OperationContractAttribute.Action Property

Gets or sets the WS-Addressing action of the request message.

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

public string Action { get; set; }

Property Value

Type: System.String
The action to use in generating the WS-Addressing Action header.


The value is null.

Use the Action property to control the action of the method's input message. Because Silverlight 5 uses this action to dispatch an incoming message to the appropriate method, messages used within a contract operation must have unique actions. The default action value is a combination of the contract namespace (the default value is "http://tempuri.org/"), the contract name (interface name or the class name, if no explicit service interface is used), the operation name, and an additional string ("Response") if the message is a correlated response. You can override this default with the Action property.

To indicate that a service operation handles all messages that the service receives but cannot be directed to a service operation, specify the value "*" (an asterisk). This type of operation, called an unmatched message handler, must have one of following method signatures, or a InvalidOperationException is thrown:

  • The service operation can take only a Message object and return a Message object.

  • The service operation can take only a Message object and return nothing (that is, return void).


A service contract can have only one service operation with the Action property set to "*". Any group of service contracts hosted at the same listenUri that a service class implements can have many service operations with the Action property set to "*" when the IsInitiating property is set to false. However, only one of those service operations can have the Action property set to "*" and the IsInitiating property set to true.

For more information, see


    // A service contract defined with a class
    // for an operation that handles all messages the service receives.
        Name = "SampleServiceContract2",
        Namespace = "http://microsoft.SL3.documentation")]
    public class CustomerService
        [OperationContract(Name = "SampleOperationContract1")]
        public int CountUsers()
            return 2;

        [OperationContract(Action = "*")]
        public User GetUser(int id)
            if (id == 1)
                return new User() { IsMember = true, Name = "Paul", Age = 24 };
                return new User() { IsMember = false, Name = "John", Age = 64 };

    public class User
        public bool IsMember { get; set; }

        public string Name { get; set; }

        public int Age { get; set; }


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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