Windows Communication Foundation (WCF) Jim Fawcett CSE775 – Distributed Objects Spring 2007

References Introducing WCF, David Chappell, www.davidchappell.com/IntroducingWCFv1.2.1.pdf Using three diagrams from this reference Programming Indigo, David Pallmann, Microsoft Press, 2005 Pro WCF, Peiris and Mulder, Apress, 2007

What is WCF? Integration of several Microsoft Technologies: Web services (ASMX) Web service extensions (WSE) WS-Security WS-Reliability WS-Addressing .Net Remoting MSMQ messaging COM+ Transactions

Chappell, ibid, pg 14

Channel Model WCF supports three types of channel activity: Asysnchronous one-way Request, wait for reply Full duplex two-way

Structure Service Contract Binding Address Service contract – RPC Interface Data contract – Type serialization Message contract – Soap message Binding Transport – HTTP, TCP, MSMQ, … Channel type – one-way, duplex, request-reply Encoding – XML, binary, MTOM (msg trans optim mech) WS-* protocols – WS-Security, … Address http://someURI net.tcp://someOtherURI net.msmq://stillAnotherURI

Chappell, ibid, pg 25

Channel Interfaces public interface IOutputChannel : IChannel { void Send(Message msg); } public interface IInputChannel : IChannel { Message Receive(); } public interface IDuplexChannel : IOutputChannel, IInputChannel {} public interface IRequestChannel : IChannel { Message Request(Message msg); } public interface IReplyChannel : IChannel { IRequestContext ReceiveRequest(); } public interface IRequestContext : Idisposable { Message RequestMessage { get; } void Reply(Message msg); }

Service Contract <%@ ServiceHost Language=“C#” Service=“MyService” %> [ServiceContract] public interface IMyService { [OperationContract] string Hello( string name); } public class MyService : IMyService { public string Hello(string name) { return “Hello “ + name; } }

Hosts WCF Services can be hosted in: Internet Information Services (IIS) Very similar to web services Windows services Exposing windows service in style of WS Console and Winform applications New style for socket like functionality

Monitoring Services Message Logging WCF Performance counters Calls, CallsOutsantding, CallsErrored, … SecurityCallsNotAuthenticated, … TxCommitted, TxAborted, … RMSessionsStarted, RMSessionsFaulted, … Windows Management Instrumentation (WMI), a COM technology

Other Topics WCF Security Credentials and claims (evidence) Transport-level security Message-level security Federated security model Authorization Auditing

Reliable Messaging ReliableSession enabled MSMQ Binding Implemented at the SOAP level not TCP packet Very similar to TCP functionality Messages not sent are held in a Transfer Window cache Will have problems with large messages MSMQ Binding Needs microsoft platforms on both ends Supports store and forward

Other Features WCF Supports transactions ACID properties Atomicity composite operations treated as a unit Consistency Operations succeed or the system is returned to prior state Isolation Each transaction is independent and isolated from other transactions Durability If an operation succeeds it becomes durable, e.g., committed to a database or other persistant store

Conclusion Convergence of programming models Flexible hosting options Desktop Application Web Application Windows Services Flexible hosting options Flexible abstractions