ServiceBehaviorAttribute.TransactionIsolationLevel Proprietà

Definizione

Specifica il livello di isolamento per le nuove transazioni create all'interno del servizio e per le transazioni in ingresso propagate da un client.Specifies the transaction isolation level for new transactions created inside the service, and incoming transactions flowed from a client.

public:
 property System::Transactions::IsolationLevel TransactionIsolationLevel { System::Transactions::IsolationLevel get(); void set(System::Transactions::IsolationLevel value); };
public System.Transactions.IsolationLevel TransactionIsolationLevel { get; set; }
member this.TransactionIsolationLevel : System.Transactions.IsolationLevel with get, set
Public Property TransactionIsolationLevel As IsolationLevel

Valore della proprietà

Valore dell'enumerazione IsolationLevel che specifica il livello di isolamento della transazione.A IsolationLevel value that specifies the transaction isolation level. Il valore predefinito è Unspecified.The default is Unspecified.

Eccezioni

Il valore non appartiene all'enumerazione IsolationLevel.The value is not one of the IsolationLevel values.

Esempi

Nell'esempio di codice seguente il livello di isolamento della transazione è impostato su ReadCommitted, non sono supportate le transazioni simultanee, è richiesta una transazione propagata dalla chiamata al metodo e viene eseguito automaticamente il commit della transazione se non si verificano eccezioni non gestite.The following code example sets the transaction isolation level to ReadCommitted, does not support concurrent transactions, requires a flowed transaction from the method call, and commits the transaction automatically if no unhandled exception occurs.

using System;
using System.ServiceModel;
using System.Transactions;

namespace Microsoft.WCF.Documentation
{
  [ServiceContract(
    Namespace="http://microsoft.wcf.documentation", 
    SessionMode=SessionMode.Required)]
  public interface IBehaviorService
  {
    [OperationContract]
    string TxWork(string message);
  }

  // Note: To use the TransactionIsolationLevel property, you 
  // must add a reference to the System.Transactions.dll assembly.
  /* The following service implementation:
   *   -- Processes messages on one thread at a time
   *   -- Creates one service object per session
   *   -- Does not release the service object when the transaction commits
   *   -- The isolation level is read committed.
   */
  [ServiceBehavior(
    ConcurrencyMode=ConcurrencyMode.Single,
    InstanceContextMode=InstanceContextMode.PerSession,
    ReleaseServiceInstanceOnTransactionComplete=false,
    TransactionIsolationLevel=System.Transactions.IsolationLevel.ReadCommitted
  )]
  public class BehaviorService : IBehaviorService, IDisposable
  {
    Guid myID;

    public BehaviorService()
    {
      myID = Guid.NewGuid();
      Console.WriteLine(
        "Object "
        + myID.ToString()
        + " created.");
    }

    /*
     * The following operation-level behaviors are specified:
     *   -- Always executes under a transaction scope.
     *   -- The transaction scope is completed when the operation terminates
     *       without an unhandled exception.
     */
    [OperationBehavior(
      TransactionAutoComplete = true,
      TransactionScopeRequired = true
    )]
    [TransactionFlow(TransactionFlowOption.Mandatory)]
    public string TxWork(string message)
    {
      // Do some transactable work.
      Console.WriteLine("TxWork called with: " + message);
      // Display transaction information.

      TransactionInformation info = Transaction.Current.TransactionInformation;
      Console.WriteLine("The distributed tx ID: {0}.", info.DistributedIdentifier);
      Console.WriteLine("The tx status: {0}.", info.Status);
      return String.Format("Hello. This was object {0}.",myID.ToString()) ;
    }

    public void Dispose()
    {
      Console.WriteLine(
        "Service "
        + myID.ToString()
        + " is being recycled."
      );
    }
  }
}


Imports System.ServiceModel
Imports System.Transactions

Namespace Microsoft.WCF.Documentation
  <ServiceContract(Namespace:="http://microsoft.wcf.documentation", SessionMode:=SessionMode.Required)> _
  Public Interface IBehaviorService
    <OperationContract> _
    Function TxWork(ByVal message As String) As String
  End Interface

  ' Note: To use the TransactionIsolationLevel property, you 
  ' must add a reference to the System.Transactions.dll assembly.
'   The following service implementation:
'   *   -- Processes messages on one thread at a time
'   *   -- Creates one service object per session
'   *   -- Does not release the service object when the transaction commits
'   *   -- The isolation level is read committed.
'   
    <ServiceBehavior(ConcurrencyMode:=ConcurrencyMode.Single, InstanceContextMode:=InstanceContextMode.PerSession, _
      ReleaseServiceInstanceOnTransactionComplete:=False, TransactionIsolationLevel:=System.Transactions.IsolationLevel.ReadCommitted)> _
    Public Class BehaviorService
        Implements IBehaviorService, IDisposable
        Private myID As Guid

