第四步：尝试发布-订阅/广播消息交换模式

您现在已经完成了第三步：设置势度Saydo Try-Me CLI工具，并了解了Solly's Coffee的相关信息。

在第四步中，您将使用势度Saydo Try-Me CLI工具更深入地了解Solly's Coffee订单管理系统（OMS），并设置一个发布-订阅消息交换，将事件消息广播给多个订阅者。

在发布-订阅消息传递中，生产者（发布者）发送的消息可以被不同的消费者（订阅者）多次处理。每个消费者都接收消息的副本以进行处理，如下图所示：

在我们第三步中介绍的Solly's Coffee OMS中，涉及OM-Order Details事件的新订单传播事件流使用发布-订阅消息交换。订单详情事件由订单管理应用发布，并由厨房楼层和咖啡师站应用接收。

设置发布-订阅消息交换

在这个练习中，我们将设置四个应用，三个订阅者和一个发布者，并发布一个事件。订阅应用是咖啡师站、厨房楼层和人力资源。发布者是订单管理。完成这些步骤后，您将拥有如下动画所示的消息交换模式：

要设置您的应用并发布事件，请执行以下步骤：

打开四个命令行终端窗口，每个应用一个。
在终端1中，订阅咖啡师站应用接收来自国家ca的所有事件，无论来源类型。输入以下命令：

stm receive --topic "coffeeshop/order/details/v1/*/ca/>" --client-name "Barista Station" --output-mode full

您应该看到以下结果：

ℹ  info      info: loading 'receive' command from configuration 'stm-cli-config.json'
…  awaiting  connecting to broker [ws://localhost:8008, vpn: default, username: default, password: ******]
ℹ  info      info: client name: Barista Station
✔  success   success: === Barista Station successfully connected and ready to receive events. ===
ℹ  info      info: subscribing to coffeeshop/order/details/v1/*/ca/>
ℹ  info      info: press Ctrl-C to exit
✔  success   success: successfully subscribed to topic: coffeeshop/order/details/v1/*/ca/>

在终端2中，订阅厨房楼层应用接收来自国家ca的所有事件，无论来源类型。输入以下命令：

stm receive --topic "coffeeshop/order/details/v1/*/ca/>" --client-name "Kitchen Floor"

您应该看到以下结果：

ℹ  info: loading 'receive' command from configuration 'stm-cli-config.json'
…  connecting to broker [ws://localhost:8008, vpn: default, username: default, password: ******]
ℹ  info: client name: Kitchen Floor
✔  success: === Kitchen Floor successfully connected and ready to receive events. ===
ℹ  info: subscribing to coffeeshop/order/details/v1/*/ca/>
ℹ  info: press Ctrl-C to exit
✔  success: successfully subscribed to topic: coffeeshop/order/details/v1/*/ca/>

在终端3中，订阅人力资源应用接收来自国家ca的所有员工到达事件。输入以下命令：

stm receive --topic "coffeeshop/staff/arrive/v2/*/ca/>" --client-name "Human Resources"

您应该看到以下结果：

ℹ  info      info: loading 'receive' command from configuration 'stm-cli-config.json'
…  awaiting  connecting to broker [ws://localhost:8008, vpn: default, username: default, password: ******]
ℹ  info      info: client name: Human Resources
✔  success   success: === Human Resources successfully connected and ready to receive events. ===
ℹ  info      info: subscribing to coffeeshop/staff/arrive/v2/*/ca/>
ℹ  info      info: press Ctrl-C to exit
✔  success   success: successfully subscribed to topic: coffeeshop/staff/arrive/v2/*/ca/>

在配置发布者之前，创建一个JSON格式的消息有效载荷。将以下文本复制并粘贴到文本编辑器中，并保存文件为order.json。

{
  "source": "mobile",
  "device": "app-android",
  "country" : "Canada",
  "region" : "Ontario",
  "storeID" : 437,
  "requestId": 44334,
  "customer": {
    "name": "John Doe",
    "email": "john.doe@example.com",
    "phone": "123-456-7890"
  },
  "items": [
    {
      "productID": "COF001",
      "productName": "Americano",
      "quantity": 2,
      "size": "Medium",
      "options": ["Extra Shot", "Whipped Cream"]
    },
    {
      "productID": "PST001",
      "productName": "Chocolate Croissant",
      "quantity": 1
    }
  ],
  "totalPrice": 12.50,
  "pickupTime": "2024-01-05T14:30:00",
  "specialInstructions": "Please make it extra hot."
}

