Network Working Group T. Melanchuk Internet-Draft Rain Willow Communications Intended status: Standards Track S. McGlashan Expires: April 17, 2009 Hewlett-Packard C. Boulton Avaya October 14, 2008 A Mixer Control Package for the Media Control Channel Framework draft-ietf-mediactrl-mixer-control-package-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 17, 2009. Melanchuk, et al. Expires April 17, 2009 [Page 1] Internet-Draft Mixer Control Package October 2008 Abstract This document defines a Mixer Control Package for the Media Control Channel Framework. This Control Package aims to fulfill Conferencing requirements using the SIP Control Framework. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 5 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Control Package Definition . . . . . . . . . . . . . . . . . . 8 4.1. Control Package Name . . . . . . . . . . . . . . . . . . . 8 4.2. Framework Message Usage . . . . . . . . . . . . . . . . . 8 4.3. Common XML Support . . . . . . . . . . . . . . . . . . . . 9 4.4. CONTROL Message Body . . . . . . . . . . . . . . . . . . . 9 4.5. REPORT Message Body . . . . . . . . . . . . . . . . . . . 9 4.6. Audit . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5. Element Definitions . . . . . . . . . . . . . . . . . . . . . 11 5.1. . . . . . . . . . . . . . . . . . . . . . . . . 11 5.2. Mixer Elements . . . . . . . . . . . . . . . . . . . . . . 12 5.2.1. Conference Elements . . . . . . . . . . . . . . . . . 13 5.2.1.1. . . . . . . . . . . . . . . . . 13 5.2.1.2. . . . . . . . . . . . . . . . . 16 5.2.1.3. . . . . . . . . . . . . . . . 17 5.2.1.4. Conference Configuration . . . . . . . . . . . . . 17 5.2.1.4.1. . . . . . . . . . . . . . . . . 18 5.2.1.4.2. . . . . . . . . . . . . . . . 18 5.2.1.4.2.1. . . . . . . . . . . . . . . 19 5.2.1.4.3. . . . . . . . . . . . . . . . . 20 5.2.1.4.3.1. Priority assignment . . . . . . . . . . . 22 5.2.1.4.4. . . . . . . . . . . . . . . . . . 22 5.2.1.4.4.1. . . . . . . . . . . . 23 5.2.2. Joining Elements . . . . . . . . . . . . . . . . . . . 23 5.2.2.1. Joining Model . . . . . . . . . . . . . . . . . . 23 5.2.2.2. . . . . . . . . . . . . . . . . . . . . . . 25 5.2.2.3. . . . . . . . . . . . . . . . . . . . 27 5.2.2.4. . . . . . . . . . . . . . . . . . . . . . 28 5.2.2.5. . . . . . . . . . . . . . . . . . . . . . 29 5.2.2.5.1. . . . . . . . . . . . . . . . . . . . 30 5.2.2.5.2. . . . . . . . . . . . . . . . . . . . 30 5.2.2.5.3. . . . . . . . . . . . . . . . . . . . 31 5.2.2.5.4. . . . . . . . . . . . . . . . . . . 31 5.2.3. . . . . . . . . . . . . . . . . . . . . . . 31 5.2.4. . . . . . . . . . . . . . . . . . . . . . . . 32 5.2.4.1. . . . . . . . . . . . . . 32 5.2.4.1.1. . . . . . . . . . . . . . . . 33 Melanchuk, et al. Expires April 17, 2009 [Page 2] Internet-Draft Mixer Control Package October 2008 5.2.4.2. . . . . . . . . . . . . . . . . . 33 5.2.4.3. . . . . . . . . . . . . . . . . . 34 5.3. Audit Elements . . . . . . . . . . . . . . . . . . . . . . 34 5.3.1. . . . . . . . . . . . . . . . . . . . . . . . 35 5.3.2. . . . . . . . . . . . . . . . . . . . 36 5.3.2.1. . . . . . . . . . . . . . . . . . . 37 5.3.2.2. . . . . . . . . . . . . . . . . . . . . . 38 5.3.2.2.1. . . . . . . . . . . . . . . 38 5.3.2.2.1.1. . . . . . . . . . . . . . . 39 5.3.2.2.1.1.1. . . . . . . . . . . . . 39 5.3.2.2.2. . . . . . . . . . . . . . . . . . 40 5.4. . . . . . . . . . . . . . . . . . . . . . . . . . 40 5.4.1. . . . . . . . . . . . . . . . . . . . . . . . 41 5.5. . . . . . . . . . . . . . . . . . . . . . . . . . 41 5.5.1. . . . . . . . . . . . . . . . . . . . . . . . 42 5.6. Response Status Codes . . . . . . . . . . . . . . . . . . 42 5.7. Type Definitions . . . . . . . . . . . . . . . . . . . . . 43 6. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 45 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 7.1. AS-MS Dialog Interaction Examples . . . . . . . . . . . . 63 7.1.1. Creating a conference mixer and joining a participant . . . . . . . . . . . . . . . . . . . . . 63 7.1.2. Receiving active talker notifications . . . . . . . . 64 8. Security Considerations . . . . . . . . . . . . . . . . . . . 65 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 66 9.1. Control Package Registration . . . . . . . . . . . . . . . 66 9.2. URN Sub-Namespace Registration . . . . . . . . . . . . . . 66 9.3. MIME Registration . . . . . . . . . . . . . . . . . . . . 66 10. Change Summary . . . . . . . . . . . . . . . . . . . . . . . . 67 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 70 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 71 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 72 13.1. Normative References . . . . . . . . . . . . . . . . . . . 72 13.2. Informative References . . . . . . . . . . . . . . . . . . 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 74 Intellectual Property and Copyright Statements . . . . . . . . . . 75 Melanchuk, et al. Expires April 17, 2009 [Page 3] Internet-Draft Mixer Control Package October 2008 1. Introduction This document defines a Media Control Channel Framework Package for conference mixers and connection mixers. The package defines mixer management elements for creating, modifying and deleting conference mixers, elements for joining, modifying and unjoining media streams between connections and conferences (including mixers between connections), as well as associated responses and notifications. The package also defines elements for auditing package capabilities and mixers. Melanchuk, et al. Expires April 17, 2009 [Page 4] Internet-Draft Mixer Control Package October 2008 2. Conventions and Terminology In this document, BCP 14/RFC 2119 [RFC2119] defines the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL". In addition, BCP 15 indicates requirement levels for compliant implementations. The following additional terms are defined for use in this document: Application server: A SIP [RFC3261] application server (AS) is a control client that hosts and executes services such as interactive media and conferencing in an operator's network. An AS controls the media server (MS), influencing and impacting the SIP sessions terminating on a media server, which the AS may have established for example using SIP third party call control. Media Server: A media server (MS) processes media streams on behalf of an AS by offering functionality such as interactive media, conferencing, and transcoding to the end user. Interactive media functionality is realized by way of dialogs, which are identified by a URI and initiated by the application server. MS Conference: A MS Conference provides the media related mixing resources and services for conferences. In this document, A MS Conference is often referred to simply as a conference. MS Connection: A Media Server connection represents the termination on a media server of one or more RTP [RFC3550] sessions that are associated to a single SIP dialog. A media server receives media from the output(s) of a connection and it transmits media on the input(s) of a connection. Media Stream: A media stream on a media server represents a media flow between either a connection and a conference, between two connections, or between two conferences. Streams may be audio or video and may be bi-directional or uni-directional. Melanchuk, et al. Expires April 17, 2009 [Page 5] Internet-Draft Mixer Control Package October 2008 3. Overview The SIP Control Framework [I-D.ietf-mediactrl-sip-control-framework] provides a generic approach for establishment and reporting capabilities of remotely initiated commands. The Framework utilizes many functions provided by the Session Initiation Protocol [RFC3261] (SIP) for the rendezvous and establishment of a reliable channel for control interactions. The Control Framework also introduces the concept of a Control Package. A Control Package is an explicit usage of the Control Framework for a particular interaction set. This specification defines a package for media conference mixers and media connection mixers. This package defines mixer management elements for creating, modifying and deleting conference mixers, elements for joining, modifying and unjoining media streams between connections and conferences (including mixers between connections), as well as associated responses and notifications. The package also defines elements for auditing package capabilities and mixers. This package has been designed to satisfy the IETF MediaCtrl requirements ([RFC5167]). The package provides the major conferencing functionality of SIP Media Server languages such as MSCML ([RFC5022]) and MSML ([MSML]). A key differentiator is that this package provides such functionality using the Media Control Channel Framework. Out of scope for this mixer package are more advanced functions including personalized video mixes for conference participants, support for floor control protocols, as well as support for video overlays and text insertion. Such functionality may be addressed by extensions to this package (through addition of foreign elements or attributes from another namespace) or use of other control packages which could build upon this package. The functionality of this package is defined by messages, containing XML [XML] elements, transported using the Media Control Channel Framework. The XML elements can be divided into two types: mixer management elements; and elements for auditing package capabilities as well as mixers managed by the package. The document is organized as follows. Section 4 descibes how this control package fulfills the requirements for a Media Control Channel Framework control package. Section 5 describes the syntax and semantics of defined elements, including mixer management (Section 5.2) and audit elements (Section 5.3). Section 6 describes an XML schema for these elements and provides extensibility by allowing attributes and elements from other namespaces. Section 7 Melanchuk, et al. Expires April 17, 2009 [Page 6] Internet-Draft Mixer Control Package October 2008 provides examples of package usage. Melanchuk, et al. Expires April 17, 2009 [Page 7] Internet-Draft Mixer Control Package October 2008 4. Control Package Definition This section fulfils the mandatory requirement for information that MUST be specified during the definition of a Control Framework Package, as detailed in Section 8 of [I-D.ietf-mediactrl-sip-control-framework]. 