CLR触发器引用WCF服务
这是本人第一次翻译文章，希望和大家一起学习。不当之处，多多请教！
这篇文章通过创建一个项目实例演示如何在SQL2005中创建CLR触发器并和WCF服务相联系实现您的设计，详细介绍了所有必要的步骤。文中不仅介绍了WCF更介绍了在SQLServer2005中如何使用WCF。
运行环境：VS 2005, WCF extensions for VS2005, .NET 3.0 Runtime
数据库：SQL 2005 or SQL 2005 Express, .NET 3.0 Runtime
创建WCF服务
1．打开visual studio
2．创建一个新的C＃控制台应用程序，并命名为“Service”
3．添加引用：System.ServiceModel
4．创建服务契约
1） 在项目中添加接口，取名“IServiceContract”
2） 用下面的代码替换
using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
namespace SampleService
{
[ServiceContract]
interface IServiceContract
{
[OperationContract]
void UpdateOccured();
[OperationContract]
void InsertOccured();
}
5．实现服务契约
1） 添加一个新类，命名为“ServiceContract”
2） 用下面代码替换类中代码
using System;
using System.Collections.Generic;
using System.Text;
namespace SampleService
{
class MyService : IServiceContract
{
public void UpdateOccured()
{
Console.WriteLine("Update Occured");
}
public void InsertOccured(int RecordID)
{
Console.WriteLine("Insert Occured");
}
}
}
6．主机服务
1） 在Program.cs中用下面代码替换
using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Description;
namespace SampleService
{
class Program
{
static void Main (string[] args)
{
//创建服务基址
Uri baseAddress = new Uri("http://localhost:8000/services");
//创建主机处理服务实例
ServiceHost MyHost = new ServiceHost(typeof(MyService), baseAddress);
//为服务绑定文本
WSHttpBinding MyBinding = new WSHttpBinding();
//声明和配置Metadata 对象，稍后添加到servcie中
ServiceMetadataBehavior smb = new ServiceMetadataBehavior();
smb.HttpGetEnabled = true;
/*添加服务终端，完整服务地址有基址http://localhost:8000/services和终端地址MyService组成，地址为：http://localhost:8000/services/MyService*/
MyHost.AddServiceEndpoint(typeof(IServiceContract), MyBinding, "MyService");
//添加事件
MyHost.Description.Behaviors.Add(smb);
//运行
MyHost.Open();
Console.WriteLine("Your service has been started");
Console.WriteLine("Press <enter /> to terminate service.");
Console.WriteLine();
Console.ReadLine();
}
}
}
配置数据库
如果你遵循这里所说的步骤它允许你配置任何数据库系统，让你访问WCF服务。
1．创建一个基本数据库名为“custDB”，用下面的列创建表“tbCR”
[CustomerName] [varchar](50)
[CustomerTel] [varchar](50)
[CustomerEmail] [varchar](50)
2．默认CLR是不行的，让CLR执行以下查询：
-- Turn advanced options on
EXEC sp_configure 'show advanced options' , '1';
go
reconfigure;
go
EXEC sp_configure 'clr enabled' , '1'
go
reconfigure;
-- Turn advanced options back off
EXEC sp_configure 'show advanced options' , '0';
Go
3．此时你的数据库是不安全配置。为了防止安全例外，你必须通过执行以下查询是数据库标志为“可信任”
use custdb
ALTER DATABASE custdb SET TRUSTWORTHY ON
Reconfigure
4．作为标准配置我们可参考的SQL Server CLR 对象是有限的，为了获取某些配置，我们必须把WCF下载到数据库中并连接它，通过以下查询实现：
CREATE ASSEMBLY
SMDiagnostics from
'C:/Windows/Microsoft.NET/Framework/v3.0/Windows Communication Foundation/SMDiagnostics.dll'
with permission_set = UNSAFE
GO
CREATE ASSEMBLY
[System.Web] from
'C:/Windows/Microsoft.NET/Framework/v2.0.50727/System.Web.dll'
with permission_set = UNSAFE
GO
CREATE ASSEMBLY
[System.Messaging] from
'C:/Windows/Microsoft.NET/Framework/v2.0.50727/System.Messaging.dll'
with permission_set = UNSAFE
GO
CREATE ASSEMBLY
[System.IdentityModel] from
'C:/Program Files/Reference Assemblies/Microsoft/Framework/v3.0/System.IdentityModel.dll'
with permission_set = UNSAFE
GO
CREATE ASSEMBLY
[System.IdentityModel.Selectors] from
'C:/Program Files/Reference Assemblies/Microsoft/Framework/v3.0/System.IdentityModel.Selectors.dll'
with permission_set = UNSAFE
GO
CREATE ASSEMBLY -- this will add service modal
[Microsoft.Transactions.Bridge] from
'C:/Windows/Microsoft.NET/Framework/v3.0/Windows Communication Foundation/Microsoft.Transactions.Bridge.dll'
with permission_set = UNSAFE
GO
错误提示
在配置过程中可能会遇到以下错误信息：
Warning: The Microsoft .Net frameworks assembly 'system.servicemodel, version= 3.0.0 .0,
culture=neutral, publickeytoken=b 77a 5c 561934e089, processorarchitecture=msil.'