在终端4中，使用您刚刚创建的消息有效载荷从订单管理应用发布事件，主题为coffeeshop/order/details/v1/{mobile}/{ca}/{437}/{44334}。输入以下命令：

stm send --topic coffeeshop/order/details/v1/mobile/ca/437/44334 --file order.json --client-name "Order Management"

您应该看到以下结果：

ℹ  info      info: loading 'send' command from configuration 'stm-cli-config.json'
…  waiting   connecting to broker [ws://localhost:8008, vpn: default, username: default, password: ******]
ℹ  info      info: client name: Order Management
✔  success   success: === Order Management successfully connected and ready to publish events. ===
…  waiting   publishing...
✔  success   success: message published to topic - [Topic coffeeshop/order/details/v1/mobile/ca/437/44334], type - TEXT
ℹ  info      info: Message Properties
Destination:                            [Topic coffeeshop/order/details/v1/mobile/ca/437/44334]
ℹ  info      info: Message Payload (bytes): 659
✔  success   success: disconnecting from Solace PubSub+ Event Broker...
✔  success   success: disconnected
✔  success   success: exiting...

现在，让我们检查订阅者是否接收到了订单管理应用发布的事件。

要检查您的订阅者，请执行以下步骤：

在终端1中检查咖啡师站应用。以下消息应该出现：

✔  success: message Received - [Topic coffeeshop/order/details/v1/mobile/ca/437/44334], type - TEXT
ℹ  info: Message Properties
Destination:                            [Topic coffeeshop/order/details/v1/mobile/ca/437/44334]
Class Of Service:                       COS1
DeliveryMode:                           DIRECT
Message Id:                             1
DMQ Eligible
Binary Attachment:                      len=664
ℹ  info: Message Payload:
{
  source: "mobile",
  device: "app-android",
  country: "Canada",
  region: "Ontario",
  storeID: 437,
  requestId: 44334,
  customer: {
    name: "John Doe",
    email: "john.doe@example.com",
    phone: "123-456-7890"
  },
  items: [
    {
      productID: "COF001",
      productName: "Americano",
      quantity: 2,
      size: "Medium",
      options: [
        "Extra Shot",
        "Whipped Cream"
      ]
    },
    {
      productID: "PST001",
      productName: "Chocolate Croissant",
      quantity: 1
    }
  ],
  totalPrice: 12.5,
  pickupTime: "2024-01-05T14:30:00",
  specialInstructions: "Please make it extra hot."
}

在终端2中检查厨房楼层应用。以下消息应该出现：

✔  success   success: message Received - [Topic coffeeshop/order/details/v1/mobile/ca/437/44334], type - TEXT
ℹ  info      info: Message Properties
Destination:                            [Topic coffeeshop/order/details/v1/mobile/ca/437/44334]
ℹ  info      info: Message Payload (bytes): 659

在终端3中检查人力资源应用。没有消息应该出现，因为订阅不匹配发布的主题。
按Control+C（在Windows和Linux上）或Command+C（在Mac上），停止应用。

现在，您已经见识了Solace事件代理的发布-订阅的强大功能。发布的事件可以根据它们定义的主题订阅被多个消费者接收。

教程步骤

您已经完成了教程的第四步。点击链接进入下一课。

步骤	描述
	设置您的第一个事件代理 - 完成
	势度Saydo EDA基础 - 完成
	设置势度Saydo Try-Me CLI工具 - 完成
	尝试发布-订阅消息交换模式 - 完成
	尝试请求-响应消息交换模式 - 下一课
	探索消费者扩展模式
	下一步

您可以随时返回到主教程页面。

设置发布-订阅消息交换​

教程步骤​

设置发布-订阅消息交换

教程步骤