在SQL Server 2005中实现异步触发器架构

USE tempdb
GO
 
-- 允许Service Broker
ALTER DATABASE tempdb SET
ENABLE_BROKER
GO

-- =======================================
-- 异步触发器对象
-- 1. service broker 对象
-- =======================================
-- a. message type, 要求使用XML 传递数据
CREATE MESSAGE TYPE MSGT_async_trigger
VALIDATION = WELL_FORMED_XML
GO
 
-- b. 只需要发送消息
CREATE CONTRACT CNT_async_trigger(
    MSGT_async_trigger SENT BY INITIATOR)
GO
 
-- c. 存储消息的队列
CREATE QUEUE dbo.Q_async_trigger
GO
 
-- d. 用于消息处理的服务
CREATE SERVICE SRV_async_trigger
    ON QUEUE dbo.Q_async_trigger(
        CNT_async_trigger)
GO
 
 
-- =======================================
-- 异步触发器对象
-- 2. 异步触发器处理的对象
-- =======================================
-- a. 登记异步触发器的表
CREATE TABLE dbo.tb_async_trigger(
    ID int IDENTITY
        PRIMARY KEY,
    table_name sysname,
    trigger_name sysname
)
 
-- b. 登记订阅异步触发器的存储过程
CREATE TABLE dbo.tb_async_trigger_subscriber(
    ID int IDENTITY
        PRIMARY KEY,
    procedure_name sysname
)
 
-- c. 异步触发器和存储过程之间的订阅关系
CREATE TABLE dbo.tb_async_trigger_subscribtion(
    trigger_id int
        REFERENCES dbo.tb_async_trigger(
            ID),
    procedure_id int
        REFERENCES dbo.tb_async_trigger_subscriber(
            ID),
    PRIMARY KEY(
        trigger_id, procedure_id)
)
GO
 
-- d. 发送消息的存储过程
CREATE PROC dbo.p_async_trigger_send
    @message xml
AS
SET NOCOUNT ON
DECLARE
    @handle uniqueidentifier
BEGIN DIALOG CONVERSATION @handle
    FROM SERVICE [SRV_async_trigger]
    TO SERVICE N"SRV_async_trigger"
    ON CONTRACT CNT_async_trigger
    WITH
        ENCRYPTION = OFF;
SEND
    ON CONVERSATION @handle
    MESSAGE TYPE MSGT_async_trigger(
        @message);
-- 消息发出即可, 不需要回复, 因此发出后即可结束会话
END CONVERSATION @handle
GO
 
-- e. 处理异步触发器发送的消息
CREATE PROC dbo.p_async_trigger_process
AS
SET NOCOUNT ON
DECLARE
    @handle uniqueidentifier,
    @message xml,
    @rows int
SET @rows = 1
WHILE @rows > 0
BEGIN
    -- 处理已经收到的消息
    WAITFOR(
        RECEIVE TOP(1)
            @handle = conversation_handle,
            @message = CASE
                            WHEN message_type_name = N"MSGT_async_trigger"
                                THEN CONVERT(xml, message_body)
                            ELSE NULL
                        END
        FROM dbo.Q_async_trigger
    ), TIMEOUT 10
    SET @rows = @@ROWCOUNT
    IF @rows > 0
    BEGIN
        -- 结束会话
        END CONVERSATION @handle;
 
        -- 处理消息
        -- a. 取发送者信息
        DECLARE
            @table_name sysname,
            @trigger_name sysname,
            @sql nvarchar(max)
        SELECT
            @table_name = @message.value("(/root/table_name)[1]", "sysname"),
            @trigger_name = @message.value("(/root/trigger_name)[1]", "sysname")
 
        -- b. 调用异步触发器订阅的存储过程
        ;WITH
        SUB AS(
            SELECT
                TR.table_name,
                TR.trigger_name,
                SUB.procedure_name
            FROM dbo.tb_async_trigger TR,
                dbo.tb_async_trigger_subscriber SUB,
                dbo.tb_async_trigger_subscribtion TRSUB
            WHERE TRSUB.trigger_id = TR.ID
                AND TRSUB.procedure_id = SUB.ID
        )
        SELECT
            @sql = (
                    SELECT
                        N"
EXEC " + procedure_name + N"
    @message
"
                    FROM SUB
                    WHERE table_name = @table_name
                        AND trigger_name = @trigger_name
                    FOR XML PATH(""), ROOT("r"), TYPE
                ).value("(/r)[1]", "nvarchar(max)")
        EXEC sp_executesql @sql, N"@message xml", @message
    END
END
GO
 
-- f. 绑定处理的存储过程到队列
ALTER QUEUE dbo.Q_async_trigger
    WITH ACTIVATION(
        STATUS = ON,
        PROCEDURE_NAME = dbo.p_async_trigger_process,
        MAX_QUEUE_READERS = 10,
        EXECUTE AS OWNER)
GO