10 Tricks and Tips for WCF (Presented at DDD, Dec 08)

1. Top 10 Tricks & Tips for WCF
Barry Dorrans
http://idunno.org

2. About the Speaker
(the ego slide)
MVP – Visual Tools, Security
barryd@idunno.org

3. Agenda
1) The test harnesses
2) Don’t use Using
3) It’s all your fault
4) Migrating an ASMX
5) Message Inspectors
6) Custom Authentication
7) Port sharing
8) Callbacks
9) Logging
10) RESTful services

4. What is WCF?
Indigo
Replaces Web Services, WSE &
Remoting
Interoperability

5. The ABCs of WCF
Address
Binding
Contract

6. Service Model
Client Server
Messaging Layer
Endpoint
Address Binding Channel
Behaviour Behaviour
Contract Binding Binding Channel
Behaviour Behaviour
Factory Listener
Channel Address Address Channel
*

7. Address
scheme:// <machineName>[:port]/path
http://localhost:8080/Account/
net.tcp://localhost:8080/Account

8. Binding
How you communicate with a service
A service may have multiple bindings
Defines the shape; security etc.

9. Contract
The external interface
Contracts for service, data and message

10. The ABCs
Address = WHERE
Binding = HOW
Contract = WHAT

11. Service Contracts
[ServiceContract()]
public interface IMyService
{
[OperationContract]
string MyOperation1(string myValue);
[OperationContract]
string MyOperation2(MyDataContract value);
}

12. Data Contracts
[DataContract]
public class MyDataContract
{
string _stuff;
[DataMember]
public string Stuff
{
get { return _stuff; }
set { stuff = value; }
}
}

13. 1 – The test harnesses

14. 2 – Don’t use Using

15. Disposing the right way
Service1Client proxy = null;
try
{
proxy = new Service1Client(....);
}
catch (...)
finally
{
if (proxy != null)
{
try
{
if (proxy.State == CommunicationState.Opened)
proxy.Close();
else if (proxy.State == CommunicationState.Faulted)
proxy.Abort();
}
catch (CommunicationException)
{
proxy.Abort();
}
catch (TimeoutException)
{
proxy.Abort();
}
}
}

16. 3 - It’s all your fault

17. Faults the right way
In Contract Code
[ServiceContract]
public interface IService1
{
[OperationContract]
[FaultContract(typeof(NegativeNumberFault))]
string GetDataWithFault(int value);
}
[DataContract]
public class NegativeNumberFault
{
}
In Service Code
throw new FaultException<NegativeNumberFault>(
new NegativeNumberFault(),
new FaultReason(quot;value was negativequot;));
In Client Code
try
{
....
}
catch (FaultException<NegativeNumberFault>)
{
....
}

18. 4 – Migrating an ASMX

19. Migrating an ASMX
1. Change the protocol binding to
basicHttpBinding
2. Match your namespaces
[ServiceContract(Namespace=quot;http:/tempuri.org/quot;)]
3. Match your actions
[OperationContract(Action = quot;http://tempuri.org/HelloWorldquot;)]
4. Match your message names (if you use them)
[OperationContract(Action = quot;http://tempuri.org/HelloWorldquot;,
Name = quot;MyMessageNamequot;)]
5. Change the serializer to use XmlSerializer
[XmlSerializerAttribute]
public class MyService

20. Migrating an ASMX
6. Make WCF answer ASMX
<buildProviders>
<remove extension=quot;.asmxquot;/>
<add extension=quot;.asmxquot;
type=quot;System.ServiceModel.Activation.ServiceBuildProvider,
System.ServiceModel, Version=3.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089quot;/>
</buildProviders>

21. 5 – Message Inspectors

22. Message Inspectors
1. Can be client or server side
2. Messages can be modified – but you must copy
the message then replace it.
3. Apply the custom behaviour via config or via
an attribute.

23. 6 – Custom Authentication

24. Custom Authentication
1. Reference System.IdentityModel and
System.IdentityModel.Selectors
2. Implement a UsernamePasswordValidator
3. Plug it in via config

25. 7 – Port Sharing

26. Port Sharing
1. Vista / Windows 2008 –
netsh http add urlacl
url=http://+:port/url/
user=Everyone
2. XP / Windows 2003 (Support Tools)–
httpcfg set urlacl
/u http://*:80/url/
/a D:(A;;GX;;;NS)
3. XP does not port share with IIS.

27. 8 – Callbacks

28. Callbacks
1. Publish / Subscribe model works best
2. Declare a callback interface
interface IMessageCallback
{
[OperationContract(IsOneWay = true)]
void OnMessageAdded(string message, DateTime timestamp);
}
3. Add the callback to the service contract.
[ServiceContract(CallbackContract = typeof(IMessageCallback))]
4. Implement callback interface on client.

29. 9 - Logging

30. 10 – RESTful services

31. RESTful services
1. Reference System.ServiceModel.Web
2. Use WebHttpBinding and WebHttpBehavior
3. Decorate contract with WebGet or WebInvoke
[OperationContract]
[WebInvoke(Method = quot;POSTquot;, UriTemplate = quot;quot;)]
void AddMessage(Message message);
[OperationContract]
[WebInvoke(Method = quot;DELETEquot;, UriTemplate = quot;{id}quot;)]
void DeleteMessage(string id);
[OperationContract]
[WebGet(UriTemplate = quot;{id}quot;)]
Message GetMessage(string id);
[OperationContract]
[WebGet(UriTemplate = quot;quot;)]
List<Message> GetMessages();

32. RESTful services
4. Avoid the hassle and use the REST starter kit
http://msdn.microsoft.com/en-us/netframework/wcf/rest

33. Questions?