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}
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