4.1. Control Package Name The Control Framework requires a Control Package definition to specify and register a unique name. The name and version of this Control Package is "msc-mixer/1.0" (Media Server Control - Mixer - version 1.0). Its IANA registration is specified in Section 9.1. 4.2. Framework Message Usage The Control Framework requires a Control Package to explicitly detail the control messages that can be used as well as provide an indication of directionality between entities. This will include which role type is allowed to initiate a request type. This package specifies CONTROL and response messages in terms of XML elements defined in Section 5. These elements describe requests, response and notifications and all are contained within a root element (Section 5.1). In this package, the MS operates as a Control Framework Server in receiving requests from, and sending responses to, the AS (operating as Control Framework Client). Mixer management requests and responses are defined in Section 5.2. Audit requests and responses are defined in Section 5.3. Mixer management and audit responses are carried in a framework 200 response or REPORT message bodies. This package's response codes are defined in Section 5.6. Note that package responses are different from framework response codes. Framework error response codes (see Section 8 of [I-D.ietf-mediactrl-sip-control-framework]) are used when the request or event notification is invalid; for example, a request is invalid XML (400), or not understood (500). The MS also operates as a Control Framework Client in sending event notification to the AS (Control Framework Server). Event notifications (Section 5.2.4) are carried in CONTROL message bodies. The AS MUST respond with a Control Framework 200 response. Melanchuk, et al. Expires April 17, 2009 [Page 8] Internet-Draft Mixer Control Package October 2008 4.3. Common XML Support The Control Framework requires a Control Package definition to specify if the attributes for media dialog or conference references are required. This package requires that the XML Schema in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] MUST be supported for media dialogs and conferences. The package uses "connectionid" and "conferenceid" attributes for various element definitions (Section 5). The XML schema (Section 6) imports the definitions of these attributes from the framework schema. 4.4. CONTROL Message Body The Control Framework requires a Control Package to define the control body that can be contained within a CONTROL command request and to indicate the location of detailed syntax definitions and semantics for the appropriate body types. When operating as Control Framework Server, the MS receives CONTROL messages with a body containing an element with either a mixer management or audit request child element. The following mixer management request elements are carried in CONTROL message bodies to MS: (Section 5.2.1.1), (Section 5.2.1.2), (Section 5.2.1.3), (Section 5.2.2.2), (Section 5.2.2.3) and (Section 5.2.2.4) elements. The request element (Section 5.3.1) is also carried in CONTROL message bodies. When operating as Control Framework Client, the MS sends CONTROL messages with a body containing a notification element (Section 5.2.4). 4.5. REPORT Message Body The Control Framework requires a control package definition to define the REPORT body that can be contained within a REPORT command request, or that no report package body is required. This section should indicate the location of detailed syntax definitions and semantics for the appropriate body types. When operating as Control Framework Server, the MS sends REPORT Melanchuk, et al. Expires April 17, 2009 [Page 9] Internet-Draft Mixer Control Package October 2008 bodies containing a element with a response child element. The response element for mixer management requests is a element (Section 5.2.3). The response element for an audit request is a element (Section 5.3.2). 4.6. Audit The Control Framework encourages Control Packages to specify whether auditing is available, how it is triggered as well as the query/ response formats. This Control Packages supports auditing of package capabilities and mixers on the MS. An audit request is carried in a CONTROL messages and an audit response in a REPORT message (or a 200 reponse to the CONTROL if it can execute the audit in time). The syntax and semantics of audit request and response elements is defined in Section 5.3. Melanchuk, et al. Expires April 17, 2009 [Page 10] Internet-Draft Mixer Control Package October 2008 5. Element Definitions This section defines the XML elements for this package. The elements are defined in the XML namespace specified in Section 9.2. The root element is (Section 5.1). All other XML elements (requests, responses and notification elements) are contained within it. Child elements describe mixer management (Section 5.2) and audit (Section 5.3) functionality. Response status codes are defined in Section 5.6 and type definitions in Section 5.7. Implementation of this control package MUST adhere to the syntax and semantics of XML elements defined in this section and the schema (Section 6). The XML schema supports extensibility by allowing attributes and elements from other namespaces. Implementations MAY support attributes and elements from other (foreign) namespaces. If an MS implementation receives a element containing attributes or elements from another namespace which it does not support, the MS MUST send a 427 response (Section 5.6). Extensible attributes and elements are not described in this section. In all other cases where there is a difference in constraints between the XML schema and the textual description of elements in this section, the textual definition takes priority. Usage examples are provided in Section 7. 5.1. The element has the following attributes (in addition to standard XML namspace attributes such as xmlns): version: a string specifying the mscmixer package version. The value is fixed as '1.0' for this version of the package. The attribute is mandatory. The element has the following defined child elements, only one of which can occur: 1. mixer management elements defined in Section 5.2: create and configure a new a conference mixer. See Section 5.2.1.1 modify the configuration of an existing conference mixer. See Section 5.2.1.2 Melanchuk, et al. Expires April 17, 2009 [Page 11] Internet-Draft Mixer Control Package October 2008 destroy an existing conference mixer. See Section 5.2.1.3 create and configure media streams between connections and/or conferences (for example, add a participant to a conference). See Section 5.2.2.2 modify the configuration of joined media streams. See Section 5.2.2.3 delete a media stream (for example, remove a participant from a conference). See Section 5.2.2.4 response to a mixer request. See Section 5.2.3 mixer or subscription notification. See Section 5.2.4 2. audit elements defined in Section 5.3: audit package capabilities and managed mixers. See Section 5.3.1 response to an audit request. See Section 5.3.2 For example, a request to the MS to create a conference mixer: and a response from the MS that the conference was sucessfully created: 5.2. Mixer Elements This section defines the mixer management XML elements for this control package. These elements are divided into requests, responses and notifications. Request elements are sent to the MS to request a specific mixer operation to be executed. The following request elements are defined: Melanchuk, et al. Expires April 17, 2009 [Page 12] Internet-Draft Mixer Control Package October 2008 create and configure a new a conference mixer. See Section 5.2.1.1 modify the configuration of an existing conference mixer. See Section 5.2.1.2 destroy an existing conference mixer. See Section 5.2.1.3 create and configure media streams between connections and/or conferences (for example, add a participant to a conference). See Section 5.2.2.2 modify the configuration of joined media streams. See Section 5.2.2.3 delete a media stream (for example, remove a participant from a conference). See Section 5.2.2.4 Responses from the MS describe the status of the requested operation. Responses are specified in a element (Section 5.2.3). The MS MUST respond to a request message with a response message. If the MS is not able to carry out the requested mixer operation, it is an error and the MS MUST indicate the error in the status code of the response. Notifications are sent from the MS to provide updates on the status of a mixer operation or subscription. Notifications are specified in an element (Section 5.2.4). 