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How to: Control Service Instancing

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Setting the instance mode of a service enables you to specify when a System.ServiceModel.InstanceContext (and its associated user-defined service object) is created. See the InstanceContextMode enumeration for the possible modes. For more information about behaviors, see Configuring and Extending the Runtime with Behaviors. For working examples, see Behaviors.

To control the service instance lifetime using code

  1. Apply the ServiceBehaviorAttribute to the service class.

  2. Set the InstanceContextMode property to one of the following values: PerCall, PerSession, or Single.

    [ServiceBehaviorAttribute(InstanceContextMode = InstanceContextMode.PerCall)]

    <ServiceBehaviorAttribute(InstanceContextMode:=InstanceContextMode.PerCall)> _
Public Class CalculatorService

Example

The following code example sets the InstanceContextMode property of the ServiceBehaviorAttribute attribute to PerCall.

// Define a service contract.
[ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
public interface ICalculator
{
    [OperationContract]
    double Add(double n1, double n2);
    [OperationContract]
    double Subtract(double n1, double n2);
    [OperationContract]
    double Multiply(double n1, double n2);
    [OperationContract]
    double Divide(double n1, double n2);
}

// Service class which implements the service contract.
[ServiceBehaviorAttribute(InstanceContextMode = InstanceContextMode.PerCall)]
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;
    }
}

' Define a service contract.
<ServiceContract([Namespace]:="http://Microsoft.ServiceModel.Samples")> _
Public Interface ICalculator
    <OperationContract()> _
    Function Add(ByVal n1 As Double, ByVal n2 As Double) As Double
    <OperationContract()> _
    Function Subtract(ByVal n1 As Double, ByVal n2 As Double) As Double
    <OperationContract()> _
    Function Multiply(ByVal n1 As Double, ByVal n2 As Double) As Double
    <OperationContract()> _
    Function Divide(ByVal n1 As Double, ByVal n2 As Double) As Double
End Interface

' Service class which implements the service contract.
<ServiceBehaviorAttribute(InstanceContextMode:=InstanceContextMode.PerCall)> _
Public Class CalculatorService
    Implements ICalculator

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

    End Function


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

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

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

See also