SQL Server 服务代理 - 消息超时

Question

我正在研究 sql server service broker 作为我们应用程序的消息处理技术。

在我们的场景中，从一个客户端应用程序 (WPF) 发送的消息需要在服务代理中排队等待其他客户端应用程序 (android) 接收。消息是时间敏感的，需要在被发布到队列后的“X”分钟(例如 2 分钟)内被接收者接收，如果此时无法接收，消息需要过期并从队列中删除排队。

有没有办法告诉服务代理在“x”分钟后超时消息？

编辑:添加了我用来测试的脚本。

CREATE DATABASE ServiceBrokerTest
GO

ALTER DATABASE ServiceBrokerTest SET ENABLE_BROKER WITH ROLLBACK IMMEDIATE 
GO

/****** Object:  MessageType [SampleMsgType] ***/
CREATE MESSAGE TYPE [SampleMsgType] AUTHORIZATION [dbo] VALIDATION = NONE
GO

/****** Object:  ServiceContract [MsgContract]    ******/
CREATE CONTRACT [MsgContract] AUTHORIZATION [dbo] ([SampleMsgType] SENT BY INITIATOR)
GO

/****** Object:  ServiceQueue [dbo].[Queue1]    ******/
CREATE QUEUE [dbo].[Queue1] WITH STATUS = ON , RETENTION = OFF , POISON_MESSAGE_HANDLING (STATUS = ON)  ON [PRIMARY] 
GO

/****** Object:  BrokerService [MsgService]    ******/
CREATE SERVICE [MsgService]  AUTHORIZATION [dbo]  ON QUEUE [dbo].[Queue1] ([MsgContract])
GO

/****** Object:  StoredProcedure [dbo].[SendMsg]  ******/
CREATE PROC [dbo].[SendMsg]
@msg NVARCHAR(MAX)
AS

BEGIN
    SET NOCOUNT ON
    DECLARE @handle UNIQUEIDENTIFIER

    BEGIN TRANSACTION
        BEGIN dialog @handle 
            FROM SERVICE [MsgService]
            TO SERVICE 'MsgService'
            ON CONTRACT [MsgContract]
            WITH ENCRYPTION = OFF, LIFETIME = 20

        ;SEND ON CONVERSATION @handle
            MESSAGE TYPE [SampleMsgType] (@msg)
        END CONVERSATION @handle
    COMMIT TRANSACTION
END

/****** Object:  StoredProcedure [dbo].[ReceiveMsg] ******/
CREATE PROC [dbo].[ReceiveMsg]
@msg NVARCHAR(MAX) OUT

AS

BEGIN
    SET NOCOUNT ON
    DECLARE @handle UNIQUEIDENTIFIER

    DECLARE @msgTable TABLE (
        handle UNIQUEIDENTIFIER,
        msg NVARCHAR(MAX),
        msgType VARCHAR(300));

    SET @handle = NULL

    WAITFOR (
        RECEIVE [conversation_handle], message_body, message_type_name
        FROM [dbo].[Queue1]
        INTO @msgTable
        ), TIMEOUT 25000

        SELECT @handle = handle
        FROM @msgTable
        WHERE msgType = 'http://schemas.microsoft.com/SQL/ServiceBroker/EndDialog'

        IF @handle is not null
            BEGIN 
                END CONVERSATION @handle
            END

        SELECT @msg = msg
        FROM @msgTable
        WHERE msgType = 'SampleMsgType'
END 

GO

Answer 1

对话生命周期可以在 BEGIN DIALOG 期间指定。声明:

BEGIN DIALOG @handle
FROM SERVICE [...]
TO SERVICE '...'
ON CONTRACT [...]
, LIFETIME = <dialog lifetime>;

对话框必须在其生命周期内完成(双方都结束)，否则会出错。因此，您可以启动一个生命周期为 2 分钟的对话，并在其上发送一条或多条消息。目标必须在这 2 分钟内接收并处理消息，否则对话框将出错。

您也可以使用conversation priorities并在更高优先级的 channel 上发送时间敏感消息。这将确保 Service Broker 传输优先考虑您的敏感消息，并且客户端应用程序 RECEIVE 语句“冒泡”优先级较高的时间敏感消息，并且它们首先被接收。