A secure and interoperable WCF binding that is designed for use with duplex service contracts that allows both services and clients to send and receive messages.
The WSDualHttpBinding provides the same support for Web Service protocols as the WSHttpBinding, but for use with duplex contracts. WSDualHttpBinding only supports SOAP security and requires reliable messaging. This binding requires that the client has a public URI that provides a callback endpoint for the service. This is provided by the ClientBaseAddress. A dual binding exposes the IP address of the client to the service. The client should use security to ensure that it only connects to services it trusts.
http://msdn.microsoft.com/en-us/library/system.servicemodel.wsdualhttpbinding.aspx
