Spring.NET实用技巧4——NHibernate分布式事务(下)

，我们已实现了在同一应用程序下的分布式事务——即多Dao层+同Service层，每个Dao对应一个数据库，一个Service调用多个Dao。但是在一些特定的子系统较多的项目中，开发人员是无法访问到某个子系统的数据库，这就意味着不能通过增加Dao层来实现分布式事务。正如一个银行的软件系统，记录了客户的账户信息和存款金额，北京的分公司和上海的分公司分别有自己的数据库和软件系统。现在，要实现北京的系统向上海的系统转账，然而各自作为开发人员来说，没有足够的权限去访问对方的数据库，但是可以提供Web Service的方式去访问其系统服务。这样，我们就需要实现基于Web Service的分布式事务。

实现基于Web Service的分布式事务的方法比较多，可以通过.NET企业服务的方式。但是为了更好的实现，我们选择WCF作为一个分布式应用程序框架。WCF在实现分布式事务中有它的优越之处。其思路在于启动MSDTC服务，将客户端的事务以流的方式传递到服务器端，在服务器端执行通过时，客户端再提交事务，相反则回滚事务。

我们模仿上篇的场景做一个demo，并使用上篇的Dao和Domain。

一、启动MSDTC服务。

二、Service层

①.Customer

CustomerManager

     public interface ICustomerManager
    {
        CustomerInfo Get( object id);

         object Save(CustomerInfo entity);

         void Update(CustomerInfo entity);
    }

     public class CustomerManager : ICustomerManager
    {
         private ICustomerDao Dao { get ; set ; }

         public CustomerInfo Get( object id)
        {
             return Dao.Get(id);
        }

         public object Save(CustomerInfo entity)
        {
             return Dao.Save(entity);
        }

         public void Update(CustomerInfo entity)
        {
             if (entity.Money > 3000 )
            {
                 throw new Exception( " 订金上限 " );
            }
            Dao.Update(entity);
        }
    }

Service.xml

<? xml version="1.0" encoding="utf-8" ?>
< objects xmlns ="http://www.springframework.net" >

   < object id ="transactionManager"
        type ="Spring.Data.NHibernate.HibernateTransactionManager, Spring.Data.NHibernate21" >
     < property name ="DbProvider" ref ="DbProvider" />
     < property name ="SessionFactory" ref ="NHibernateSessionFactory" />
   </ object >

   < object id ="transactionInterceptor" type ="Spring.Transaction.Interceptor.TransactionInterceptor, Spring.Data" >
     < property name ="TransactionManager" ref ="transactionManager" />
     < property name ="TransactionAttributeSource" >
       < object type ="Spring.Transaction.Interceptor.AttributesTransactionAttributeSource, Spring.Data" />
     </ property >
   </ object >

   < object id ="BaseTransactionManager"   type ="Spring.Transaction.Interceptor.TransactionProxyFactoryObject, Spring.Data" abstract ="true" >
     < property name ="PlatformTransactionManager" ref ="transactionManager" />
     < property name ="TransactionAttributes" >
       < name-values >
         < add key ="*" value ="PROPAGATION_REQUIRED" />
       </ name-values >
     </ property >
   </ object >

   < object id ="Customer.CustomerManager" parent ="BaseTransactionManager" >
     < property name ="Target" >
       < object type ="Customer.Service.Implement.CustomerManager, Customer.Service" >
         < property name ="Dao" ref ="Customer.CustomerDao" />
       </ object >
     </ property >
   </ object >

</ objects >

②.Order

OrderManager

     public interface IOrderManager
    {
         object Save(OrderInfo entity);
    }

     public class OrderManager : IOrderManager
    {
         public IOrderDao Dao { get ; set ; }

         public object Save(OrderInfo entity)
        {
             return Dao.Save(entity);
        }
    }

Service.xml

<? xml version="1.0" encoding="utf-8" ?>
< objects xmlns ="http://www.springframework.net" >

