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OperationBehaviorAttribute.ReleaseInstanceMode Property

Gets or sets a value that indicates when in the course of an operation invocation to recycle the service object.

Namespace: System.ServiceModel
Assembly: System.ServiceModel (in system.servicemodel.dll)

public ReleaseInstanceMode ReleaseInstanceMode { get; set; }
/** @property */
public ReleaseInstanceMode get_ReleaseInstanceMode ()

/** @property */
public void set_ReleaseInstanceMode (ReleaseInstanceMode value)

public function get ReleaseInstanceMode () : ReleaseInstanceMode

public function set ReleaseInstanceMode (value : ReleaseInstanceMode)

Not applicable.

Property Value

One of the ReleaseInstanceMode values. The default is None.

Exception typeCondition


The value is not one of the ReleaseInstanceMode values.

Use the ReleaseInstanceMode property to specify when Windows Communication Foundation (WCF) recycles a service object in the course of executing a method. The default behavior is to recycle a service object according to the InstanceContextMode value. Setting the ReleaseInstanceMode property changes that default behavior.

The ReleaseInstanceMode makes no threading guarantees. If you must have a new, unmodified object when your service runs, set the InstanceContextMode property to PerCall.

In transaction scenarios, the ReleaseInstanceMode property is often used to ensure that old data associated with the service object is cleaned up prior to processing a method call. You can also ensure that service objects associated with transactions are recycled after the transaction successfully completes by setting the ReleaseServiceInstanceOnTransactionComplete property to true.

You can choose the following behaviors:

  • Recycle a service object before an operation is called.

  • Recycle a service object after an operation is called.

  • Recycle a service object both before and after an operation is called.

  • No recycling behavior.

You can also use OperationBehaviorAttribute to configure a callback contract operation in a duplex client application. When used on a callback operation, the ReleaseInstanceMode property must be None or an InvalidOperationException exception is thrown at run time.

In addition, it is important to realize that if the service is created by passing a service object to the System.ServiceModel.ServiceHost(Object,Uri[]) constructor, the value of this property is treated as if it were None.

The following example code shows the use of ReleaseInstanceMode to recycle service objects both before and after a call.

class SampleService : ISampleService
  private Guid id;
  private string session;

  public SampleService()
    id = Guid.NewGuid();
    session = OperationContext.Current.SessionId;
    Console.WriteLine("Object {0} has been created.", id);
    Console.WriteLine("For session {0}", session);
  public string  SampleMethod(string msg)
    Console.WriteLine("The caller said: \"{0}\"", msg);
    Console.WriteLine("For session {0}", OperationContext.Current.SessionId);
    return "The service greets you: " + msg;

    Console.WriteLine("Object {0} has been destroyed.", id);
    Console.WriteLine("For session {0}", session);

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0

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