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IInstanceContextProvider Interface

Implement to participate in the creation or choosing of a System.ServiceModel.InstanceContext object, especially to enable shared sessions.

Namespace:  System.ServiceModel.Dispatcher
Assembly:  System.ServiceModel (in System.ServiceModel.dll)

public interface IInstanceContextProvider

The IInstanceContextProvider type exposes the following members.

Public methodGetExistingInstanceContextCalled when a new message is received.
Public methodInitializeInstanceContextCalled when null is returned from the GetExistingInstanceContext method.
Public methodIsIdleCalled when all InstanceContext activities have completed to enable implementers to prevent the InstanceContext from being recycled.
Public methodNotifyIdleCalled when the IsIdle method returns false to enable implementers to provide a callback to notify WCF when the InstanceContext object is finished.

Implement the IInstanceContextProvider interface to provide the appropriate System.ServiceModel.InstanceContext object to the system. Typically, this interface is implemented to support shared sessions, enable service instance pooling, control lifetimes of service instances, or to group contexts among clients.

For example, to implement sharing, insert a custom IInstanceContextProvider to decide which session or call from a client is associated with which InstanceContext object. For an example that demonstrates the sharing of instance contexts, see InstanceContextSharing.


When an IInstanceContextProvider is inserted into Windows Communication Foundation (WCF), the normal property that controls the creation of InstanceContext objects (the ServiceBehaviorAttribute.InstanceContextMode property) is no longer checked and has no effect.

A more generic mechanism by which you can initialize InstanceContext objects when created (for example, to attach custom extensions to each InstanceContext) is the System.ServiceModel.Dispatcher.IInstanceContextInitializer.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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