you are registering is not fully tested in SQL Server hosted environment.
我的测试系统是SQL2005（未打补丁），在配置过程中出现了许多“out of memory”错误。解决问题的方法就是安装SQL 2005 SP2
创建CLR对象
1． 在解决方案中添加新的C＃SQL数据库项目，命名为“ServiceClient”
2． 为你的目标数据库选择或添加注释。（如果未被提示：右击ServiceClient项目，选择属性，数据库，浏览并选择你的连接）
3． 为创建的服务添加声明
1） 在解决方案浏览器中右击“service”项目，选择“调试”>“Start New Instance”
2） 服务运行：右击“ServiceClient”项目，选择“Add Service Reference”
3） 在“Service URI”中输入：http://localhost:8000/services
4） 点击“OK”
4． 项目中添加触发器，命名“WCFTrigger”
1） 用以下代码替换
using System;
using System.Data;
using System.Data.SqlClient;
using Microsoft.SqlServer.Server;
using System.ServiceModel.Description;
using System.ServiceModel;
using System.Collections;
using System.Diagnostics;
using System.Threading;
public partial class Triggers
{
//Create an endpoint addresss for our serivce
public static EndpointAddress endpoint = new EndpointAddress(new Uri("http://localhost:8000/services/myservice"));
//Create a binding method for our service
public static WSHttpBinding httpBinding = new WSHttpBinding();
//Create an instance of the service proxy
public static ServiceClient.localhost.ServiceContractClient myClient = new ServiceClient.localhost.ServiceContractClient(httpBinding, endpoint);
//A delegate that is used to asynchrounously talk to the service when using the FAST METHOD
public delegate void MyDelagate(String crudType);
[SqlProcedure()]
public static void SendData(String crudType)
{
/*A very simple procedure that accepts a string parameter based on the CRUD action performed by the
* trigger. It switches based on this parameter and calls the appropriate method on the service proxy*/
switch (crudType)
{
case "Update":
myClient.UpdateOccured();
break;
case "Insert":
myClient.InsertOccured();
break;
}
}
[Microsoft.SqlServer.Server.SqlTrigger(Name = "WCFTrigger", Target = "tbCR", Event = "FOR UPDATE, INSERT")]
public static void Trigger1()
{
/*This is a very basic trigger that performs two very simple actions:
* 1) Gets the current trigger Context and then switches based on the triggeraction
* 2) Makes a call to a stored procedure
* Two methods of calling the stored procedure are presented here.
* View the article on Code Project for a discussion on these methods
*/
SqlTriggerContext myContext = SqlContext.TriggerContext;
//Used for the FAST METHOD
MyDelagate d;
switch (myContext.TriggerAction)
{
case TriggerAction.Update:
//Slow method - NOT REMCOMMEND IN PRODUCTION!
SendData("Update");
//Fast method - STRONGLY RECOMMENDED FOR PRODUCTION!
//d = new MyDelagate(SendData);
//d.BeginInvoke("Update",null,null);
break;
case TriggerAction.Insert:
//Slow method - NOT REMCOMMEND IN PRODUCTION!
SendData("Insert");
//Fast method - STRONGLY RECOMMENDED FOR PRODUCTION!
//d = new MyDelagate(SendData);
//d.BeginInvoke("Insert", null, null);
break;
}
}
}
上面的代码在数据库中创建了两个对象。存储过程SendData需要利用服务代理。触发器WCFTrigger当我们表中有更新或插入操作时触发。
在我的测试中，使用SQL编译器，基于方法的授权使查询时间从100ms减少到8ms
说明：在这个项目中慢（异步）方法作为默认的解决方案，它是以牺牲简洁性为代价的。我强烈建议在任何生产实施中使用快（同步）方法。
运行
一切准备妥当，开始运行。在表格中输入一些插入和更新操作，你会看到相应输出结果。