Which WCF Attribute Specifies That the Data Type Can Be Used by Client Application?

When working with Windows Communication Foundation (WCF), it is often necessary to specify the data types that can be used by client applications. This can be achieved using the ServiceKnownType attribute in WCF.

The ServiceKnownType attribute allows you to specify additional types that should be known to the service and can be used by client applications. By default, only the types explicitly marked with DataContract or Serializable attributes are considered known types.

To specify a data type that can be used by a client application, you need to apply the ServiceKnownType attribute to the service contract interface or service implementation class.

Syntax of ServiceKnownType Attribute:

The syntax of the ServiceKnownType attribute is as follows:

[ServiceKnownType(typeof(Type))]
public interface IServiceContract
{
    // Service contract definition..
}

In the above syntax, you need to replace Type with the actual data type that should be known to the service.

An Example:

To understand how to use the ServiceKnownType, let’s consider an example where we have a service contract named IProductService. This service contract defines a method named GetProductDetails(), which returns a list of products. The product entity has two properties:

• Name (string)
• Description (string)

If we want our client application to also know about another data type called Currency, we can use the ServiceKnownType attribute as follows:

[ServiceKnownType(typeof(Currency))]
public interface IProductService
{
    [OperationContract]
    List<Product> GetProductDetails();
}

In the above example, we have specified that the Currency type should be known to the service and can be used by client applications.

Conclusion:

The ServiceKnownType attribute is an essential attribute in WCF that allows you to specify additional data types that can be used by client applications. By using this attribute, you can ensure that your service contracts are aware of all the necessary data types required by client applications.

By properly utilizing the ServiceKnownType attribute, you can enhance the interoperability and flexibility of your WCF services.