InstanceContextMode Enum

Definition

public enum class InstanceContextMode

public enum InstanceContextMode

type InstanceContextMode = 

Public Enum InstanceContextMode

Inheritance

Object

ValueType

Enum

InstanceContextMode

Fields

Examples

The following code illustrates how to set the InstanceContextMode for a service class:

// Service class which implements the service contract.
[ServiceBehavior(InstanceContextMode=InstanceContextMode.PerSession)]
public class CalculatorService : ICalculator
{
 public double Add(double n1, double n2)
 {
 return n1 + n2;
 }

 public double Subtract(double n1, double n2)
 {
 return n1 - n2;
 }

 public double Multiply(double n1, double n2)
 {
 return n1 * n2;
 }

 public double Divide(double n1, double n2)
 {
 return n1 / n2;
 }
}

' Service class which implements the service contract.
Public Class CalculatorService
Implements ICalculator

 Public Function Add(n1 As Double, n2 As Double) As Double Implements ICalculator.Add
 Return n1 + n2
 End Function

 Public Function Subtract(n1 As Double, n2 As Double) As Double Implements ICalculator.Subtract
 Return n1 - n2
 End Function

 Public Function Multiply(n1 As Double, n2 As Double) As Double Implements ICalculator.Multiply
 Return n1 * n2
 End Function

 Public Function Divide(n1 As Double, n2 As Double) As Double Implements ICalculator.Divide
 Return n1 / n2
 End Function

End Class

Remarks

The System.ServiceModel.InstanceContext class manages the association between the channel and the user-defined service objects. Use the InstanceContextMode enumeration with the ServiceBehaviorAttribute.InstanceContextMode property to specify the lifetime of the InstanceContext object. Windows Communication Foundation (WCF) can create a new InstanceContext object for every call, every session, or specify that the InstanceContext object is bound to a single service object. For a working example, see Instancing.

The Single value specifies that a single InstanceContext object should be used for the lifetime of the service. Several caveats are associated with the Single value:

• If the ServiceBehaviorAttribute.InstanceContextMode value is set to Single, your service can only process one message at a time unless you also set the ConcurrencyMode value to ConcurrencyMode.Multiple.

• For singleton lifetime behavior (for example, if the host application calls the ServiceHost.ServiceHost constructor and passes an object to use as the service), the service class must set ServiceBehaviorAttribute.InstanceContextMode to Single, or an exception is thrown when the service host is opened.

See also

• InstanceContextMode
• ReleaseInstanceMode