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ASPNET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 ServerMicrosoft 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SystemEnterpriseServices上
<%@ Assembly name=SystemEnterpriseServicesVersion=Culture=neutralPublicKeyToken=bfffdaa %>
添加引用到SystemWebServices和SystemEnterpriseServices域名空间
[C#]
using SystemWebServices;
using SystemEnterpriseServices;
[Visual Basic]
Imports SystemWebServices
Imports SystemEnterpriseServices
声明一个XML Web服务方法设置WebMethod属性的TransactionOption属性为TransactionOptionRequiresNew
[C#]
[ WebMethod(TransactionOption=TransactionOptionRequiresNew)]
public int DeleteAuthor(string lastName)
[Visual Basic]
< WebMethod(TransactionOption:=TransactionOptionRequiresNew)> _
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=SystemEnterpriseServicesVersion=Culture=neutralPublicKeyToken=bfffdaa %>
using System;
using SystemData;
using SystemDataSqlClient;
using SystemWebServices;
using SystemEnterpriseServices;
public class Orders : WebService
{
[ WebMethod(TransactionOption=TransactionOptionRequiresNew)]
public int DeleteAuthor(string lastName)
{
String deleteCmd = DELETE FROM authors WHERE au_lname= +
lastName + ;
String exceptionCausingCmdSQL = DELETE FROM NonExistingTable WHERE
au_lname= + lastName + ;
SqlConnection sqlConn = new SqlConnection(
Persist Security Info=False;Integrated Security=SSPI;database=pubs;server=myserver);
SqlCommand deleteCmd = new SqlCommand(deleteCmdSQLsqlConn);
SqlCommand exceptionCausingCmd = new
SqlCommand(exceptionCausingCmdSQLsqlConn);
// This command should execute properly
deleteCmdConnectionOpen();
deleteCmdExecuteNonQuery();
// 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 ASPNET
// automatically aborts the transaction The deleteCmd that
// executed properly is rolled back
int cmdResult = exceptionCausingCmdExecuteNonQuery();
sqlConnClose();
return cmdResult;
}
}
[Visual Basic]
<%@ WebService Language=VB Class=Orders %>
<%@ assembly name=SystemEnterpriseServices %>
Imports System
Imports SystemData
Imports SystemDataSqlClient
Imports SystemWebServices
Imports SystemWebUtil
Imports SystemEnterpriseServices
Public Class Orders
<WebMethod(TransactionOption:=TransactionOptionRequiresNew)> _
Public Function DeleteAuthor (lastName as String) as Integer
Dim 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(deleteCmdSQLsqlConn)
Dim exceptionCausingCmd As SqlCommand = New _
SqlCommand(exceptionCausingCmdSQLsqlConn)
This command should execute properly
deleteCmdConnectionOpen()
deleteCmdExecuteNonQuery()
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 ASPNET
automatically aborts the transaction The deleteCmd that
executed properly is rolled back
Dim cmdResult As Integer = exceptionCausingCmdExecuteNonQuery()
sqlConnClose()
Return cmdResult
End Function
End Class