5.2.1. Conference Elements 5.2.1.1. The element is sent to the MS to request creation of a new conference (multiparty) mixer. The element has the following attributes: conferenceid: string indicating a unique name for the new conference. If this attribute is not specified, the MS MUST create a unique name for the conference. The value is used in subsequent references to the conference (e.g. as conferenceid in a ). The attribute is optional. There is no default value. Melanchuk, et al. Expires April 17, 2009 [Page 13] Internet-Draft Mixer Control Package October 2008 reserved-talkers: indicates the requested number of guaranteed speaker slots to be reserved for the conference. A valid value is a non-negative integer (see Section 5.7.2). The attribute is optional. The default value is 0. reserved-listeners: indicates the requested number of guaranteed listener slots to be reserved for the conference. A valid value is a non-negative integer (see Section 5.7.2). The attribute is optional. The default value is 0. The element has the following sequence of child elements: : an element to configure the codecs supported by the conference (see Section 5.4). The element is optional. : an element to configure the audio mixing characteristics of a conference (see Section 5.2.1.4.1). The element is optional. : an element to configure the video layouts of a conference (see Section 5.2.1.4.2). The element is optional. : an element to configure the video switch policy for the layout of a conference (see Section 5.2.1.4.3). The element is optional. : an element to request subscription to conference events. (see Section 5.2.1.4.4). The element is optional. If the conferenceid attribute specifies the name of a conference which already exists, the MS MUST report an error (403) and MUST NOT create the conference. If the MS is unable to configure the conference according to a specified element, the MS MUST report an error (410) and MUST NOT create the conference. If the MS is unable to configure the conference according to a specified element, the MS MUST report an error (405) and MUST NOT create the conference. If the MS is unable to configure the conference according to a specified element, the MS MUST report an error (408) and MUST NOT create the conference. If the MS is unable to configure the conference according to a specified element, the MS MUST report an error (409) Melanchuk, et al. Expires April 17, 2009 [Page 14] Internet-Draft Mixer Control Package October 2008 and MUST NOT create the conference. If the MS is unable to configure the conference according to specified reserved-talkers or reserved-listeners attributes, the MS MUST report an error (407) and MUST NOT create the conference. If the MS is unable to configure the conference for any specified conference event specified in the element, the MS MUST report an error (406) and MUST NOT create the conference. When a MS has finished processing a request, it MUST reply with an appropriate element (Section 5.2.3). For example, a request to create an audio video conference mixer with specified codecs, video layout, video switch and subscription: H264 PCMA single-view dual-view quad-view and a response from the MS if the conference was sucessfully created: alternatively, a response if MS could not create the conference due to a lack of support for the H264 codec: Melanchuk, et al. Expires April 17, 2009 [Page 15] Internet-Draft Mixer Control Package October 2008 5.2.1.2. The element is sent to the MS to request modification of an existing conference. The element has the following attributes: conferenceid: string indicating the name of the conference to modify. This attribute is mandatory. The element has the following sequence of child elements (1 or more): : an element to configure the codecs supported by the conference (see Section 5.4). Existing participants are unaffected by any policy chage. The element is optional. : an element to configure the audio mixing characteristics of a conference (see Section 5.2.1.4.1). The element is optional. : an element to configure the video layouts of a conference (see Section 5.2.1.4.2). The element is optional. : an element to configure the video switch policy for the layout of a conference (see Section 5.2.1.4.3). The element is optional. : an element to request subscription to conference events. (see Section 5.2.1.4.4). The element is optional. If the conferenceid attribute specifies the name of a conference which does not exist, the MS MUST report an error (404). If the MS is unable to configure the conference according to a specified element, the MS MUST report an error (410) and MUST NOT modify the conference. If the MS is unable to configure the conference according to a specified element, the MS MUST report an error (405) and MUST NOT modify the conference in any way. If the MS is unable to configure the conference according to a Melanchuk, et al. Expires April 17, 2009 [Page 16] Internet-Draft Mixer Control Package October 2008 specified element, the MS MUST report an error (408) and MUST NOT modify the conference in any way. If the MS is unable to configure the conference according to a specified element, the MS MUST report an error (409) and MUST NOT modify the conference in any way. If the MS is unable to configure the conference for any specified conference event specified in the element, the MS MUST report an error (406) and MUST NOT modify the conference in anyway. When a MS has finished processing a request, it MUST reply with an appropriate element (Section 5.2.3). 5.2.1.3. The element is sent to the MS to request destruction of an existing conference. The element has the following attributes: conferenceid: string indicating the name of the conference to destroy. This attribute is mandatory. The element does not specify any child elements. If the conferenceid attribute specifies the name of a conference which does not exist, the MS MUST report an error (404). When a MS has finished processing a request, it MUST reply with an appropriate element (Section 5.2.3). Successfully destroying the conference (status code 200) will result in all connection or conference particpants being removed from the conference mixer, notification events (Section 5.2.4.2) being sent for each conference participant and a notification event (Section 5.2.4.3) indicating that conference has exited. A with any other status code indicates that the conference mixer still exists and participants are still joined to the mixer. 5.2.1.4. Conference Configuration The elements in this section are used to establish and modify the configuration of conferences. Melanchuk, et al. Expires April 17, 2009 [Page 17] Internet-Draft Mixer Control Package October 2008 5.2.1.4.1. The element defines the configuration of the conference audio mix. It has no child elements and has the following attributes: type: is a string indicating the audio stream mixing policy. Defined values are: "nbest" (where the N best participant signals are mixed) and "controller" (where the contributing participant(s) is/are selected by the controlling AS via an external floor control protocol). The default value is "nbest". The attribute is optional. 5.2.1.4.2. The element describe the video presentation layout configuration for participants providing a video input stream to the conference. This element allows multiple video layouts to be specified so that the MS automatically changes layout depending on the number of video-enabled participants. The element has no attributes. The element has the following sequence of child elements (1 or more): : element describing a video layout (Section 5.2.1.4.2.1). If the MS does not support video conferencing at all, or does not support multiple video layouts, or does not support a specific video layout, the MS MUST report an 408 error in the response to the request element containing the element. An MS MAY support more than one element, although only one layout can be active at a time. A is active if the number of participants in the conference is equal to or greater than the value of its "min-participants" attribute, but less than the value of the "min-participants" attribute for any other element. An MS MUST report an error if more than one has the same value for the "min-participants" attribute. When the number of regions within the active layout is greater than the number of participants in the conference, the display of unassigned regions is implementation-specific. The assignment of participant video streams to regions within the layout is according to the video switch policy specified by the element (Section 5.2.1.4.3). Melanchuk, et al. Expires April 17, 2009 [Page 18] Internet-Draft Mixer Control Package October 2008 For example, a fragment describing a single layout: single-view And a fragment describing a sequence of layouts: single-view dual-view quad-view multiple-3x3 When the conference has one participant providing a video input stream to the conference, then the single-view format is used. When the conference has two such participants, the dual-view layout is used. When the conference has three or four particpants, the quad- view layout is used. When the conference has five or more particpants, the multiple-3x3 layout is used. 5.2.1.4.2.1. The element describes a video layout containing one or more regions in which participant video input stream are displayed. The element has the following attributes: min-participants: the minimum number of conference participants needed to allow this layout to be active. A valid value is a positive integer (see Section 5.7.3). The attribute is optional. The default value is 1. The element has a content model specifying the name of the video layout. It is RECOMMENDED that an MS support the predefined video layouts defined in the XCON conference information data model ([I-D.ietf-xcon-common-data-model]). The MS MAY support other video layouts. It is RECOMMENDED that non-XCON layouts are prefixed with a label; for example, mylayout:single-view. Each video layout has associated with it one or more regions. The XCON layouts have associated the following named regions: Melanchuk, et al. Expires April 17, 2009 [Page 19] Internet-Draft Mixer Control Package October 2008 single-view one region with name "region1" dual-view two regions: left named "region1", right "region2" XXX etc [Editors Note: MIXER-003. ASCII art help required to draw the layout and name the regions for the remaining XCON layouts. ] 5.2.1.4.3. The element describe the configuration of the conference policy for how participant's input video