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In computer networking, the Message Session Relay Protocol (MSRP) is a protocol for transmitting a series of related instant messages in the context of a communications session. An application instantiates the session with the Session Description Protocol (SDP) over Session Initiation Protocol (SIP) or other rendezvous methods. The MSRP protocol is defined in RFC 4975.〔RFC 4975, ''The Message Session Relay Protocol (MSRP)'', B. Campbell (Ed.), R. Mahy (Ed.), C. Jennings (Ed.), The Internet Society (September 2007)〕 MSRP messages can also be transmitted by using intermediaries peers, by using the relay extensions defined in RFC 4976.〔RFC 4976, ''Relay Extensions for the Message Session Relay Protocol (MSRP)'', C. Jennings (Ed.), R. Mahy (Ed.), A. B. Roach (Ed.), The Internet Society (September 2007)〕 MSRP is used in the RCS context, especially for the instant messaging, file transfer and photo sharing features. ==Protocol design== MSRP has similar syntax as other IETF text based protocol such as SIP, HTTP and RTSP. Each message is either a request or a response, uses URIs, a message contains headers and a body that can carry any type of data, including binary information. Unlike SIP, MSRP is much simpler. The first 2 headers must be To-Path and From-Path and the last must be Content-Type, this significantly reduces the complexity of parsers. Messages must also end with 7 dash ('-') characters, followed by a transaction identifier which appears in the first line, these are followed by a continuation flag, which is a single character and end of line (CRLF). This last line at the end of messages makes it rather simple to find and detect the message boundaries. MSRP is not defined for connection-less protocols, such as UDP, thus one be certain that a response to a request would arrive on the same connection. MSRP also relies on a reliable transport layer, that is, guarantees delivery and maintains the order of the messages, which further simplifies the protocol design. An MSRP URI has a scheme (which is "msrp" or "msrps"), authority, as defined by RFC 3986, which holds the IP/domain name and possibly the port, an optional session identifier, the transport and additional optional parameters. For example: msrp://atlanta.example.com:7654/jshA7weztas;tcp * ''msrp'' is the scheme * ''atlanta.example.com:7654'' is the authority * ''jshA7weztas'' is the session identifier * ''tcp'' is the transport 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Message Session Relay Protocol」の詳細全文を読む スポンサード リンク
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