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

2. References
Introducing WCF, David Chappell,
Using three diagrams from this reference
Programming Indigo, David Pallmann, Microsoft Press, 2005
Pro WCF, Peiris and Mulder, Apress, 2007

3. 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

4. Chappell, ibid, pg 14

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

6. Channel Shapes IOutputChannel IInputChannel IRequestChannel
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Channel Shapes
IOutputChannel
IInputChannel
IRequestChannel
IReplyChannel
3 types of Channel Shapes (BEANBAGS)
1. Datagram: Messages are “fire and forget”. (THROW BEANBAG OVER HEAD)
This is like sending a postcard in the mail (could get lost). Or like UDP. This is a building block for Messaging since arbitrary protocols can be built on top of it.
2. Request-Response: (THROW BACK AND FORTH BETWEEN KENNY AND YASSER)
Common MEP. RPC, browser GETs, etc.
3. Duplex: bi-directional communication. (KEEP THROWING IN RANDOM ORDER)
This is like speaking to a co-worker, etc.
* Also Session-ful variants of each of these protocols.
* Factories can support multiple shapes
For Request-Response you get an IRequestContext instead of a Message (this comment should go in later slides though, doesn’t matter for the overview)
IDuplexChannel
©2005 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.

7. Endpoints and Channels
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Endpoints and Channels
ServiceHost host = new ServiceHost(typeof(MyService));
Uri address
= new Uri(“net.tcp://kennyw2/Service/endpoint”);
Binding binding = new NetTcpBinding();
Type contract = typeof(IMyContract);
host.AddEndpoint(address, binding, contract);
host.Open();
©2005 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.

8. 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
net.tcp://someOtherURI
net.msmq://stillAnotherURI

9. Chappell, ibid, pg 25

10. 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); }

11. 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; } }

12. 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

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

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

15. 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

16. 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

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