Network Working Group T. Melanchuk, Ed.
Request for Comments: 5567 Rain Willow Communications
Category: Informational June 2009
Network Working Group T. Melanchuk, Ed.
Request for Comments: 5567 Rain Willow Communications
Category: Informational June 2009
An Architectural Framework for Media Server Control
媒体服务器控制的体系结构框架
Status of This Memo
关于下段备忘
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
本备忘录为互联网社区提供信息。它没有规定任何类型的互联网标准。本备忘录的分发不受限制。
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版权公告
Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2009 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document.
本文件受BCP 78和IETF信托在本文件出版之日生效的与IETF文件有关的法律规定的约束(http://trustee.ietf.org/license-info). 请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。
This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.
本文件可能包含2008年11月10日之前发布或公开的IETF文件或IETF贡献中的材料。控制某些材料版权的人员可能未授予IETF信托允许在IETF标准流程之外修改此类材料的权利。在未从控制此类材料版权的人员处获得充分许可的情况下，不得在IETF标准流程之外修改本文件，也不得在IETF标准流程之外创建其衍生作品，除了将其格式化以RFC形式发布或将其翻译成英语以外的其他语言。
Abstract
摘要
This document describes an architectural framework for Media Server control. The primary focus will be to define logical entities that exist within the context of Media Server control, and define the appropriate naming conventions and interactions between them.
本文档描述了媒体服务器控制的体系结构框架。主要重点将是定义媒体服务器控制上下文中存在的逻辑实体，并定义适当的命名约定和它们之间的交互。
Table of Contents
目录
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Architecture Overview ...........................................4
4. SIP Usage .......................................................7
5. Media Control for IVR Services .................................10
5.1. Basic IVR Services ........................................11
5.2. IVR Services with Mid-Call Controls .......................11
5.3. Advanced IVR Services .....................................11
6. Media Control for Conferencing Services ........................12
6.1. Creating a New Conference .................................14
6.2. Adding a Participant to a Conference ......................14
6.3. Media Controls ............................................15
6.4. Floor Control .............................................16
7. Security Considerations ........................................21
8. Acknowledgments ................................................22
9. Contributors ...................................................22
10. Informative References ........................................23
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Architecture Overview ...........................................4
4. SIP Usage .......................................................7
5. Media Control for IVR Services .................................10
5.1. Basic IVR Services ........................................11
5.2. IVR Services with Mid-Call Controls .......................11
5.3. Advanced IVR Services .....................................11
6. Media Control for Conferencing Services ........................12
6.1. Creating a New Conference .................................14
6.2. Adding a Participant to a Conference ......................14
6.3. Media Controls ............................................15
6.4. Floor Control .............................................16
7. Security Considerations ........................................21
8. Acknowledgments ................................................22
9. Contributors ...................................................22
10. Informative References ........................................23
Application Servers host one or more instances of a communications application. Media Servers provide real-time media processing functions. This document presents the core architectural framework to allow Application Servers to control Media Servers. An overview of the architecture describing the core logical entities and their interactions is presented in Section 3. The requirements for Media Server control are defined in [RFC5167].
应用服务器承载一个或多个通信应用程序实例。媒体服务器提供实时媒体处理功能。本文档介绍了允许应用程序服务器控制媒体服务器的核心体系结构框架。第3节概述了描述核心逻辑实体及其交互的体系结构。[RFC5167]中定义了媒体服务器控制的要求。
The Session Initiation Protocol (SIP) [RFC3261] is used as the session establishment protocol within this architecture. Application Servers use it both to terminate media streams on Media Servers and to create and manage control channels for Media Server control between themselves and Media Servers. The detailed model for Media Server control together with a description of SIP usage is presented in Section 4.
会话发起协议（SIP）[RFC3261]用作此体系结构中的会话建立协议。应用程序服务器使用它来终止媒体服务器上的媒体流，并创建和管理控制通道，以便在它们自己和媒体服务器之间进行媒体服务器控制。第4节介绍了媒体服务器控制的详细模型以及SIP使用说明。
Several services are described using the framework defined in this document. Use cases for Interactive Voice Response (IVR) services are described in Section 5, and conferencing use cases are described in Section 6.
使用本文档中定义的框架描述了几个服务。交互式语音应答（IVR）服务的用例在第5节中描述，会议用例在第6节中描述。
The following terms are defined for use in this document in the context of Media Server control:
以下术语定义用于本文档中的媒体服务器控制上下文：
Application Server (AS): A functional entity that hosts one or more instances of a communication application. The application server may include the conference policy server, the focus, and the conference notification server, as defined in [RFC4353]. Also, it may include communication applications that use IVR or announcement services.
应用程序服务器（AS）：承载一个或多个通信应用程序实例的功能实体。应用服务器可以包括会议策略服务器、焦点和会议通知服务器，如[RFC4353]中所定义。此外，它还可能包括使用IVR或公告服务的通信应用程序。
Media Functions: Functions available on a Media Server that are used to supply media services to the AS. Some examples are Dual-Tone Multi-Frequency (DTMF) detection, mixing, transcoding, playing announcement, recording, etc.
媒体功能：媒体服务器上可用的功能，用于向AS提供媒体服务。例如双音多频（DTMF）检测、混音、转码、播放公告、录制等。
Media Resource Broker (MRB): A logical entity that is responsible for both the collection of appropriate published Media Server (MS) information and supplying of appropriate MS information to consuming entities. The MRB is an optional entity and will be discussed in a separate document.
媒体资源代理（MRB）：一个逻辑实体，负责收集适当的已发布媒体服务器（MS）信息，并向使用实体提供适当的MS信息。MRB是一个可选实体，将在单独的文件中讨论。
Media Server (MS): The media server includes the mixer as defined in [RFC4353]. The media server plays announcements, it processes media streams for functions like DTMF detection and transcoding. The media server may also record media streams for supporting IVR functions like announcing conference participants. In the architecture for the 3GPP IP Multimedia Subsystem (IMS) a Media Server is referred to as a Media Resource Function (MRF).
媒体服务器（MS）：媒体服务器包括[RFC4353]中定义的混音器。媒体服务器播放公告，它处理媒体流以实现DTMF检测和转码等功能。媒体服务器还可以记录媒体流以支持IVR功能，例如宣布会议参与者。在3GPP IP多媒体子系统（IMS）的体系结构中，媒体服务器被称为媒体资源功能（MRF）。
Media Services: Application service requiring media functions such as Interactive Voice Response (IVR) or media conferencing.
媒体服务：需要媒体功能的应用服务，如交互式语音应答（IVR）或媒体会议。
Media Session: From the Session Description Protocol (SDP) specification [RFC4566]: "A multimedia session is a set of multimedia senders and receivers and the data streams flowing from senders to receivers. A multimedia conference is an example of a multimedia session."
媒体会话：来自会话描述协议（SDP）规范[RFC4566]：“多媒体会话是一组多媒体发送方和接收方以及从发送方流向接收方的数据流。多媒体会议是多媒体会话的一个示例。”
MS Control Channel: A reliable transport connection between the AS and MS used to exchange MS Control PDUs. Implementations must support the Transport Control Protocol (TCP) [RFC0793] and may support the Stream Control Transmission Protocol (SCTP) [RFC4960]. Implementations must support TLS [RFC5246] as a transport-level security mechanism although its use in deployments is optional.
MS控制通道：AS和MS之间的可靠传输连接，用于交换MS控制PDU。实现必须支持传输控制协议（TCP）[RFC0793]，并且可以支持流控制传输协议（SCTP）[RFC4960]。实现必须支持TLS[RFC5246]作为传输级安全机制，尽管其在部署中的使用是可选的。
MS Control Dialog: A SIP dialog that is used for establishing a control channel between the user agent (UA) and the MS.
MS控制对话框：用于在用户代理（UA）和MS之间建立控制通道的SIP对话框。
MS Control Protocol: The protocol used for by an AS to control an MS. The MS Control Protocol assumes a reliable underlying transport protocol for the MS Control Channel.
MS控制协议：AS用于控制MS的协议。MS控制协议假定MS控制通道有可靠的底层传输协议。
MS Media Dialog: A SIP dialog between the AS and MS that is used for establishing media sessions between a user device such as a SIP phone and the MS.
MS媒体对话：AS和MS之间的SIP对话，用于在用户设备（如SIP电话）和MS之间建立媒体会话。
The definitions for AS, MS, and MRB above are taken from [RFC5167].
上述AS、MS和MRB的定义取自[RFC5167]。
A Media Server (MS) is a network device that processes media streams. Examples of media processing functionality may include:
媒体服务器（MS）是处理媒体流的网络设备。媒体处理功能的示例可包括：
o Control of the Real-Time Protocol (RTP) [RFC3550] streams using the Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF) [RFC4585].
o 使用基于实时传输控制协议（RTCP）的反馈（RTP/AVPF）的扩展RTP配置文件控制实时协议（RTP）[RFC3550]流[RFC4585]。
o Mixing of incoming media streams.
o 混合传入媒体流。
o Media stream source (for multimedia announcements).
o 媒体流源（用于多媒体公告）。
o Media stream processing (e.g., transcoding, DTMF detection).
o 媒体流处理（例如，转码、DTMF检测）。
o Media stream sink (for multimedia recordings).
o 媒体流接收器（用于多媒体录制）。
An MS supplies one or more media processing functionalities, which may include others than those illustrated above, to an Application Server (AS). An AS is able to send a particular call to a suitable MS, either through discovery of the capabilities that a specific MS provides or through the use of a Media Resource Broker.
