2. CON 413 Justin Smith Technical Evangelist http://blogs.msdn.com/justinjsmith

3. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher and Behaviors

4. Receiver Channels Sender Proxy Sender Application Dispatcher Receiver Application Channel Layer ServiceModel Layer Channels

5. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher and Behaviors

6. Abstraction of messaging functionality Transport, security, transaction options, protocols Creates a collection of BindingElement objects Arrangement in collection is important NetTcpBinding b = new NetTcpBinding(); foreach (BindingElement el in b.CreateBindingElements()) { Console.WriteLine(el.GetType().Name); } // outputs TransactionFlowBindingElement // protocol BinaryMessageEncodingBindingElement // encoding WindowsStreamSecurityBindingElement // security TcpTransportBindingElement // transport

7. Create Channel Listeners & Channel Factories listeners on receiver / factories on sender collectively known as Channel Managers Collection creates a stack (listeners/factories) via BindingContext and CustomBinding types BindingContext keeps a mutable list of BindingElement objects in Collection CustomBinding is isomorphic

8. Channel Factory Stack BindingContext CustomBinding NetTcpBinding TransactionFlowBindingElement BinaryMessageEncodingBindingElement WindowsStreamSecurityBindingElement TcpTransportBindingElement BuildChannelFactory BuildInnerChannelFactory TcpChannelFactory TransactionFlowChannelFactory Encoding and StreamSecurity absorbed by TcpChannelFactory via BindingContext

9. public abstract class Binding : IDefaultCommunicationTimeouts { public virtual IChannelFactory BuildChannelFactory ( BindingParameterCollection parameters) { BindingContext context1 = new BindingContext(new CustomBinding(this), parameters); IChannelFactory factory1 = context1.BuildInnerChannelFactory (); return factory1; } // creates BindingContext, then calls BuildInnerChannelFactory } public class BindingContext { public IChannelFactory BuildInnerChannelFactory () { return this.RemoveNextElement().BuildChannelFactory (this); } // removes B.E. from list, then calls BuildChannelFactory on it } public class MyBindingElement : BindingElement { public virtual IChannelFactory BuildChannelFactory (BindingContext c) { return new MyChannelFactory (c); // ctor calls context’s } // returns the Channel Factory // BuildInnerChannelFactory }

10. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher and Behaviors

11. Create sending Channels Stack of Channel Factories creates Channel stack Channel Factory stack is opaque GetProperty allows some query capabilities Each Channel Factory in stack: Refers to the next Channel Factory Delegates GetProperty calls when unknown EndpointAddress needed in channel stack Uri for Via can be used as well

12. Listens for incoming messages & Creates receiving channel stacks Bottom-most Channel Listener listens on transport Embrace “Accept” semantics similar to sockets “Accept” returns a Channel Listener stacks are opaque Symmetry with Channel Factory design

13. Channel Stack CreateChannel Channel Factory Stack TcpChannelFactory TransactionChannelFactory CreateChannel TcpChannel TransactionChannel From a Channel Factory: From a Channel Listener: Channel Listener Stack TcpChannelListener TransactionChannelListener AcceptChannel Channel Stack TcpChannel TransactionChannel AcceptChannel message passing to channel stack not precise

14. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher and Behaviors

15. Sends and/or receives Message objects For specific transport or protocol functionality Commonly stacked w / other Channel objects Have shape described by interfaces MEP (datagram, request/reply, duplex) Composition of channel stack dictates messaging functionality

16. SenderReceiver CreateSequence CreateSequenceResponse (ID) X Sequence (ID, Msg #2) Sequence (ID, Msg #1) Sequence (ID, Msg #3, LastMessage) SequenceAck (ID, Msg #1, Msg #3) Sequence (ID, Msg #2, AckRequested) SequenceAck (ID, Msg #1 - Msg #3) TerminateSequence (ID)

17. Sending Application Channel Stack Receiving Application Sequence (#2, LastMessage) CreateSequence / CreateSequenceResponse Sequence (#1)Ack (Msg #1-2) Client HttpRequestChannel ReliableOutputSessionChannel TerminateSequence

