SIP 学习入门范例4.doc

SIP 学习入门范例 (4)四、SIP 状态和及时短消息范例 这个实例最简单的说法就是，利用 SIP 获取好友状态信息以及发送及时消息。我们经常用的 QQ 或MSN 就是这种方式。一方用户可以获取另一方用户状态信息。状态信息用来表示该用户目前的工作状态，例如：工作中、休息中等等。目前新版本的聊天工具还可以显示个人消息的能力。 在 SIP 协议中，规定可以使用 SUBSCRIBE 来请求状态或者改写状态，用 NOTIFY 获得状态信息。在本例中，Chebychev 希望和 Possion 通信。为了能够知道 Possion 的状态情况，Chebychev 通过发送 SUBSCRIBE 订阅 Possion 状态信息，消息内容如下： SUBSCRIBE sip: SIP/2.0Via SIP/2.0/TCP lecturehall21.academy.ru:5060;branch=z9hG4bK348471123Max-Forwards: 70To: M. Poisson From: P. L. Chebychev ;tag=21171Call-ID: 58dkfj34924lk34452k592520CSeq: 3412 SUBSCRIBEAllow-Events: presenceAllow: ACK, INVITE, CANCEL, BYE, NOTIFY, SUBSCRIBE, MESSAGEContact: Event: presenceContent-Length: 0 Poisson 接收到 SUBSCRIBE 消息后，发送 202 Accepted 响应返回到 Chebychev SIP/2.0 202 AcceptedVia SIP/2.0/TCP lecturehall21.academy.ru:5060;branch=z9hG4bK348471123;received=To: M. Poisson ;tag=25140From: P. L. Chebychev ;tag=21171Call-ID: 58dkfj34924lk34452k592520CSeq: 3412 SUBSCRIBEAllow-Events: presenceAllow: ACK, INVITE, CANCEL, BYE, NOTIFY, SUBSCRIBE, MESSAGEContact: Event: presenceExpires: 3600Content-Length: 0 之后，Possion 向 Chebychev 发送 NOTIFY消息，表示其当前状态 NOTIFY sip:pafnutylecturehall21.academy.ru SIP/2.0Via SIP/2.0/TCP :5060;branch=z9hG4bK4321Max-Forwards: 70To: P. L. Chebychev ;tag=21171From: M. Poisson ;tag=25140Call-ID: 58dkfj34924lk34452k592520CSeq: 1026 NOTIFYAllow: ACK, INVITE, CANCEL, BYE, NOTIFY, SUBSCRIBE, MESSAGEAllow-Events: dialogContact: Subscription-State: active;expires=3600Event: presenceContent-Type: application/cpim-pidf+xmlContent-Length: 244 closed Chebychev 发送 200 OK 响应 NOTIFY SIP/2.0 200 OKVia SIP/2.0/TCP :5060;branch=z9hG4bK4321;received=To: P. L. Chebychev ;tag=21171From: M. Poisson ;tag=25140Call-ID: 58dkfj34924lk34452k592520CSeq: 1026 NOTIFYContent-Length: 0 之后，当 Poisson 登陆后，再次发送 NOTIFY 消息 NOTIFY sip:pafnutylecturehall21.academy.ru SIP/2.0Via SIP/2.0/TCP :5060;branch=z9hG4bK334241Max-Forwards: 70To: P. L. Chebychev ;tag=21171From: M. Poisson ;tag=25140Call-ID: 58dkfj34924lk34452k592520CSeq: 1027 NOTIFYAllow: ACK, INVITE, CANCEL, BYE, NOTIFY, SUBSCRIBE, MESSAGEAllow-Events: presenceContact: Subscription-State: active;expires=1800Event: presenceContent-Type: application/cpim-pidf+xmlContent-Length: 325 open sip:;transport=tcp Chebychev 发 200 OK 确认 SIP/2.0 200 OKVia SIP/2.0/TCP :5060;branch=z9hG4bK334241;received=To: P. L. Chebychev ;tag=21171From: M. Poisson ;tag=25140Call-ID: 58dkfj34924lk34452k592520CSeq: 1027 NOTIFYContent-Length: 0 现在 Chebychev 已经知道 Possion 在线了，开始发送及时消息。 MESSAGE sip: SIP/2.0Via SIP/2.0/TCP lecturehall21.academy.ru:5060;branch=z9hG4bK3gtr2Max-Forwards: 70To: M. Poisson From: P. L. Chebychev ;tag=4542Call-ID: 9dkei93vjq1ei3CSeq: 15 MESSAGEAllow: ACK, INVITE, CANCEL, BYE, NOTIFY, SUBSCRIBE, MESSAGEContent-Type: text/plainContent-Length: 9Hi There! 注意到这里，MESSAGE 是独立与会话的，它不属于任何会话。每个消息都含有一个新的 Call-ID 和 From tag。200 OK 用来确认收到该信息。 SIP/2.0 200 OKVia SIP/2.0/TCP lecturehall21.academy.ru:5060;branch=z9hG4bK3gtr2;received=To: M. Poisson ;tag=2321From: P. L. Chebychev ;tag=4542Call-ID: 9dkei93vjq1ei3CSeq: 15 MESSAGEContent-Length: 0 Possion 开始回复消息 MESSAGE sip:chebychevacademy.ru SIP/2.0Via SIP/2.0/TCP :5060;branch=z9hG4bK4526245Max-Forwards: 70To: P. L. Chebychev From: M. Poisson ;tag=14083Call-ID: lk34452k592520CSeq: 2321 MESSAGEAllow: ACK, INVITE, CANCEL, BYE, NOTIFY, SUBSCRIBE, MESSAGEContent-Type: text/plainContent-Length: 30Well, hello there to you, too! 收到消息后，发 200 OK SIP/2.0 200 OKVia SIP/2.0/T