我们知道事务是通过参与方进行WCF事务投票(Voting)来决定 "提交(Complete)" 或者 "回滚(Rollback)" 操作的。默认情况下,WCF 通过 OperationBehavior(TransactionAutoComplete = true) 来完成投票动作。(TransactionAutoComplete = true 是缺省值,不需要显式声明。)
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我们将服务方法默认的 TransactionAutoComplete=true 改为 false,看看结果 。
- // ---- Service1 -----
- [ServiceContract(SessionModeSessionMode=SessionMode.Required)]
- public interface IService1
- {
- [OperationContract]
- [TransactionFlow(TransactionFlowOption.Allowed)]
- void Test();
- }
- public class MyService1 : IService1
- {
- [OperationBehavior(TransactionScopeRequired=true,
TransactionAutoComplete=false)]- public void Test()
- {
- string connStr = "server=(local);uid=sa;pwd=sa;database=temp";
- using (SqlConnection conn = new SqlConnection(connStr))
- {
- conn.Open();
- SqlCommand cmd = new SqlCommand("insert into [User]
([name]) values (@name)",- conn);
- cmd.Parameters.Add(new SqlParameter("@name", "ZhangSan"));
- cmd.ExecuteNonQuery();
- }
- }
- }
- // ---- Service2 -----
- [ServiceContract(SessionMode = SessionMode.Required)]
- public interface IService2
- {
- [OperationContract]
- [TransactionFlow(TransactionFlowOption.Allowed)]
- void Test();
- }
- public class MyService2 : IService2
- {
- [OperationBehavior(TransactionScopeRequired = true,
TransactionAutoComplete = false)]- public void Test()
- {
- string connStr = "server=(local);uid=sa;pwd=sa;database=temp";
- using (SqlConnection conn = new SqlConnection(connStr))
- {
- conn.Open();
- SqlCommand cmd = new SqlCommand("insert into Account ([user],
[money]) values (@user, @money)",- conn);
- cmd.Parameters.Add(new SqlParameter("@user", "ZhangSan"));
- cmd.Parameters.Add(new SqlParameter("@money", 100));
- cmd.ExecuteNonQuery();
- }
- }
- }
- public class WcfTest
- {
- public static void Test()
- {
- // ---- Host -----
- AppDomain.CreateDomain("Server").DoCallBack(delegate
- {
- NetTcpBinding bindingServer = new NetTcpBinding();
- bindingServer.TransactionFlow = true;
- ServiceHost host1 = new ServiceHost(typeof(MyService1),
new Uri("net.tcp://localhost:8080"));- host1.AddServiceEndpoint(typeof(IService1), bindingServer, "");
- host1.Open();
- ServiceHost host2 = new ServiceHost(typeof(MyService2),
new Uri("net.tcp://localhost:8081"));- host2.AddServiceEndpoint(typeof(IService2), bindingServer, "");
- host2.Open();
- });
- // ---- Client -----
- NetTcpBinding bindingClient = new NetTcpBinding();
- bindingClient.TransactionFlow = true;
- IService1 client1 = ChannelFactory
.CreateChannel(bindingClient, - new EndpointAddress("net.tcp://localhost:8080"));
- IService2 client2 = ChannelFactory
.CreateChannel(bindingClient, - new EndpointAddress("net.tcp://localhost:8081"));
- using (TransactionScope scope = new TransactionScope())
- {
- try
- {
- client1.Test();
- client2.Test();
- scope.Complete();
- }
- finally
- {
- (client1 as IDisposable).Dispose();
- (client2 as IDisposable).Dispose();
- }
- }
- }
- }
运行结果表明事务无法提交,触发 TransactionAbortedException 异常,显示 "事务终止"。那么除了默认被称之为 "声明投票(Declarative voting)" 的方式外,我们还能怎么做?OperationContext 有个 SetTransactionComplete() 方法,允许我们在代码中完成WCF事务投票行为。这种投票方式更加灵活,便于我们在代码中做出更多的控制,被称之为 "显式投票(Explicit voting)"。
在上面两个 Test() 方法的***一行,添加 "OperationContext.Current.SetTransactionComplete();",再次运行,事务被正确提交。
- [OperationBehavior(TransactionScopeRequired=true,
TransactionAutoComplete=false)]- public void Test()
- {
- // ...
