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ContractDescription Class

Describes a Windows Communication Foundation (WCF) contract that specifies what an endpoint communicates to the outside world.

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

Public Class ContractDescription
Dim instance As ContractDescription

A WCF contract is a collection of operations that specifies what the endpoint communicates to the outside world. Each operation is a message exchange. For example, a request message and an associated reply message form a request/reply message exchange.

A ContractDescription object is used to describe WCF contracts and their operations. Within a ContractDescription, each contract operation has a corresponding OperationDescription that describes aspects of the each operation that is part of the contract, such as whether the operation is one-way or request/reply. Each OperationDescription also describes the messages that make up the operation using a MessageDescriptionCollection. ContractDescription contains a reference to an interface that defines the contract using the programming model. This interface is marked with ServiceContractAttribute and its methods that correspond to endpoint operations are marked with the OperationContractAttribute.

A duplex contract defines the following logical sets of operations:

  • A set that the service exposes for the client to call.

  • A set that the client exposes for the service to call.

The programming model for defining a duplex contract is to split each set in a separate interface and apply attributes to each interface. In this case, ContractDescription contains a reference to each of the interfaces that groups them into one duplex contract.

Similar to bindings, each contract has a Name and Namespace that uniquely identify it in the metadata of the service.

The following example shows a number of ways to create or retrieve a ContractDescription object. It then displays the various pieces of information that are stored in the ContractDescription object.

Uri baseAddress = new Uri("http://localhost:8001/Simple");
ServiceHost serviceHost = new ServiceHost(typeof(CalculatorService), baseAddress);

    new WSHttpBinding(),

// Enable Mex
ServiceMetadataBehavior smb = new ServiceMetadataBehavior();
smb.HttpGetEnabled = true;


ContractDescription cd0 = new ContractDescription("ICalculator");
ContractDescription cd1 = new ContractDescription("ICalculator", "");
ContractDescription cd2 = ContractDescription.GetContract(typeof(ICalculator));
CalculatorService calcSvc = new CalculatorService();
ContractDescription cd3 = ContractDescription.GetContract(typeof(ICalculator), calcSvc);
ContractDescription cd4 = ContractDescription.GetContract(typeof(ICalculator), typeof(CalculatorService));
ContractDescription cd = serviceHost.Description.Endpoints[0].Contract;         

Console.WriteLine("Displaying information for contract: {0}", cd.Name.ToString());

KeyedByTypeCollection<IContractBehavior> behaviors = cd.Behaviors;
Console.WriteLine("\tDisplay all behaviors:");
foreach (IContractBehavior behavior in behaviors)
    Console.WriteLine("\t\t" + behavior.ToString());

Type type = cd.CallbackContractType;

string configName = cd.ConfigurationName;
Console.WriteLine("\tConfiguration name: {0}", configName);

Type contractType = cd.ContractType;
Console.WriteLine("\tContract type: {0}", contractType.ToString());

bool hasProtectionLevel = cd.HasProtectionLevel;
if (hasProtectionLevel)
    ProtectionLevel protectionLevel = cd.ProtectionLevel;
    Console.WriteLine("\tProtection Level: {0}", protectionLevel.ToString());

string name = cd.Name;
Console.WriteLine("\tName: {0}", name);

string namespc = cd.Namespace;
Console.WriteLine("\tNamespace: {0}", namespc);

OperationDescriptionCollection odc = cd.Operations;
Console.WriteLine("\tDisplay Operations:");
foreach (OperationDescription od in odc)
    Console.WriteLine("\t\t" + od.Name);

SessionMode sm = cd.SessionMode;
Console.WriteLine("\tSessionMode: {0}", sm.ToString());

Collection<ContractDescription> inheretedContracts = cd.GetInheritedContracts();
Console.WriteLine("\tInherited Contracts:");
foreach (ContractDescription contractdescription in inheretedContracts)
    Console.WriteLine("\t\t" + contractdescription.Name);

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

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