gPRC入门笔记

This blog is about learning gRPC
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0. Before study

• All the information comes from gRPC website, and I strongly recommend you to read it by yourself.
  • Introduction to gRPC
  • Quick start
  • Basic tutorail

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1. Introduction

1. An overview
   • gRPC is a kind of tool which you can create a server and many client, while the server handle every call of the client and respond them.
   • You can easily create your server in Java with client in Go, Python and so on, which is a huge advantage.
   • gRPC use protocol buffers to transmit the message.

2. What is protocol buffers?

1. Introduction

   • Protocol buffers provide a language-neutral, platform-neutral, extensible mechanism for serializing structured data in a forward-compatible and backward-compatible way.
   • It’s like JSON, except it’s smaller and faster, and it generates native language bindings.

2. Workflow:
   

3. A very simple example

   1. In .proto definition, use Java to write down:

      message Person {
        optional string name = 1;
        optional int32 id = 2;
        optional string email = 3;
      }
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   2. After compiling this, you will get a Builder class:

      Person john = Person.newBuilder()
          .setId(1234)
          .setName("John Doe")
          .setEmail("jdoe@example.com")
          .build();
      output = new FileOutputStream(args[0]);
      john.writeTo(output);
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   3. Then you can deserialize the data and use the methods protocol buffers creates in other languages, like C++:

      Person john;
      fstream input(argv[1], ios::in | ios::binary);
      john.ParseFromIstream(&input);
      int id = john.id();
      std::string name = john.name();
      std::string email = john.email();
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3. Core concept

1. In this section I will show you an simple but complete gPRC service, and explain what they mean:

   service HelloService {
     rpc SayHello (HelloRequest) returns (HelloResponse);
   }
   
   message HelloRequest {
     string greeting = 1;
   }
   
   message HelloResponse {
     string reply = 1;
   }
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   • service: Define what your server want to receive and what to reply according to the message.
   • message: Define every message detail information.

2. gPRC let you define four kinds of service method(you can also see the website for more detailed information):

   1. rpc SayHello(HelloRequest) returns (HelloResponse);
   2. rpc LotsOfReplies(HelloRequest) returns (stream HelloResponse);
   3. rpc LotsOfGreetings(stream HelloRequest) returns (HelloResponse);
   4. rpc BidiHello(stream HelloRequest) returns (stream HelloResponse);

4. A guidance of gPRC in python

• See the website by yourself~

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