Indicates that an interface or a class defines a service contract in a Silverlight client application.
Assembly: System.ServiceModel (in System.ServiceModel.dll)
Thetype exposes the following members.
|CallbackContract||Gets or sets the type of callback contract when the contract is a duplex contract.|
|ConfigurationName||Gets or sets the name used to locate the service in an application configuration file.|
|Name||Gets or sets the name for the <portType> element in Web Services Description Language (WSDL).|
|Namespace||Gets or sets the namespace of the <portType> element in Web Services Description Language (WSDL).|
|Equals||Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)|
|Finalize||Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)|
|GetHashCode||Returns the hash code for this instance. (Inherited from Attribute.)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|Match||When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)|
|MemberwiseClone||Creates a shallow copy of the current Object. (Inherited from Object.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
Use the attribute on an interface (or class) to define a service contract. Then use the OperationContractAttribute attribute on one or more of the class (or interface) methods to define the contract's service operations.
The information expressed by a and its interface are loosely related to the Web Services Description Language (WSDL) <portType> element. A service contract is used on the service to specify what the service’s endpoint exposes to callers. It is also used on the client to specify the contract of the endpoint with which the client communicates.
An interface or class that is marked with must also have at least one method marked with the OperationContractAttribute attribute to expose any functionality. See the Examples section for a code example of the most basic use of the two attributes to define and implement a service.
Use the properties to modify the service contract.
The CallbackContract property specifies the return contract in a two-way (duplex) conversation.
Services implement service contracts, which represent the data exchange that a service type supports. A service class can implement a service contract (by implementing an interface marked with that has methods marked with OperationContractAttribute) or it can be marked with the and apply the OperationContractAttribute attribute to its own methods. (If a class implements an interface marked with , it cannot be itself marked with .) Methods on service types that are marked with the OperationContractAttribute are treated as part of a default service contract specified by the service type itself.
For more information aboutservice operations, see OperationContractAttribute.
By default, the Name and Namespace properties are the name of the contract type and http://tempuri.org, respectively. It is recommended that service contracts explicitly set their names and namespaces using these properties. Doing so builds a contract that is not directly connected to the managed type information, enabling you to re-factor your managed code and namespaces without breaking the contract as it is expressed in WSDL.
Clients either use the service contract interface (the interface marked with ) to create a channel to the service or they use the client objects (which combine the type information of the service contract interface with the ClientBase(Of TChannel) class) to communicate with your service.
Using a class or interface to inherit from another class or interface extends the parent contract. For example, if an IChildContract interface is marked with and inherited from another service contract interface, IParentContract, the IChildContract service contract contains the methods of both IParentContract and IChildContract. Extending contracts (whether on classes or interfaces) is very similar to extending managed classes and interfaces.
The most flexible approach to creating clients is to define service contract interfaces first and then have your client class implement that interface. Building clients directly by marking a class with and its methods with OperationContractAttribute works as well.
'The following code contains an example of a duplex contract that contains a callback contract. <ServiceContract(Name := "SampleContract", Namespace := "Silverlight", CallbackContract := GetType(IDuplexClient))> _ Public Interface IDuplexService <OperationContract(IsOneWay := True)> _ Sub Order(ByVal name As String, ByVal quantity As Integer) End Interface <ServiceContract> _ Public Interface IDuplexClient <OperationContract(IsOneWay := True)> _ Sub Receive(ByVal order As Order) End Interface Public Class Order Private privateStatus As OrderStatus Public Property Status() As OrderStatus Get Return privateStatus End Get Set(ByVal value As OrderStatus) privateStatus = value End Set End Property Private privatePayload As List(Of String) Public Property Payload() As List(Of String) Get Return privatePayload End Get Set(ByVal value As List(Of String)) privatePayload = value End Set End Property End Class Public Enum OrderStatus Processing Completed End Enum
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.