《Windows Azure Platform 系列文章目录》
在之前的Azure Service Bus中，我们已经介绍了Service Bus 队列(Queue)的基本概念。
在本章中，笔者将介绍如何使用Visual Studio ，开发一个Service Bus Queue的Demo Project。
场景：
1.在前端有一个页面，客户从输入框输入数据，并且通过按钮进行提交
2.输入框输入的数据，会被后端的WorkerRoleWithSBQueue接受处理，并在后端显示
主要步骤有：
1.使用Azure Management Portal，创建Service Bus
2.修改Web Role逻辑
3.创建Cloud Project，添加Web Role和Service Bus Worker Role
4.配置WebRole和ServiceBusWorkerRole
3.DEMO
一.笔者已经在之前的文章中，介绍如何创建Service Bus了。不熟悉的读者，可以参考Windows Azure Service Bus (2) 队列(Queue)入门
二.创建Cloud Project
1.首先我们以管理员身份，运行VS
2.创建一个新的Cloud Service，命名为LeiServiceBusQueue，如下图：
3.增加Web Role和Worker Role with Service Bus Queue。如下图
二.设置WorkerRoleWithSBQueue1
1.在WorkerRoleWithSBQueue1项目中，修改WorkerRole.cs代码，如下：
using System;using System.Collections.Generic;using System.Diagnostics;using System.Linq;using ;using System.Threading;using Microsoft.ServiceBus;using Microsoft.ServiceBus.Messaging;using Microsoft.WindowsAzure;using Microsoft.WindowsAzure.ServiceRuntime;namespace WorkerRoleWithSBQueue1{public class WorkerRole : RoleEntryPoint{// The name of your queueconst string QueueName = "ProcessingQueue";// QueueClient is thread-safe. Recommended that you cache // rather than recreating it on every request QueueClient Client;ManualResetEvent CompletedEvent = new ManualResetEvent(false);public override void Run(){Trace.WriteLine("Starting processing of messages");// Initiates the message pump and callback is invoked for each message that is received, calling close on the client will stop the pump.Client.OnMessage((receivedMessage) =>{try{// Process the messageTrace.WriteLine("Processing Service Bus message: " + receivedMessage.SequenceNumber.ToString());string received = receivedMessage.GetBody<string>();Trace.WriteLine("You input is" + received);}catch{// Handle any message processing specific exceptions here}});CompletedEvent.WaitOne();}
public override bool OnStart(){// Set the maximum number of concurrent connections ServicePointManager.DefaultConnectionLimit = 12;// Create the queue if it does not exist alreadystring connectionString = CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString");var namespaceManager = NamespaceManager.CreateFromConnectionString(connectionString);if (!namespaceManager.QueueExists(QueueName)){namespaceManager.CreateQueue(QueueName);}// Initialize the connection to Service Bus QueueClient = QueueClient.CreateFromConnectionString(connectionString, QueueName);return base.OnStart();}public override void OnStop(){// Close the connection to Service Bus Queue Client.Close();CompletedEvent.Set();base.OnStop();}}}
在上面的WokerRole.cs类代码中，分为两个逻辑：
(1)OnStart函数，表示WorkerRole在启动的时候，初始化了ProcessingQueue对象
(2)Run函数，表示在WorkerRole在执行的时候，将ProcessingQueue的内容输出
三.设置Web Role
1.在Web Role的根目录下，创建一个新的ASPX页面，重命名为ServiceBusQueue.aspx
在ServiceBusQueue.aspx页面中，
-增加一个TextBox控件，重命名为txbInput
-增加一个Button控件，重命名为BtnSend
2.在WebRole1项目中，增加NuGet，添加ServiceBus引用。如下图:
3.在ServiceBusQueue.aspx.cs中，增加如下代码
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using Microsoft.WindowsAzure;using Microsoft.ServiceBus;using Microsoft.ServiceBus.Messaging;namespace WebRole1{public partial class ServiceBusQueue : System.Web.UI.Page{const string QueueName = "ProcessingQueue";
protected void Page_Load(object sender, EventArgs e){}protected void BtnSend_Click(object sender, EventArgs e){string strinput = txbInput.Text.ToString();Send(strinput);txbInput.Text = string.Empty;}private void Send(string text){string connectionString = CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString");MessagingFactory factory = MessagingFactory.CreateFromConnectionString(connectionString);// Initialize the connection to Service Bus QueueMessageSender sender = factory.CreateMessageSender(QueueName);BrokeredMessage message1 = new BrokeredMessage(text);sender.Send(message1);}}}
上面的代码中，会将用户从界面的输入值，插入到ProcessingQueue对象中
四.配置WebRole和ServiceBusWorkerRole
我们修改WebRole的配置文件，如下图：
在WebRole1的Settings中，点击Add Setting增加Microsoft.ServiceBus.ConnectionString对象，如下图:
上图中，需要将Value值修改为我们在Azure Management Portal中创建的ServiceBus连接字符串，如下图：
修改完毕后，我们需要修改ServiceBusWorkerRole的配置文件
将Microsoft.ServiceBus.ConnectionString的Value属性，修改为我们在Azure Management Portal中创建的ServiceBus连接字符串。如下图:
五.然后我们用Visual Studio的Azure模拟器运行。
我们依次在ServiceBusQueue.aspx中，输入不同的值。如下图:
我们可以在Azure Compute模拟器中，查看到2次输入的结果。如下图:
可以观察到，首先输入的值，最先被处理。这也说明了Service Bus Queue 先进先出的特性。
最后我们还可以在Management Portal中，查看到由代码生成的processingqueue对象
=====================================分隔符=======================================================
看到最后，如果有读者觉得，从Azure Compute Emulator查看到aspx页面的输入，这也太不智能啦。
放心，其实我们可以将aspx页面的输入，返回到另外的ReturnQueue对象中去，并在前端aspx进行显示：
(1)ProcessingQueue:插入(Send)数据
(2)ProcessingQueue:返回(Receive)数据
别问我为什么不能保存到代码中申明的ProcessingQueue中，笔者试验过，不能对ProcessingQueue同时执行Send和Receive操作
ServiceBusQueue.aspx.cs代码如下
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using Microsoft.WindowsAzure;using Microsoft.ServiceBus;using Microsoft.ServiceBus.Messaging;namespace WebRole1{public partial class ServiceBusQueue : System.Web.UI.Page{const string QueueName = "ProcessingQueue";const string ReturnQueueName = "ReturnQueue";protected void Page_Load(object sender, EventArgs e){}protected void BtnSend_Click(object sender, EventArgs e){string strinput = txbInput.Text.ToString();Send(strinput);txbInput.Text = string.Empty;}private void Send(string text){string connectionString = CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString");MessagingFactory factory = MessagingFactory.CreateFromConnectionString(connectionString);// Initialize the connection to Service Bus QueueMessageSender sender = factory.CreateMessageSender(QueueName);BrokeredMessage message1 = new BrokeredMessage(text);sender.Send(message1);}protected void btnReceiveMessage_Click(object sender, EventArgs e){string connectionString = CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString");QueueClient Client = QueueClient.CreateFromConnectionString(connectionString, ReturnQueueName);var message = Client.Receive(TimeSpan.FromSeconds(3));if (message != null){var ret = message.GetBody<string>();plete();}}}}
WorkerRole.cs代码如下：
using System;using System.Collections.Generic;using System.Diagnostics;using System.Linq;using ;using System.Threading;using Microsoft.ServiceBus;using Microsoft.ServiceBus.Messaging;using Microsoft.WindowsAzure;using Microsoft.WindowsAzure.ServiceRuntime;namespace WorkerRoleWithSBQueue1{public class WorkerRole : RoleEntryPoint{// The name of your queueconst string QueueName = "ProcessingQueue";const string ReturnQueueName = "ReturnQueue";// QueueClient is thread-safe. Recommended that you cache // rather than recreating it on every request QueueClient Client;ManualResetEvent CompletedEvent = new ManualResetEvent(false);public override void Run(){Trace.WriteLine("Starting processing of messages");// Initiates the message pump and callback is invoked for each message that is received, calling close on the client will stop the pump.Client.OnMessage((receivedMessage) =>{try{// Process the messageTrace.WriteLine("Processing Service Bus message: " + receivedMessage.SequenceNumber.ToString());string received = receivedMessage.GetBody<string>();Trace.WriteLine("You input is" + received);SendToReturnQueue(ReturnQueueName, received);}catch{// Handle any message processing specific exceptions here}});CompletedEvent.WaitOne();}private void SendToReturnQueue(string queueName, string inputString){ string connectionString = CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString");MessagingFactory factory = MessagingFactory.CreateFromConnectionString(connectionString);// Initialize the connection to Service Bus QueueMessageSender sender = factory.CreateMessageSender(queueName);BrokeredMessage message1 = new BrokeredMessage(inputString);sender.Send(message1);}public override bool OnStart(){// Set the maximum number of concurrent connections ServicePointManager.DefaultConnectionLimit = 12;// Create the queue if it does not exist alreadystring connectionString = CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString");var namespaceManager = NamespaceManager.CreateFromConnectionString(connectionString);if (!namespaceManager.QueueExists(QueueName)){namespaceManager.CreateQueue(QueueName);}if (!namespaceManager.QueueExists(ReturnQueueName)){namespaceManager.CreateQueue(ReturnQueueName);}// Initialize the connection to Service Bus QueueClient = QueueClient.CreateFromConnectionString(connectionString, QueueName);return base.OnStart();}public override void OnStop(){// Close the connection to Service Bus Queue Client.Close();CompletedEvent.Set();base.OnStop();}}}
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