streams are assigned to regions within the active video layout. The element has the following attributes: type: a string indicating the video switching policy of the conference. Defined values are: vas (Voice Activated Switching) enables automatic display of the most active speaker participant also providing a video input stream to the conference. Participants who do not provide an audio stream are not considered for automatic display. If a participant provides more than one audio stream, then the policy for inclusion of such a participant in the VAS is implementation-specific; an MS could select one stream, sum audio streams or ignore the participant for VAS consideration. If there is only one region in the layout, then the most active speaker is displayed there. If more than one region is available, then the most active speaker is displayed in the largest region, if any, and then in the first region from the top-left corner of the layout. The MS assigns the remaining regions based on the priority mechanism described in Section 5.2.1.4.3.1. controller enables manual control over video switching. The controller AS determines how the regions are assigned based on an external floor control policy. The MS receives , and commands with a element (Section 5.2.2.5) indicating the region where the stream is displayed. If no explicit region is specified, the MS assigns the region based on the priority mechanism described in Section 5.2.1.4.3.1. An MS MAY support other video switching policies. It is RECOMMENDED that other policy names are prefixed with a label; e.g. "mypolicies:policy1". The attribute is optional. The Melanchuk, et al. Expires April 17, 2009 [Page 20] Internet-Draft Mixer Control Package October 2008 default value is 'vas'. interval: specifies the period between video switches as a number of seconds. In the case of 'vas' policy, a speaker needs to be the most active speaker for the interval before the switch takes place. A valid value is a non-negative integer (see Section 5.7.2). A value of 0 indicates that switching is applied immediately. The attribute is optional. The default value is 3 (seconds). activespeakermix: indicates whether or not the active speaker participant receives a video stream without themselves displayed in the case of the 'vas' switching policy. If enabled, the MS needs to generate two video streams for each conference mix: one for the active speaker participant without themselves displayed - details of this video layout are implementation-specific; and one for other participants as described in the 'vas' switch policy above. A valid value is a boolean (see Section 5.7.1). A value of true indicates that a separate video mix is generated for the active speaker without themselves being displayed. A value of false indicates that all participants receive the same video mix. The attribute is optional. The default value is false. If the type attribute is not set to 'vas', the MS MUST ignore this attribute. If the MS does not support the specified video switching policy or other configuration parameters (including separate active speaker video mixes), then MS MUST report a 409 error (Section 5.6) in the response to the request element containing the element. If the MS receives a or request containing a a element (Section 5.2.2.5) specifying a region and the conference video switching policy is set to 'vas', then the MS MUST ignore the region (i.e. conference switching policy takes precedence). The element has no child elements. For example, a fragment specifying a 'vas' video switching policy with an interval of 2s For example, a fragment specifying a 'controller' video switching policy where video switching takes place immediately: Melanchuk, et al. Expires April 17, 2009 [Page 21] Internet-Draft Mixer Control Package October 2008 5.2.1.4.3.1. Priority assignment In cases where the video switching policy does not explicitly determine the region to which a participant is assigned, the following priority assignment mechanism applies: 1. Each participant has an (positive integer) priority value: the lower the value, the higher the priority. The priority value is determined by the child element (Section 5.2.2.5.4) of . If not explicitly specified, the default priority value is 100. 2. The MS uses priority values to assign participants to regions in the video layout which remain unfilled after application of the video switching policy. The MS MUST dedicate larger and/or more prominent portions of the layout to participants with higher priority values first (e.g. first all participants with priority 1, then those with 2, 3, etc). 3. The policy for displaying participants with the same priority is implementation-specific. The MS applies this priority policy each time the video layout is changed or updated. It is RECOMMENDED that the MS does not move a participant from one region to another unless required by the video switching policy when an active video layout is updated. This model allows the MS to apply default video layouts after applying the video switch policy. For example, region 2 is statically assigned to Bob, so the priority mechanism only applies to regions 1, 3, 4, etc. 5.2.1.4.4. The element is a container for specifying conference notification events to which a controlling entity subscribes. Notifications of conference events are delivered using the element (see Section 5.2.4). The element has no attributes, but has the following child element: : subscription to active talker events (Section 5.2.1.4.4.1). The element is optional. The MS SHOULD support a subscription. It MAY support other event subscriptions. If the MS does not support a requested subscription, it MUST send a with a 406 status Melanchuk, et al. Expires April 17, 2009 [Page 22] Internet-Draft Mixer Control Package October 2008 code. 5.2.1.4.4.1. The element has the following attributes: interval: the minimum amount of time (in seconds) that must elapse before further active talker events can be generated. A valid value is a non-negative integer (see Section 5.7.2). A value of 0 suppresses further notifications. The attribute is optional. The default value is 3 (seconds). The element has no child elements. Active talker notifications are delivered in the element (Section 5.2.4.1). 5.2.2. Joining Elements 5.2.2.1. Joining Model The operation creates a media stream between a connection and a conference, between connections, or between conferences. This sub- section describes the model of conferences and connections and specifies the behaviour for join requests to targets that already have an associated media stream. Conferences support multiple inputs and have resources to mix them together. A media server conference in essence is a mixer that combines media streams. A simple audio mix simply sums its input audio signals to create a single common output. Conferences however use a more complex algorithm so that participants do not hear themselves as part of the mix. That algorithm, sometimes called an n-minus mix, subtracts each participants input signal from the summed input signals, creating a unique output for each contributing participant. Each operation to a conference uses one of the conferences available inputs and/or outputs, to the maximum number of supported participants. A connection is the termination of a RTP session(s) on a media server. It has a single input and output for each media session established by its SIP dialog. The output of a connection may feed several different inputs such as both a conference mix and a recording of that participants audio. Joining two connections which are are not joined to anything else simply creates a media stream from the outputs(s) of one connection to the corresponding inputs(s) of the other connection. It is not Melanchuk, et al. Expires April 17, 2009 [Page 23] Internet-Draft Mixer Control Package October 2008 necessary to combine media from multiple sources in this case. There are however several common scenarios where combining media from several sources to create a single input to a connection is needed. In the first case, a connection may be receiving media from one source, for example a conference, and it is necessary to play an announcement to the connection so that both the conference audio and announcement can be heard by the conference participant. This is sometimes referred to as a whisper announcement. An alternative to a whisper announcement is to have the announcement pre-empt the conference media. Another common case is the call centre coaching scenario where a supervisor can listen to the conversation between an agent and a customer, and provide hints to the agent, which are not heard by the customer. Both of these cases can be solved by having the controlling AS create one or more conferences for audio mixing and to join and unjoin the media streams as required. A better solution is to have the media server automatically mix media streams that are requested to be joined to a common input when only the simple summing of audio signals as described above is required. This is the case for both the use cases presented above. Automatically mixing streams has several benefits. Conceptually, it is straight forward and simple, requiring no indirect requests on the part of the controlling AS. This increases transport efficiency and reduces the coordination complexity and the latency of the overall operation. Therefore, it is RECOMMENDED that a media server be able to automatically mix at least two audio streams where only the simple summing of signals is required. When a media server receives a request, it MUST automatically mix all of the media streams included in the request with any streams already joined to one of the entities identified in the request, or it MUST fail the request and MUST NOT join any of the streams. A controlling AS MUST use the request for