Windows Communication Foundation WCF Jim Fawcett CSE 775

Windows Communication Foundation (WCF) Jim Fawcett CSE 775 – Distributed Objects Spring 2007

References n Introducing WCF, David Chappell, www. davidchappell. com/Introducing. WCFv 1. 2. 1. pdf – Using three diagrams from this reference n n Programming Indigo, David Pallmann, Microsoft Press, 2005 Pro WCF, Peiris and Mulder, Apress, 2007

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

Chappell, ibid, pg 14

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

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

Chappell, ibid, pg 25

Channel Interfaces n public interface IOutput. Channel : IChannel { void Send(Message msg); } n public interface IInput. Channel : IChannel { Message Receive(); } n public interface IDuplex. Channel : IOutput. Channel, IInput. Channel {} n public interface IRequest. Channel : IChannel { Message Request(Message msg); } n public interface IReply. Channel : IChannel { IRequest. Context Receive. Request(); } n public interface IRequest. Context : Idisposable { Message Request. Message { get; } void Reply(Message msg); }

Service Contract n <%@ Service. Host Language=“C#” Service=“My. Service” %> [Service. Contract] public interface IMy. Service { [Operation. Contract] string Hello( string name); } public class My. Service : IMy. Service { public string Hello(string name) { return “Hello “ + name; } }

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

Monitoring Services n n Message Logging WCF Performance counters – – n Calls, Calls. Outsantding, Calls. Errored, … Security. Calls. Not. Authenticated, … Tx. Committed, Tx. Aborted, … RMSessions. Started, RMSessions. Faulted, … Windows Management Instrumentation (WMI), a COM technology

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

Reliable Messaging n Reliable. Session enabled – – – 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 n MSMQ Binding – Needs microsoft platforms on both ends – Supports store and forward

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

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