利用Service bus中的queue中转消息

有需求就有对策就有市场。

由于公司global的policy，导致对公司外发邮件的service必须要绑定到固定的ip地址，所以别的程序需要调用发邮件程序时，问题就来了，如何在azure上跨service进行work role的调用呢？（work role和web role是两个不同的东西，主要区别在work role是每个单独的不依附与web application，web role则不是）

微软的解决方案有几：

1，  目前发送Email的Cloud Service的workrole同时实现接收发送email的请求，可以有多种接收请求的模式：

a)         通过Azure Service Bus Queue实现，需要发送email的应用将发生的信息打包发送到指定的Azure Service Bus Queue，workrole会侦听该queue，有信息到时接收信息，并触发email发送功能

b)        通过TCP或HTTP协议对外提供侦听服务，该协议的侦听端口通过Cloud Service的endpoint对外开放，需要发送email的应用通过这些服务端口向该workrole发送信息，通知workrole发送email

c)　　　（不推荐，需前期部署时就进行分配）watch out net

此次贪图方便，选了方案一：利用queue进行监听，并触发Email发送功能

Azure Service Bus Queue是一个云端的消息队列PAAS服务，可以参考以下的文档来创建和开发Service Bus Queue的功能：

1，  管理和初步Queue代码：https://www.azure.cn/documentation/articles/service-bus-dotnet-how-to-use-queues/

2，  Service Bus开发指南：https://www.azure.cn/documentation/articles/service-bus-create-queues/

3，  样例代码：https://www.azure.cn/documentation/articles/service-bus-samples/

首先在请求的project中web.config配置：

  <appSettings>
     <add key="Microsoft.ServiceBus.ConnectionString" value="Endpoint=sb://xxx.servicebus.chinacloudapi.cn;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=xxx" />
   </appSettings>

webconfig

发送请求的代码：

 string connectionString = ConfigurationManager.AppSettings["Microsoft.ServiceBus.ConnectionString"];

             var namespaceManager =
                 NamespaceManager.CreateFromConnectionString(connectionString);
             if (!namespaceManager.QueueExists("EmailQueue"))
             {
                 namespaceManager.CreateQueue("EmailQueue");
             }
             //queue.AddMessageAsync(new CloudQueueMessage(message));
             QueueClient Client =
     QueueClient.CreateFromConnectionString(connectionString, "EmailQueue");

             // Create message, passing a string message for the body.
             BrokeredMessage message = new BrokeredMessage("Email Message");

             // Set some addtional custom app-specific properties.
             message.Properties["sender"] = sender;
             message.Properties["subject"] = mailSubject;
             message.Properties["address"] = mailAddress;
             message.Properties["body"] = mailBody;

             try
             {
                 // Send message to the queue.
                 Client.Send(message);
             }
             catch (Exception ex)
             {
                 throw ex;
             }

接收service的app.config配置：

 <appSettings>
     <!-- Service Bus specific app setings for messaging connections -->
     <add key="Microsoft.ServiceBus.ConnectionString" value="Endpoint=sb://xxx.servicebus.chinacloudapi.cn;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=xxx" />
   </appSettings>

appconfig

接收的程序代码：

 private void RunServiceBus()
         {
             string connectionString =
    CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString");
             Microsoft.ServiceBus.Messaging.QueueClient Client =
               Microsoft.ServiceBus.Messaging.QueueClient.CreateFromConnectionString(connectionString, "EmailQueue");

             // Configure the callback options.
             OnMessageOptions options = new OnMessageOptions();
             options.AutoComplete = false;
             options.AutoRenewTimeout = TimeSpan.FromMinutes();

             string sender = string.Empty;
             string mailSubject = string.Empty;
             string mailAddress = string.Empty;
             string mailBody = string.Empty;

             // Callback to handle received messages.
             Client.OnMessage((message) =>
             {
                 try
                 {
                     // Process message from queue.
                     sender = message.Properties["sender"].ToString();
                     mailSubject = message.Properties["subject"].ToString();
                     mailAddress = message.Properties["address"].ToString();
                     mailBody = message.Properties["body"].ToString();
                     SendEmail(sender, mailSubject, mailAddress, mailBody);

                     // Remove message from queue.
                     message.Complete();
                 }
                 catch (Exception)
                 {
                     // Indicates a problem, unlock message in queue.
                     message.Abandon();
                 }
             }, options);

         }