   < object id ="transactionManager"
        type ="Spring.Data.NHibernate.HibernateTransactionManager, Spring.Data.NHibernate21" >
     < property name ="DbProvider" ref ="DbProvider" />
     < property name ="SessionFactory" ref ="NHibernateSessionFactory" />
   </ object >

   < object id ="transactionInterceptor" type ="Spring.Transaction.Interceptor.TransactionInterceptor, Spring.Data" >
     < property name ="TransactionManager" ref ="transactionManager" />
     < property name ="TransactionAttributeSource" >
       < object type ="Spring.Transaction.Interceptor.AttributesTransactionAttributeSource, Spring.Data" />
     </ property >
   </ object >

   < object id ="BaseTransactionManager"   type ="Spring.Transaction.Interceptor.TransactionProxyFactoryObject, Spring.Data" abstract ="true" >
     < property name ="PlatformTransactionManager" ref ="transactionManager" />
     < property name ="TransactionAttributes" >
       < name-values >
         < add key ="*" value ="PROPAGATION_REQUIRED" />
       </ name-values >
     </ property >
   </ object >

   < object id ="Order.OrderManager" parent ="BaseTransactionManager" >
     < property name ="Target" >
       < object type ="Order.Service.Implement.OrderManager, Order.Service" >
         < property name ="Dao" ref ="Order.OrderDao" />
       </ object >
     </ property >
   </ object >

</ objects >

三、服务契约和Host。

1、契约

作为服务契约，需要启用Session，并且设置TransactionFlowOption的等级为Allowed或Mandatory来接收客户端事务流。

作为契约的实现部分，需要设置TransactionScopeRequired为true来启用事务作用域。

①.Customer

CustomerContract

    [ServiceContract(SessionMode = SessionMode.Required)]
     public interface ICustomerContract
    {
        [OperationContract]
        [TransactionFlow(TransactionFlowOption.Allowed)]
        CustomerInfo Get( object id);

        [OperationContract]
        [TransactionFlow(TransactionFlowOption.Allowed)]
         object Save(CustomerInfo entity);

        [OperationContract]
        [TransactionFlow(TransactionFlowOption.Allowed)]
         void Update(CustomerInfo entity);
    }

    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
     public class CustomerServer : ICustomerContract
    {
         public ICustomerManager Manager { get ; set ; }

        [OperationBehavior(TransactionScopeRequired = true )]
         public CustomerInfo Get( object id)
        {
             return Manager.Get(id);
        }

        [OperationBehavior(TransactionScopeRequired = true )]
         public object Save(CustomerInfo entity)
        {

             return Manager.Save(entity);
        }

        [OperationBehavior(TransactionScopeRequired = true )]
         public void Update(CustomerInfo entity)
        {
            Manager.Update(entity);
        }

②.Order

IOrderContract

    [ServiceContract(SessionMode = SessionMode.Required)]
     public interface IOrderContract
    {
        [OperationContract]
        [TransactionFlow(TransactionFlowOption.Allowed)]
         object Save(OrderInfo entity);
    }

   [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
     public class OrderServer : IOrderContract
    {
         public IOrderManager Manager { get ; set ; }

        [OperationBehavior(TransactionScopeRequired = true )]
         public object Save(OrderInfo entity)
        {
             return Manager.Save(entity);
        }
    }

2、配置

然而，Spring.NET针对NHibernate的Session管理使用的是OSIV模式(Open Session In View)，即使用httpModule去拦截HTTP请求，在每次请求开始时打开Session作用域(SessionScope)，最后在请求结束后关闭SessionScope。这样一来，在客户端每请求一次时都会打开SessionScope，在请求结束会关闭SessionScope，然后当请求结束后再去处理分布式就会提示“无法使用已释放对象”的错误。所以说，OSIV是无法正常管理分布式事务的。出于上述原因，我们决定在Global.asax的配置，在Session(这里的Session是ASP.NET中的Session)启动时候打开SessionScope，在Session结束时关闭SessionScope。这样分布式事务就会与SessionScope同步了。

