Imports System
Imports System.Collections.Generic
Imports System.Diagnostics
Imports System.Linq
Imports System.Net
Imports System.Threading
Imports Microsoft.Azure
Imports Microsoft.ServiceBus
Imports Microsoft.ServiceBus.Messaging
Imports Microsoft.WindowsAzure.ServiceRuntime

Public Class WorkerRole
    Inherits RoleEntryPoint

    ' 队列的名称
    Const QueueName As String = "ProcessingQueue"

    ' QueueClient 是线程安全的。建议你进行缓存，
    ' 而不是针对每一个请求重新创建它
    Dim Client As QueueClient
    Dim CompletedEvent = New ManualResetEvent(False)

    Public Overrides Sub Run()

        Trace.WriteLine("正在开始处理消息")

        ' 启动消息泵，并且将为每个已收到的消息调用回调，在客户端上调用关闭将停止该泵。
        Client.OnMessage(Sub(receivedMessage As BrokeredMessage)
                             Try
                                 ' 处理消息
                                 Trace.WriteLine("正在处理 Service Bus 消息: " + receivedMessage.SequenceNumber.ToString())
                             Catch
                                 ' 在此处处理任何处理特定异常的消息
                             End Try
                         End Sub)

        CompletedEvent.WaitOne()

    End Sub

    Public Overrides Function OnStart() As Boolean

        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12

        ' 设置最大并发连接数
        ServicePointManager.DefaultConnectionLimit = 12

        ' 如果队列不存在，则创建队列
        Dim connectionString As String = CloudConfigurationManager.GetSetting("Microsoft.ServiceBus.ConnectionString")
        Dim namespaceManager As NamespaceManager = namespaceManager.CreateFromConnectionString(connectionString)
        If (Not namespaceManager.QueueExists(QueueName)) Then
            namespaceManager.CreateQueue(QueueName)
        End If

        ' 获取客户端以使用队列
        Client = QueueClient.CreateFromConnectionString(connectionString, QueueName)
        Return MyBase.OnStart()

    End Function

    Public Overrides Sub OnStop()

        ' 关闭与 Service Bus 队列的连接
        Client.Close()
        CompletedEvent.Set()
        MyBase.OnStop()

    End Sub

End Class