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How can we Host WCF Services?
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They are
1. IIS
2. Self Hosting
3. WAS (Windows Activation Service)
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What are different elements of WCF Srevices Client configuration file?
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WCF Services client configuration file contains endpoint, address, binding and contract. A sample client config file looks like
<system.serviceModel>
<client>
<endpoint name = "MyEndpoint"
address = "http://localhost:8000/MyService/"
binding = "wsHttpBinding"
contract = "IMyContract"
/>
</client>
</system.serviceModel>
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How to define a service as REST based service in WCF?
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WCF 3.5 provides explicit support for RESTful communication using a new binding named WebHttpBinding.
The below code shows how to expose a RESTful service
[ServiceContract]
interface IStock
{
[OperationContract]
[WebGet]
int GetStock(string StockId);
}
By adding the WebGet Attribute, we can define a service as REST based service that can be accessible using HTTP GET operation.
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What are contracts in WCF?
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In WCF, all services expose contracts. The contract is a platform-neutral and standard way of describing what the service does.
WCF defines four types of contracts.
Service contracts
Describe which operations the client can perform on the service.
There are two types of Service Contracts.
ServiceContract - This attribute is used to define the Interface.
OperationContract - This attribute is used to define the method inside Interface.
[ServiceContract]
interface IMyContract
{
[OperationContract]
string MyMethod( );
}
class MyService : IMyContract
{
public string MyMethod( )
{
return "Hello World";
}
}
Data contracts
Define which data types are passed to and from the service. WCF defines implicit contracts for built-in types such as int and string, but we can easily define explicit opt-in data contracts for custom types.
There are two types of Data Contracts.
DataContract - attribute used to define the class
DataMember - attribute used to define the properties.
[DataContract]
class Contact
{
[DataMember]
public string FirstName;
[DataMember]
public string LastName;
}
If DataMember attributes are not specified for a properties in the class, that property can't be passed to-from web service.
Fault contracts
Define which errors are raised by the service, and how the service handles and propagates errors to its clients.
Message contracts
Allow the service to interact directly with messages. Message contracts can be typed or untyped, and are useful in interoperability cases and when there is an existing message format we have to comply with.
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How to deal with operation overloading while exposing the WCF services?
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By default overload operations (methods) are not supported in WSDL based operation. However by using Name property of OperationContract attribute, we can deal with operation overloading scenario.
[ServiceContract]
interface ICalculator
{
[OperationContract(Name = "AddInt")]
int Add(int arg1,int arg2);
[OperationContract(Name = "AddDouble")]
double Add(double arg1,double arg2);
}
Notice that both method name in the above interface is same (Add), however the Name property of the OperationContract is different. In this case client proxy will have two methods with different name AddInt and AddDouble.
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How to set the timeout property for the WCF Service client call?
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The timeout property can be set for the WCF Service client call using binding tag.
<client>
<endpoint
...
binding = "wsHttpBinding"
bindingConfiguration = "LongTimeout"
...
/>
</client>
<bindings>
<wsHttpBinding>
<binding name = "LongTimeout" sendTimeout = "00:04:00"/>
</wsHttpBinding>
</bindings>
If no timeout has been specified, the default is considered as 1 minute.
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How to configure Reliability while communicating with WCF Services?
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Reliability can be configured in the client config file by adding reliableSession under binding tag.
<system.serviceModel>
<services>
<service name = "MyService">
<endpoint
address = "net.tcp://localhost:8888/MyService"
binding = "netTcpBinding"
bindingConfiguration = "ReliableCommunication"
contract = "IMyContract"
/>
</service>
</services>
<bindings>
<netTcpBinding>
<binding name = "ReliableCommunication">
<reliableSession enabled = "true"/>
</binding>
</netTcpBinding>
</bindings>
</system.serviceModel>
Reliability is supported by following bindings only
NetTcpBinding
WSHttpBinding
WSFederationHttpBinding
WSDualHttpBinding
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What is address in WCF and how many types of transport schemas are there in WCF?
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Address is a way of letting client know that where a service is located. In WCF, every service is associated with a unique address. This contains the location of the service and transport schemas.
WCF supports following transport schemas
HTTP
TCP
Peer network
IPC (Inter-Process Communication over named pipes)
MSMQ
The sample address for above transport schema may look like
http://localhost:81
http://localhost:81/MyService
net.tcp://localhost:82/MyService
net.pipe://localhost/MyPipeService
net.msmq://localhost/private/MyMsMqService
net.msmq://localhost/MyMsMqService
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What is service and client in perspective of data communication?
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A service is a unit of functionality exposed to the world.
The client of a service is merely the party consuming the service.
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Is it possible to host Tcp endpoint wcf service in IIS 6?
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IIS 5.1 and IIS 6 can only host HTTP bindings.
IIS7 has WAS (Windows Activation Service) which allows hosting of endpoints bound to any transport protocol... so it would be capable of TCP.
If you must host with IIS 6, then you're stuck with the HTTP bindings. If not, consider self-hosting in a Windows Service.
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