1 Device Discovery
两种mode： Discoverable(一旦连接发送hello消息，并且总是监听Probe and Resolve消息), Non-Discoverable（侦听和回复消息）。
知名端口，ws-discovery(3702)。
该消息为组播消息，Device接收到client的Probe消息后，回复ProbeMatch消息，ProbeMatch中包含了xAddress,Num, Scopes。就可以根据回复的消息发现设备。
2 Scope理解
Refer to《ONVIF-Core-Specification-v220.pdf》中第七章Device discovery。
Refer to 7.3.2.2.1 Example。Scopes用于匹配。
3 Profile理解
Refer to ONVIF_WG-APG-Application_Programmer's_Guide.pdf中7 Streaming list to understand the profile meanings and usage.
4 Events理解
The ONVIF specification includes three different types of event notifications:
?1) Real-time Pull-Point Notification Interface
?2)Basic Notification Interface (WS-BaseNotification)
?3)Notification Streaming Interface (metadata streaming)
Event使用两种方式上报事件，push/pull。Pull采用client定时发送获取告警的消息，device如果有告警，则上报，将notification中填入告警的信息，client根据notification中的信息显示告警。Push应该是采用device一旦有告警发生，则主动上报给client，client实时监听device的上报信息。所以，push实时性应该更好，pull模式的实时性差一点。