Apollo Advanced Lesson | Google Protocol Buffers

Posted 2022-12-08 Justin-Yip

Contents

• • • What Are Protocol Buffers
    • Why Use Protocol Buffers?
    • How Write Your C++ ProtoBuf?

–This article is excerpted from Google’s official about Protocol Buffers, please indicate the source for reprinting–

What Are Protocol Buffers

• You can use protocol buffer to read/write you structure data across processes(such as IPC, event across different PC machines) ,which is language-neutral, platform-neutral, extensible mechanism for serializing structured data.

Why Use Protocol Buffers?

• Faster
• smaller run-time cost.
• neutral: language,platform neutral.

How Write Your C++ ProtoBuf?

Syntax note:

• Enum
  • First element must set to zero ,for compatibility with the proto2 semantic.
  • allow_alias option , allow your use alias that different enumerations maps to the same value.

   message MyMsg
   	emum EnumAllowingAlias
   		option allow_alias = true;
   		UNKNOW = 0;
   		STARTED = 1;
   		RUNNING = 1;
   		
   

• repeated
  This Type familiar to std::vector.

• import
  You can use the definitions in other .proto files by using key word import.

import "myproject/other_protos.proto";

• Using proto2 Message Types
  You can use proto2 definitions only importing from a proto2 file,other than use them directly in the proto3 syntax.

• Nest Types
  you can refer the inner message type by using _Parent_._Type_

message SomeOtherMessage 
  SearchResponse.Result result = 1;

• Any : to be done

referring to:
Protocol-buffers official