.NET serializer and WCF bindings for AMF with full Flex compatibility. Just add AMF endpoints to your existing WCF services and you are ready to go.
C#
Latest commit 3b5f199 Nov 29, 2015 @artema Added NuGet packages.

README.md

NuGet packages: DotAmf (serializer) and DotAmf.Wcf (service layer).

About

.NET serializer and WCF bindings for AMF with full Flex remoting support.

Action Message Format (AMF) is a binary format used to serialize object graphs such as ActionScript objects and XML, or send messages between an Adobe Flash client and a remote service, usually a Flash Media Server or third party alternatives. The Actionscript 3 language provides classes for encoding and decoding from the AMF format.

http://en.wikipedia.org/wiki/Action_Message_Format

AMF has several advantages over existing serialization formats, including the ability to maintain objects graph, a small footprint when storing a set of identical objects (including strings) or references to the same object, and a wide range of natively supported types (such as XmlDocument, DateTime and Dictionary).

WCF Configuration

Consider the following service contracts:

    using System;
    using System.Runtime.Serialization;
    using System.ServiceModel;
    using System.Xml;

    namespace ExampleService
    {
        [ServiceContract]
        public interface IMyService
        {
            [OperationContract]
            ProductVo[] GetAllProducts();

            [OperationContract(Name = "GetUser")] //Custom procedure name
            User GetUserDataContract(int id);

            [OperationContract]
            int AddUser(User user);

            [OperationContract]
            Content SendContent(Content content);

            [OperationContract]
            User[] SendGraph(User[] users);

            [OperationContract]
            void DoStuff();

            [OperationContract]
            [FaultContract(typeof(CustomFault))]
            void DoFault();
        }

        [DataContract] //Will have the "ExampleService.User" alias
        public class User
        {
            [DataMember(Name = "id")] //Custom field name
            public int Id { get; set; }

            [DataMember(Name = "is_active")]
            public bool IsActive { get; set; }

            [DataMember] //Use explicit name
            public string name { get; set; }

            [DataMember(Name = "products")]
            public ProductVo[] Products { get; set; }
        }

        [DataContract(Name = "Product")] //Custom alias
        public class ProductVo
        {
            [DataMember(Name = "id")]
            public int Id { get; set; }
        }

        [DataContract]
        public class CustomFault
        {
            [DataMember(Name = "date")]
            public DateTime Date { get; set; }

            [DataMember(Name = "message")]
            public string Message { get; set; }
        }

        [DataContract]
        public class Content
        {
            [DataMember(Name = "data")]
            public byte[] Data { get; set; }

            [DataMember(Name = "xml")]
            public XmlDocument Xml { get; set; }
        }
    }

To add an AMF support to a service, you only need to update your configuration:

<?xml version="1.0"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <extensions>
      <behaviorExtensions>
        <add name="amfBehaviorExtension" type="DotAmf.ServiceModel.Configuration.AmfBehaviorExtensionElement, DotAmf.Wcf"/>
      </behaviorExtensions>
      <bindingElementExtensions>
        <add name="amfBindingExtension" type="DotAmf.ServiceModel.Configuration.AmfBindingExtensionElement, DotAmf.Wcf"/>
      </bindingElementExtensions>
    </extensions>
    <behaviors>
      <endpointBehaviors>
        <behavior name="amfEndpoint">
          <amfBehaviorExtension/>
        </behavior>
      </endpointBehaviors>
      <serviceBehaviors>
        <behavior name="amfServiceBehavior">
          <serviceMetadata httpGetEnabled="false"/>
          <serviceDebug includeExceptionDetailInFaults="true" httpHelpPageEnabled="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <bindings>
      <customBinding>
        <binding name="amfBinding">
          <amfBindingExtension/>
          <httpTransport/>
        </binding>
      </customBinding>
    </bindings>
    <services>
      <service name="ExampleService.MyService" behaviorConfiguration="amfServiceBehavior">
        <endpoint address="" contract="ExampleService.IMyService" binding="customBinding" bindingConfiguration="amfBinding" behaviorConfiguration="amfEndpoint"/>
      </service>
    </services>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true"/>
  </system.serviceModel>
 <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
    <directoryBrowse enabled="false"/>
  </system.webServer>
</configuration>

See the Examples folder for a complete service and client implementations.

Serialization

You can use DataContractAmfSerializer to serialize and deserialize from binary AMF data outside of the WCF.

CustomType objectToWrite;

var knownTypes = new[] {
    typeof(KnownType1),
    typeof(KnownType2)
};
var serializer = new DataContractAmfSerializer(typeof(CustomType), knownTypes);

using (var stream = new MemoryStream())
    serializer.WriteObject(stream, objectToWrite);