并行处理，可在预定事件前72小时唤醒和发送电子邮件警报

Question

我有一个用MSSQLMVC2编写的应用程序，它将用户预定事件的日期和时间存储在ASP.NET数据库中。我需要应用程序发送一个电子邮件警报到用户72小时前存储的事件发生，没有任何人工干预。

实现这种并行过程的最佳方式是什么(我已经有了电子邮件代码)？

Answer 1

假设您已将事件存储在数据库中，我将创建一个Windows Service，它独立于asp.net应用程序运行，该应用程序定期轮询数据库以查找要完成的工作。

Answer 2

如果你可以控制服务器，那么我可能会选择Windows Service (如The Evil Greebo said)。

但假设您没有这样做，我将创建一个类，可能类似于下面的类，您可以使用/继承它。在global.asax中的"Application_start“事件期间实例化这个类，并在缓存中保存它的副本。将您的逻辑放在"ExecuteProcess“方法中。你的逻辑可能看起来像(伪代码)：

while(true) 
   check for events that need to have notifications sent

   send any needed notifications

   wait x seconds and repeate

loop

请确保您的MSSQL数据库表中有一个字段，用于跟踪是否已发送通知。

基本基类：

Imports System.Threading

Public MustInherit Class LongRunningProcess
    Public ReadOnly Property Running() As Boolean
        Get
            Return _Running
        End Get
    End Property

    Public ReadOnly Property Success() As Boolean
        Get
            Return _Success
        End Get
    End Property

    Public ReadOnly Property Exception() As Exception
        Get
            Return _Exception
        End Get
    End Property

    Public ReadOnly Property StartTime() As DateTime
        Get
            Return _StartTime
        End Get
    End Property

    Public ReadOnly Property EndTime() As DateTime
        Get
            Return _EndTime
        End Get
    End Property

    Public ReadOnly Property Args() As Object
        Get
            Return _Args
        End Get
    End Property


    Protected _Running As Boolean = False
    Protected _Success As Boolean = False
    Protected _Exception As Exception = Nothing
    Protected _StartTime As DateTime = DateTime.MinValue
    Protected _EndTime As DateTime = DateTime.MinValue
    Protected _Args() As Object = Nothing
    Protected WithEvents _Thread As Thread

    Private _locker As New Object()

    Public Sub Execute(ByVal Arguments As Object)
        SyncLock (_locker)
            'if the process is not running, then...'
            If Not _Running Then
                'Set running to true'
                _Running = True
                'Set start time to now'
                _StartTime = DateTime.Now
                'set arguments'
                _Args = Arguments
                'Prepare to process in a new thread'
                _Thread = New Thread(New ThreadStart(AddressOf ExecuteProcess))

                'Start the thread'
                _Thread.Start()
            End If
        End SyncLock
    End Sub

    Protected MustOverride Sub ExecuteProcess()
End Class

Args属性允许您从"ExecuteProcess“中访问您可能需要的任何参数/变量。