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly p
33、ublished. - ITU-T Recommendation F.58 1 (1 993), Guidelines for Programming Communication InterfQces (PCIs) definition: Service Recommendation. ITU-T Recommendation H.320 (1 997), Narrow-band visual telephone systems and terminal equipment. ITU-T Recommendation T.30 (1 996), Procedures for document
34、facsimile transmission in the general switched telephone network. - ITU-T Recommendation T. 120 (1 996), Data protocols for multimedia conferencing. - ITU-T Recommendation T. 12 1 (1 996), Generic application template. - ITU-T Recommendation T. 122 (1998), Multipoint communication service - Service
35、definition. ITU-T Recommendation T. 123 (1 996), Network speczpc data protocol stacks for multimedia conferencing. ITU-T Recommendation T. 124 (1 998), Generic Conference Control. specijkation. ITU-T Recommendation T. 127 (1 999, Multipoint binaryfile transferprotocol. - - - - - ITU-T Recommendation
36、 T. 125 (1 994), Multipoint communication service protocol - STDaITU-T RECflN T-LBO-ENGL 1978 W 48b259L Ob58149 760 ITU-T Recommendation T.434 (1 996), BinaryJile transfer format for the telematic services. ITU-T Recommendation X.200 (1 994) I ISODEC 7498-1 : 1994, Information technology - Open Syst
37、ems Interconnection - Basic Reference Model: The Basic Model. 3 Definitions 3.1 For the purposes of this Recommendation, the following terms as defined in Recommendation X.200 apply: - 0-connection ; - )-entity; - 0-layer ; - 0-service; - )-Service Access Point (SAP). 3.2 For the purposes of this Re
38、commendation, the following terms as defined in Recommendation T.124 apply: - conference; - Multipoint Control Unit; - node; - terminal. 3.3 This Recommendation defines the following terms: 3.3.1 application connection: Serves for communication between application entities. 3.3.2 application entity:
39、 A service user, or some other entity, which may participate in a connection. 3.3.3 application system: A protocol stack comprising some or all of the OS1 layers 5 (Session) to 7 (Application). 3.3.4 communication endpoint: Synonymously used for “Service Endpoint“. 3.3.5 communication platform: Cons
40、ists in a number of communication service providers, in a homogeneous access mechanism, by means of which service users, which are distributed in space, may establish communication between them. 3.3.6 conference control: Encompasses functions such as conference establishment and termination, informa
41、tion about each node which is participating in the same conference, information about each application entity in the conference, coordination of conference conductorship, as well as other miscellaneous functions. 3.3.7 connection: A logical association between two or more entities, enabling communic
42、ation between them. 3.3.8 control entity: A specific service user which handles conference control and which may participate in a connection. 3.3.9 control connection: Serves for communication between control entities. 3.3.1 O multipeer relationship: In a multipeer relationship, the users may negoti
43、ate the characteristics of their interaction and, afterwards, communicate with each other obeying the rules they have negotiated: all users (an entity and its peers) have potential equal rights. STD-ITU-T RECMN T.LBO-ENGL 1998 I 48b259L Ob58150 be2 I 3.3.11 multipoint aware application: An applicati
44、on entity which is able to participate in a multipoint connection. 3.3.12 multipoint connection: A connection between more than two entities. 3.3.13 Peer-to-peer relationship: In a peer-to-peer relationship, the users may negotiate the characteristics of their interaction and, afterwards, communicat
45、e obeying the rules they have negotiated: both users (an entity and its peer entity) have potential equal rights. 3.3.14 point-to-point connection: A connection between two entities. 3.3.15 protocol module: The implementation of a communication protocol whose services can be accessed via the XAPI. U
46、sually a protocol module implements a single layer in the OS1 sense. 3.3.16 service access point: The point at which services are provided to a user. Associated with each SAP is an address. 3.3.17 service endpoint: Specifies the local link between a service user and a service provider. It consists o
47、f two parts: a SAP address and an additional identifier (optional), which is unique within the scope of the SAP. 3.3.18 service provider: A communication protocol stack that provides a certain service to the user at the upper interface of its topmost protocol module. 3.3.19 session: A peer-to-peer o
48、r multipeer relationship between application entities which are communicating via an application connection. In general, a session brings into focus a specific topic of discussion. 3.3.20 transport system: A protocol stack comprising some or all of the OS1 layers 1 (Physic) to 4 (Transport). 4 Abbre
49、viations This Recommendation uses the following abbreviations: AAL ACSE ATM AVC BFT CLS cos cscw Fd GCC HDLC IDL ISDN MBFT MCS ATM Adaptation Layer Association Control Service Element Asynchronous Transfer Mode Audiovisual Control Binary File Transfer Connectionless Service Connection oriented Service Computer-Supported Cooperative Work File Descriptor Generic Conference Control High-Level Data-Link Control Interface Definition Language Integrated Services Digital Network Multipoint Binary File Transfer Multipoint Communication Service STD-ITU-T RECMN TmLBO-ENGL L998 M 4862591 Oh58151 5L9