MS向应用服务器（AS）提供一个或多个媒体处理功能，所述媒体处理功能可以包括除上述那些以外的其它功能。AS能够通过发现特定MS提供的功能或通过使用媒体资源代理向合适的MS发送特定调用。
The type of processing that a Media Server performs on media streams is specified and controlled by an Application Server. Application Servers are logical entities that are capable of running one or more instances of a communications application. Examples of Application Servers that may interact with a Media Server are an AS acting as a Conference 'Focus' as defined in [RFC4353], or an IVR application using a Media Server to play announcements and detect DTMF key presses.
媒体服务器对媒体流执行的处理类型由应用服务器指定和控制。应用服务器是能够运行通信应用程序的一个或多个实例的逻辑实体。可能与媒体服务器交互的应用服务器示例包括[RFC4353]中定义的充当会议“焦点”的AS，或使用媒体服务器播放公告和检测DTMF按键的IVR应用程序。
Application servers use SIP to establish control channels between themselves and MSs. An MS Control Channel implements a reliable transport protocol that is used to carry the MS Control Protocol. A
应用服务器使用SIP在它们自己和MSs之间建立控制通道。MS控制信道实现用于承载MS控制协议的可靠传输协议。A.
SIP dialog used to establish a control channel is referred to as an MS Control Dialog.
用于建立控制通道的SIP对话框称为MS控制对话框。
Application Servers terminate SIP [RFC3261] signaling from SIP User Agents and may terminate other signaling outside the scope of this document. They use SIP Third Party Call Control [RFC3725] (3PCC) to establish, maintain, and tear down media streams from those SIP UAs to a Media Server. A SIP dialog used by an AS to establish a media session on an MS is referred to as an MS Media Dialog.
应用服务器终止来自SIP用户代理的SIP[RFC3261]信令，并可能终止本文档范围之外的其他信令。他们使用SIP第三方呼叫控制[RFC3725]（3PCC）来建立、维护和中断从这些SIP UA到媒体服务器的媒体流。AS用于在MS上建立媒体会话的SIP对话称为MS媒体对话。
Media streams go directly between SIP User Agents and Media Servers. Media Servers support multiple types of media. Common supported RTP media types include audio and video, but others such as text and the Binary Floor Control Protocol (BFCP) [RFC4583] are also possible. This basic architecture, showing session establishment signaling between a single AS and MS is shown in Figure 1 below.
媒体流直接在SIP用户代理和媒体服务器之间传输。媒体服务器支持多种类型的媒体。通常支持的RTP媒体类型包括音频和视频，但也可以使用文本和二进制地板控制协议（BFCP）[RFC4583]等其他媒体类型。下面的图1显示了这个基本架构，它显示了单个AS和MS之间的会话建立信令。
+-------------+ +--------------+
| | SIP (MS Control Dialog) | |
| Application |<----------------------->| Media |
| Server | | Server |
| |<----------------------->| |
+-------------+ SIP (MS Media Dialog) +--------------+
^ ^
\ | RTP/SRTP
\ | audio/
\ | video/etc)
\ |
\ v
\ +--------------+
\ SIP | |
+-------------->| SIP |
| User Agent |
| |
+--------------+
+-------------+ +--------------+
| | SIP (MS Control Dialog) | |
| Application |<----------------------->| Media |
| Server | | Server |
| |<----------------------->| |
+-------------+ SIP (MS Media Dialog) +--------------+
^ ^
\ | RTP/SRTP
\ | audio/
\ | video/etc)
\ |
\ v
\ +--------------+
\ SIP | |
+-------------->| SIP |
| User Agent |
| |
+--------------+
Figure 1: Basic Signaling Architecture
图1：基本信令架构
The architecture must support a many-to-many relationship between Application Servers and Media Servers. In real world deployments, an Application Server may interact with multiple Media Servers and/or a Media Server may be controlled by more than one Application Server.
该体系结构必须支持应用服务器和媒体服务器之间的多对多关系。在实际部署中，应用服务器可能与多个媒体服务器交互，和/或媒体服务器可能由多个应用服务器控制。
Application Servers can use the SIP URI as described in [RFC4240] to request basic functions from Media Servers. Basic functions are characterized as requiring no mid-call interactions between the AS and MS. Examples of these functions are simple announcement-playing
应用服务器可以使用[RFC4240]中所述的SIPURI从媒体服务器请求基本功能。基本功能的特点是不需要as和MS之间的通话中交互。这些功能的示例包括简单的公告播放
or basic conference-mixing where the AS does not need to explicitly control the mixing.
或基本会议混合，其中AS不需要明确控制混合。
Most services however have interactions between the AS and MS during a call or conference. The type of interactions can be generalized as follows:
然而，大多数服务在呼叫或会议期间在AS和MS之间进行交互。相互作用的类型可概括如下：
o commands from an AS to an MS to request the application or configuration of a function. The request may apply to a single media stream, multiple media streams associated with multiple SIP dialogs, or to properties of a conference mix.
o AS向MS发出命令，请求应用或配置功能。该请求可应用于单个媒体流、与多个SIP对话框相关联的多个媒体流或会议混合的属性。
o responses from an MS to an AS reporting on the status of particular commands.
o MS对AS的响应，报告特定命令的状态。
o notifications from an MS to an AS that report results from commands or notify changes to subscribed status.
o 从MS到AS的通知，该通知报告命令的结果或通知对订阅状态的更改。
Commands, responses, and notifications are transported using one or more dedicated control channels between the Application Server and the Media Server. Dedicated control channels provide reliable, sequenced, peer-to-peer transport for Media Server control interactions. Implementations must support the Transport Control Protocol (TCP) [RFC0793] and may support the Stream Control Transmission Protocol (SCTP) [RFC4960]. Because MS control requires sequenced reliable delivery of messages, unreliable protocols such as the User Datagram Protocol (UDP) are not suitable. Implementations must support TLS [RFC5246] as a transport-level security mechanism although its use in deployments is optional. A dedicated control channel is shown in Figure 2 below.
命令、响应和通知使用应用程序服务器和媒体服务器之间的一个或多个专用控制通道进行传输。专用控制通道为媒体服务器控制交互提供可靠、有序的对等传输。实现必须支持传输控制协议（TCP）[RFC0793]，并且可以支持流控制传输协议（SCTP）[RFC4960]。由于MS控制要求消息的顺序可靠传递，不可靠的协议（如用户数据报协议（UDP））不适用。实现必须支持TLS[RFC5246]作为传输级安全机制，尽管其在部署中的使用是可选的。专用控制通道如下图2所示。
+-------------+ +--------------+
| | | |
| Application | MS ctrl channel | Media |
| Server |<------------------->| Server |
| | | |
+-------------+ +--------------+
^ ^ ^
RTP/SRTP | | |
(audio/ | | |
video/etc) | | |
| | v
+---|-v-------+
+-|---v-------+ |
+-|-----------+ | |
| | | |
| SIP | | |
| User Agent | |-+
| |-+
+-------------+
+-------------+ +--------------+
| | | |
| Application | MS ctrl channel | Media |
| Server |<------------------->| Server |
| | | |
+-------------+ +--------------+
^ ^ ^
RTP/SRTP | | |
(audio/ | | |
video/etc) | | |
| | v
+---|-v-------+
+-|---v-------+ |
+-|-----------+ | |
| | | |
| SIP | | |
| User Agent | |-+
| |-+
+-------------+
Figure 2: Media Server Control Architecture
图2：媒体服务器控制体系结构
Both Application Servers and Media Servers may interact with other servers for specific purposes beyond the scope of this document. For example, Application Servers will often communicate with other infrastructure components that are usually based on deployment requirements with links to back-office data stores and applications. Media Servers will often retrieve announcements from external file servers. Also, many Media Servers support IVR dialog services using VoiceXML [W3C.REC-voicexml20-20040316]. In this case, the MS interacts with other servers using HTTP during standard VoiceXML processing. VoiceXML Media Servers may also interact with speech engines (for example, using the Media Resource Control Protocol version 2 (MRCPv2)) for speech recognition and generation purposes.
应用服务器和媒体服务器都可以出于本文档范围之外的特定目的与其他服务器进行交互。例如，应用程序服务器通常会与其他基础架构组件通信，这些组件通常基于部署需求，并链接到后台数据存储和应用程序。媒体服务器通常会从外部文件服务器检索公告。此外，许多媒体服务器支持使用VoiceXML的IVR对话服务[W3C.REC-voicexml20-20040316]。在这种情况下，MS在标准VoiceXML处理期间使用HTTP与其他服务器交互。VoiceXML媒体服务器还可以与语音引擎交互（例如，使用媒体资源控制协议版本2（MRCPv2））以进行语音识别和生成。
Some specific types of interactions between Application and Media servers are also out of scope for this document. MS resource reservation is one such interaction. Also, any interactions between Application Servers, or between Media Servers, are also out of scope.
