Transports in Windows Communication Foundation

Transports in Windows Communication Foundation

The main transports used in Windows Communication Foundation (WCF) are HTTP, HTTPS, TCP, and named pipes. The topics in this section discuss choosing among these transports, configuring the transport, and setting tuning properties.

Choosing a Transport

This topic discusses criteria for choosing among the three main transports that are included in Windows Communication Foundation (WCF): HTTP, TCP, and named pipes.

The WCF programming model separates endpoint operations (as expressed in a service contract) from the transport mechanism that connects two endpoints. This gives you the flexibility to decide how to expose your services to the network. If you must connect to an existing client or server, you may not have a choice about using a particular transport. However, WCF services can be made accessible through multiple endpoints, each with a different transport. When a single transport does not cover the intended audience for your service, consider exposing the service over multiple endpoints. Client applications can then use the endpoint that is best for them.

When to Use HTTP Transport

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.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.

When to Use the TCP Transport

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.

When to Use the Named Pipe Transport

A named pipe is an object in the Windows operating system kernel, such as a section of shared memory that processes can use for communication. A named pipe has a name, and can be used for one-way or duplex communication between processes on a single machine.When communication is required between different WCF applications on a single computer, and you want to prevent any communication from another machine, then use the named pipes transport. An additional restriction is that processes running from Windows Remote Desktop may be restricted to the same Windows Remote Desktop session unless they have elevated privileges.