Dapr牵手.NET学习笔记：发布订阅

　　queue，是很好的削峰填谷工具，在业内也是主流；发布订阅，可以有效的解耦两个应用，所以dapr把他们进行了有效的封装，我们使用起来更简单高效。

　　本篇的案例是下完订单后，会把消息发布到redis（当然也可以是其他）中，通知系统和支付系统会订单这个消息，同时，通知系统和支付系统的两个实例中，只会有一个实例接收到这个消息，进行处理，调用示意图如下：

 项目结构如下：

 

一、配置

用docker-compose部署，docker-compose.yml内容

version: '3.4'

services:
  #┌────────────────────────────────┐
  #│ ordersystem app + Dapr sidecar │
  #└────────────────────────────────┘
  ordersystem:
    image: ${DOCKER_REGISTRY-}ordersystem
    depends_on:
      - redis
      - placement
    build:
      context: ../
      dockerfile: OrderSystem/Dockerfile
    ports:
      - "3500:3500"
    volumes:   
      - ../OrderSystem:/OrderSystem  
    networks:
      - b2c-dapr
  ordersystem-dapr:
     image: "daprio/daprd:latest"
     command: [ "./daprd", "-app-id", "order", "-app-port", "80","-placement-host-address", "placement:50006","-components-path","/components"]
     depends_on:
       - ordersystem
     network_mode: "service:ordersystem"
     volumes:   
      - ../components:/components  
  
  #┌───────────────────────────────────┐
  #│ paymentsystem1 app + Dapr sidecar │
  #└───────────────────────────────────┘  
  paymentsystem1:
    image: ${DOCKER_REGISTRY-}paymentsystem
    build:
      context: ../
      dockerfile: PaymentSystem/Dockerfile
    ports:
      - "3601:3500"
    volumes:   
      - ../PaymentSystem:/PaymentSystem      
    networks:
      - b2c-dapr      
  paymentsystem1-dapr:
     image: "daprio/daprd:latest"
     command: [ "./daprd", "-app-id", "pay", "-app-port", "80","-placement-host-address", "placement:50006","-components-path","/components" ]
     depends_on:
       - paymentsystem1
     network_mode: "service:paymentsystem1"
     volumes:   
      - ../components:/components 
 
  #┌───────────────────────────────────┐
  #│ paymentsystem2 app + Dapr sidecar │
  #└───────────────────────────────────┘   
  paymentsystem2:
    image: ${DOCKER_REGISTRY-}paymentsystem
    build:
      context: ../
      dockerfile: PaymentSystem/Dockerfile
    volumes:   
      - ../PaymentSystem:/PaymentSystem            
    ports:
      - "3602:3500"
    networks:
      - b2c-dapr      
  paymentsystem2-dapr:
     image: "daprio/daprd:latest"
     command: [ "./daprd", "-app-id", "pay", "-app-port", "80" ,"-placement-host-address", "placement:50006","-components-path","/components"]
     depends_on:
       - paymentsystem2
     network_mode: "service:paymentsystem2"
     volumes:   
      - ../components:/components       

  #┌───────────────────────────────────┐
  #│ noticesystem1 app + Dapr sidecar │
  #└───────────────────────────────────┘  
  noticesystem1:
    image: ${DOCKER_REGISTRY-}noticesystem
    build:
      context: ../
      dockerfile: NoticeSystem/Dockerfile
    ports:
      - "3701:3500"
    volumes:   
      - ../NoticeSystem:/NoticeSystem      
    networks:
      - b2c-dapr      
  noticesystem1-dapr:
     image: "daprio/daprd:latest"
     command: [ "./daprd", "-app-id", "notice", "-app-port", "80","-placement-host-address", "placement:50006","-components-path","/components" ]
     depends_on:
       - noticesystem1
     network_mode: "service:noticesystem1"
     volumes:   
      - ../components:/components 

  #┌───────────────────────────────────┐
  #│ noticesystem2 app + Dapr sidecar │
  #└───────────────────────────────────┘  
  noticesystem2:
    image: ${DOCKER_REGISTRY-}noticesystem
    build:
      context: ../
      dockerfile: NoticeSystem/Dockerfile
    ports:
      - "3702:3500"
    volumes:   
      - ../NoticeSystem:/NoticeSystem      
    networks:
      - b2c-dapr      
  noticesystem2-dapr:
     image: "daprio/daprd:latest"
     command: [ "./daprd", "-app-id", "notice", "-app-port", "80","-placement-host-address", "placement:50006","-components-path","/components" ]
     depends_on:
       - noticesystem2
     network_mode: "service:noticesystem2"
     volumes:   
      - ../components:/components 

