SOME/IP
基础
Scalable service-Oriented MiddlewarE over IP (SOME/IP)
SOME/IP Protocol Specification
SOME/IP 用于车载ECU之间的Remote Procedure Call (RPC) 通信，inter-ECU Client/Server Serialization
remote procedure calls, event notifications, underlying serialization/wire format
AUTOSAR支持解析SOME/IP的RPC PDU(protocol data units)，将信号传到目标app
Protocol Specification
service 提供 events, methods, fields
Events 提供 周期性发送的data，或者当data有变化时从provider传给subscriber
Methods 提供 subscriber 调用 remote procedure calls, 而在provider侧执行
Fields 有下述3种：
- 当data有变化时，由provider -> subscriber送notifier
- subscriber向provider查询value，getter
- subscriber更新provider的value，setter
notifier of events 只在change时发送
notifier of fields 在subscription后就send the data
Format
Message ID (Service ID/Method ID) 32bit 整个系统唯一；Service ID 16bit, 0 (1bit), Method ID 15bit；Service ID 16bit, 1 (1bit), Event ID 15bit
Length 32bit
Request ID (Client ID/Session ID) 32bit 对provider而言，无需了解request ID的内部结构；Client ID 16bit, Session ID 16bit；每次调用后，Session ID应该increment
Protocol Version 8bit, Interface Version 8bit
Message Type 8bit 第3高位的bit如果置1，则是TP-Flag，标识当前SOME/IP消息是一个segment
Return Code 8bit
Payload (variable size)
transport protocol
data > 1400bytes, no hard latency requirement => TCP
very hard latency requirement < 100ms => UDP
data > 1400bytes, hard latency requirement => UDP + SOME/IP-TP