应用程序和媒体服务器之间的某些特定类型的交互也超出了本文档的范围。MS资源预留就是这样一种交互。此外，应用程序服务器之间或媒体服务器之间的任何交互也不在范围之内。
The Session Initiation Protocol (SIP) [RFC3261] was developed by the IETF for the purposes of initiating, managing, and terminating multimedia sessions. The popularity of SIP has grown dramatically since its inception and is now the primary Voice over IP (VoIP) protocol. This includes being selected as the basis for architectures such as the IP Multimedia Subsystem (IMS) in 3GPP and
会话启动协议（SIP）[RFC3261]由IETF开发，用于启动、管理和终止多媒体会话。SIP自诞生以来就得到了极大的发展，现在已成为IP语音（VoIP）的主要协议。这包括被选择作为诸如3GPP和3GPP中的IP多媒体子系统（IMS）等架构的基础
included in many of the early live deployments of VoIP-related systems. Media servers are not a new concept in IP telephony networks and there have been numerous signaling protocols and techniques proposed for their control. The most popular techniques to date have used a combination of SIP and various markup languages to convey media service requests and responses.
包括在许多VoIP相关系统的早期实时部署中。媒体服务器在IP电话网络中并不是一个新概念，已经有许多信令协议和技术被提出用于它们的控制。迄今为止，最流行的技术使用SIP和各种标记语言的组合来传递媒体服务请求和响应。
As discussed in Section 3 and illustrated in Figure 1, the logical architecture described by this document involves interactions between an Application Server (AS) and a Media Server (MS). The SIP interactions can be broken into "MS media dialogs" that are used between an AS and an MS to establish media sessions between an endpoint and a Media Server, and "MS control dialogs" that are used to establish and maintain MS control channels.
如第3节所述和图1所示，本文描述的逻辑体系结构涉及应用服务器（As）和媒体服务器（MS）之间的交互。SIP交互可分为“MS媒体对话”和“MS控制对话”，前者用于AS和MS之间建立端点和媒体服务器之间的媒体会话，后者用于建立和维护MS控制通道。
SIP is the primary signaling protocol for session signaling and is used for all media sessions directed towards a Media Server as described in this document. Media Servers may support other signaling protocols but this type of interaction is not considered here. Application Servers may terminate non-SIP signaling protocols but must gateway those requests to SIP when interacting with a Media Server.
SIP是会话信令的主要信令协议，用于指向媒体服务器的所有媒体会话，如本文档所述。媒体服务器可能支持其他信令协议，但这里不考虑这种类型的交互。应用服务器可以终止非SIP信令协议，但在与媒体服务器交互时必须将这些请求网关化到SIP。
SIP will also be used for the creation, management, and termination of the dedicated MS control channel(s). Control channel(s) provide reliable sequenced delivery of MS Control Protocol messages. The Application and Media Servers use the SDP attributes defined in [RFC4145] to allow SIP negotiation of the control channel. A control channel is closed when SIP terminates the corresponding MS control dialog. Further details and example flows are provided in the SIP Control Framework [SIP-CTRL-FW]. The SIP Control Framework also includes basic control message semantics corresponding to the types of interactions identified in Section 3. It uses the concept of "packages" to allow domain-specific protocols to be defined using the Extensible Markup Language (XML) [W3C.REC-xml-20060816] format. The MS Control Protocol is made up of one or more packages for the SIP Control Framework.
SIP还将用于创建、管理和终止专用MS控制信道。控制通道提供MS控制协议消息的可靠顺序传递。应用程序和媒体服务器使用[RFC4145]中定义的SDP属性来允许控制信道的SIP协商。当SIP终止相应的MS控制对话框时，控制通道关闭。SIP控制框架[SIP-CTRL-FW]中提供了进一步的细节和示例流。SIP控制框架还包括与第3节中确定的交互类型相对应的基本控制消息语义。它使用“包”的概念，允许使用可扩展标记语言（XML）[W3C.REC-XML-20060816]格式定义特定于域的协议。MS控制协议由SIP控制框架的一个或多个包组成。
Using SIP for both media and control dialogs provides a number of inherent benefits over other potential techniques. These include:
与其他潜在技术相比，将SIP用于媒体和控制对话框提供了许多固有的好处。这些措施包括：
1. The use of SIP location and rendezvous capabilities, as defined in [RFC3263]. This provides core mechanisms for routing a SIP request based on techniques such as DNS SRV and NAPTR records. The SIP infrastructure makes heavy use of such techniques.
1. 使用[RFC3263]中定义的SIP定位和会合功能。这提供了基于DNS SRV和NAPTR记录等技术路由SIP请求的核心机制。SIP基础设施大量使用此类技术。
2. The security and identity properties of SIP; for example, using TLS for reliably and securely connecting to another SIP-based
2. SIP协议的安全性和身份属性；例如，使用TLS可靠、安全地连接到另一个基于SIP的网络
entity. The SIP protocol has a number of identity mechanisms that can be used. [RFC3261] provides an intra-domain digest-based mechanism and [RFC4474] defines a certificate-based inter-domain identity mechanism. SIP with S/MIME provides the ability to secure payloads using encrypted and signed certificate techniques.
实体SIP协议有许多可以使用的标识机制。[RFC3261]提供基于域内摘要的机制，[RFC4474]定义基于证书的域间身份机制。带有S/MIME的SIP提供了使用加密和签名证书技术保护有效负载的能力。
3. SIP has extremely powerful and dynamic media-negotiation properties as defined in [RFC3261] and [RFC3264].
3. SIP具有[RFC3261]和[RFC3264]中定义的极其强大的动态媒体协商属性。
4. The ability to select an appropriate SIP entity based on capability sets as discussed in [RFC3840]. This provides a powerful function that allows Media Servers to convey a specific capability set. An AS is then free to select an appropriate MS based on its requirements.
4. 根据[RFC3840]中讨论的能力集选择适当SIP实体的能力。这提供了一个强大的功能，允许媒体服务器传递特定的功能集。AS可以根据其需求自由选择适当的MS。
5. Using SIP also provides consistency with IETF protocols and usages. SIP was intended to be used for the creation and management of media sessions, and this provides a correct usage of the protocol.
5. 使用SIP还提供了与IETF协议和用法的一致性。SIP旨在用于创建和管理媒体会话，这提供了协议的正确用法。
As mentioned previously in this section, media services using SIP are fairly well understood. Some previous proposals suggested using the SIP INFO [RFC2976] method as the transport vehicle between the AS and MS. Using SIP INFO in this way is not advised for a number of reasons, which include:
正如本节前面提到的，使用SIP的媒体服务是相当容易理解的。以前的一些提案建议使用SIP INFO[RFC2976]方法作为as和MS之间的运输工具。由于以下原因，不建议以这种方式使用SIP INFO：
o INFO is an opaque request with no specific semantics. A SIP endpoint that receives an INFO request does not know what to do with it based on SIP signaling.
o INFO是一个不透明的请求，没有特定的语义。接收信息请求的SIP端点不知道基于SIP信令如何处理它。
o SIP INFO was not created to carry generic session control information along the signaling path, and it should only really be used for optional application information, e.g., carrying mid-call Public Switched Telephone Network (PSTN) signaling messages between PSTN gateways.
o SIP INFO的创建并不是为了沿着信令路径携带通用会话控制信息，它实际上应该只用于可选的应用程序信息，例如，在PSTN网关之间携带呼叫中公共交换电话网（PSTN）信令消息。
o SIP INFO traverses the signaling path, which is an inefficient use for control messages that can be routed directly between the AS and MS.
o SIP INFO遍历信令路径，这对于可以在AS和MS之间直接路由的控制消息来说是一种低效的使用。
o [RFC3261] contains rules when using an unreliable protocol such as UDP. When a packet reaches a size close to the Maximum Transmission Unit (MTU), the protocol should be changed to TCP. This type of operation is not ideal when constantly dealing with large payloads such as XML-formatted MS control messages.
o [RFC3261]包含使用不可靠协议（如UDP）时的规则。当数据包达到接近最大传输单元（MTU）的大小时，协议应更改为TCP。在不断处理大型有效负载（如XML格式的MS控制消息）时，这种类型的操作并不理想。
One of the functions of a Media Server is to assist an Application Server that is implementing IVR services by performing media processing functions on media streams. Although "IVR" is somewhat generic terminology, the scope of media functions provided by an MS addresses the needs for user interaction dialogs. These functions include media transcoding, basic announcements, user input detection (via DTMF or speech), and media recording.
媒体服务器的功能之一是通过对媒体流执行媒体处理功能来帮助正在实现IVR服务的应用服务器。虽然“IVR”在某种程度上是通用术语，但MS提供的媒体功能范围满足了用户交互对话框的需求。这些功能包括媒体转码、基本公告、用户输入检测（通过DTMF或语音）和媒体录制。
A particular IVR or user dialog application typically requires the use of several specific media functions, as described above. The range and complexity of IVR dialogs can vary significantly, from a simple single announcement play-back to complex voice mail applications.
如上所述，特定的IVR或用户对话应用程序通常需要使用几种特定的媒体功能。IVR对话框的范围和复杂性可能会有很大的不同，从简单的单一公告播放到复杂的语音邮件应用程序。
As previously discussed, an AS uses SIP [RFC3261] and SDP [RFC4566] to establish and configure media sessions to a Media Server. An AS uses the MS control channel, established using SIP, to invoke IVR requests and to receive responses and notifications. This topology is shown in Figure 3 below.