  #┌────────────────────────┐
  #│ Dapr placement service │
  #└────────────────────────┘  
  placement:
    image: "daprio/dapr"
    command: ["./placement", "-port", "50006"]
    ports:
      - "50006:50006"
    networks:
      - b2c-dapr

  #┌───────────────────┐
  #│ Redis state store │
  #└───────────────────┘  
  redis:
    image: "redis:latest"
    ports:
      - "6380:6379"
    networks:
      - b2c-dapr
networks:
    b2c-dapr:

pubsub.yaml（在components文件夹下 ）内容是默认，如下

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: pubsub
spec:
  type: pubsub.redis
  version: v1
  metadata:
  - name: redisHost
    value: redis:6379
  - name: redisPassword
    value: ""

订阅配置文件如下subscription.yaml（在components文件夹下 ）

apiVersion: dapr.io/v1alpha1
kind: Subscription
metadata:
  name: myevent-subscription
spec:
  topic: orderComplete
  route: /ordercomplete
  pubsubname: pubsub
scopes:
- pay
- notice

二、代码

OrderSystem项目的appsettings.json

"PublishUrl": "http://localhost:3500/v1.0/publish/pubsub/orderComplete"

OrderSystem项目的发布方法

 [HttpGet("/orderpub/{orderno}")]
    public async Task<IActionResult> OrderPub(string orderno)
    {
        try
        {
            _logger.LogInformation($"Order,publish");
            await Task.Delay(400);
            var client = _clientFactory.CreateClient();

            var stringContent = new StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(new { OrderNo = orderno, Amount = 30000, OrderTime = DateTime.UtcNow}), System.Text.Encoding.UTF8, "application/json");
            _logger.LogInformation(stringContent.ToString());
            var content = await client.PostAsync(_publishUrl, stringContent);
            return new JsonResult(new { order_result = "Order success,and publish", pay_result = content });
        }
        catch (Exception exc)
        {
            _logger.LogCritical(exc, exc.Message);
            return new JsonResult(new { order_result = "Order success,and publish,pay exception", message = exc.Message });
        }
    }

PaymentSystem和NoticeSystem项目中的订阅实现

两个实体类

public class PubBody
{
    public string id { get; set; }
    public string source { get; set; }
    public string pubsubname { get; set; }
    public string traceid { get; set; }
    public PubOrder data { get; set; }
    public string specversion { get; set; }
    public string datacontenttype { get; set; }
    public string type { get; set; }
    public string topic { get; set; }
}

public class PubOrder
{
    public string OrderNo { get; set; }
    public decimal Amount { get; set; }
    public DateTime OrderTime { get; set; }
}

NoticeSystem和PaymentSystem两个项目中的订阅方法如下

 [HttpPost("/ordercomplete")]
    public async Task<IActionResult> OrderComplete()
    {
        try
        {
            _logger.LogInformation("PaymentSystem OrderComplete runing……");
            using var reader = new StreamReader(Request.Body, System.Text.Encoding.UTF8);
            var content = await reader.ReadToEndAsync();
            var pubBody = Newtonsoft.Json.JsonConvert.DeserializeObject<PubBody>(content);
            _logger.LogInformation($"---------  HostName:{Dns.GetHostName()},OrderNo:{pubBody?.data.OrderNo},OrderAmount:{pubBody?.data.Amount},OrderTime:{pubBody?.data.OrderTime} -----------");
            await Task.Delay(200);
            _logger.LogInformation($"subscription pay complete");
            _logger.LogInformation($"return  SUCCESS");
            return new JsonResult(new
            {
                Status = "SUCCESS"
            });
        }
        catch (Exception exc)
        {
            _logger.LogCritical(exc, exc.Message);
            _logger.LogInformation($"return  RETRY");
            return new JsonResult(new
            {
                Status = "RETRY"
            });
        }
    }

三、发布测试

进入在B2C目发，用命令行启动docker compose

docker-compose up -d

可以测试了，调用OrderSystem的对外地址，下订单NO0001，和NO0002

localhost:3500/v1.0/invoke/order/method/orderpub/NO0001和

localhost:3500/v1.0/invoke/order/method/orderpub/NO0001

查看容器noticesystem1

 

 查看容器noticesystem2

 

 查看容器paymentsystem1

 

 查看容器paymentsystem2

 

 　　NoticeSystem和PaymentSystem同时订阅OrderSystem项目的发布orderComplete，两个实例会轮询处理订阅结果。Dapr就这样，把复杂的发布订阅，封装成一个api一样的简单调用和接收，项目中没有一点的痕迹。

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