SOME/IP报文格式-Message Type
Message Type [8 Bit]
- The Message Type field is used to differentiate different types of messages and shall contain the following values：
Message Type用来区别不同类型的message，且应当包含如下的值：
| Number | Value | Description |
|---|---|---|
| 0x00 | REQUEST | A request expecting a response (even void) |
| 0x01 | REQUEST_NO_RETURN | A fire&forget request |
| 0x02 | NOTIFICATION | A request of a notification/event callback expecting no response |
| 0x40 | REQUEST_ACK | Acknowledgment for REQUEST (optional) |
| 0x41 | REQUEST_NO_RETURN_ACK | Acknowledgment for REQUEST_NO_RETURN (informational) |
| 0x42 | NOTIFICATION_ACK | Acknowledgment for NOTIFICATION (informational) |
| 0x80 | RESPONSE | The response message |
| 0x81 | ERROR | The response containing an error |
| 0xC0 | RESPONSE_ACK | The Acknowledgment for RESPONSE (informational) |
| 0xC1 | ERROR_AC | Acknowledgment for ERROR (informational) |
-
Regular request (message type 0x00) will be answered by a response (message type 0x80), when no error occurred. If errors occur an error message (message type 0x81) will be sent. It is also possible to send a request that does not have a response message(message type 0x01). For updating values through notification a callback interface exists (message type 0x02).
常规request(消息类型0x00)将在未发生错误时由response(消息类型0x80)应答。如果发生错误，则会发送error消息(消息类型0x81)。 也可以发送不需要响应消息的请求(消息类型0x01)。为了通过notification更新值，存在一个callback接口(消息类型0x02)。 -
For all messages an optional acknowledgment (ACK) exists. These care is defined for transport protocols (i.e. UDP) that do not acknowledge a received message. ACKs are only transported when the interface specification requires it. Only the usage of the REQUEST_ACK is currently specified in this document. All other ACKs are currently informational and do not need to be implemented.
对于所有消息，存在可选的acknowledgment 报文(ACK) 。 这是为那些并不告知收到消息的某些传输层协议(如UDP)而定义的。 ACK只在interface specification要求时才被传输。 本文档中仅规定了REQUEST_ACK的用法。 所有其他ACK现在都是信息性的，不需要实施。