如前所述，As使用SIP[RFC3261]和SDP[RFC4566]建立和配置到媒体服务器的媒体会话。AS使用使用使用SIP建立的MS控制通道来调用IVR请求并接收响应和通知。该拓扑如下图3所示。
+-------------+ SIP +-------------+
| Application |<---------------------------->| Media |
| Server | (media & MS Control dialogs) | Server |
| | | |
| | MS Control Protocol (IVR) | |
| |<---------------------------->| (IVR media |
| (App logic) | (CtrlChannel) | functions) |
+-------------+ +-------------+
^ ^^
\ || R
\ || T
\ || P
\ || /
\ || S
\ || R
\ || T
\ || P
\ vv
\ call signaling +-----------+
---------------------------->| User |
(e.g., SIP) | Equipment |
+-----------+
+-------------+ SIP +-------------+
| Application |<---------------------------->| Media |
| Server | (media & MS Control dialogs) | Server |
| | | |
| | MS Control Protocol (IVR) | |
| |<---------------------------->| (IVR media |
| (App logic) | (CtrlChannel) | functions) |
+-------------+ +-------------+
^ ^^
\ || R
\ || T
\ || P
\ || /
\ || S
\ || R
\ || T
\ || P
\ vv
\ call signaling +-----------+
---------------------------->| User |
(e.g., SIP) | Equipment |
+-----------+
Figure 3: IVR Topology
图3:IVR拓扑
The variety in complexity of Application Server IVR services requires support for different levels of media functions from the Media Server as described in the following sub-sections.
应用服务器IVR服务的复杂性要求媒体服务器支持不同级别的媒体功能，如下小节所述。
For simple basic announcement requests, the MS control channel, as depicted in Figure 3 above, is not required. Simple announcement requests may be invoked on the Media Server using the SIP URI mechanism defined in [RFC4240]. This interface allows no digit detection or collection of user input and no mid-call dialog control. However, many applications only require basic media services, and the processing burden on the Media Server to support more complex interactions with the AS would not be needed in that case.
对于简单的基本公告请求，不需要MS控制通道，如上图3所示。可以使用[RFC4240]中定义的SIP URI机制在媒体服务器上调用简单公告请求。此界面不允许数字检测或收集用户输入，也不允许中间通话对话框控制。但是，许多应用程序只需要基本的媒体服务，在这种情况下，不需要媒体服务器承担处理负担来支持与AS的更复杂交互。
For more complex IVR dialogs, which require mid-call interaction and control between the Application Server and the Media Server, the MS control channel (as shown in Figure 3 above) is used to invoke specific media functions on the Media Server. These functions include, but are not limited to, complex announcements with barge-in facility, user-input detection and reporting (e.g., DTMF) to an Application Server, DTMF and voice-activity controlled recordings, etc. Composite services, such as play-collect and play-record, are also addressed by this model.
对于更复杂的IVR对话框，需要在应用程序服务器和媒体服务器之间进行呼叫中交互和控制，MS控制通道（如上图3所示）用于调用媒体服务器上的特定媒体功能。这些功能包括但不限于，具有驳入设施的复杂公告、用户输入检测和向应用服务器报告（如DTMF）、DTMF和语音活动控制录音等。该模型还解决了播放采集和播放录制等复合服务。
Mid-call control also allows Application Servers to subscribe to IVR-related events and for the Media Server to notify the AS when these events occur. Examples of such events are announcement completion events, record completion events, and reporting of collected DTMF digits.
Mid call control还允许应用程序服务器订阅IVR相关事件，并允许媒体服务器在这些事件发生时通知AS。此类事件的示例包括公告完成事件、记录完成事件和收集的DTMF数字的报告。
Although IVR services with mid-call control, as described above, provide a comprehensive set of media functions expected from a Media Server, the advanced IVR services model allows a higher level of abstraction describing application logic, as provided by VoiceXML, to be executed on the Media Server. Invocation of VoiceXML IVR dialogs may be via the "Prompt and Collect" mechanism of [RFC4240]. Additionally, the IVR control protocol can be extended to allow VoiceXML requests to also be invoked over the MS control channel. VoiceXML IVR services invoked on the Media Server may require an HTTP interface (not shown in Figure 3) between the Media Server and one or more back-end servers that host or generate VoiceXML documents. The back-end server(s) may or may not be physically separate from the Application Server.
尽管如上所述，具有中间呼叫控制的IVR服务提供了媒体服务器所需的一组全面的媒体功能，但高级IVR服务模型允许更高级别的抽象描述应用程序逻辑，如VoiceXML所提供的，在媒体服务器上执行。可以通过[RFC4240]的“提示和收集”机制调用VoiceXML IVR对话框。此外，可以扩展IVR控制协议，以允许通过MS控制通道调用VoiceXML请求。在媒体服务器上调用的VoiceXML IVR服务可能需要在媒体服务器和承载或生成VoiceXML文档的一个或多个后端服务器之间使用HTTP接口（图3中未显示）。后端服务器可能在物理上与应用服务器分离，也可能不与应用服务器分离。
[RFC4353] describes the overall architecture and protocol components needed for multipoint conferencing using SIP. The framework for centralized conferencing [RFC5239] extends the framework to include a protocol between the user and the conferencing server. [RFC4353] describes the conferencing server decomposition but leaves the specifics open.
[RFC4353]描述了使用SIP的多点会议所需的总体架构和协议组件。集中式会议框架[RFC5239]扩展了该框架，包括用户和会议服务器之间的协议。[RFC4353]描述了会议服务器的分解，但保留了细节。
This section describes the decomposition and discusses the functionality of the decomposed functional units. The conferencing factory and the conference focus are part of the Application Server described in this document.
本节描述分解并讨论分解功能单元的功能。会议工厂和会议焦点是本文档中描述的应用程序服务器的一部分。
An Application Server uses SIP Third Party Call Control [RFC3725] to establish media sessions from SIP user agents to a Media Server. The same mechanism is used by the Application Server as described in this section to add/remove participants to/from a conference, as well as to handle the involved media streams set up on a per-user basis. Since the XCON framework has been conceived as protocol-agnostic when talking about the Call Signaling Protocol used by users to join a conference, an XCON-compliant Application Server will have to take care of gatewaying non-SIP signaling negotiations. This is in order to set up and make available valid SIP media sessions between itself and the Media Server, while still keeping the non-SIP interaction with the user in a transparent way.
应用服务器使用SIP第三方呼叫控制[RFC3725]建立从SIP用户代理到媒体服务器的媒体会话。应用服务器使用与本节所述相同的机制向会议中添加/删除参与者，以及处理基于每个用户设置的相关媒体流。由于在讨论用户加入会议所使用的呼叫信令协议时，XCON框架被认为是协议不可知的，因此符合XCON的应用服务器必须负责网关非SIP信令协商。这是为了在自身和媒体服务器之间建立并提供有效的SIP媒体会话，同时仍然以透明的方式保持与用户的非SIP交互。
+------------+ +------------+
| | SIP (2m+1c) | |
| Application|-------------| Media |
| Server | | Server |
| (Focus) |-------------| (Mixer) |
| | CtrlChannel | |
+------------+ +------------+
| \ .. .
| \\ RTP... .
| \\ .. .
| H.323 \\ ... .
SIP | \\ ... .RTP
| ..\ .
| ... \\ .
| ... \\ .
| .. \\ .
| ... \\ .
| .. \ .
+-----------+ +-----------+
|Participant| |Participant|
+-----------+ +-----------+
+------------+ +------------+
| | SIP (2m+1c) | |
| Application|-------------| Media |
| Server | | Server |
| (Focus) |-------------| (Mixer) |
| | CtrlChannel | |
+------------+ +------------+
| \ .. .
| \\ RTP... .
| \\ .. .
| H.323 \\ ... .
SIP | \\ ... .RTP
| ..\ .
| ... \\ .
| ... \\ .
| .. \\ .
| ... \\ .
| .. \ .
+-----------+ +-----------+
|Participant| |Participant|
+-----------+ +-----------+
Figure 4: Conference Topology
图4：会议拓扑
To complement the functionality provided by 3PCC and by the XCON control protocol, the Application Server makes use of a dedicated Media Server control channel in order to set up and manage media conferences on the Media Server. Figure 4 shows the signaling and media paths for a two-participant conference. The three SIP dialogs between the AS and MS establish one control session (1c) and two media sessions (2m) from the participants (one originally signaled using H.323 and then gatewayed into SIP and one signaled directly in SIP).
为了补充3PCC和XCON控制协议提供的功能，应用服务器使用专用媒体服务器控制通道在媒体服务器上设置和管理媒体会议。图4显示了两人会议的信令和媒体路径。AS和MS之间的三个SIP对话建立了来自参与者的一个控制会话（1c）和两个媒体会话（2m）（一个最初使用H.323发信号，然后通过网关接入SIP，另一个直接在SIP发信号）。
As a conference focus, the Application Server is responsible for setting up and managing a media conference on the Media Servers, in order to make sure that all the media streams provided in a conference are available to its participants. This is achieved by using the services of one or more mixer entities (as described in RFC 4353), whose role as part of the Media Server is described in this section. Services required by the Application Server include, but are not limited to, means to set up, handle, and destroy a new media conference, adding and removing participants from a conference, managing media streams in a conference, controlling the layout and the mixing configuration for each involved media, allowing per-user custom media profiles, and so on.
作为会议焦点，应用服务器负责在媒体服务器上设置和管理媒体会议，以确保会议中提供的所有媒体流都可供参与者使用。这是通过使用一个或多个混音器实体（如RFC 4353中所述）的服务来实现的，其作为媒体服务器的一部分的角色在本节中描述。应用服务器所需的服务包括但不限于设置、处理和销毁新媒体会议、添加和删除会议参与者、管理会议中的媒体流、控制每个相关媒体的布局和混合配置、允许每个用户自定义媒体简档、，等等
As a mixer entity, in such a multimedia conferencing scenario, the Media Server receives a set of media streams of the same type (after transcoding if needed) and then takes care of combining the received media in a type-specific manner, redistributing the result to each authorized participant. The way each media stream is combined, as well as the media-related policies, is properly configured and handled by the Application Server by means of a dedicated MS control channel.