generic conferences where the complex mixing algorithm is required. Specifications which extend this package to handle additional media types such as text or video, MUST define the semantics of the join operation when multiple streams are requested to be joined to a single input, such as that for a connection with a single RTP session per media type. Melanchuk, et al. Expires April 17, 2009 [Page 24] Internet-Draft Mixer Control Package October 2008 5.2.2.2. The element is sent to the MS to request creation one or more media streams either between a connection and a conference, between connections, or between conferences. The two entities to join are specified by the attributes of . Streams may be of any media type, and may be bi-directional or uni- directional. A bi-directional stream is implicitly composed of two uni-directional streams that can be manipulated independently. The streams to be established are specified by child elements (see Section 5.2.2.5). The element has the following attributes: id1: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. id2: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. Note: Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] defines the semantics for a conference identifier but not its syntax. Media server implementations need to distinguish between conferences and connections based upon the values of the "id1" and "id2" attributes. The element has the following child element (0 or more): : an element that both identifies the media streams to join and defines the way that they are to be joined (see Section 5.2.2.5). The element is optional. If no elements are specified, then the default is to join all streams between the entities according to the media configuration of the connection or conference. One or more elements may be specified so that individual media streams can be controlled independently. For example, if a connection supports both audio and video streams, a element could be used to indicate that only the audio stream is used in receive mode. In cases where there are multiple media streams of the same type for a connection or conference, it is RECOMMENDED that the configuration is explicitly specified using elements. Melanchuk, et al. Expires April 17, 2009 [Page 25] Internet-Draft Mixer Control Package October 2008 It is an error if a element is in conflict with (a) another element, (b) with specified connection or conference media capabilities, (c) with a SDP label value as part of the connection-id (see Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]) or (d) if the media stream configuration is not supported by the MS. If the MS is unable to execute the join as specified in elements, the MS MUST report an error (424) and MUST NOT join the entities. If the MS is unable to join an entity to a conference because it is full, then the MS MUST report an error (421). If the specified entities are already joined, then the MS MUST report an error (425). If the MS does not support joining two specified connections together, the MS MUST report an error (422). If the MS does not support joining two specified conferences together, the MS MUST report an error (423). If the MS is unable to join the specified entities for any other reason, the MS MUST report an error (420). When the MS has finished processing a request, it MUST reply with an element (Section 5.2.3). [Editors Note: MIXER-008. Should the draft allow multiple joins of the same user to the same conference? a (maybe silly) use case for this might be having a user's video appear in 2 different regions of the same conference. With the current specification an "already joined" 425 error would be generated, considering that the same connection/conference can only be attached once to each other. (Lorenzo) ] [Editors Note: MIXER-009. The package isn't clear on the behavior of connectionid with a label part (i.e. from~to~label) permitted in Section 17.1 of the Control Framework. Connection identity: how is from1~to1 related to from1~to1~label1 related to one another? If from1~to1 is unjoined, then is from1~to1~label1 also unjoined? Some possible approaches: (a) remove connectionids with label part from the Control Framework? (like this package, other packages can use a element to control the behavior). (b) explicitly specify this package does not support the label part of connection (or make a 'special' feature in the Control Framework. Or (c) clarify usage in Control Framework and this package. (Lorenzo) ] Melanchuk, et al. Expires April 17, 2009 [Page 26] Internet-Draft Mixer Control Package October 2008 For example, a request to join two connection together: and the response if the MS doesn't support joining media streams between connections: 5.2.2.3. The element is sent to the MS to request changes in the configuration of media stream(s) that were previously established between a connection and a conference, between two connections, or between two conferences. The element has the following attributes: id1: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. id2: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. The element has the following child elements (1 or more): : an element that both identifies the media streams to modify and defines the way that each stream should now be configured (see Section 5.2.2.5). The MS MUST support for any stream that was established using or modified by a previous operation. The media server MUST configure the streams that are included within to that stated by the child elements. It MUST NOT change the configuration of any streams not included as child elements. If the MS is unable to modify the join as specified in Melanchuk, et al. Expires April 17, 2009 [Page 27] Internet-Draft Mixer Control Package October 2008 elements, the MS MUST report an error (424) and MUST NOT modify the join between the entities. If the specified entities are not already joined, then the MS MUST report an error (426). If the MS is unable to modify the join between the specified entities for any other reason, the MS MUST report an error (420). When an MS has finished processing a request, it MUST reply with an appropriate element (Section 5.2.3). 5.2.2.4. The element is sent to the MS to request removal of previously established media stream(s) from between a connection and a conference, between two connections, or between two conferences. The element has the following attributes: id1: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. id2: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. The element has the following child element (0 or more occurrences): : an element that identifies the media stream(s) to remove (see Section 5.2.2.5). The element is optional. When not present, all currently established streams between "id1" and "id2" are removed. The MS MUST support for any stream that was established using or modified using and have not already been removed. If the MS is unable to terminate any join as specified in elements, the MS MUST report an error (424) and MUST NOT terminate the join between the entities. If the specified entities are not already joined, then the MS MUST report an error (426). Melanchuk, et al. Expires April 17, 2009 [Page 28] Internet-Draft Mixer Control Package October 2008 If the MS is unable to terminate the join between the specified entities for any other reason, the MS MUST report an error (420). When an MS has successfully processed a request, it MUST reply with a successful element (Section 5.2.3). 5.2.2.5. , and require the identification and manipulations of media streams. Media streams represent the flow of media between a participant connection and a conference, between two connections, or between two conferences. The element is used (as a child to , and element has the following attributes: media: a string indicating the type of media associated with the stream. It is strongly recommended that the following values are used for common types of media: "audio" for audio media, and "video" for video media. The attribute is mandatory. label: a string indicating the SDP label associated with a media stream ([RFC4574]). The attribute is optional. direction: a string indicating the allowed media flow of the stream relative to the value of the "id1" attribute of the parent element. Defined values are: "sendrecv" (media can be sent and received), "sendonly" (media can only be sent), "recvonly" (media can only be received) and "inactive" (stream is not to be used). The default value is "sendrecv". The attribute is optional. [Editors Note: MIXER-010. "inactive" value: clarify that this value means the stream is not established. Alternative: it is established but no send/receive media flow. This has an impact when a makes an established stream inactive (removed?), or a previously inactive stream is made active in sendrecv direction, for example. ]. The element has the following sequence of child elements: : an element to configure the volume or gain of the media stream (Section 5.2.2.5.1). The element is optional. Melanchuk, et al. Expires April 17, 2009 [Page 29] Internet-Draft Mixer Control Package October 2008 : an element to configure filtering and removal of tones from a media stream (Section 5.2.2.5.2). The element is optional. : an element to configure region within a video layout where the media stream is displayed (Section 5.2.2.5.3). The element is optional. : an element to configure priority associated with the stream in the media mix (Section 5.2.2.5.4). The element is optional. If the "media" attribute does not have the value of "audio", then the MS MUST ignored and elements. If the "media" attribute does not have the value of "video", then the MS MUST ignored element. 