Communication via TCP instead of HTTP for web services

HTTP is a request/response protocol between clients and servers. The most common application consists of Web-browser clients that communicate with a Web server. The client sends a request to a server, which listens for client request messages. When the server receives a request, it returns a response, which contains the status of the request. If successful, optional data, such as a Web page, an error message, or other information is returned. For more information about the HTTP protocol, see HTTP - Hypertext Transfer Protocol.

The HTTP protocol is not connection-based—once the response is sent, no state is maintained. To handle multiple-page transactions, the application must persist any necessary state.

In WCF, the HTTP transport binding is optimized for interoperability with legacy non-WCF systems. If all communicating parties are using WCF, the TCP-based or named pipes-based bindings are faster. For more information, see NetTcpBinding and NetNamedPipeBinding.

TCP is a connection-based, stream-oriented delivery service with end-to-end error detection and correction. Connection-based means that a communication session between hosts is established before exchanging data. A host is any device on a TCP/IP network identified by a logical IP address.

TCP provides reliable data delivery and ease of use. Specifically, TCP notifies the sender of packet delivery, guarantees that packets are delivered in the same order in which they are sent, retransmits lost packets, and ensures that data packets are not duplicated. Note that this reliable delivery applies between two TCP/IP nodes, and is not the same thing as WS-ReliableMessaging, which applies between endpoints, no matter how many intermediate nodes they may include.

The WCF TCP transport is optimized for the scenario where both ends of the communication are using WCF. This binding is the fastest WCF binding for scenarios that involve communicating between different machines. The message exchanges use the BinaryMessageEncodingBindingElement for optimized message transfer. TCP provides duplex communication and so can be used to implement duplex contracts, even if the client is behind network address translation (NAT).