支持XML Web服务的事务利用公共语言运行期中的支持，其是基于Microsoft Transaction Server ( MTS)和COM+ Services中相同的分布式事务模型。该模型基于明确的判断一个对象是否参与一个事务，而不是编写特定的代码用来处理委托和回调一个事务。对于一个使用ASP.NET创建的XML Web服务，你可以通过设置其应用到一个XML Web服务方法上的WebMethod属性的TransactionOption属性来声明一个XML Web服务的事务行为。如果该XML Web服务方法执行的时候抛出一个异常，那么该事务自动地结束；相反，如果没有发生异常，该事务自动委托。
WebMethod属性的TransactionOption属性规定一个XML Web服务方法如何参与一个事务。虽然这个声明级别表示一个事务逻辑，但是它是消除实际事务的一个步骤。当事物对象访问数据源（如数据库或消息队列）时实际事务产生。关联该对象的事务自动流向适当的资源管理程序。像.NET Framework Data Provider（用于SQL Server或OLE DB）这样的.NET Framework数据提供者在对象的上下文中查找事务并通过Distributed Transaction Coordinator (DTC，分布式事务协调程序)编目事务。全部的事务自动产生。
XML Web服务方法只能参与一个作为新事务的根的事务。作为一个新事务的根，所有的与资源管理器（像运行Microsoft SQL Server、Microsoft Message Queuing和Microsoft Host Integration Server的服务器）的相互作用维护需要运行健壮的分布式应用程序的ACID性质。调用其他的XML Web服务方法的XML Web服务方法参与不同的事务，因为事务不流经XML Web服务方法。
使用来自XML Web服务方法的事务
声明一个XML Web服务。
[C#]＜%@ WebService Language="C#" Class="Orders" %＞[Visual Basic]＜%@ WebService Language="VB" Class="Orders" %＞
把一个汇编指令加到System.EnterpriseServices上。
＜%@ Assembly name="System.EnterpriseServices,Version=1.0.3300.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a" %＞
添加引用到System.Web.Services和System.EnterpriseServices域名空间。
[C#]using System.Web.Services;using System.EnterpriseServices;[Visual Basic]Imports System.Web.ServicesImports System.EnterpriseServices
声明一个XML Web服务方法，设置WebMethod属性的TransactionOption属性为TransactionOption.RequiresNew。
[C#][ WebMethod(TransactionOption=TransactionOption.RequiresNew)]public int DeleteAuthor(string lastName)[Visual Basic]＜ WebMethod(TransactionOption:=TransactionOption.RequiresNew)＞ _Public Function DeleteAuthor(lastName As String) As Integer
下面的代码示例显示一个使用单个XML Web服务方法的XML Web服务，调用DeleteDatabase。这个XML Web服务方法执行一个事务范围内的数据库操作。如果该数据库操作抛出一个异常，该事务自动地停止；否则，该事务自动地委托。
[C#]＜%@ WebService Language="C#" Class="Orders" %＞＜%@ Assembly name="System.EnterpriseServices,Version=1.0.3300.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a" %＞using System;using System.Data;using System.Data.SqlClient;using System.Web.Services;using System.EnterpriseServices;public class Orders : WebService{[ WebMethod(TransactionOption=TransactionOption.RequiresNew)]public int DeleteAuthor(string lastName){String deleteCmd = "DELETE FROM authors WHERE au_lname='" +lastName + "'" ;String exceptionCausingCmdSQL = "DELETE FROM NonExistingTable WHEREau_lname='" + lastName + "'" ;SqlConnection sqlConn = new SqlConnection("Persist Security Info=False;Integrated Security=SSPI;database=pubs;server=myserver");SqlCommand deleteCmd = new SqlCommand(deleteCmdSQL,sqlConn);SqlCommand exceptionCausingCmd = newSqlCommand(exceptionCausingCmdSQL,sqlConn);// This command should execute properly.deleteCmd.Connection.Open();deleteCmd.ExecuteNonQuery();// This command results in an exception, so the first command is// automatically rolled back. Since the XML Web service method is// participating in a transaction, and an exception occurs, ASP.NET// automatically aborts the transaction. The deleteCmd that// executed properly is rolled back.int cmdResult = exceptionCausingCmd.ExecuteNonQuery();sqlConn.Close();return cmdResult;}}[Visual Basic]＜%@ WebService Language="VB" Class="Orders" %＞＜%@ assembly name="System.EnterpriseServices" %＞Imports SystemImports System.DataImports System.Data.SqlClientImports System.Web.ServicesImports System.Web.UtilImports System.EnterpriseServicesPublic Class Orders＜WebMethod(TransactionOption:=TransactionOption.RequiresNew)＞ _Public Function DeleteAuthor (lastName as String) as IntegerDim deleteCmdSQL As String = "DELETE FROM authors WHERE au_lname='" + _lastName + "'"Dim exceptionCausingCmdSQL As String = "DELETE FROM " + _"NonExistingTable WHERE au_lname='" + lastName + "'"Dim sqlConn As SqlConnection = New SqlConnection( _"Persist Security Info=False;Integrated Security=SSPI;database=pubs;server=myserver")Dim deleteCmd As SqlCommand = New SqlCommand(deleteCmdSQL,sqlConn)Dim exceptionCausingCmd As SqlCommand = New _SqlCommand(exceptionCausingCmdSQL,sqlConn)' This command should execute properly.deleteCmd.Connection.Open()deleteCmd.ExecuteNonQuery()' This command results in an exception, so the first command is' automatically rolled back. Since the XML Web service method is' participating in a transaction, and an exception occurs, ASP.NET' automatically aborts the transaction. The deleteCmd that' executed properly is rolled back.Dim cmdResult As Integer = exceptionCausingCmd.ExecuteNonQuery()sqlConn.Close()Return cmdResultEnd FunctionEnd Class