最后，在配置appSettings节点增加
<add key="Spring.Data.NHibernate.Support.SessionScope.SessionFactoryObjectName" value="NHibernateSessionFactory"/>

另外配置WCF的binding时需要选择一种支持Session的binding(如wsHttpBinding)并且将binding中的transactionFlow属性设置为true。

Global.asax

     public class Global : System.Web.HttpApplication
    {

         protected void Application_Start( object sender, EventArgs e)
        {
            log4net.Config.XmlConfigurator.Configure();
        }

         protected void Session_Start( object sender, EventArgs e)
        {
            SessionScope sessionScope = new SessionScope( " appSettings " , typeof (SessionScope), false );
            sessionScope.Open();
            HttpContext.Current.Session[ " SessionScope " ] = sessionScope;
        }


         protected void Session_End( object sender, EventArgs e)
        {
            SessionScope sessionScope = HttpContext.Current.Session[ " SessionScope " ] as SessionScope;
             if (sessionScope != null )
            {
                sessionScope.Close();
            }
        }

    }

①.Customer

Web.config

<? xml version="1.0" encoding="utf-8" ?>
< configuration >

..............

< spring xmlns ="http://www.springframework.net" >
     < parsers >
       < parser type ="Spring.Data.Config.DatabaseNamespaceParser, Spring.Data" />
       < parser type ="Spring.Transaction.Config.TxNamespaceParser, Spring.Data" />
     </ parsers >
     < context >
       < resource uri ="config://spring/objects" />

       
       < resource uri ="assembly://Customer.Dao/Customer.Dao.Config/Dao.xml" />
       
       < resource uri ="assembly://Customer.Service/Customer.Service.Config/Service.xml" />

     </ context >
     < objects xmlns ="http://www.springframework.net"
             xmlns:aop ="http://www.springframework.net/aop" >

       < object id ="Customer.Host" type ="Customer.Host.Implement.CustomerServer, Customer.Host" >
         < property name ="Manager" ref ="Customer.CustomerManager" />
       </ object >

     </ objects >
   </ spring >

   < appSettings >
     < add key ="Spring.Data.NHibernate.Support.SessionScope.SessionFactoryObjectName" value ="NHibernateSessionFactory" />
   </ appSettings >

   < system.web >
     < compilation debug ="true" targetFramework ="4.0" />

     < httpModules >
       < add name ="Spring" type ="Spring.Context.Support.WebSupportModule, Spring.Web" />
     </ httpModules >

   </ system.web >
   < system.serviceModel >
     < services >
       < service name ="Customer.Host" >
         < endpoint address ="" binding ="wsHttpBinding" bindingConfiguration ="ServerBinding" contract ="Customer.Host.ICustomerContract" />
         < endpoint address ="mex" binding ="mexHttpBinding" contract ="IMetadataExchange" />
       </ service >
     </ services >
     < bindings >
       < wsHttpBinding >
         < binding name ="ServerBinding" transactionFlow ="true" >
         </ binding >
       </ wsHttpBinding >
     </ bindings >
     < behaviors >
       < serviceBehaviors >
         < behavior >
           
           < serviceMetadata httpGetEnabled ="true" />
           
           < serviceDebug includeExceptionDetailInFaults ="true" />
         </ behavior >
       </ serviceBehaviors >
     </ behaviors >
     < serviceHostingEnvironment multipleSiteBindingsEnabled ="true" aspNetCompatibilityEnabled ="true" />
   </ system.serviceModel >
< system.webServer >
     < modules runAllManagedModulesForAllRequests ="true" />
   </ system.webServer >

</ configuration >

<% @ ServiceHost Language = " C# " Debug = " true " Service = " Customer.Host " Factory = " Spring.ServiceModel.Activation.ServiceHostFactory " %>

②.Order

Web.config

<? xml version="1.0" encoding="utf-8" ?>
< configuration >

  ..........

