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Binding Class

Contains the binding elements that specify the protocols, transports, and message encoders used for communication between clients and services.

Namespace:  System.ServiceModel.Channels
Assembly:  System.ServiceModel (in System.ServiceModel.dll)

public abstract class Binding : IDefaultCommunicationTimeouts

Represents a collection of binding elements, each of which describes an aspect of how an endpoint communicates with other endpoints and that are built, consistently, into a channel factory on the client and into a channel listener on the service. A binding contains a collection of binding elements that correspond to protocol channels, transport channels, and message encoders. There can be any number of binding elements for protocol channels but one and only one binding element for each the transport and message encoder. There are commonly six layers of binding elements in a binding. Only the transport and encoding binding elements at the bottom of the stack are required. Because an encoding is required for each binding, if an encoding is not specified, Windows Communication Foundation (WCF) adds a default encoding for you. The default is Text/XML for the HTTP and HTTPS transports, and Binary for other transports.

The following table summarizes the options for each layer.




Transaction Flow







Symmetric, Asymmetric, Transport-Level


Shape Change



Transport Upgrades

SSL stream, Windows stream, Peer Resolver



Text, Binary, MTOM, Custom



TCP, Named Pipes, HTTP, HTTPS, MSMQ, Custom


Each binding element provides the specification for building a channel factory on the client and a channel listener on the service. When the channel factory stack is constructed, for example, there is one channel factory in the stack for each binding element in the binding. The same sort of mapping applies to the channel listeners in the stack on the service. Consistency on the client and service is critical for establishing the channel-based connection between these endpoints. Each factory and listener, in turn, processes the sending and accepting of the corresponding channels in the channel stack that connects them, and these channels can then send and receive the messages used to communicate.

Each instance of a Binding has a Name and Namespace that together uniquely identify it in the metadata of the service. If no name or namespace is specified, WCF adds a default values for you. The default name is null and the default namespace is This user name for the binding is distinct from the specification of the protocol name, which is specified by the Scheme property. If you want to add more HTTP bindings, for example, you can name them whatever you want and set all of their schemes to "http". There is no inherent application or machine dispatch based on the Scheme. So you avoid the common problem of being unable to register additional handlers for well-known protocols. You can also easily work with multiple versions of a binding side-by-side by giving each version a different name.

The Binding class implements the IDefaultCommunicationTimeouts interface to mitigate Denial of Service (DOS) attacks that rely on tying up resources for extended intervals of time. The implementation specifies the communication timeouts values for opening and closing connections and for the reading and writing operations associated with receiving and sending messages. The properties used to get and set these timeouts and their default values operations are summarized in the following table.

Timeout Property

Default Value


1 minute


1 minute


1 minute


10 minutes

When you create a binding by inheriting from Binding, you must override CreateBindingElements.

In addition, you can define your own binding elements and insert them between any of the defined layers in the preceding table. For more information, see the CustomBinding class.

BasicHttpBinding binding = new BasicHttpBinding();

binding.Name = "binding1";

Uri baseAddress = new Uri("http://localhost:8000/servicemodelsamples/service");
Uri address = new Uri("http://localhost:8000/servicemodelsamples/service/calc");

// Create a ServiceHost for the CalculatorService type and provide the base address. 
using (ServiceHost serviceHost = new ServiceHost(typeof(CalculatorService), baseAddress))
    serviceHost.AddServiceEndpoint(typeof(ICalculator), binding, address);

    // Open the ServiceHostBase to create listeners and start listening for messages.

    // The service can now be accessed.
    Console.WriteLine("The service is ready.");
    Console.WriteLine("Press <ENTER> to terminate service.");
    // Close the ServiceHostBase to shutdown the service.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0

.NET Compact Framework

Supported in: 3.5