作为混频器实体，在这样的多媒体会议场景中，媒体服务器接收相同类型的一组媒体流（如果需要，在转码之后），然后负责以特定类型的方式组合所接收的媒体，将结果重新分发给每个经授权的参与者。应用服务器通过专用MS控制通道正确配置和处理每个媒体流的组合方式以及与媒体相关的策略。
To summarize, the AS needs to be able to manage Media Servers at a conference and participant level.
总之，AS需要能够在会议和参与者级别管理媒体服务器。
When a new conference is created, as a result of a previous conference scheduling or of the first participant dialing in to a specified URI, the Application Server must take care of appropriately creating a media conference on the Media Server. It does so by sending an explicit request to the Media Server. This can be by means of an MS control channel message. This request may contain detailed information upon the desired settings and policies for the conference (e.g., the media to involve, the mixing configuration for them, the relevant identifiers, etc.). The Media Server validates such a request and takes care of allocating the needed resources to set up the media conference.
创建新会议时，由于先前的会议安排或第一个参与者拨入指定的URI，应用程序服务器必须负责在媒体服务器上适当创建媒体会议。它通过向媒体服务器发送显式请求来实现。这可以通过MS控制通道消息实现。该请求可能包含关于会议所需设置和策略的详细信息（例如，要涉及的媒体、它们的混合配置、相关标识符等）。媒体服务器验证此类请求，并负责分配设置媒体会议所需的资源。
Application Servers may use mechanisms other than sending requests over the control channel to establish conferences on a Media Server, and then subsequently use the control channel to control the conference. Examples of other mechanisms to create a conference include using the Request-URI mechanism of [RFC4240] or the procedures defined in [RFC4579].
应用服务器可以使用除通过控制通道发送请求以外的机制在媒体服务器上建立会议，然后使用控制通道控制会议。创建会议的其他机制的示例包括使用[RFC4240]的请求URI机制或[RFC4579]中定义的过程。
Once done, the MS informs the Application Server about the result of the request. Each conference will be referred to by a specific identifier, which both the Application Server and the Media Server will include in subsequent transactions related to the same conference (e.g., to modify the settings of an extant conference).
完成后，MS会将请求的结果通知应用服务器。每个会议将由特定标识符引用，应用服务器和媒体服务器将在与同一会议相关的后续事务中包括该标识符（例如，修改现有会议的设置）。
As stated before, an Application Server uses SIP 3PCC to establish media sessions from SIP user agents to a Media Server. The URI that the AS uses in the INVITE to the MS may be one associated with the conference on the MS. More likely however, the media sessions are first established to the Media Server using a URI for the Media Server and then subsequently joined to the conference using the MS
如前所述，应用服务器使用SIP 3PCC建立从SIP用户代理到媒体服务器的媒体会话。AS在邀请MS中使用的URI可以是与MS上的会议相关联的URI。然而，更可能的是，媒体会话首先使用媒体服务器的URI建立到媒体服务器，然后使用MS加入到会议
Control Protocol. This allows IVR dialogs to be performed prior to joining the conference.
控制协议。这允许在加入会议之前执行IVR对话框。
The AS as a 3PCC correlates the media session negotiation between the UA and the MS, in order to appropriately establish all the needed media streams based on the conference policies.
AS作为3PCC将UA和MS之间的媒体会话协商关联起来，以便根据会议策略适当地建立所有需要的媒体流。
The XCON Common Data Model [XCON-DM] currently defines some basic media-related controls, which conference-aware participants can take advantage of in several ways, e.g., by means of an XCON conference control protocol or IVR dialogs. These controls include the possibility to modify the participants' own volume for audio in the conference, configure the desired layout for incoming video streams, mute/unmute oneself, and pause/unpause one's own video stream. Such controls are exploited by conference-aware participants through the use of dedicated conference control protocol requests to the Application Server. The Application Server takes care of validating such requests and translates them into the Media Server Control Protocol, before forwarding them over the MS Control Channel to the MS. According to the directives provided by the Application Server, the Media Server manipulates the involved media streams accordingly.
XCON通用数据模型[XCON-DM]目前定义了一些与媒体相关的基本控制，会议感知参与者可以通过多种方式利用这些控制，例如通过XCON会议控制协议或IVR对话框。这些控制包括修改与会者自己的会议音频音量、为传入视频流配置所需布局、静音/取消静音以及暂停/取消自己的视频流。会议感知参与者通过使用专用的会议控制协议向应用服务器请求来利用这些控制。应用服务器负责验证此类请求并将其转换为媒体服务器控制协议，然后再通过MS控制通道将其转发给MS。根据应用服务器提供的指令，媒体服务器相应地操纵相关媒体流。
+------------+ +------------+
| | 'Include audio | |
| Application| sent by user X | Media |
| Server | in conf Y mix' | Server |
| (Focus) |----------------->| (Mixer) |
| | (MS CtrlChn) | |
+------^-----+ +------------+
| ..
| ...
| 'Unmute me' ... RTP
| (XCON) ...
| ...
| ...
+-----------+ ...
|Participant|...
+-----------+
+------------+ +------------+
| | 'Include audio | |
| Application| sent by user X | Media |
| Server | in conf Y mix' | Server |
| (Focus) |----------------->| (Mixer) |
| | (MS CtrlChn) | |
+------^-----+ +------------+
| ..
| ...
| 'Unmute me' ... RTP
| (XCON) ...
| ...
| ...
+-----------+ ...
|Participant|...
+-----------+
Figure 5: Conferencing Example: Unmuting A Participant
图5：会议示例：取消参与者静音
The Media Server may need to inform the AS of events like in-band DTMF tones during the conference.
媒体服务器可能需要在会议期间向AS通知诸如带内DTMF音之类的事件。
The XCON framework introduces "floor control" functionality as an enhancement upon [RFC4575]. Floor control is a means to manage joint or exclusive access to shared resources in a (multiparty) conferencing environment. Floor control is not a mandatory mechanism for a conferencing system implementation, but it provides advanced media input control features for conference-aware participants. Such a mechanism allows for coordinated and moderated access to any set of resources provided by the conferencing system. To do so, a so-called floor is associated to a set of resources, thus representing for participants the right to access and manipulate the related resources themselves. In order to take advantage of the floor control functionality, a specific protocol, the Binary Floor Control Protocol, has been specified [RFC4582]. [RFC4583] provides a way for SIP UAs to set up a BFCP connection towards the Floor Control Server and exploit floor control by means of a Connection-Oriented Media (COMEDIA) [RFC4145] negotiation.
XCON框架引入了“地板控制”功能，作为对[RFC4575]的增强。楼层控制是在（多方）会议环境中管理对共享资源的联合或独占访问的一种方法。楼层控制不是会议系统实施的强制机制，但它为会议感知参与者提供了高级媒体输入控制功能。这种机制允许协调和有节制地访问会议系统提供的任何一组资源。为此，所谓的楼层与一组资源相关联，从而代表参与者访问和操纵相关资源本身的权利。为了利用地板控制功能，指定了一个特定的协议，即二进制地板控制协议[RFC4582]。[RFC4583]为SIP UAs提供了一种方法，通过面向连接的媒体（COMEDIA）[RFC4145]协商，建立指向楼层控制服务器的BFCP连接，并利用楼层控制。
In the context of the AS-MS interaction, floor control constitutes a further means to control participants' media streams. A typical example is a floor associated with the right to access the shared audio channel in a conference. A participant who is granted such a floor is granted by the conferencing system the right to talk, which means that its audio frames are included by the MS in the overall audio conference mix. Similarly, when the floor is revoked, the participant is muted in the conference, and its audio is excluded from the final mix.
在AS-MS交互环境中，楼层控制构成了控制参与者媒体流的进一步手段。一个典型的例子是与会议中访问共享音频频道的权限相关联的楼层。获得此类发言权的参与者由会议系统授予发言权，这意味着MS将其音频帧包括在整个音频会议组合中。类似地，当取消发言权时，与会者在会议中被静音，其音频被排除在最终混音之外。
The BFCP defines a Floor Control Server (FCS) and the floor chair. It is clear that the floor chair making decisions about floor requests is part of the application logic. This implies that when the role of floor chair in a conference is automated, it will normally be part of the AS.
BFCP定义了地板控制服务器（FCS）和地板椅。很明显，楼层主席决定楼层请求是应用程序逻辑的一部分。这意味着，当会议主席的角色自动化时，它通常是AS的一部分。
The example makes it clear that there can be a direct or indirect interaction between the Floor Control Server and the Media Server, in order to correctly bind each floor to its related set of media resources. Besides, a similar interaction is needed between the Floor Control Server and the Application Server as well, since the latter must be aware of all the associations between floors and resources, in order to opportunely orchestrate the related bindings with the element responsible for such resources (e.g., the Media Server when talking about audio and/or video streams) and the operations upon them (e.g., mute/unmute a participant in a conference). For this reason, the Floor Control Server can be co-
该示例清楚地表明，楼层控制服务器和媒体服务器之间可以进行直接或间接的交互，以便将每个楼层正确地绑定到其相关的媒体资源集。此外，楼层控制服务器和应用服务器之间也需要类似的交互，因为后者必须知道楼层和资源之间的所有关联，以便与负责此类资源的元素适当地协调相关绑定（例如，谈论音频和/或视频流时的媒体服务器）及其操作（例如，会议参与者静音/取消静音）。因此，地板控制服务器可以与-
located with either the Media Server or the Application Server, as long as both elements are allowed to interact with the Floor Control Server by means of some kind of protocol.