5.2.2.5.1. The element is used to configure the volume of an audio media stream. It may be set to a specific gain amount, to automatically adjust the gain to a desired target level, or to mute the volume. The element has no child elements but has the following attributes: controltype: a string indicating the type of volume control to use for the stream. Defined values are: "automatic" (the volume will be adjusted automatically to the level specified by the "value" attribute), "setgain" (use the value of the "value" attribute as a specific gain measured in dB to apply), "setstate" (set the state of the stream to "mute" or "unmute" as specified by the value of the "value" attribute). The attribute is mandatory. value: a string specifying the amount or state for the volume control defined by the value of the "controltype" attribute. The attribute is optional. There is no default value. 5.2.2.5.2. The element is used to configure whether tones should be filtered and removed from a media stream. The element has no child elements but has the following attributes: Melanchuk, et al. Expires April 17, 2009 [Page 30] Internet-Draft Mixer Control Package October 2008 tones: A list of the tones to remove. The attribute is manadatory. 5.2.2.5.3. The element is used to explicitly specify the region within a video layout where the media stream is displayed. The element has no attributes and its content model specifies the name of the region layout. If the region name is invalid, then the MS MUST report an 428 error in the response to the request element containing the element. 5.2.2.5.4. The element is used to explicitly specify the priority of a participant. The MS uses this priority to determine where the media stream is displayed within a video layout (Section 5.2.1.4.3.1). The element has no attributes and its content model specifies a positive integer (see Section 5.7.3). The lower the value, the higher the priority. 5.2.3. Reponses to requests are indicated by a element. The element has following attributes: status: numeric code indicating the response status. Valid valies are defined in Section 5.6. The attribute is mandatory. reason: string specifying a reason for the response status. The attribute is optional. conferenceid: string identifying the conference (see Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]). The attribute is optional. connectionid: string identifying the SIP dialog connection (see Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]). The attribute is optional. For example, a response when a conference was created successfully: Melanchuk, et al. Expires April 17, 2009 [Page 31] Internet-Draft Mixer Control Package October 2008 Success The response if conference creation failed due to the requested conference id already existing: Conf already exists 5.2.4. When a mixer generates a notification event, the MS sends the event using an element. The element has no attributes, but has the following sequence of child elements (0 or more instances of each child): specifies an active talkers notification (Section 5.2.4.1). notifies that a connection or conference has been completely unjoined (Section 5.2.4.2). notifies that a conference has exited (Section 5.2.4.3). 5.2.4.1. The element describes zero or more speakers that have been active in a conference during the specified interval (see Section 5.2.1.4.4.1). The element has the following attributes: conferenceid: string indicating the name of the conference from which the event orginated. This attribute is mandatory. The element has the following sequence of child elements (0 or more occurences): element describing an active talker (Section 5.2.4.1.1). Melanchuk, et al. Expires April 17, 2009 [Page 32] Internet-Draft Mixer Control Package October 2008 5.2.4.1.1. The element describes an active talker, associated with either a connection or conference participant in a conference. The element has the following attributes: connectionid: string indicating the connectionid of the active talker. This attribute is optional. There is no default value. conferenceid: string indicating the conferenceid of the active talker. This attribute is optional. There is no default value. It is an error (429) if both the connectionid and conferenceid attributes are specified. The element has no child elements. 5.2.4.2. The element describes a notification event where a connection and/or conference have been completely unjoined. The element has the following attributes: status: a status code indicating why the unjoin occurred. A valid value is a non-negative integer (see Section 5.7.2). A value of 1 indicates that the join has been terminated by a request. A value of 2 indicates that the unjoin occured because the a connection or conference has terminated. A value of 3 indicates the join terminated due to an internal error. Any other value indicates an error defined by the MS. The attribute is mandatory. reason: a textual description providing a reason for the status code; e.g. details about an error. A valid value is a string (see Section 5.7.4). The attribute is optional. There is no default value. id1: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. id2: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. Melanchuk, et al. Expires April 17, 2009 [Page 33] Internet-Draft Mixer Control Package October 2008 The element has no child elements. 5.2.4.3. The element indicates that a conference has exited because it has been terminated or because a error occurred (for example, a hardware error in the conference mixing unit). This event MUST be sent by the MS whenever a successfully created conference exits. The element has the following attributes: conferenceid: string indicating the name of the conference. This attribute is mandatory. status: a status code indicating why the conference exited. A valid value is a non-negative integer (see Section 5.7.2). A value of 1 indicates that the conference has been terminated by a request. Any other value indicates an error defined by the MS. The attribute is mandatory. reason: a textual description providing a reason for the status code; e.g. details about an error. A valid value is a string (see Section 5.7.4). The attribute is optional. There is no default value. The element has no child elements. When a MS sends a event, the identifier for the conference (conferenceid attribute) is no longer valid on the MS and can be reused for another conference. For example, the following notification event would be sent from the MS when the conference with identifier "conference99" exits due to a successful : 5.3. Audit Elements The audit elements defined in this section allow the MS to be audited for package capabilities as well as mixers managed by the package. Auditing is particularly important for two use cases. First, it Melanchuk, et al. Expires April 17, 2009 [Page 34] Internet-Draft Mixer Control Package October 2008 enables discovery of package capabilities supported on an MS before an AS creates a conference mixer or joins connections and conferences. The AS may then use this informaton to create request elements using supported capabilities and, in the case of codecs, to negotiate an appropriate SDP for a user agent's connection. Second, auditing enables discovery of the existence and status of mixers currently managed by the package on the MS. This allows one AS to take over management of mixers when the AS which initiated the mixers fails or is no longer available. 5.3.1. The request element is sent to the MS to request information about the capabilities of, and mixers currently managed with, this control package. Capabilities include supported conference codecs and video layouts. Mixer information includes the status of managed mixers as well as codecs. The element has the following attributes: capabilities: indicates whether package capabilities are to be audited. A valid value is a boolean (see Section 5.7.1). A value of true indicates that capability information is to be reported. A value of false indicates that capability information is not to be reported. The attribute is optional. The default value is true. mixers: indicates whether mixers currently managed by the package are to be audited. A valid value is a boolean (see Section 5.7.1). A value of true indicates that mixer information is to be reported. A value of false indicates that mixer information is not to be reported. The attribute is optional. The default value is true. conferenceid: string identifying a specific conference mixer to audit. It is an error (404) if the conferenceid attribute is specified and the conference identifier is not valid. The attribute is optional. There is no default value. If the mixers attribute has the value true and conferenceid attribute is specified, then only audit information about the specified conference mixer is reported. If the mixers attribute has the value false, then no mixer audit information is reported even if a conferenceid attribute is specified. The element has no child elements. When the MS receives a request, it MUST reply with a Melanchuk, et al. Expires April 17, 2009 [Page 35] Internet-Draft Mixer Control Package October 2008 element (Section 5.3.2). If the request is successful, contains (depending on atrribute values) a element (Section 5.3.2.1) reporting package capabilities and a element (Section 5.3.2.2) reporting managed mixer information. For example, a request to audit capabilities and mixers managed by the package: In this example, only capabilities are to be audited: With this example, only a specific conference mixer is to be audited: 5.3.2. The element describes a response to a request. The element has the following attributes: status: numeric code indicating the audit response status. The attribute is mandatory. Valid values are defined in Section 5.6. reason: string specifying a reason for the status. The attribute is optional. The element has the following sequence of child elements: element (Section 5.3.2.1) describing capabilities of the package. The element is optional. element (Section 5.3.2.2) describing information about managed mixers. The element is optional. For example, a successful response to a request requesting Melanchuk, et al. Expires April 17, 2009 [Page 36] Internet-Draft Mixer Control Package October 2008 capabilities and mixer information: H263 H264 PCMU PCMA PCMA 5.3.2.1. The element provides audit information about package capabilities. The element has no attributes. The element has the following sequence of child elements: Melanchuk, et al. Expires April 17, 2009 [Page 37] Internet-Draft Mixer Control Package October 2008 : element (Section 5.4) describing codecs available to the package. The element is mandatory. For example, a fragment describing capabilities: H263 H264 PCMU PCMA 5.3.2.2. The element provides audit information about mixers. The element has no attributes. The element has the following sequence of child elements (0 or more occurences, any order): : audit information for a conference mixer (Section 5.3.2.2.1). The element is optional. : audit information for a join mixer (Section 5.3.2.2.2). The element is optional. 