解析：基于Service Broker的异步消息传递
本文演示的是同一个SQL Server中不同数据库之间的基于Service Broker的异步消息传递，其中Stored Procedure充当Service Program。HelloWorldDB为目标数据库，DotNetFun2则为消息发送发的数据库。
同时，假设Server Broker的基本对象类型已经创建，如MessageType(XMLMessage), Contract(XMLContract), Queue(SendingQueue and ReceivingQueue)等等，具体操作可以参考《A simple tutorial on SQL Server 2005 Beta 2 Service Broker》。另外，因为在不同的Databases之间进行消息传递，因此需要创建Route。
1.创建Stored Procedure作为Internal Service Program。
USE HelloWorldDBGOAlter Procedure HelloWorldResponderAsBeginDeclare @conversationHandle UNIQUEIDENTIFIERDeclare @message_body nvarchar(MAX)Declare @message_type_name SYSNAMEWHILE (1=1)BEGINBEGIN TRANSACTION-- Wait for 1 seconds for messages to arriveWAITFOR (-- For simplicity we process one message at a timeRECEIVE TOP(1)@message_type_name=message_type_name,@conversationHandle=conversation_handle,@message_body=message_bodyFROM [ReceivingQueue]), TIMEOUT 1000-- If a message was received, process it, else skipIF (@@rowcount <= 0)BREAK;-- If this is a XML message,-- respond with an appropriate greetingIF @message_type_name = 'XMLMessage'BEGINSEND ON CONVERSATION @conversationHandleMESSAGE TYPE XMLMessage('<hello>Hello From Rickie</hello>')END CONVERSATION @conversationHandleENDCOMMITENDCOMMITENDGO |
该Stored Procedure负责从ReceivingQueue中检索消息，并根据Queue的Retention设置，来确定从Queue中移除消息或更新Queue中消息的状态。
2.设置目标队列（Target Queue）的激活机制
Use HelloWorldDBgoALTER QUEUE [ReceivingQueue] WITHACTIVATION (STATUS = ON, -- Turn on internal activationPROCEDURE_NAME = [HelloWorldResponder], -- Our stored procMAX_QUEUE_READERS = 4, -- Up to 4 concurrent readersEXECUTE AS SELF) -- Execute as user of incoming dialog |
设置上述创建的Stored Procedure，该Stored Procedure将被激活并处理Queue中的消息。
3.在Initiator端发送消息
Use DotNetFun2goDECLARE @conversationHandle uniqueidentifierBEGIN TRANSACTION-- Begin a dialog to the Hello World ServiceBEGIN DIALOG @conversationHandleFROM SERVICE [SendingService]TO SERVICE 'ReceivingService','a727462b-52e7-4405-9eee-d19923729790'ON CONTRACT [XMLContract]WITH ENCRYPTION = OFF, LIFETIME = 600;-- Send messageSEND ON CONVERSATION @conversationHandleMESSAGE TYPE [XMLMessage]('<hello>Welcome to Rickie Lee''s blog,www.cnblogs.com/rickie</hello>');Select * From sys.conversation_endpointsCOMMIT |
其中，TO SERVICE 'ReceivingService','a727462b-52e7-4405-9eee-d19923729790'，’ReceivingSerice’表示目标Service名称，'a727462b-52e7-4405-9eee-d19923729790'则指定目标Service所在的数据库，可以通过如下SQL Script获取：
-- Retrieve remote broker instance guidSELECT service_broker_guidFROM sys.databasesWHERE database_id = DB_ID('HelloWorldDB') |
另外，可以通过如下的SQL script来检测Initiator端收到的Reply消息：
Select cast(message_body as XML) From SendingQueueReceive message_type_name,cast(message_body as XML)From SendingQueue |
4.查询对话端点状态（State of Conversation Endpoints）
最后，你可以通过在Target/Initiator端查询sys.conversation_endpoints表，获取Dialog对话状态：
Select * From sys.conversation_endpoints |
