RPC Implement & Call

In a large system, there must be data transfer between multiple subsystems (services). If there is data transfer, you need a communication method. You can choose the simplest http for communication or rpc service for communication. In go-zero, we use zrpc to communicate between services, which is based on grpc.

Scenes#

In the front, we have improved the interface protocol for user login, user query of books, etc., but the user did not do any user verification when querying the book. If the current user is a non-existent user, we do not allow him to view book information. From the above information, we can know that the user service needs to provide a method to obtain user information for use by the search service, so we need to create a user rpc service and provide a getUser method.

rpc service writing#

Compile the proto file

  $ vim service/user/rpc/user.proto

syntax = "proto3";

package user;

option go_package = "./user";

message IdReq{
  int64 id = 1;
}

message UserInfoReply{
  int64 id = 1;
  string name = 2;
  string number = 3;
  string gender = 4;
}

service user {
  rpc getUser(IdReq) returns(UserInfoReply);
}

Generate rpc service code

$ cd service/user/rpc
$ goctl rpc protoc user.proto --go_out=./types --go-grpc_out=./types --zrpc_out=.

tip

If the installed version of protoc-gen-go is larger than 1.4.0, it is recommended to add go_package to the proto file

Add configuration and improve yaml configuration items

$ vim service/user/rpc/internal/config/config.go

type Config struct {
    zrpc.RpcServerConf
    Mysql struct {
        DataSource string
    }
    CacheRedis cache.CacheConf
}

$ vim /service/user/rpc/etc/user.yaml

Name: user.rpc
ListenOn: 127.0.0.1:8080
Etcd:
  Hosts:
    - $etcdHost
  Key: user.rpc
Mysql:
  DataSource: $user:$password@tcp($url)/$db?charset=utf8mb4&parseTime=true&loc=Asia%2FShanghai
CacheRedis:
  - Host: $host
    Pass: $pass
    Type: node  

tip

$user: mysql database user

$password: mysql database password

$url: mysql database connection address

$db: mysql database db name, that is, the database where the user table is located

$host: Redis connection address Format: ip:port, such as: 127.0.0.1:6379

$pass: redis password

$etcdHost: etcd connection address, format: ip:port, such as: 127.0.0.1:2379

For more configuration information, please refer to rpc configuration introduction

Add resource dependency

$ vim service/user/rpc/internal/svc/servicecontext.go  

type ServiceContext struct {
    Config    config.Config
    UserModel model.UserModel
}

func NewServiceContext(c config.Config) *ServiceContext {
    conn := sqlx.NewMysql(c.Mysql.DataSource)
    return &ServiceContext{
        Config: c,
        UserModel: model.NewUserModel(conn, c.CacheRedis),
    }
}

Add rpc logic

$ service/user/rpc/internal/logic/getuserlogic.go

func (l *GetUserLogic) GetUser(in *user.IdReq) (*user.UserInfoReply, error) {
    one, err := l.svcCtx.UserModel.FindOne(in.Id)
    if err != nil {
        return nil, err
    }
    
    return &user.UserInfoReply{
        Id:     one.Id,
        Name:   one.Name,
        Number: one.Number,
        Gender: one.Gender,
    }, nil
}

Use rpc#

Next we call user rpc in the search service

Add UserRpc configuration and yaml configuration items

$ vim service/search/api/internal/config/config.go

type Config struct {
    rest.RestConf
    Auth struct {
        AccessSecret string
        AccessExpire int64
    }
    UserRpc zrpc.RpcClientConf
}

$ vim service/search/api/etc/search-api.yaml

Name: search-api
Host: 0.0.0.0
Port: 8889
Auth:
  AccessSecret: $AccessSecret
  AccessExpire: $AccessExpire
UserRpc:
  Etcd:
    Hosts:
      - $etcdHost
    Key: user.rpc

tip

$AccessSecret: This value must be consistent with the one declared in the user api.

$AccessExpire: Valid period

$etcdHost： etcd connection address

The Key in etcd must be consistent with the Key in the user rpc service configuration

Add dependency

$ vim service/search/api/internal/svc/servicecontext.go

type ServiceContext struct {
    Config  config.Config
    Example rest.Middleware
    UserRpc user.User
}

func NewServiceContext(c config.Config) *ServiceContext {
    return &ServiceContext{
        Config:  c,
        Example: middleware.NewExampleMiddleware().Handle,
        UserRpc: user.NewUser(zrpc.MustNewClient(c.UserRpc)),
    }
}

Supplementary logic

$ vim /service/search/api/internal/logic/searchlogic.go

func (l *SearchLogic) Search(req types.SearchReq) (*types.SearchReply, error) {
    userIdNumber := json.Number(fmt.Sprintf("%v", l.ctx.Value("userId")))
    logx.Infof("userId: %s", userIdNumber)
    userId, err := userIdNumber.Int64()
    if err != nil {
        return nil, err
    }
    
    // use user rpc
    _, err = l.svcCtx.UserRpc.GetUser(l.ctx, &user.IdReq{
        Id: userId,
    })
    if err != nil {
        return nil, err
    }

    return &types.SearchReply{
        Name:  req.Name,
        Count: 100,
    }, nil
}

Start and verify the service#

Start etcd, redis, mysql
Start user rpc

$ cd service/user/rpc
$ go run user.go -f etc/user.yaml

Starting rpc server at 127.0.0.1:8080...

Start search api

$ cd service/search/api
$ go run search.go -f etc/search-api.yaml

Verification Service
$ curl -i -X GET \
'http://127.0.0.1:8889/search/do?name=%E8%A5%BF%E6%B8%B8%E8%AE%B0' \
-H 'authorization: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2MTI4NjcwNzQsImlhdCI6MTYxMjc4MDY3NCwidXNlcklkIjoxfQ.JKa83g9BlEW84IiCXFGwP2aSd0xF3tMnxrOzVebbt80'
HTTP/1.1 200 OK
Content
-Type: application/json
Date: Tue, 09 Feb 2021 06:05:52 GMT
Content-Length: 32

{"name":"xiyouji","count":100}