位于媒体服务器或应用服务器上，只要允许两个元素通过某种协议与楼层控制服务器交互。
In the following text, both the approaches will be described in order to better explain the interactions between the involved components in both the topologies.
在下文中，将描述这两种方法，以便更好地解释两种拓扑中涉及的组件之间的相互作用。
When the AS and the FCS are co-located, the scenario is quite straightforward. In fact, it can be considered as a variation of the case depicted in Figure 5. The only relevant difference is that in this case the action the AS commands on the control channel is triggered by a change in the floor control status instead of a specific control requested by a participant himself. The sequence diagram in Figure 6 describes the interaction between the involved parties in a typical scenario. It assumes that a BFCP connection between the UA and the FCS (which we assume is co-located with the AS) has already been negotiated and established, and that the UA has been made aware of all the relevant identifiers and floors-resources-associations (e.g., by means of [RFC4583]). It also assumes that the AS has previously configured the media mixing on the MS using the MS control channel. Every frame the UA might be sending on the related media stream is currently being dropped by the MS, since the UA still isn't authorized to use the resource. For a SIP UA, this state could be consequent to a 'sendonly' field associated to the media stream in a re-INVITE originated by the MS. It is worth pointing out that the AS has to make sure that no user media control mechanisms, such as mentioned in the previous sub-section, can override the floor control.
当AS和FCS位于同一地点时，场景非常简单。事实上，可以将其视为图5所示情况的一个变体。唯一相关的区别是，在这种情况下，控制通道上的AS命令是由楼层控制状态的更改而不是参与者自己请求的特定控制触发的。图6中的序列图描述了典型场景中相关方之间的交互。它假设UA和FCS之间的BFCP连接（我们假设该连接与AS位于同一位置）已经协商并建立，并且UA已经知道所有相关标识符和楼层资源关联（例如，通过[RFC4583]）。它还假设AS先前已使用MS控制通道在MS上配置了介质混合。UA可能在相关媒体流上发送的每一帧当前都被MS丢弃，因为UA仍然无权使用该资源。对于SIP UA，此状态可能是与MS发起的重新邀请中的媒体流相关联的“sendonly”字段的结果。值得指出的是，AS必须确保没有用户媒体控制机制（如前一小节中提到的）可以覆盖楼层控制。
UA AS MS
(Floor Participant) (FCS)
| | |
|<===================== One-way RTP stream ======================|
| | |
| FloorRequest(BFCP) | |
|------------------------------------>| |
| | |
| FloorRequestStatus[PENDING](BFCP) | |
|<------------------------------------| |
| |--+ apply |
| | | policies |
| |<-+ to request |
| | |
| FloorRequestStatus[ACCEPTED](BFCP) | |
|<------------------------------------| |
| | |
. . .
. . .
| | |
| FloorRequestStatus[GRANTED](BFCP) | |
|<------------------------------------| |
| | 'Unmute UA' (CtrlChn) |
| |------------------------->|
| | |
|<==================== Bidirectional RTP stream ================>|
| | |
. . .
. . .
UA AS MS
(Floor Participant) (FCS)
| | |
|<===================== One-way RTP stream ======================|
| | |
| FloorRequest(BFCP) | |
|------------------------------------>| |
| | |
| FloorRequestStatus[PENDING](BFCP) | |
|<------------------------------------| |
| |--+ apply |
| | | policies |
| |<-+ to request |
| | |
| FloorRequestStatus[ACCEPTED](BFCP) | |
|<------------------------------------| |
| | |
. . .
. . .
| | |
| FloorRequestStatus[GRANTED](BFCP) | |
|<------------------------------------| |
| | 'Unmute UA' (CtrlChn) |
| |------------------------->|
| | |
|<==================== Bidirectional RTP stream ================>|
| | |
. . .
. . .
Figure 6: Conferencing Example: Floor Control Call Flow
图6：会议示例：楼层控制呼叫流
A UA, which also acts as a floor participant, sends a "FloorRequest" to the floor control server (FCS, which is co-located with the AS), stating his will to be granted the floor associated with the audio stream in the conference. The AS answers the UA with a "FloorRequestStatus" message with a PENDING status, meaning that a decision on the request has not been made yet. The AS, according to the BFCP policies for this conference, makes a decision on the request, i.e., accepting it. Note that this decision might be relayed to another participant in case he has previously been assigned as chair of the floor. Assuming the request has been accepted, the AS notifies the UA about the decision with a new "FloorRequestStatus", this time with an ACCEPTED status in it. The ACCEPTED status of course only means that the request has been accepted, which doesn't mean the floor has been granted yet. Once the queue management in the FCS, according to the specified algorithms for scheduling, states that the floor request previously
UA也充当场内参与者，向场内控制服务器（FCS，与as位于同一位置）发送“场内请求”，说明其将被授予与会议中音频流相关的场内请求。AS以“FloorRequestStatus”消息回答UA，消息的状态为PENDING，这意味着尚未对请求做出决定。AS根据本次会议的BFCP政策，对请求作出决定，即接受请求。请注意，该决定可能会传达给另一位参与者，以防他之前被指定为会议主席。假设请求已被接受，AS将使用新的“FloorRequestStatus”通知UA该决定，这一次使用的是已接受状态。当然，接受状态只意味着请求已被接受，这并不意味着发言权已被批准。一旦FCS中的队列管理根据指定的调度算法声明，楼层请求之前
made by the UA can be granted, the AS sends a new "FloorRequestStatus" to the UA with a GRANTED status, and takes care of unmuting the participant in the conference by sending a directive to the MS through the control channel. Once the UA receives the notification stating his request has been granted, he can start sending its media, aware of the fact that now his media stream won't be dropped by the MS. In case the session has been previously updated with a 'sendonly' associated to the media stream, the MS must originate a further re-INVITE stating that the media stream flow is now bidirectional ('sendrecv').
当UA发出的指令可以被授予时，AS向UA发送一个新的“FloorRequestStatus”，并通过控制通道向MS发送指令，负责取消会议参与者的静音。一旦UA收到通知，说明其请求已被批准，他就可以开始发送其媒体，意识到现在他的媒体流不会被MS丢弃。如果会话之前已使用与媒体流相关联的“sendonly”进行了更新，MS必须发起进一步的重新邀请，说明媒体流现在是双向的（“sendrecv”）。
As mentioned before, this scenario envisages an automated floor chair role, where it's the AS, according to some policies, which makes decisions on floor requests. The case of a chair role performed by a real person is exactly the same, with the difference that the incoming request is not directly handled by the AS according to its policies, but it is instead forwarded to the floor control participant that the chair UA is exploiting. The decision on the request is then communicated by the chair UA to the AS-FCS by means of a 'ChairAction' message.
如前所述，该场景设想了一个自动化的楼层主席角色，根据某些策略，该角色由As对楼层请求做出决策。由真人执行主席角色的情况完全相同，不同之处在于，传入请求不是由AS根据其策略直接处理的，而是转发给主席UA正在利用的楼层控制参与者。然后，主席UA通过“主席行动”信息将请求决定传达给AS-FCS。
The rest of this section will instead explore the other scenario, which assumes that the interaction between AS-FCS happens through the MS control channel. This scenario is compliant with the H.248.19 document related to conferencing in 3GPP. The following sequence diagram describes the interaction between the involved parties in the same use-case scenario that has been explored for the previous topology: consequently, the diagram makes exactly the same assumptions that have been made for the previously described scenario. This means that the scenario again assumes that a BFCP connection between the UA and the FCS has already been negotiated and established, and that the UA has been made aware of all the relevant identifiers and floors-resources-associations. It also assumes that the AS has previously configured the media mixing on the MS using the MS control channel. This time it includes identifying the BFCP-moderated resources, establishing basic policies and instructions about chair identifiers for each resource, and subscribing to events of interest, because the FCS is not co-located with the AS anymore. Additionally, a BFCP session has been established between the AS (which in this scenario acts as a floor chair) and the FCS (MS). Every frame the UA might be sending on the related media stream is currently being dropped by the MS, since the UA still isn't authorized to use the resource. For a SIP UA, this state could be consequent to a 'sendonly' field associated to the media stream in a re-INVITE originated by the MS. Again, it is worth pointing out that the AS has to make sure that no user media control mechanisms, such as mentioned in the previous sub-section, can override the floor control.