5.3.2.2.1. The element has the following attributes: conferenceid: string identifying the conference (see Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]). The attribute is mandatory. The element has the following sequence of child elements: Melanchuk, et al. Expires April 17, 2009 [Page 38] Internet-Draft Mixer Control Package October 2008 element describing codecs used in the conference. See Section 5.4. The element is optional. element listing connections or conferences joined to the conference. See Section 5.3.2.2.1.1. The element is optional. element describing the active video layout for the conference. See Section 5.2.1.4.2.1. The element is optional. For example, a fragment describing a conference which has been created but has no participants: And a fragment when the same conference has three participants (two connections and another conference) joined to it: PCMU 5.3.2.2.1.1. The element is a container for elements (Section 5.3.2.2.1.1.1). The element has no attributes, but the following child elements are defined (0 or more): : specifies a participant (Section 5.3.2.2.1.1.1). 5.3.2.2.1.1.1. The element describes a participant. The element has the following attributes: Melanchuk, et al. Expires April 17, 2009 [Page 39] Internet-Draft Mixer Control Package October 2008 id: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]. The attribute is mandatory. The element has no children. 5.3.2.2.2. The element has the following attributes: id1: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. id2: an identifier for either a connection or a conference. The identifier MUST conform to the syntax defined in Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework] The attribute is mandatory. The element has no children. [Editors Note: MIXER-006. Do we need to specify stream information associated with the join?] For example, a fragment describing an audit of two join mixers, one between connections and the second between conferences: 5.4. The element is a container for one or more codec definitions. Codec definitions are used by an AS to specify the codecs allowed for a conference (e.g. when used as a child of or element has no attributes. The element has the following sequence of child elements (0 or more occurences): Melanchuk, et al. Expires April 17, 2009 [Page 40] Internet-Draft Mixer Control Package October 2008 : defines a codec and optionally its policy(Section 5.4.1). The element is optional. For example, a fragment describing two codecs: PCMA H263 5.4.1. The element describes a codec. The element is modeled on the element in the XCON conference information data model ([I-D.ietf-xcon-common-data-model]) and allows addition information (e.g. rate, speed, etc) to be specified. The element has no attributes. The element has the following sequence of child elements: : element describing the codec's name. The possible values of this element are the values of the 'subtype' column of the RTP Payload Format media types per [RFC4855] defined in IANA ([IANA]). The element is mandatory. : element (Section 5.5) describing additional information about the codec. This package is agnostic to the names and values of the codec parameters supported by an implementation. The element is optional. For example, a fragment with a element describing the H263 codec: H263 5.5. The element is a container for elements (Section 5.5.1). The element has no attributes, but the following child Melanchuk, et al. Expires April 17, 2009 [Page 41] Internet-Draft Mixer Control Package October 2008 elements are defined (0 or more): : specifies a parameter name and value (Section 5.5.1). 5.5.1. The element describes a parameter name and value. The element has the following attributes: name: a string indicating the name of the parameter. The attribute is mandatory. type: specifies a type indicating how the inline value of the parameter is to be interpreted. A valid value is a MIME media type (see Section 5.7.6). The attribute is optional. The default value is "text/plain". The element content model is the value of the parameter. Note that a value which contains XML characters (e.g. "<") needs to be escaped following standard XML conventions. 5.6. Response Status Codes The following status codes for mixer management reponses (Section 5.2.3) and audit responses Section 5.3.2) responses are defined. +-----------+-------------------------------------------------------+ | code | description | +-----------+-------------------------------------------------------+ | 200 | OK | | | | | 403 | Conference already exists | | | | | 404 | Conference does not exist | | | | | 405 | Unable to configure audio mix | | | | | 406 | Unable to create subscription | | | | | 407 | Conference reservation failed | | | | | 408 | Unable to configure video layouts | | | | | 409 | Unable to configure video switch | | | | | 410 | Unable to configure codecs | Melanchuk, et al. Expires April 17, 2009 [Page 42] Internet-Draft Mixer Control Package October 2008 | 420 | Unable to join requested entities | | | | | 421 | Unable to join - conference full | | | | | 422 | Unable to join - mixing connections not supported | | | | | 423 | Unable to join - mixing conferences not supported | | | | | 424 | invalid joining stream configuration | | | | | 425 | joining already joined | | | | | 426 | joining entities not joined | | | | | 427 | Unsupported foreign namespace attribute or element | | | | | 428 | Invalid region identifier | | | | | 429 | Syntax constraint violation | | | | | 450 | Unknown or unsupported element | | | | | 451 | Element required | | | | | 452 | Unknown or unsupported attribute | | | | | 453 | Attribute required | +-----------+-------------------------------------------------------+ Table 1: response status codes 5.7. Type Definitions This section defines types referenced in attribute definitions. 5.7.1. Boolean The value space of boolean is the set {true, false}. 5.7.2. Non-Negative Integer The value space of non-negative integer is the infinite set {0,1,2,...}. 5.7.3. Positive Integer The value space of positive integer is the infinite set {1,2,...}. Melanchuk, et al. Expires April 17, 2009 [Page 43] Internet-Draft Mixer Control Package October 2008 5.7.4. String A string in the character encoding associated with the XML element. 5.7.5. Time Designation A time designation consists of a non-negative real number followed by a time unit identifier. The time unit identifiers are: "ms" (milliseconds) and "s" (seconds). Examples include: "3s", "850ms", "0.7s", ".5s" and "+1.5s". 5.7.6. MIME Media Type A string formated as a IANA MIME media type ([MIME.mediatypes]). Melanchuk, et al. Expires April 17, 2009 [Page 44] Internet-Draft Mixer Control Package October 2008 6. Formal Syntax This section defines the XML schema for the Mixer Control Package. The schema defines datatypes, attributes, and mixer elements in the urn:ietf:params:xml:ns:msc-mixer namespace. In most elements the order of child elements is significant. The schema is extensible: elements allow attributes and child elements from other namespaces. Elements from outside this package's namespace can occur after elements defined in this package. The schema is dependent upon the schema (framework.xsd) defined in Section 17.1 of the Control Framework [I-D.ietf-mediactrl-sip-control-framework]. IETF MediaCtrl Mixer 1.0 (20081010) This is the schema of the Mixer control package. It defines request, response and notification elements for mixing. The schema namespace is urn:ietf:params:xml:ns:msc-mixer This import brings in the framework attributes for conferenceid and connectionid. This type is extended by other component types to allow elements and attributes from other namespaces to be added. Melanchuk, et al. Expires April 17, 2009 [Page 46] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 47] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 48] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 49] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 50] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 51] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 52] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 54] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 56] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 57] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 59] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 60] Internet-Draft Mixer Control Package October 2008 Melanchuk, et al. Expires April 17, 2009 [Page 61] Internet-Draft Mixer Control Package October 2008 Figure 1: Mixer Package XML Schema Melanchuk, et al. Expires April 17, 2009 [Page 62] Internet-Draft Mixer Control Package October 2008 7. Examples This section provides examples of the Mixer Control package. 