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ServiceKnownTypeAttribute Class
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ServiceKnownTypeAttribute Class

Specifies known types to be used by a service when serializing or deserializing.

System.Object
  System.Attribute
    System.ServiceModel.ServiceKnownTypeAttribute

Namespace:  System.ServiceModel
Assemblies:   System.ServiceModel.Primitives (in System.ServiceModel.Primitives.dll)
  System.ServiceModel (in System.ServiceModel.dll)

[AttributeUsageAttribute(AttributeTargets.Class|AttributeTargets.Method|AttributeTargets.Interface, Inherited = true, 
	AllowMultiple = true)]
public sealed class ServiceKnownTypeAttribute : Attribute

The ServiceKnownTypeAttribute type exposes the following members.

  NameDescription
Public methodSupported by Portable Class LibraryServiceKnownTypeAttribute(String)Initializes a new instance of the ServiceKnownTypeAttribute class and specifies the name of a method that returns the known types.
Public methodSupported by Portable Class LibraryServiceKnownTypeAttribute(Type)Initializes a new instance of the ServiceKnownTypeAttribute class with the specified known type.
Public methodSupported by Portable Class LibraryServiceKnownTypeAttribute(String, Type)Initializes a new instance of the ServiceKnownTypeAttribute class with the name of a method that returns the known types and the type that contains the method (or methods) that returns the known types.
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  NameDescription
Public propertySupported by Portable Class LibraryDeclaringTypeGets the type that contains the methods that return the known types.
Public propertySupported by Portable Class LibraryMethodNameGets the name of a method that returns the collection of known types.
Public propertySupported by Portable Class LibraryTypeThe known type that can be included in an object graph.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodSupported by Portable Class LibraryEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Public methodSupported by Portable Class LibraryGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Public methodSupported by Portable Class LibraryToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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The ServiceKnownTypeAttribute is intended for use when creating Windows Communication Foundation (WCF) service contracts (interfaces that define the service and its methods). The known types are types that may be present in an object graph when serialization or deserialization occurs. For more information about known types, see Data Contract Known Types.

To use the MethodName property, create a class that contains a method (or methods) that returns an array of types (each being a known type). When applying the attribute, set the methodName to the name of a method that returns the list of types and set the declaringType to the type that contains the method. The method must return a type that implements the IEnumerable<T> interface. The method must also include a parameter of type ICustomAttributeProvider.

You can also apply the attribute several times to an interface, class, or method, each time specifying a new known type.

NoteNote

You can use the word ServiceKnownType in your Microsoft Visual Basic or C# code instead of the longer ServiceKnownTypeAttribute.

The following example applies the ServiceKnownTypeAttribute attribute to an interface where the attribute specifies a method name and a declaring type.

    // Define a service contract and apply the ServiceKnownTypeAttribute 
    // to specify types to include when generating client code.  
    // The types must have the DataContractAttribute and DataMemberAttribute 
    // applied to be serialized and deserialized. The attribute specifies the  
    // name of a method (GetKnownTypes) in a class (Helper) defined below.
    [ServiceKnownType("GetKnownTypes", typeof(Helper))]
    [ServiceContract()]
    public interface ICatalog
    {
        // Any object type can be inserted into a Hashtable. The  
        // ServiceKnownTypeAttribute allows you to include those types 
        // with the client code.
        [OperationContract]
        Hashtable GetItems();
    }

    // This class has the method named GetKnownTypes that returns a generic IEnumerable. 
    static class Helper
    {
        public static IEnumerable<Type> GetKnownTypes(ICustomAttributeProvider provider)
        {
            System.Collections.Generic.List<System.Type> knownTypes =
                new System.Collections.Generic.List<System.Type>();
            // Add any types to include here.
            knownTypes.Add(typeof(Widget));
            knownTypes.Add(typeof(Machine));
            return knownTypes;
        }
    }

    [DataContract()]
    public class Widget
    {
        [DataMember]
        public string Id;
        [DataMember]
        public string Catalog;
    }

    [DataContract()]
    public class Machine : Widget
    {
        [DataMember]
        public string Maker;
    }

Alternatively, apply the attribute to the interface specifying the known type to include.

// Apply the ServiceKnownTypeAttribute to the  
// interface specifying the type to include. Apply  
// the attribute more than once if needed.
[ServiceKnownType(typeof(Widget))]
[ServiceKnownType(typeof(Machine))]
[ServiceContract()]
public interface ICatalog2
{
    // Any object type can be inserted into a Hashtable. The  
    // ServiceKnownTypeAttribute allows you to include those types 
    // with the client code.
    [OperationContract]
    Hashtable GetItems();
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library

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