RABBITMQ Communication between Micro services

RABBITMQ Communication between Micro services

MicroServices are independent of each other, unlike individual engineering modules can be directly through the method call to achieve communication, mutual independent service direct general communication is to use HTTP协议 , rpc协议 or use message middleware such as RabbitMQ``Kafka

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In this article using Golang and MongoDB to build MicroServices has implemented a microservices application, in the article has implemented the direct communication of the various services, is the form of use HTTP , how the various services through the RabbitMQ message communication, we now have to implement a function, is a user to book movie ticket interface, need to service User Service (port 8000) and services Booking service (port 8003) communication between the user after booking, the booking information to write to in the booking database

InstallationRabbitMQ

Before installation, RabbitMQ you need to install the Erlang environment, and then download the installation RABBITMQ, please select the corresponding version, after the installation is completed, RABBITMQ on Windows as a service in the background to run, about RabbitMQ the interface how to use, please refer to the official website of the tutorial, There are various mainstream language implementations we are using a Go version, please download the corresponding implementation interfacego get github.com/streadway/amqp

The RabbitMQ interface to do a simple package

• Define an interface

messaging/message.go

type IMessageClient interface {    ConnectToBroker(connectionStr string) error    PublishToQueue(data []byte, queueName string) error    SubscribeToQueue(queueName string, handlerFunc func(amqp.Delivery)) error    Close()}type MessageClient struct {    conn *amqp.Connection}

• Connection interface

func (m *MessageClient) ConnectToBroker(connectionStr string) error {    if connectionStr == "" {        panic("the connection str mustnt be null")    }    var err error    m.conn, err = amqp.Dial(connectionStr)    return err}

• Publish Message interface

func (m *MessageClient) PublishToQueue(body []byte, queueName string) error {    if m.conn == nil {        panic("before publish you must connect the RabbitMQ first")    }    ch, err := m.conn.Channel()    defer ch.Close()    failOnError(err, "Failed to open a channel")    q, err := ch.QueueDeclare(        queueName,        false,        false,        false,        false,        nil,    )    failOnError(err, "Failed to declare a queue")    err = ch.Publish(        "",        q.Name,        false,        false,        amqp.Publishing{            ContentType: "application/json",            Body:        body,        },    )    failOnError(err, "Failed to publish a message")    return nil}

• Subscribe to the Messaging interface

func (m *MessageClient) SubscribeToQueue(queueName string, handlerFunc func(amqp.Delivery)) error {    ch, err := m.conn.Channel()    //defer ch.Close()    failOnError(err, "Failed to open a channel")    q, err := ch.QueueDeclare(        queueName,        false,        false,        false,        false,        nil,    )    failOnError(err, "Failed to declare a queue")    msgs, err := ch.Consume(        q.Name,        "",        true,        false,        false,        false,        nil,    )    failOnError(err, "Failed to register a consumer")    go consumeLoop(msgs, handlerFunc)    return nil}

Achieve communication

A new interface is defined in the user Service , which POST implements the /user/{name}/booking subscriber's booking function, and after the reservation, RabbitMQ a message is issued to
Booking Service, after theBooking service receives the message, does the corresponding processing (writes the database)

User Service

• InitializationMessageClient

users/controllers/user.go

var client messaging.IMessageClientfunc init() {    client = &messaging.MessageClient{}    err := client.ConnectToBroker("amqp://guest:guest@localhost:5672/")    if err != nil {        fmt.Println("connect to rabbitmq error", err)    }}

• Add a new route and implementation

routes.go

register("POST", "/user/{name}/booking", controllers.NewBooking, nil)

users/controllers/user.go

func NewBooking(w http.ResponseWriter, r *http.Request) {    params := mux.Vars(r)    user_name := params["name"]    defer r.Body.Close()    var bookings models.Booking    body, _ := ioutil.ReadAll(r.Body)    err := json.Unmarshal(body, &bookings)    if err != nil {        fmt.Println("the format body error ", err)    }    fmt.Println("user name:", user_name, bookings)    go notifyMsg(body)}

• Implement the publication of a message with a single process

func notifyMsg(body []byte) {    err := client.PublishToQueue(body, "new_booking")    if err != nil {        fmt.Println("Failed to publis message", err)    }}

Booking Service

• Initialize Messageclient

var client messaging.IMessageClientfunc initMessage() {    client = &messaging.MessageClient{}    err := client.ConnectToBroker("amqp://guest:guest@localhost:5672/")    if err != nil {        fmt.Println("Failed to connect to RabbitMQ", err)    }    err = client.SubscribeToQueue("new_booking", getBooking)    if err != nil {        fmt.Println("Failed to comsuer the msg", err)    }}

Start before the Web service

func main() {    initMessage()    r := routes.NewRouter()    http.ListenAndServe(":8003", r)}

• Post-Receive Message processing

func getBooking(delivery amqp.Delivery) {  var booking models.Booking    json.Unmarshal(delivery.Body, &booking)  booking.Id = bson.NewObjectId().Hex()    dao.Insert("Booking", "BookModel", booking)    fmt.Println("the booking msg", booking)}

Verify that the User service and Booking service need to be started
Use Postman to send corresponding data

post 127.0.0.1:8000/user/kevin_woo/booking{    "name":"kevin_woo",    "books":[        {            "date":"20180727",            "movies":["5b4c45d49d5e3e33c4a5b97a"]        },        {            "date":"20180810",            "movies":["5b4c45ea9d5e3e33c4a5b97b"]        }    ]}

You can see that the database already has a new booking information

Note that my post data is the structure of the booking database, the actual need to encapsulate the data, in the post data, the data is not validated,
In the actual development process need to do the corresponding validation of the data, here is mainly to see the process of RABBITMQ message delivery processing

SOURCE Github