18. Channel Managers and Channels have shape Shape represents the supported MEP(s) Datagram, Request/Reply, Duplex WCF represents shape via interfaces Datagram: IInputChannel, IOutputChannel Request / Reply: IRequestChannel, IReplyChannel Duplex: IDuplexChannel Sessionful variants also exist Interfaces have common type hierarchy

19. public interface IInputChannel : IChannel, ICommunicationObject { Message Receive(); // standard Begin / End methods also exist (and timeouts)... } public interface IOutputChannel : IChannel, ICommunicationObject { void Send(Message msg); // standard Begin / End methods also exist (and timeouts)... } public interface IDuplexChannel : IInputChannel, IOutputChannel, IChannel, ICommunicationObject { } public interface IRequestChannel : IChannel, ICommunicationObject { Message Request(Message msg); // standard Begin / End methods also exist (and timeouts)... } // IReplyChannel omitted for clarity

20. Channels and Channel Managers have a common state machine (also Faulted state) Predictable state transitions

21. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher Behaviors

22. Fundamental unit of communication Channel layer interacts with Message objects Seldom surfaces to the contract CLR abstraction of a SOAP message Body can be streamed, headers buffered Can do non-SOAP formats (POX, JSON) public abstract class Message : IDisposable { public static Message CreateMessage(MessageVersion v, String a) {…} // lots of factory methods public void WriteMessage(XmlDictionaryWriter writer) {} // lots of write and read methods public abstract MessageHeaders Headers { get; } }

23. EnvelopeVersion identifies SOAP specs 1.1, 1.2, none AddressingVersion identifies WS- Addressing Aug 2004, 1.0, none MessageVersion wraps both None == no SOAP please

24. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher and Behaviors

25. An abstract type derived from XmlWriter Wraps a System.IO.Stream Created via factory methods Specialized for binary, MTOM, text, JSON MemoryStream stream = new MemoryStream(); XmlDictionaryWriter dictionaryWriter = XmlDictionaryWriter.CreateTextWriter(stream, Encoding.UTF8, false); dictionaryWriter.WriteElementString("localname", “http://namespace", "someValue"); dictionaryWriter.Flush();

26. An abstract type derived from XmlReader Wraps a System.IO.Stream or buffer Created via factory methods Specialized for binary, MTOM, text, JSON // Continued from previous slide stream.Position = 0; XmlDictionaryReader reader = XmlDictionaryReader.CreateTextReader(stream); reader.Read(); Console.WriteLine(reader.ReadOuterXml());

27. MemoryStream stream = new MemoryStream(); using (XmlDictionaryWriter writer = XmlDictionaryWriter.CreateTextWriter(stream, Encoding.UTF8, false)) { writer.WriteStartDocument(); writer.WriteElementString(“SongName”, “urn:ContosoRockabilia”, “Aqualung”); writer.Flush(); } // then read from Stream XmlDictionaryWriter (Text-UTF8) wrote 97 bytes 3C-3F-78-6D-6C-20-76-65-72-73-69-6F-6E-3D-22-31-2E- 30-22-20-65-6E-63-6F-64-69-6E-67-3D-22-75-74-66-2D- 38-22-3F-3E-3C-53-6F-6E-67-4E-61-6D-65-20-78-6D-6C- 6E-73-3D-22-75-72-6E-3A-43-6F-6E-74-6F-73-6F-52-6F- 63-6B-61-62-69-6C-69-61-22-3E-41-71-75-61-6C-75-6E- 67-3C-2F-53-6F-6E-67-4E-61-6D-65-3E data read from stream: Aqualung

28. MemoryStream stream = new MemoryStream(); using (XmlDictionaryWriter writer = XmlDictionaryWriter.CreateBinaryWriter(stream, null, null)) { writer.WriteStartDocument(); writer.WriteElementString(“SongName”, “urn:ContosoRockabilia”, “Aqualung”); writer.Flush(); } // then read from Stream XmlDictionaryWriter (Binary) wrote 43 bytes 3F-08-53-6F-6E-67-4E-61-6D-65-04-15-75-72-6E-3A-43- 6F-6E-74-6F-73-6F-52-6F-63-6B-61-62-69-6C-69-61-A1- 08-41-71-75-61-6C-75-6E-67 data read from stream: N/A

29. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher and Behaviors

30. Known as Encoding Via MessageEncoder and XmlWriter MessageEncoder use Message.WriteMessage Message.WriteMessage uses XmlWriter public class MyEncoder : MessageEncoder { public override void WriteMessage(Message msg, Stream stream){ XmlWriter writer = XmlWriter.CreateWriter(stream); msg.WriteMessage(writer); writer.Flush(); } // other members omitted }

31. Known as Decoding Done via ReadMessage uses one of the Message.CreateMessage overloads CreateMessage overload accepts an XmlReader public class MyEncoder : MessageEncoder { public override Message ReadMessage(Stream st, Int32 s, String ct){ XmlReader reader= XmlReader.Create(st); MessageVersion version = MessageVersion.Soap12WSAddressing10; return Message.CreateMessage(reader, s, version); } // other members omitted }

32. Channel Message Encoder Channel Message Encoder WriteMessage Sender Receiver Message XmlWriter Message ReadMessage XmlReaderBytes Message

34. Bindings Channel Managers Channels Messages XmlWriters and XmlReaders Message Encoders Dispatcher and Behaviors

35. In the abstract, the Dispatcher hides from the receiver the fact that the receiving application is receiving messages The Dispatcher is the realm of the contract Messages go in, Parameters come out, and a method is invoked Receiver Dispatcher Receiving Application Protocol / Shaping / Transport Channels Parameters

36. Message Inspection Service Behaviors Operation Selector Message Formatting Operation Invoker Channel Method1(…) DispatchOperation Method2(…) DispatchOperation DispatchRuntime Parameter Inspection Operation Behaviors

37. To extend the Dispatcher, define a type that implements one of the following IOperationInvoker Invokes method on target object IDispatchMessageFormatter to control format of the Message IDispatchOperationSelector to select operation on target object IDispatchMessageInspector to inspect the Message IParameterInspector

38. 1. Define a type that implements one of the previous interfaces 2. Define a type that implements one of the Behavior interfaces and instantiates the type in Step # 1 3. Add the Behavior from Step #2 to the description via the appropriate place in the ServiceDescription 4. OPTIONAL – add configuration support 5. OPTIONAL – add support for attribute annotation

39. Enables control over the invocation of a method on the receiving object public interface IOperationInvoker { bool IsSynchronous { get; } object[] AllocateInputs(); object Invoke(object instance, object[] inpts, out object[] outputs); IAsyncResult InvokeBegin(object instance, object[] inpts, AsyncCallback cbck, object state); object InvokeEnd(object instance, out object[] outputs, IAsyncResult result); }

40. Enables control over received Message deserialization and outbound Message serialization SerializeReply returns a serialized Message object DeserializeRequest returns an Object deserialized from the Message MessageVersion fed from the Binding SerializeReply is not invoked if operation is OneWay public interface IDispatchMessageFormatter { void DeserializeRequest(Message msg, object[] parameters); Message SerializeReply(MessageVersion version, object[] parameters, object result); }

41. Enables the selection of a particular DispatchOperation SelectOperation returns the name of the method associated with the DispatchOperation Normally loaded from the ContractDescription public interface IDispatchOperationSelector { String SelectOperation(ref Message message); }

42. Enables a last view of the Message before it is sent into the Channel stack and at the point when the reply surfaces Notice that the Message is passed by reference Be careful of Message state transitions Request and Reply messages can be correlated manually If the operation is OneWay, BeforeReceiveReply not invoked public interface IDispatchMessageInspector { Object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext); void BeforeSendReply(ref Message reply, object correlationState); }

43. Enables the inspection of parameters before the request is deserialized or the reply is serialized BeforeCall invoked before the Message is deserialized into parameters AfterCall invoked after the reply is sent If the operation is a OneWay operation, then AfterCall is not invoked BeforeCall and AfterCall can be correlated via an Object public interface IParameterInspector { void AfterCall(String operationName, Object[] outputs, Object returnValue, Object correlationState); Object BeforeCall(String operationName, Object[] inputs); }

44. IDispatchOperationSelector IDispatchMessageInspector IOperationInvoker IDispatchMessageFormatter IDispatchMessageInspector IDispatchMessageFormatter IParameterInspector Sender IParameterInspector IOperationInvoker