本节其余部分将探讨另一个场景，该场景假设AS-FCS之间的交互通过MS控制通道进行。此场景符合与3GPP中的会议相关的H.248.19文档。下面的序列图描述了在相同的用例场景中涉及的各方之间的交互，该场景已经针对之前的拓扑进行了探索：因此，该图做出了与之前描述的场景完全相同的假设。这意味着该场景再次假设UA和FCS之间的BFCP连接已经协商和建立，并且UA已经了解所有相关标识符和资源关联。它还假设AS先前已使用MS控制通道在MS上配置了介质混合。这一次，它包括识别BFCP主持的资源，为每个资源建立关于主席标识符的基本政策和说明，以及订阅感兴趣的事件，因为FCS不再与AS位于同一地点。此外，已在AS（在本场景中充当现场主席）和FCS（MS）之间建立了BFCP会议。UA可能在相关媒体流上发送的每一帧当前都被MS丢弃，因为UA仍然无权使用该资源。对于SIP UA，该状态可能是与MS发起的重新邀请中的媒体流相关联的“sendonly”字段的结果。同样，值得指出的是，AS必须确保没有用户媒体控制机制（如前一小节中提到的）可以覆盖楼层控制。
UA AS MS
(Floor Participant) (Floor Chair) (FCS)
| | |
|<===================== One-way RTP stream ======================|
| | |
| FloorRequest(BFCP) | |
|--------------------------------------------------------------->|
| | |
| | FloorRequestStatus[PENDING](BFCP) |
|<---------------------------------------------------------------|
| | FloorRequestStatus[PENDING](BFCP) |
| |<-----------------------------------|
| | |
| | ChairAction[ACCEPTED] (BFCP) |
| |----------------------------------->|
| | ChairActionAck (BFCP) |
| |<-----------------------------------|
| | |
| | FloorRequestStatus[ACCEPTED](BFCP) |
|<---------------------------------------------------------------|
| | |
. . .
. . .
| | |
| | FloorRequestStatus[GRANTED](BFCP) |
|<---------------------------------------------------------------|
| | 'Floor has been granted' (CtrlChn) |
| |<-----------------------------------|
| | |
|<==================== Bidirectional RTP stream ================>|
| | |
. . .
. . .
UA AS MS
(Floor Participant) (Floor Chair) (FCS)
| | |
|<===================== One-way RTP stream ======================|
| | |
| FloorRequest(BFCP) | |
|--------------------------------------------------------------->|
| | |
| | FloorRequestStatus[PENDING](BFCP) |
|<---------------------------------------------------------------|
| | FloorRequestStatus[PENDING](BFCP) |
| |<-----------------------------------|
| | |
| | ChairAction[ACCEPTED] (BFCP) |
| |----------------------------------->|
| | ChairActionAck (BFCP) |
| |<-----------------------------------|
| | |
| | FloorRequestStatus[ACCEPTED](BFCP) |
|<---------------------------------------------------------------|
| | |
. . .
. . .
| | |
| | FloorRequestStatus[GRANTED](BFCP) |
|<---------------------------------------------------------------|
| | 'Floor has been granted' (CtrlChn) |
| |<-----------------------------------|
| | |
|<==================== Bidirectional RTP stream ================>|
| | |
. . .
. . .
Figure 7: Conferencing Example: Floor Control Call Flow
图7：会议示例：楼层控制呼叫流
A UA, which also acts as a floor participant, sends a "FloorRequest" to the floor control server (FCS, which is co-located with the MS), stating his will to be granted the floor associated with the audio stream in the conference. The MS answers the UA with a "FloorRequestStatus" message with a PENDING status, meaning that a decision on the request has not been made yet. It then notifies the AS, which in this example handles the floor chair role, about the new request by forwarding there the received request. The AS, according to the BFCP policies for this conference, makes a decision on the request, i.e., accepting it. It informs the MS about its decision through a BFCP "ChairAction" message. The MS then acknowledges the 'ChairAction' message and then notifies the UA about the decision
UA也充当场内参与者，向场内控制服务器（FCS，与MS位于同一位置）发送“场内请求”，说明其将被授予与会议音频流相关的场内请求。MS向UA回复一条“FloorRequestStatus”消息，消息状态为未决状态，这意味着尚未对请求做出决定。然后，它通过将接收到的请求转发给AS，将新请求通知AS（在本例中，AS处理落座椅角色）。AS根据本次会议的BFCP政策，对请求作出决定，即接受请求。它通过BFCP“ChairAction”消息通知MS其决定。MS随后确认“ChairAction”消息，然后将该决定通知UA
with a new "FloorRequestStatus", this time with an ACCEPTED status in it. The ACCEPTED status of course only means that the request has been accepted, which doesn't mean the floor has been granted yet. Once the queue management in the MS, according to the specified algorithms for scheduling, states that the floor request previously made by the UA can be granted, the MS sends a new "FloorRequestStatus" to the UA with a GRANTED status, and takes care of unmuting the participant in the conference. Once the UA receives the notification stating his request has been granted, he can start sending its media, aware of the fact that now his media stream won't be dropped by the MS. In case the session has been previously updated with a 'sendonly' associated to the media stream, the MS must originate a further re-INVITE stating that the media stream flow is now bidirectional ('sendrecv').
使用新的“FloorRequestStatus”，这一次使用接受状态。当然，接受状态只意味着请求已被接受，这并不意味着发言权已被批准。一旦MS中的队列管理根据指定的调度算法声明可以授予UA先前发出的发言权请求，MS就向UA发送一个新的具有授予状态的“FloorRequestStatus”，并负责取消会议参与者的静音。一旦UA收到通知，说明其请求已被批准，他就可以开始发送其媒体，意识到现在他的媒体流不会被MS丢弃。如果会话之前已使用与媒体流相关联的“sendonly”进行了更新，MS必须发起进一步的重新邀请，说明媒体流现在是双向的（“sendrecv”）。
This scenario envisages an automated floor chair role, where it's the AS, according to some policies, which makes decisions on floor requests. Again, the case of a chair role performed by a real person is exactly the same, with the difference that the incoming request is not forwarded to the AS but to the floor control participant that the chair UA is exploiting. The decision on the request is communicated by means of a 'ChairAction' message in the same way.
该场景设想了一个自动化的楼层主席角色，根据一些策略，该角色由AS对楼层请求做出决策。同样，由真人执行主席角色的情况完全相同，不同之处在于传入请求不是转发给AS，而是转发给主席UA正在利用的楼层控制参与者。请求的决定通过“主席行动”消息以相同的方式传达。
Another typical scenario is a BFCP-moderated conference with no chair to manage floor requests. In such a scenario, the MS has to take care of incoming requests according to some predefined policies, e.g., always accepting new requests. In this case, no decisions are required by external entities, since all are instantly decided by means of policies in the MS.
另一个典型的场景是BFCP主持的会议，没有主席来管理发言请求。在这种情况下，MS必须根据一些预定义的策略处理传入请求，例如，始终接受新请求。在这种情况下，外部实体不需要作出任何决定，因为所有决定都是通过MS中的策略立即作出的。
As stated before, the case of the FCS co-located with the AS is much simpler to understand and exploit. When the AS has full control upon the FCS, including its queue management, the AS directly instructs the MS according to the floor status changes, e.g., by instructing the MS through the control channel to unmute a participant who has been granted the floor associated to the audio media stream.
如前所述，FCS与As共存的情况更易于理解和利用。当AS完全控制FCS（包括其队列管理）时，AS根据楼层状态变化直接指示MS，例如，通过控制通道指示MS取消已被授予与音频媒体流相关的楼层的参与者的静音。
This document describes the architectural framework to be used for Media Server control. Its focus is the interactions between Application Servers and Media Servers. User agents interact with Application Servers by means of signaling protocols such as SIP. These interactions are beyond the scope of this document. Application Servers are responsible for utilizing the security mechanisms of their signaling protocols, combined with application-specific policy, to ensure they grant service only to authorized users. Media interactions between user agents and Media Servers are
本文档描述了用于媒体服务器控制的体系结构框架。它的重点是应用服务器和媒体服务器之间的交互。用户代理通过SIP等信令协议与应用服务器交互。这些交互超出了本文档的范围。应用服务器负责利用其信令协议的安全机制，并结合特定于应用程序的策略，以确保它们仅向授权用户授予服务。用户代理和媒体服务器之间的媒体交互是
also outside the scope of this document. Those interactions are at the behest of Application Servers, which must ensure that appropriate security mechanisms are used. For example, if the MS is acting as the FCS, then the BFCP connection between the user agent and the MS is established to the MS by the AS using SIP and the SDP mechanisms described in [RFC4583]. BFCP [RFC4582] strongly imposes the use of TLS for BFCP.
也不在本文件的范围内。这些交互是应用服务器的要求，应用服务器必须确保使用适当的安全机制。例如，如果MS充当FCS，则as使用SIP和[RFC4583]中描述的SDP机制建立用户代理和MS之间的BFCP连接。BFCP[RFC4582]强烈要求将TLS用于BFCP。
Media Servers are valuable network resources and need to be protected against unauthorized access. Application Servers use SIP and related standards both to establish control channels to Media Servers and to establish media sessions, including BFCP sessions, between an MS and end users. Media servers use the security mechanisms of SIP to authenticate requests from Application servers and to ensure the integrity of those requests. Leveraging the security mechanisms of SIP ensures that only authorized Application Servers are allowed to establish sessions to an MS and to access MS resources through those sessions.
媒体服务器是宝贵的网络资源，需要防止未经授权的访问。应用服务器使用SIP和相关标准来建立到媒体服务器的控制通道，并在MS和最终用户之间建立媒体会话，包括BFCP会话。媒体服务器使用SIP的安全机制来验证来自应用服务器的请求，并确保这些请求的完整性。利用SIP的安全机制可确保仅允许授权的应用程序服务器建立与MS的会话，并通过这些会话访问MS资源。
Control channels between an AS and MS carry the MS control protocol, which affects both the service seen by end users and the resources used on a Media Server. TLS [RFC5246] must be implemented as the transport-level security mechanism for control channels to guarantee the integrity of MS control interactions.
