WCF Data Services

Offered by the BasicHttpBinding class, this is designed to expose a WCF service as a legacy ASMX web service, so that old clients can work with new services. When used by the client, this binding enables new WCF clients to work with old ASMX services.

Offered by the NetTcpBinding class, this uses TCP for cross-machine communication on the intranet. It supports a variety of features, including reliability, transactions, and security, and is optimized for WCF-to-WCF communication. As a result, it requires both the client and the service to use WCF.

Peer network binding

Offered by the NetPeerTcpBinding class, this uses peer networking as a transport. The peer network-enabled client and services all subscribe to the same grid and broadcast messages to it.

IPC binding

Offered by the NetNamedPipeBinding class, this uses named pipes as a transport for same-machine communication. It is the most secure binding since it cannot accept calls from outside the machine and it supports a variety of features similar to the TCP binding.

Offered by the WSHttpBinding class, this uses HTTP or HTTPS for transport, and is designed to offer a variety of features such as reliability, transactions, and security over the Internet.

Offered by the WSFederationHttpBinding class, this is a specialization of the WS binding, offering support for federated security.

Offered by the WSDualHttpBinding class, this is similar to the WS binding except it also supports bidirectional communication from the service to the client.

Offered by the NetMsmqBinding class, this uses MSMQ for transport and is designed to offer support for disconnected queued calls.

Offered by the MsmqIntegrationBinding class, this converts WCF messages to and from MSMQ messages, and is designed to interoperate with legacy MSMQ clients.

Windows Communication Foundation (WCF) is an SDK for developing and deploying services on Windows. WCF provides a runtime environment for services, enabling you to expose CLR types as services, and to consume other services as CLR types.

WCF is part of .NET 3.0 and requires .NET 2.0, so it can only run on systems that support it.

A service is a unit of functionality exposed to the world.

The client of a service is merely the party consuming the service.

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

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";

}

}

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;

}

Define which errors are raised by the service, and how the service handles and propagates errors to its clients.

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.

Every WCF services must be hosted somewhere. There are three ways of hosting WCF services.

They are

1. IIS

2. Self Hosting

3. WAS (Windows Activation Service)

Every service must have Address that defines where the service resides, Contract that defines what the service does and a Binding that defines how to communicate with the service. In WCF the relationship between Address, Contract and Binding is called Endpoint.

The Endpoint is the fusion of Address, Contract and Binding.

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 WebGetAttribute, we can define a service as REST based service that can be accessible using HTTP GET operation.