实践流程
查阅官方提供的示例，按官方的示例手动练习一次：
首先我们写一个pubsub的服务，用于我们的服务的订阅：
1）.编写一个pubsub.proto
syntax = "proto3";
// Example message
message Event {
// unique id
string id = 1;
// unix timestamp
int64 timestamp = 2;
// message
string message = 3;
}
2）然后生成对应的文件信息：
protoc --proto_path=. --micro_out=. --go_out=. srv/proto/pubsub.proto
3）然后编写我们的微服务的启动的入口main.go（实现消息的消费）:
package main
import (
proto "gotodolist2/pubsub/srv/proto"
"github.com/micro/go-micro/v2"
"github.com/micro/go-micro/v2/metadata"
"github.com/micro/go-micro/v2/server"
"github.com/micro/go-micro/v2/util/log"
"context"
)
// All methods of Sub will be executed when
// a message is received
type Sub struct{}
// Method can be of any name
func (s *Sub) Process(ctx context.Context, event *proto.Event) error {
md, _ := metadata.FromContext(ctx)
log.Logf("[pubsub.1] Received event %+v with metadata %+v\n", event, md)
// do something with event
return nil
}
// Alternatively a function can be used
func subEv(ctx context.Context, event *proto.Event) error {
md, _ := metadata.FromContext(ctx)
log.Logf("[pubsub.2] Received event %+v with metadata %+v\n", event, md)
// do something with event
return nil
}
func main() {
// create a service
service := micro.NewService(
micro.Name("go.micro.srv.pubsub"),
)
// parse command line
service.Init()
// register subscriber
micro.RegisterSubscriber("example.topic.pubsub.1", service.Server(), new(Sub))
// register subscriber with queue, each message is delivered to a unique subscriber
micro.RegisterSubscriber("example.topic.pubsub.2", service.Server(), subEv, server.SubscriberQueue("queue.pubsub"))
if err := service.Run(); err != nil {
log.Fatal(err)
}
}
主要的中音的是实现主题的订阅：
micro.RegisterSubscriber("example.topic.pubsub.1", service.Server(), new(Sub))
// register subscriber with queue, each message is delivered to a unique subscriber
micro.RegisterSubscriber("example.topic.pubsub.2", service.Server(), subEv, server.SubscriberQueue("queue.pubsub"))
注意事项点：1. 引入的proto文件不能导入其他包的
4）编写一个测试cli,用于事件的发布（消息生产者）main.go:
package main
import (
"fmt"
//"gotodolist2/task-srv2/handler"
"time"
"context"
proto "gotodolist2/pubsub/srv/proto"
"github.com/micro/go-micro/v2"
"github.com/micro/go-micro/v2/util/log"
"github.com/pborman/uuid"
)
// send events using the publisher
func sendEv(topic string, p micro.Publisher) {
t := time.NewTicker(time.Second)
for _ = range t.C {
// create new event
ev := &proto.Event{
Id: uuid.NewUUID().String(),
Timestamp: time.Now().Unix(),
Message: fmt.Sprintf("Messaging you all day on %s", topic),
}
log.Logf("publishing %+v\n", ev)
// publish an event
if err := p.Publish(context.Background(), ev); err != nil {
log.Logf("error publishing: %v", err)
}
}
}
func main() {
// create a service
service := micro.NewService(
micro.Name("go.micro.cli.pubsub"),
)
// parse command line
service.Init()
// create publisher
pub1 := micro.NewPublisher("example.topic.pubsub.1", service.Client())
//pub2 := micro.NewPublisher("example.topic.pubsub.2", service.Client())
pub2 := micro.NewEvent("example.topic.pubsub.2", service.Client())
// pub to topic 1
go sendEv("example.topic.pubsub.1", pub1)
// pub to topic 2
go sendEv("example.topic.pubsub.2", pub2)
// block forever