   
   < spring xmlns ="http://www.springframework.net" >
     < parsers >
       < parser type ="Spring.Data.Config.DatabaseNamespaceParser, Spring.Data" />
       < parser type ="Spring.Transaction.Config.TxNamespaceParser, Spring.Data" />
     </ parsers >
     < context >
       < resource uri ="config://spring/objects" />

       
       < resource uri ="assembly://Order.Dao/Order.Dao.Config/Dao.xml" />
       
       < resource uri ="assembly://Order.Service/Order.Service.Config/Service.xml" />

     </ context >
     < objects xmlns ="http://www.springframework.net"
             xmlns:aop ="http://www.springframework.net/aop" >

       < object id ="Order.Host" type ="Order.Host.Implement.OrderServer, Order.Host" >
         < property name ="Manager" ref ="Order.OrderManager" />
       </ object >

     </ objects >
   </ spring >

   < appSettings >
     < add key ="Spring.Data.NHibernate.Support.SessionScope.SessionFactoryObjectName" value ="NHibernateSessionFactory" />
   </ appSettings >

   < system.web >
     < compilation debug ="true" targetFramework ="4.0" />

     < httpModules >
       < add name ="Spring" type ="Spring.Context.Support.WebSupportModule, Spring.Web" />
     </ httpModules >

   </ system.web >
   < system.serviceModel >
     < services >
       < service name ="Order.Host" >
         < endpoint address ="" binding ="wsHttpBinding" bindingConfiguration ="ServerBinding" contract ="Order.Host.IOrderContract" />
         < endpoint address ="mex" binding ="mexHttpBinding" contract ="IMetadataExchange" />
       </ service >
     </ services >
     < bindings >
       < wsHttpBinding >
         < binding name ="ServerBinding" transactionFlow ="true"    >
         </ binding >
       </ wsHttpBinding >
     </ bindings >
     < behaviors >
       < serviceBehaviors >
         < behavior >
           
           < serviceMetadata httpGetEnabled ="true" />
           
           < serviceDebug includeExceptionDetailInFaults ="true" />
         </ behavior >
       </ serviceBehaviors >
     </ behaviors >
     < serviceHostingEnvironment multipleSiteBindingsEnabled ="true" aspNetCompatibilityEnabled ="true" />
   </ system.serviceModel >
< system.webServer >
     < modules runAllManagedModulesForAllRequests ="true" />
   </ system.webServer >

</ configuration >

<% @ ServiceHost Language = " C# " Debug = " true " Service = " Order.Host " Factory = " Spring.ServiceModel.Activation.ServiceHostFactory " %>

四、客户端

HostTest

[TestFixture]
     public class HostTest
    {
         private CustomerContractClient customerProxy;

         private OrderContractClient orderProxy;

        [SetUp]
         public void Init()
        {
            customerProxy = new CustomerContractClient();
            orderProxy = new OrderContractClient();
        }

        [Test]
         public void InitData()
        {
             using (TransactionScope scope = new TransactionScope())
            {
                customerProxy.Save( new CustomerInfo
                {
                    Name = " 刘冬 "
                });

                scope.Complete();
            }
        }

        [Test]
         public void DistributedTransactionTest()
        {
             using (TransactionScope scope = new TransactionScope())
            {
                 try
                {
                    CustomerInfo customer = customerProxy.Get( 1 );
                    orderProxy.Save( new OrderInfo
                    {
                        Address = " 中国北京 " ,
                        CustomerId = ( int )customer.ID,
                        OrderDate = DateTime.Now
                    });
                    customer.Money += 1000 ;
                    customerProxy.Update(customer);
                    scope.Complete();
                    Console.WriteLine( " 分布式事务已提交 " );
                }
                 catch (Exception ex)
                {
                    Transaction.Current.Rollback();
                    Console.WriteLine( " 发送错误：分布式事务已回滚 " );
                }
            }
        }
    }

五、运行效果

1.初始化数据