Specifies the number of service instances available for handling calls that are contained in incoming messages.
Assembly: System.ServiceModel (in System.ServiceModel.dll)
| Member name | Description | |
|---|---|---|
| PerSession | A new InstanceContext object is created for each session. | |
| PerCall | A new InstanceContext object is created prior to and recycled subsequent to each call. If the channel does not create a session this value behaves as if it were PerCall. | |
| Single | 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.Note For singleton lifetime behavior (for example, if the host application calls the ServiceHost constructor and passes an object to use as the service), the service class must set InstanceContextMode to InstanceContextMode.Single, or an exception is thrown when the service host is opened. |
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. 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 Sample.
The Single value specifies that a single InstanceContext 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 Multiple. |
The following code illustrates how to set the InstanceContextMode for a service class:
' 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
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role not supported), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.- 5/19/2010
- David Stucki [MS]