        Public Sub New()
            myID = Guid.NewGuid()
            Console.WriteLine("Object " & myID.ToString() & " created.")
        End Sub

        '    
        '     * The following operation-level behaviors are specified:
        '     *   -- Always executes under a transaction scope.
        '     *   -- The transaction scope is completed when the operation terminates
        '     *       without an unhandled exception.
        '     
        <OperationBehavior(TransactionAutoComplete:=True, TransactionScopeRequired:=True), TransactionFlow(TransactionFlowOption.Mandatory)> _
        Public Function TxWork(ByVal message As String) As String Implements IBehaviorService.TxWork
            ' Do some transactable work.
            Console.WriteLine("TxWork called with: " & message)
            ' Display transaction information.

            Dim info As TransactionInformation = Transaction.Current.TransactionInformation
            Console.WriteLine("The distributed tx ID: {0}.", info.DistributedIdentifier)
            Console.WriteLine("The tx status: {0}.", info.Status)
            Return String.Format("Hello. This was object {0}.", myID.ToString())
        End Function

        Public Sub Dispose() Implements IDisposable.Dispose
            Console.WriteLine("Service " & myID.ToString() & " is being recycled.")
        End Sub
    End Class
End Namespace

Affinché l'esempio di codice seguente venga eseguito correttamente, è necessario che l'associazione sottostante supporti le transazioni propagate.The underlying binding must support flowed transactions for the following code example to execute properly. Per supportare le transazioni propagate utilizzando l'associazione WSHttpBinding, ad esempio, impostare la proprietà TransactionFlow su true nel codice o in un file di configurazione dell'applicazione.To support flowed transactions using the WSHttpBinding, for example, set the TransactionFlow property to true in code or in an application configuration file. Nell'esempio di codice seguente viene illustrato un file di configurazione per l'esempio precedente.The following code example shows a configuration file for the preceding sample.

<configuration>
  <system.serviceModel>
    <services>
      <service  
        name="Microsoft.WCF.Documentation.BehaviorService" 
        behaviorConfiguration="mex"
        >
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8080/BehaviorService"/>
            <add baseAddress="net.tcp://localhost:8081/BehaviorService"/>
          </baseAddresses>
        </host>
        <!--
          Note:
            This example code uses the WSHttpBinding to support transactions using the 
            WS-AtomicTransactions (WS-AT) protocol. WSHttpBinding is configured to use the  
            protocol, but the protocol is not enabled on some computers. Use the xws_reg -wsat+ 
            command to enable the WS-AtomicTransactions protocol in the MSDTC service.          
          -->
        <endpoint 
           contract="Microsoft.WCF.Documentation.IBehaviorService"
           binding="wsHttpBinding"
           bindingConfiguration="wsHttpBindingWithTXFlow"
           address="http://localhost:8080/BehaviorService"
          />
        <endpoint 
               contract="Microsoft.WCF.Documentation.IBehaviorService"
               binding="netTcpBinding"
               bindingConfiguration="netTcpBindingWithTXFlow"
               address="net.tcp://localhost:8081/BehaviorService"
          />
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="mex">
          <serviceMetadata httpGetEnabled="true"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <!-- binding configuration - configures a WSHttpBinding to require transaction flow -->
    <bindings>
      <wsHttpBinding>
        <binding name="wsHttpBindingWithTXFlow" transactionFlow="true" />
      </wsHttpBinding>
      <netTcpBinding>
        <binding name="netTcpBindingWithTXFlow" transactionFlow="true" />
      </netTcpBinding>
    </bindings>

  </system.serviceModel>
</configuration>

Commenti

Il livello di isolamento nel quale viene eseguita la transazione determina le modalità di trattamento dei dati nel caso in cui vengano apportate modifiche in altre transazioni e per quanto tempo la transazione deve mantenere i blocchi per proteggersi da tali modifiche.The isolation level in which your transaction runs determines how data is treated when changes are made in other transactions and how long your transaction must hold locks to protect against these changes. Ad esempio, il valore predefinito, Unspecified, specifica che non può avvenire alcun aggiornamento o inserimento fino a quando la transazione non è completata.For example, the default value, Unspecified, specifies that no updating or inserting can occur until the transaction is complete.

Questa proprietà può inoltre essere utilizzata per limitare il livello di isolamento delle transazioni in ingresso propagate da un client.This property can also be used to restrict the isolation level of incoming transactions flowed from a client.

Si applica a