select {}
}
注意点：
image.png
对应的事件对象创建不一样了！
5）启动这两个main.go:
- cli-main.go生产者端的日志：
[id:"31b100e7-6214-11eb-8b08-40b07681cf65" timestamp:1611912443 message:"Messaging you all day on example.topic.pubsub.2" ]
2021-01-29 17:27:24 file=cli/main.go:27 level=info publishing %+v
[id:"3249a31d-6214-11eb-8b08-40b07681cf65" timestamp:1611912444 message:"Messaging you all day on example.topic.pubsub.2" ]
2021-01-29 17:27:24 file=cli/main.go:27 level=info publishing %+v
[id:"3249a31d-6214-11eb-8b09-40b07681cf65" timestamp:1611912444 message:"Messaging you all day on example.topic.pubsub.1" ]
2021-01-29 17:27:25 file=cli/main.go:27 level=info publishing %+v
[id:"32e1f826-6214-11eb-8b09-40b07681cf65" timestamp:1611912445 message:"Messaging you all day on example.topic.pubsub.2" ]
2021-01-29 17:27:25 file=cli/main.go:27 level=info publishing %+v
[id:"32e21f1b-6214-11eb-8b09-40b07681cf65" timestamp:1611912445 message:"Messaging you all day on example.topic.pubsub.1" ]
2021-01-29 17:27:26 file=cli/main.go:27 level=info publishing %+v
[id:"337ac234-6214-11eb-8b0a-40b07681cf65" timestamp:1611912446 message:"Messaging you all day on example.topic.pubsub.1" ]
2021-01-29 17:27:26 file=cli/main.go:27 level=info publishing %+v
[id:"337ac234-6214-11eb-8b09-40b07681cf65" timestamp:1611912446 message:"Messaging you all day on example.topic.pubsub.2" ]
- pubsub-main.go消息消费端的日志：
2021-01-29 17:27:33 file=srv/main.go:21 level=info [pubsub.1] Received event %+v with metadata %+v
[id:"37a6ea9a-6214-11eb-8b0e-40b07681cf65" timestamp:1611912453 message:"Messaging you all day on example.topic.pubsub.1" map[Micro-From-Service:go.micro.cli.pubsub Micro-Topic:example.topic.
pubsub.1]]
2021-01-29 17:27:33 file=srv/main.go:29 level=info [pubsub.2] Received event %+v with metadata %+v
[id:"37a6ea9a-6214-11eb-8b0d-40b07681cf65" timestamp:1611912453 message:"Messaging you all day on example.topic.pubsub.2" map[Micro-From-Service:go.micro.cli.pubsub Micro-Topic:example.topic.
pubsub.2]]
2021-01-29 17:27:34 file=srv/main.go:29 level=info [pubsub.2] Received event %+v with metadata %+v
[id:"383f3fd0-6214-11eb-8b0e-40b07681cf65" timestamp:1611912454 message:"Messaging you all day on example.topic.pubsub.2" map[Micro-From-Service:go.micro.cli.pubsub Micro-Topic:example.topic.
pubsub.2]]
2021-01-29 17:27:34 file=srv/main.go:21 level=info [pubsub.1] Received event %+v with metadata %+v
[id:"383f66bf-6214-11eb-8b0e-40b07681cf65" timestamp:1611912454 message:"Messaging you all day on example.topic.pubsub.1" map[Micro-From-Service:go.micro.cli.pubsub Micro-Topic:example.topic.
pubsub.1]]
2021-01-29 17:27:35 file=srv/main.go:29 level=info [pubsub.2] Received event %+v with metadata %+v
[id:"38d7e427-6214-11eb-8b0e-40b07681cf65" timestamp:1611912455 message:"Messaging you all day on example.topic.pubsub.2" map[Micro-From-Service:go.micro.cli.pubsub Micro-Topic:example.topic.
pubsub.2]]
2021-01-29 17:27:35 file=srv/main.go:21 level=info [pubsub.1] Received event %+v with metadata %+v
[id:"38d809df-6214-11eb-8b0e-40b07681cf65" timestamp:1611912455 message:"Messaging you all day on example.topic.pubsub.1" map[Micro-From-Service:go.micro.cli.pubsub Micro-Topic:example.topic.
pubsub.1]]