1.1 Glossary

This document uses the following terms:

200 OK: A response to indicate that the request has succeeded.

202 Accepted: A response that indicates that a request was accepted for processing.

Augmented Backus-Naur Form (ABNF): A modified version of Backus-Naur Form (BNF), commonly used by Internet specifications. ABNF notation balances compactness and simplicity with reasonable representational power. ABNF differs from standard BNF in its definitions and uses of naming rules, repetition, alternatives, order-independence, and value ranges. For more information, see [RFC5234].

base64 encoding: A binary-to-text encoding scheme whereby an arbitrary sequence of bytes is converted to a sequence of printable ASCII characters, as described in [RFC4648].

Best Effort NOTIFY (BENOTIFY): A Session Initiation Protocol (SIP) method that is used to send notifications to a subscriber, as described in [MS-SIP]. Unlike the NOTIFY method, the BENOTIFY method does not require the recipient of the request to send a SIP response.

conference: A Real-Time Transport Protocol (RTP) session that includes more than one participant.

conference URI (conference-URI): A Session Initiation Protocol (SIP) URI that uniquely identifies the focus of a conference.

dialog: A peer-to-peer Session Initiation Protocol (SIP) relationship that exists between two user agents and persists for a period of time. A dialog is established by SIP messages, such as a 2xx response to an INVITE request, and is identified by a call identifier, a local tag, and a remote tag.

endpoint: A device that is connected to a computer network.

focus: A single user agent that maintains a dialog and Session Initiation Protocol (SIP) signaling relationship with each participant, implements conference policies, and ensures that each participant receives the media that comprise the tightly coupled conference.

Globally Routable User Agent URI (GRUU): A URI that identifies a user agent and is globally routable. A URI possesses a GRUU property if it is useable by any user agent client (UAC) that is connected to the Internet, routable to a specific user agent instance, and long-lived.

globally unique identifier (GUID): A term used interchangeably with universally unique identifier (UUID) in Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the value. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the GUID. See also universally unique identifier (UUID).

IM MCU: A Multipoint Control Unit (MCU) that supports Instant Messaging (IM) conferencing.

Instant Message Delivery Notification (IMDN): A notification that is sent from a multipoint control unit (MCU) to the sender of a message. It contains details about any failures that occurred when forwarding the message to other participants in a conference.

INVITE: A Session Initiation Protocol (SIP) method that is used to invite a user or a service to participate in a session.

Multipoint Control Unit (MCU): A server endpoint that offers mixing services for multiparty, multiuser conferencing. An MCU typically supports one or more media types, such as audio, video, and data.

Multipurpose Internet Mail Extensions (MIME): A set of extensions that redefines and expands support for various types of content in email messages, as described in [RFC2045], [RFC2046], and [RFC2047].

notification: A process in which a subscribing Session Initiation Protocol (SIP) client is notified of the state of a subscribed resource by sending a NOTIFY message to the subscriber.

participant: A user who is participating in a conference or peer-to-peer call, or the object that is used to represent that user.

Session Description Protocol (SDP): A protocol that is used for session announcement, session invitation, and other forms of multimedia session initiation. For more information see [MS-SDP] and [RFC3264].

Session Initiation Protocol (SIP): An application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. SIP is defined in [RFC3261].

SIP response code: A three-digit code in a Session Initiation Protocol (SIP) message, as described in [RFC3261].

subscribe: The process of registering to receive updates about presence information for client devices. The updates are delivered by using Wide Area Network Device Presence Protocol (WAN DPP).

subscription: The result of a SUBSCRIBE request from a Session Initiation Protocol (SIP) element.

Transmission Control Protocol (TCP): A protocol used with the Internet Protocol (IP) to send data in the form of message units between computers over the Internet. TCP handles keeping track of the individual units of data (called packets) that a message is divided into for efficient routing through the Internet.

Transport Layer Security (TLS): A security protocol that supports confidentiality and integrity of messages in client and server applications communicating over open networks. TLS supports server and, optionally, client authentication by using X.509 certificates (as specified in [X509]). TLS is standardized in the IETF TLS working group.

Uniform Resource Identifier (URI): A string that identifies a resource. The URI is an addressing mechanism defined in Internet Engineering Task Force (IETF) Uniform Resource Identifier (URI): Generic Syntax [RFC3986].

user agent client (UAC): A logical entity that creates a new request, and then uses the client transaction state machinery to send it. The role of UAC lasts only for the duration of that transaction. In other words, if a piece of software initiates a request, it acts as a UAC for the duration of that transaction. If it receives a request later, it assumes the role of a user agent server (UAS) for the processing of that transaction.

user agent server (UAS): A logical entity that generates a response to a Session Initiation Protocol (SIP) request. The response either accepts, rejects, or redirects the request. The role of the UAS lasts only for the duration of that transaction. If a process responds to a request, it acts as a UAS for that transaction. If it initiates a request later, it assumes the role of a user agent client (UAC) for that transaction.

XML: The Extensible Markup Language, as described in [XML1.0].

XML schema: A description of a type of XML document that is typically expressed in terms of constraints on the structure and content of documents of that type, in addition to the basic syntax constraints that are imposed by XML itself. An XML schema provides a view of a document type at a relatively high level of abstraction.

MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.