InstanceContextMode InstanceContextMode InstanceContextMode InstanceContextMode Enum

Definition

Specifies the number of service instances available for handling calls that are contained in incoming messages.

public enum class InstanceContextMode
public enum InstanceContextMode
type InstanceContextMode = 
Public Enum InstanceContextMode
Inheritance
InstanceContextModeInstanceContextModeInstanceContextModeInstanceContextMode

Fields

PerCall PerCall PerCall PerCall 1

A new InstanceContext object is created prior to and recycled subsequent to each call.

PerSession PerSession PerSession PerSession 0

A new InstanceContext object is created for each session. If the channel does not create a session this value behaves as if it were PerCall.

Single Single Single Single 2

Only one InstanceContext object is used for all incoming calls and is not recycled subsequent to the calls. If a service object does not exist, one is created.

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 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 the Instancing.

The Single value specifies that a single Single object should be used for the lifetime of the service.

Note

If the InstanceContextMode value is set to Single the result is that your service can only process one message at a time unless you also set the ConcurrencyMode value to ConcurrencyMode.

Applies to

See Also