<PackageReference Include="System.ServiceModel.Primitives" Version="6.0.0" />

System.ServiceModel.IDuplexContextChannel

namespace System.ServiceModel { public interface IDuplexContextChannel : IContextChannel, IChannel, ICommunicationObject, IExtensibleObject<IContextChannel> { bool AutomaticInputSessionShutdown { get; set; } InstanceContext CallbackInstance { get; set; } IAsyncResult BeginCloseOutputSession(TimeSpan timeout, AsyncCallback callback, object state); void EndCloseOutputSession(IAsyncResult result); void CloseOutputSession(TimeSpan timeout); } }