Windows Communication Foundation (WCF) is a framework for building service-oriented
applications. Using WCF, you can send data as asynchronous messages
from one service endpoint to another. A service endpoint can be part of a
continuously available service hosted by IIS, or it can be a service hosted in
an application.
WCF = WebService + .Net Remoting +
MSMQ + COM+
Scenarios where WCF must be used
1.
A secure service to process business
transactions.
2.
A service that supplies current data to
others, such as a traffic report or other monitoring service.
3.
A chat service that allows two people to
communicate or exchange data in real time.
4.
A dashboard application that polls one or
more services for data and presents it in a logical presentation.
5.
Exposing a workflow implemented using
Windows Workflow Foundation as a WCF service.
6.
A Silverlight application to poll a service
for the latest data feeds.
Features
of WCF
- Service Orientation
- Interoperability
- Multiple Message Patterns
- Service Metadata
- Data Contracts
- Security
- Multiple Transports and Encodings
- Reliable and Queued Messages
- Durable Messages
- Transactions
- AJAX and REST Support
- Extensibility
The
advantages of WCF
- WCF can be configured to work independently
of SOAP and use RSS instead.
- WCF is one of the fastest communication
technologies and offers excellent performance compared to other Microsoft
specifications.
- To improve communication, transmission
speed needs to be optimized. This is achieved by transmitting binary-coded XML
data instead of plain text to decrease latency.
- Object life-cycle management and
distributed transaction management are applicable on any application developed
using WCF.
- WCF uses WS specifications to provide
reliability, security and transaction management.
- Messages can be queued using persistence
queuing. As a result, no delays occur, even under high traffic conditions.
Now
we will learn basic of WCF:
·
The
ABC of Windows Communication Foundation
"A" stands for
Address: Where is the service?
"B" stands for Binding: How do I talk to the service?
"C" stands for Contract: What can the service do for me?
- "A" stands for Address—as
expressed in the wsdl:service section and links wsdl:binding to a concrete
service endpoint address.
- "B" stands for Binding—as
expressed in the wsdl:binding section and binds a wsdl:portType contract
description to a concrete transport, an envelope format and associated
policies.
- "C" stands for Contract—as
expressed in the wsdl:portType, wsdl:message and wsdl:type sections and describes
types, messages, message exchange patterns and operations.
Address # The address specifies the location of the service which will be exposed
for clients that will use it to communicate with the service. The address's
protocol that WCF can provide:
- HTTP
- TCP
- NamedPipe
- Peer2Peer
- MSMQ
Binding
#
Specifies how a service is accessible. In other words: how the two parties will
communicate in terms of transport (HTTP, TCP, NamedPipe, Peer2Peer, MSMQ)
,encoding (text, binary etc.) and protocols (like transactional support or
reliable messaging).
Bindings supported by WCF 4.0:
- basicHttpBinding
- wsHttpBinding
- wsDualHttpBinding
- wsFederationHttpBinding
- netTcpBinding
- netNamedPipeBinding
- netMsmqBinding
- netPeerTcpBinding
- msmqIntegrationBinding
- basicHttpContextBinding
- netTcpContextBinding
- webHttpBinding
- wsHttpContextBinding
Contract
#
A contract is an agreement between two parties. It defines how a client should
communicate with your service.
Contracts
in WCF:
- Service Contract
- Data Contract
- Fault Contract
- Message Contract
Now we will learn this by creating a simple HelloWCF
program.
Open visual Studio -> File -> New Project
Image 1.
Select WCF Service Application. Give it a name.
Image 2.
Remove IService1.cs and Service1.svc file from here.
Now Right click on solution explorer-> add new item.
Image 3.
Now open IMyService.cs and add below method:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
namespace Hello_WCF_Service
{
// NOTE: You can use
the "Rename" command on the "Refactor" menu to change the
interface name "IMyService" in both code and config file together.
[ServiceContract]
public interface IMyService
{
[OperationContract]
string AddText(string Name);
}
}
Now open MyService.cs File
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
namespace Hello_WCF_Service
{
// NOTE: You can use
the "Rename" command on the "Refactor" menu to change the
class name "MyService" in code, svc and config file together.
// NOTE: In order to
launch WCF Test Client for testing this service, please select MyService.svc or
MyService.svc.cs at the Solution Explorer and start
debugging.
public class MyService : IMyService
{
public string AddText(string Name)
{
return "Welcome " + Name;
}
}
}
Now run your service.
Image 4.
You can test your method.
Image 5.
You can view config file like below.
Image 6.
See your service in browser.
Image 7.
Now we will consume this service in our web
application. So Right click on solution explorer and add new project.
Image 8.
Select Web -> ASP.NET Web Application.
Image 9.
Now add WCF Service reference. Right Click on your
project-> Add Service reference.
Image 10.
Image 11.
Now open your Default.aspx page:
<table cellpadding="10" cellspacing="10" width="90%" style="border: solid 4px green;">
<tr>
<td>Enter Name #
</td>
<td>
<asp:TextBox ID="txtName" runat="server" Width="250px"></asp:TextBox>
</td>
</tr>
<tr>
<td></td>
<td>
<asp:Button ID="btnCallService" runat="server" Text="Click Me" OnClick="btnCallService_Click" />
</td>
</tr>
<tr>
<td></td>
<td>
<asp:Label ID="lblMessage" runat="server" Font-Bold="true" Font-Size="16pt" ForeColor="Red"></asp:Label>
</td>
</tr>
</table>
Now open Default.aspx.cs page and
call your WCF Service methid:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace MyProject
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnCallService_Click(object sender, EventArgs e)
{
MyWCFService.MyServiceClient myService = new MyWCFService.MyServiceClient();
lblMessage.Text =
myService.AddText(txtName.Text);
}
}
}
Now run you application.
Image 12.
Image 13.