7.1. AS-MS Dialog Interaction Examples The following example assume a control channel has been established and synced as described in the Media Control Channel Framework ([I-D.ietf-mediactrl-sip-control-framework]). The XML messages are in angled brackets (with the root omitted); the REPORT status is in round brackets. Other aspects of the protocol are omitted for readability. 7.1.1. Creating a conference mixer and joining a participant A conference mixer is created successfully and a participant is joined. Application Server (AS) Media Server (MS) | | | (1) CONTROL: | | ----------------------------------------> | | | | (2) 202 | | <--------------------------------------- | | | | | | (3) REPORT: | | (terminate) | | <---------------------------------------- | | | | (4) 200 | | ----------------------------------------> | | | | (5) CONTROL: | | ----------------------------------------> | | | | (6) 202 | | <--------------------------------------- | | | | (7) REPORT: | | (terminate) | | <---------------------------------------- | | | | (8) 200 | | ----------------------------------------> | Melanchuk, et al. Expires April 17, 2009 [Page 63] Internet-Draft Mixer Control Package October 2008 7.1.2. Receiving active talker notifications An active talker notification event is sent by the MS. Application Server (AS) Media Server (MS) | | | (1) CONTROL: | | <--------------------------------------- | | | | (4) 200 | | ----------------------------------------> | | | Melanchuk, et al. Expires April 17, 2009 [Page 64] Internet-Draft Mixer Control Package October 2008 8. Security Considerations As this control package processes XML markup, implementations MUST address the security considerations of [RFC3023]. As a Control Package of the Media Control Channel Framework, security, confidentiality and integrity of messages transported over the control channel MUST be addressed as described in Section 11 of the Media Control channel Framework ([I-D.ietf-mediactrl-sip-control-framework]), including Session Establishment, Transport Level Protection and Control Channel Policy Management. The Media Control Channel Framework permits additional policy management, including resource access and control channel usage, to be specified at the control package level beyond that specified for the Media Control Channel Framework (see Section 11.3 of [I-D.ietf-mediactrl-sip-control-framework]). Since creation of conferences and other mixers is associated with media mixing resources on the MS, policy management for this control package MUST address how such mixers are managed across multiple control channels. This includes which channels are used to deliver mixer event notifications, and whether channels are permitted to originate requests managing a mixer which was not created through that channel (e.g. a conference mixer has been created via channel X and a request to terminate the conference, or join a participant, originates from channel Y). Melanchuk, et al. Expires April 17, 2009 [Page 65] Internet-Draft Mixer Control Package October 2008 9. IANA Considerations This specification instructs IANA to register a new Media Control Channel Framework Package, a new XML namespace and a new mime type. 9.1. Control Package Registration Control Package name: msc-mixer/1.0 9.2. URN Sub-Namespace Registration XML namspace: urn:ietf:params:xml:ns:msc-mixer 9.3. MIME Registration Mime type: application/msc-mixer+xml Melanchuk, et al. Expires April 17, 2009 [Page 66] Internet-Draft Mixer Control Package October 2008 10. Change Summary Note to RFC Editor: Please remove this whole section. The following are the major changes between the -01 and -00 versions. o [MIXER-001]/5.2.4.3: Added notification event. o [MIXER-003]/5.2.1.4.2.1: Added ASCII diagrams for video layouts. o [MIXER-004]/5.3.2.2.1: Added active information to . o [MIXER-007]/5.4.1: Added inside so additional codec information can be specified. o 5.2.1.1: Fixed example with missing min- participants attributes. o 5: Changed handling of unsupported foreign namespace elements and attributes. The MS send a 427 error response if it encounters foreign elements and attributes it does not support. o 5.2.1.4.3: . Clarified that the VAS policy is implementation-specific if a participant provides more than one audio stream. o 5.2.2.2/5.2.2.3/5.2.2.4: Clarified that joining behavior so that streams which have previously been ed or ed are not affected by a general . o 5.2.1.4.3: : Added support for whether active speaker is displayed on their video layout ('activespeakermix' attribute) and clarified that personal video mixes are out of scope for this package. o 5.2.1.4.3/5.2.2.5.4: : Added support for a priority mechanism in video switching policy and a . o 8:Updated security section o 13:Updated references o 5.2.1.4.4.1: Added default of 3 seconds for interval. Melanchuk, et al. Expires April 17, 2009 [Page 67] Internet-Draft Mixer Control Package October 2008 o 5.2.2.5.1: controltype attribute set to mandatory. o Updated schema The following are the major changes between the -00 of this work group item draft and the individual submission -04 version. o Control package name is now 'msc-mixer/1.0'. Namespace is now 'urn:ietf:params:xml:ns:msc-mixer'. Mime type is now 'application/msc-mixer+xml'. o Added XML root element . o Editorial tidy up of sections. o Added audit request/response elements. o Added video layout and switching conference configuration. o : changed 'mix-type' attribute to 'type' (consistency with video-switch) o Added "inactive" as value of 's direction attribute. o Added child to element. o : element is no longer mandatory; added and child elements. reserved- talkers and reserved-listeners as attributes. o replaced conf-id attribute with conferenceid attribute. o Removed element. Active talkers subscription and notifications used dedicated elements now. o Added notification event to indicate when (un)expected joins occur. Use case: connection or conference joined to a conference and conference exits (either by request or runtime error. The following are the major changes between the -04 of the draft and the -03 version. o Updated reference for Media Control Channel Framework The following are the major changes between the -03 of the draft and the -02 version. Melanchuk, et al. Expires April 17, 2009 [Page 68] Internet-Draft Mixer Control Package October 2008 o None The following are the major changes between the -02 of the draft and the -01 version. o clarified the model for join operations and introduced several new package error codes o added definition for MS connection The following are the major changes between the -01 of the draft and the -00 version. o restructured into single request response model for non-trival operations o aligned with XML structure of other control framework packages Melanchuk, et al. Expires April 17, 2009 [Page 69] Internet-Draft Mixer Control Package October 2008 11. Contributors Asher Shiratzky from Radvision provided valuable support and contributions to early versions of this document. The authors would like to thank the Mixer design team consisting of Roni Even, Lorenzo Miniero, Adnan Saleem, Diego Besprosvan and Mary Barnes who provided valuable feedback, input and text to this document. Melanchuk, et al. Expires April 17, 2009 [Page 70] Internet-Draft Mixer Control Package October 2008 12. Acknowledgments The authors would like to thank Roni Even, Lorenzo Miniero and Steve Buko for expert reviews of this work. Melanchuk, et al. Expires April 17, 2009 [Page 71] Internet-Draft Mixer Control Package October 2008 13. References 13.1. Normative References [I-D.ietf-mediactrl-sip-control-framework] Boulton, C., Melanchuk, T., and S. McGlashan, "Media Control Channel Framework", draft-ietf-mediactrl-sip-control-framework-04 (work in progress), August 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [RFC4574] Levin, O. and G. Camarillo, "The Session Description Protocol (SDP) Label Attribute", RFC 4574, August 2006. [XML] Bray, T., Paoli, J., Sperberg-McQueen, C M., Maler, E., and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Third Edition)", W3C Recommendation, February 2004. 13.2. Informative References [I-D.ietf-xcon-common-data-model] Novo, O., Camarillo, G., Morgan, D., and R. Even, "Conference Information Data Model for Centralized Conferencing (XCON)", draft-ietf-xcon-common-data-model-11 (work in progress), June 2008. [IANA] "IANA registry for RTP Payload Types", . [MIME.mediatypes] "IANA registry for MIME Media Types", . [MSML] Saleem, A., Xin, Y., and G. Sharratt, "Media Session Markup Language (MSML)", draft-saleem-msml-07 (work in progress), August 2008. [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. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Melanchuk, et al. Expires April 17, 2009 [Page 72] Internet-Draft Mixer Control Package October 2008 Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [RFC4855] Casner, S., "Media Type Registration of RTP Payload Formats", RFC 4855, February 2007. [RFC5022] Van Dyke, J., Burger, E., and A. Spitzer, "Media Server Control Markup Language (MSCML) and Protocol", RFC 5022, September 2007. [RFC5167] Dolly, M. and R. Even, "Media Server Control Protocol Requirements", RFC 5167, March 2008. Melanchuk, et al. Expires April 17, 2009 [Page 73] Internet-Draft Mixer Control Package October 2008 Authors' Addresses Tim Melanchuk Rain Willow Communications Email: tim.melanchuk@gmail.com Scott McGlashan Hewlett-Packard Gustav III:s boulevard 36 SE-16985 Stockholm, Sweden Email: scott.mcglashan@hp.com Chris Boulton Avaya Building 3 Wern Fawr Lane St Mellons Cardiff, South Wales CF3 5EA Email: cboulton@avaya.com Melanchuk, et al. Expires April 17, 2009 [Page 74] Internet-Draft Mixer Control Package October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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