AS和MS之间的控制通道承载MS控制协议，该协议影响最终用户看到的服务和媒体服务器上使用的资源。TLS[RFC5246]必须作为控制通道的传输级安全机制来实现，以保证MS控制交互的完整性。
The resources of an MS can be shared by more than one AS. Media Servers must prevent one AS from accessing and manipulating the resources that have been assigned to another AS. This may be achieved by an MS associating ownership of a resource to the AS that originally allocates it, and then insuring that future requests involving that resource correlate to the AS that owns and is responsible for it.
MS的资源可以由多个AS共享。媒体服务器必须阻止一个AS访问和操作已分配给另一个AS的资源。这可以通过MS将资源的所有权与最初分配该资源的AS相关联，然后确保涉及该资源的未来请求与拥有并负责该资源的AS相关联来实现。
The authors would like to thank Spencer Dawkins for detailed reviews and comments, Gary Munson for suggestions, and Xiao Wang for review and feedback.
作者要感谢斯宾塞·道金斯的详细评论和评论，加里·蒙森的建议，小王的评论和反馈。
This document is a product of the Media Control Architecture Design Team. In addition to the editor, the following individuals constituted the design team and made substantial textual contributions to this document:
本文档是媒体控制体系结构设计团队的产品。除编辑外，以下人员组成了设计团队，并对本文件做出了实质性的文字贡献：
Chris Boulton: cboulton@ubiquity.net
克里斯·博尔顿：cboulton@ubiquity.net
Martin Dolly: mdolly@att.com
马丁·多利：mdolly@att.com
Roni Even: roni.even@polycom.co.il
罗尼：罗尼。even@polycom.co.il
Lorenzo Miniero: lorenzo.miniero@unina.it
洛伦佐·米尼罗：洛伦佐。miniero@unina.it
Adnan Saleem: Adnan.Saleem@radisys.com
阿德南·萨利姆：阿德南。Saleem@radisys.com
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981.
[RFC0793]Postel，J.，“传输控制协议”，标准7，RFC 793，1981年9月。
[RFC2976] Donovan, S., "The SIP INFO Method", RFC 2976, October 2000.
[RFC2976]Donovan，S.，“SIP信息方法”，RFC 29762000年10月。
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002.
[RFC3261]Rosenberg，J.，Schulzrinne，H.，Camarillo，G.，Johnston，A.，Peterson，J.，Sparks，R.，Handley，M.，和E.Schooler，“SIP：会话启动协议”，RFC 3261，2002年6月。
[RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol (SIP): Locating SIP Servers", RFC 3263, June 2002.
[RFC3263]Rosenberg，J.和H.Schulzrinne，“会话启动协议（SIP）：定位SIP服务器”，RFC 3263，2002年6月。
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002.
[RFC3264]Rosenberg，J.和H.Schulzrinne，“具有会话描述协议（SDP）的提供/应答模型”，RFC 3264，2002年6月。
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003.
[RFC3550]Schulzrinne，H.，Casner，S.，Frederick，R.，和V.Jacobson，“RTP：实时应用的传输协议”，STD 64，RFC 35502003年7月。
[RFC3725] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. Camarillo, "Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP)", BCP 85, RFC 3725, April 2004.
[RFC3725]Rosenberg，J.，Peterson，J.，Schulzrinne，H.，和G.Camarillo，“会话启动协议（SIP）中第三方呼叫控制（3pcc）的当前最佳实践”，BCP 85，RFC 37252004年4月。
[RFC3840] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)", RFC 3840, August 2004.
[RFC3840]Rosenberg，J.，Schulzrinne，H.，和P.Kyzivat，“指出会话启动协议（SIP）中的用户代理功能”，RFC 3840，2004年8月。
[RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in the Session Description Protocol (SDP)", RFC 4145, September 2005.
[RFC4145]Yon，D.和G.Camarillo，“会话描述协议（SDP）中基于TCP的媒体传输”，RFC 41452005年9月。
[RFC4240] Burger, E., Van Dyke, J., and A. Spitzer, "Basic Network Media Services with SIP", RFC 4240, December 2005.
[RFC4240]Burger，E.，Van Dyke，J.，和A.Spitzer，“具有SIP的基本网络媒体服务”，RFC 42402005年12月。
[RFC4353] Rosenberg, J., "A Framework for Conferencing with the Session Initiation Protocol (SIP)", RFC 4353, February 2006.
[RFC4353]Rosenberg，J.，“会话启动协议（SIP）会议框架”，RFC 4353，2006年2月。
[RFC4474] Peterson, J. and C. Jennings, "Enhancements for Authenticated Identity Management in the Session Initiation Protocol (SIP)", RFC 4474, August 2006.
[RFC4474]Peterson，J.和C.Jennings，“会话启动协议（SIP）中身份验证管理的增强”，RFC 4474，2006年8月。
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006.
[RFC4566]Handley，M.，Jacobson，V.，和C.Perkins，“SDP：会话描述协议”，RFC4566，2006年7月。
[RFC4575] Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session Initiation Protocol (SIP) Event Package for Conference State", RFC 4575, August 2006.
[RFC4575]Rosenberg，J.，Schulzrinne，H.，和O.Levin，“会议状态的会话启动协议（SIP）事件包”，RFC 45752006年8月。
[RFC4579] Johnston, A. and O. Levin, "Session Initiation Protocol (SIP) Call Control - Conferencing for User Agents", BCP 119, RFC 4579, August 2006.
[RFC4579]Johnston，A.和O.Levin，“会话发起协议（SIP）呼叫控制-用户代理会议”，BCP 119，RFC 4579，2006年8月。
[RFC4582] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor Control Protocol (BFCP)", RFC 4582, November 2006.
[RFC4582]Camarillo，G.，Ott，J.，和K.Drage，“二进制地板控制协议（BFCP）”，RFC 4582，2006年11月。
[RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format for Binary Floor Control Protocol (BFCP) Streams", RFC 4583, November 2006.
[RFC4583]Camarillo，G.“二进制地板控制协议（BFCP）流的会话描述协议（SDP）格式”，RFC4583，2006年11月。
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, "Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July 2006.
[RFC4585]Ott，J.，Wenger，S.，Sato，N.，Burmeister，C.，和J.Rey，“基于实时传输控制协议（RTCP）的反馈（RTP/AVPF）的扩展RTP配置文件”，RFC 45852006年7月。
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 4960, September 2007.
[RFC4960]Stewart，R.，“流控制传输协议”，RFC 49602007年9月。
[RFC5167] Dolly, M. and R. Even, "Media Server Control Protocol Requirements", RFC 5167, March 2008.
[RFC5167]Dolly，M.和R.Een，“媒体服务器控制协议要求”，RFC 51672008年3月。
[RFC5239] Barnes, M., Boulton, C., and O. Levin, "A Framework for Centralized Conferencing", RFC 5239, June 2008.
[RFC5239]Barnes，M.，Boulton，C.，和O.Levin，“集中会议的框架”，RFC 5239，2008年6月。
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5246]Dierks，T.和E.Rescorla，“传输层安全（TLS）协议版本1.2”，RFC 5246，2008年8月。
[SIP-CTRL-FW] Boulton, C., Melanchuk, T., and S. McGlashan, "Media Control Channel Framework", Work in Progress, February 2009.
[SIP-CTRL-FW]Boulton，C.，Melanchuk，T.，和S.McGrashan，“媒体控制渠道框架”，正在进行的工作，2009年2月。
[W3C.REC-voicexml20-20040316] Carter, J., Tryphonas, S., Danielsen, P., Burnett, D., Rehor, K., McGlashan, S., Ferrans, J., Porter, B., Lucas, B., and A. Hunt, "Voice Extensible Markup Language (VoiceXML) Version 2.0", World Wide Web Consortium Recommendation REC-voicexml20-20040316, March 2004, <http://www.w3.org/TR/2004/REC-voicexml20-20040316>.
[W3C.REC-voicexml20-20040316]Carter，J.，Tryphonas，S.，Danielsen，P.，Burnett，D.，Rehor，K.，McGlashan，S.，Ferrans，J.，Porter，B.，Lucas，B.，和A.Hunt，“语音可扩展标记语言（VoiceXML）版本2.0”，万维网联盟建议REC-voicexml20-20040316，2004年3月<http://www.w3.org/TR/2004/REC-voicexml20-20040316>.
[W3C.REC-xml-20060816] Sperberg-McQueen, C., Paoli, J., Bray, T., Maler, E., and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fourth Edition)", World Wide Web Consortium Recommendation REC-xml-20060816, August 2006, <http://www.w3.org/TR/2006/REC-xml-20060816>.
[W3C.REC-xml-20060816]Sperberg McQueen，C.，Paoli，J.，Bray，T.，Maler，E.，和F.Yergeau，“可扩展标记语言（xml）1.0（第四版）”，万维网联盟建议REC-xml-20060816，2006年8月<http://www.w3.org/TR/2006/REC-xml-20060816>.
[XCON-DM] Novo, O., Camarillo, G., Morgan, D., and J. Urpalainen, "Conference Information Data Model for Centralized Conferencing (XCON)", Work in Progress, April 2009.
[XCON-DM]Novo，O.，Camarillo，G.，Morgan，D.，和J.Urpalainen，“集中会议的会议信息数据模型（XCON）”，正在进行的工作，2009年4月。
Author's Address
作者地址
Tim Melanchuk (editor) Rain Willow Communications
Tim Melanchuk（编辑）雨柳通讯
EMail: tim.melanchuk@gmail.com
EMail: tim.melanchuk@gmail.com