Difference between HTTP and Tcp Duplex Communication

In WCF, HTTP and Tcp Protocols are often used for duplex communication. The corresponding protocols are WsDualHttpBinding and NetTcpBinding.
HTTP is based on the application layer protocol, while Tcp is based on the transport layer protocol. Tcp uses three handshakes to establish a reliable connection between the client and the server. Both the client initiating the request and the server of the callback client can use one connection. When HTTP is used, the connection is closed after a request is sent from the client to the server and the server returns a reply to the client.
Due to the non-connectivity of HTTP, the duplex Based on WsDualHttpBinding may be slightly different from NetTcpBinding when the server calls back the client.
1. NetTcpBinding implements duplex www.2cto.com 1.1 Contract Section: 1.1.1 contract interface Definition: [ServiceContract (CallbackContract = typeof (ICallback)] public interface ICalculator {[OperationContract] void Add (double x, double y);} 1.1.2 callback interface Definition: public interface ICallback {[OperationContract] void Display (double x, double y, double result);} 1.2 service implementation: public void Add (double x, double y) {Console. writeLine ("START Add Calculation"); ICallback callbac K = OperationContext. current. getCallbackChannel <ICallback> (); callback. display (x, y, x + y); Console. writeLine (string. format ("{0}, {1}", x, y);} The Service uses OperationContext. current. getCallbackChannel <T> generic method to obtain the callback proxy class for the client, and calls back the public T GetCallbackChannel <T> () {if (this. channel! = Null )&&! This. isUserContext) {return (T) this. channel. proxy;} return default (T); www.2cto.com} 1.3 server configuration: <system. serviceModel> <services> <service name = "Services. calculatorServices "> <endpoint address =" Calaulator "binding =" netTcpBinding "contract =" Contract. ICalculator "> </endpoint>
Client:
2. WsDualHttpBinding implements duplex. Operating System: XP SP3. IIS Version: Take the same contract as above 5.1 as an example. In the packet or request-response mode, if you change the protocol, you only need to change the binding used. We changed the client configuration to the following: <system. serviceModel> <client> <endpoint address = "http: // 127.0.0.1: 8866/Calaulator/ws" binding = "wsDualHttpBinding" contract = "Contract. ICalculator "name =" calculatorWsDual "> </endpoint> </client> </system. serviceModel> then use calculatorWsDual to regenerate ChannelFactory: using:

The solution is to configure the binding behavior for the Endpoint as follows: <system. serviceModel> <bindings> <wsDualHttpBinding> <binding name = "myWsDualBinding" clientBaseAddress = "http: // 127.0.0.1: 3636/Service/CallbackService "> </binding> </wsDualHttpBinding> </bindings> <client> <endpoint address =" http: // 127.0.0.1: 8888/Service/Calculator "binding =" wsDualHttpBinding "contract =" Contracts. ICalculator "name =" calculatorService "bindingConfiguration =" myWsDualBinding "/> </client> </system. serviceModel> in this way, the problem is solved by the author tyb1222.