- OperationContext.Current.SetTransactionComplete();
- }
- ...
接下来,我们设想另外一种情况。事务不由 Client 发起,在 Service1.Test() 调用 Service2.Test(),那么事务会是个什么样子呢?Service1、Service2 的参数 "OperationBehavior(TransactionScopeRequired = true)" 决定了如果没有外界传入的环境事务,那么会自动创建一个根事务。所以 Service1.Test() 会创建一个根事务,而 Service2.Test() 会参与这个事务。可问题在于 Service.Test() 中并没有显示调用 Transaction.Complete,事务能被提交吗?
- // ---- Service1 -----
- [ServiceContract]
- public interface IService1
- {
- [OperationContract]
- [TransactionFlow(TransactionFlowOption.Allowed)]
- void Test();
- }
- public class MyService1 : IService1
- {
- [OperationBehavior(TransactionScopeRequired=true)]
- public void Test()
- {
- string connStr = "server=(local);uid=sa;pwd=sa;database=temp";
- using (SqlConnection conn = new SqlConnection(connStr))
- {
- conn.Open();
- SqlCommand cmd = new SqlCommand("insert into [User]
([name]) values (@name)",- conn);
- cmd.Parameters.Add(new SqlParameter("@name", "ZhangSan"));
- cmd.ExecuteNonQuery();
- }
- InvokeService2();
- }
- public void InvokeService2()
- {
- NetTcpBinding bindingClient = new NetTcpBinding();
- bindingClient.TransactionFlow = true;
- IService2 client2 = ChannelFactory
.CreateChannel
(bindingClient,- new EndpointAddress("net.tcp://localhost:8081"));
- using (client2 as IDisposable)
- {
- client2.Test();
- }
- }
- }
- // ---- Service2 -----
- [ServiceContract]
- public interface IService2
- {
- [OperationContract]
- [TransactionFlow(TransactionFlowOption.Allowed)]
- void Test();
- }
- public class MyService2 : IService2
- {
- [OperationBehavior(TransactionScopeRequired = true)]
- public void Test()
- {
- string connStr = "server=(local);uid=sa;pwd=sa;database=temp";
- using (SqlConnection conn = new SqlConnection(connStr))
- {
- conn.Open();
- SqlCommand cmd = new SqlCommand("insert into Account
([user], [money]) values (@user, @money)",- conn);
- cmd.Parameters.Add(new SqlParameter("@user", "ZhangSan"));
- cmd.Parameters.Add(new SqlParameter("@money", 100));
- cmd.ExecuteNonQuery();
- }
- }
- }
- public class WcfTest
- {
- public static void Test()
- {
- // ---- Host -----
- AppDomain.CreateDomain("Server").DoCallBack(delegate
- {
- NetTcpBinding bindingServer = new NetTcpBinding();
- bindingServer.TransactionFlow = true;
- ServiceHost host1 = new ServiceHost(typeof(MyService1),
new Uri("net.tcp://localhost:8080"));- host1.AddServiceEndpoint(typeof(IService1), bindingServer, "");
- host1.Open();
- ServiceHost host2 = new ServiceHost(typeof(MyService2),
new Uri("net.tcp://localhost:8081"));- host2.AddServiceEndpoint(typeof(IService2), bindingServer, "");
- host2.Open();
- });
- // ---- Client -----
- NetTcpBinding bindingClient = new NetTcpBinding();
- bindingClient.TransactionFlow = true;
- IService1 client1 = ChannelFactory
.CreateChannel
(bindingClient,- new EndpointAddress("net.tcp://localhost:8080"));
- try
- {
- client1.Test();
- }
- finally
- {
- (client1 as IDisposable).Dispose();
- }
- }
- }
运行结果表明,事务被正确提交。看来这和客户端使用 TransactionScope 必须显式调用 Complete() 有所不同。同样,如果将 Service2.Test() 设为 TransactionAutoComplete=false,在不调用 "OperationContext.Current.SetTransactionComplete();" 的情况下,也会触发事务失败异常。
以上就是我们为大家介绍的WCF事务投票的相关实现方法。
本文名称:深入分析WCF事务投票实现方式
转载来源:http://www.36103.cn/qtweb/news44/594.html
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