WCF 2 - Building Blocks

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Building Blocks of Service

Service is a

• Collection of operations that are exposed to the clients.
• Service contract defines what operations are available and how clients use them.
• Data contract describes data that the client and service can exchange.

Service Contracts

Service Contracts

• Describe the operations supported by a service, the message exhange pattern used and format of each
  message.
• ServiceContract attribute marks an interface as a service contract.
• OperationContract attribute exposes methods of the interface.

Code snippet

[ServiceContract]
public interface IHelloService 
{
     [OperationContract]
     string SayHello (string yourName);
}

Data Contracts

A data contracts

• Describes how CLR types are mapped to XSD schema definitions.
• Enable complex types to be serialized and deserialized so it can be passed across.
• DataContract attribute identiifes each class that can be serialized.
• DataMember attribute identifies members that needs to be exposed to the clients.

Code snippet

Here's an example of a data contract for a account class.

[DataContract]

public class Account

{

    [DataMember]

    public sting AccountNo { get; set; }
    [DataMember]

    public sting AccountType { get; set; }

}

 

Endpoints

The client communicates with service  via endpoints.

• Host application makes the service available by providing one or more endpoints to the clients.
• Endpoint consist of
  - Address of service (Where?)
  - Binding (How?)
  - Contract (What?)
• Client and Service use the same endpoint.

Address-Binding-Contract are the ABC's of service. 

Bindings

• Specify how a service endpoint communicates with client endpoints.
• Consist of binding elements describing some essential aspect of communication like
  - Transport (HTTP, TCP, etc)
  - Protocol (security, reliability, transctions, sessions etc)
  - Messge encoding (text, binary etc)
• Can be declared programatically or declaratively in the config file.

Out of box Bindings

• BasicHttpBinding
  Compatible with ASMX Web Services.
• WSHttpBinding
  - Conforms to WS* specifications for reliability, security and transactions.
  - Default
• WS2007HttpBinding
  - Conforms to OASIS specifications for reliability, security and transactions.
• WSDualHttpBinding
  - Supports WS-* + two-way communication
• WSFederationBinding
  - Supports the WS-Federation specification for sharing identities across multiple systems.
• WS2007FederationBinding
  - Supports federated security.
• NetTcpBinding
  - Communicates across processes and machines.
• NetNamedPipeBinding
  - Communicates on same machine
• NetPeerBinding
  - Peer to peer communications over TCP
• NetMsmqBinding
  - Uses MSMQ to transmit messages
• MsmqIntegrationBinding
  - Service can send or receive messages from a MSMQ queue.

The most frequently used binding is the BasicHttpBinding, the WSHttpBinding and the NetTcpBinding.

That's it for now!!!