ASP.NET Web API

ASP.NET Web API is a framework that simplifies the creation of HTTP services
Using ASP.NET Web API we can create HTTP services those are non-SOAP based like plain XML or JSON strings etc. with added advantages.

• Allowing to create resource-oriented services using the full features of HTTP.
• Exposing services to a variety of clients easily like browsers or mobile devices etc.

Before diving into details, I would like to clarify one misconception that ASP.NET Web API has replaced WCF. WCF is still a powerful programming model for creating SOAP based services that use a variety of transport protocols like HTTP, TCP, Named Pipes or MSMQ etc. 

So here  my first application using mvc web api 

1. Create Web API Project

• Open Visual Studio and create “New Project” i.e. File -> New Project.
• Choose “ASP.NET MVC 4 Web Application” template and name project as “FirstWebAPIService”.
• When you click “OK” button, a new window will appear for selecting a sub-template. Actually for ASP.NET MVC 4 Web Application, we have multiple sub-options i.e. Empty, Internet Application, Web API etc.
• Choose “Web API” and simply press “OK” button.
• A default ASP.NET MVC 4 Web API template project is created. As its an MVC application template, so you will easily find “Model”, “View” and “Controller” folders inside it.

2. Preparing domain Model

Now in a second step, we need to prepare the model.

• Right click on the “Model” folder and choose “Class” under “Add” from the context menu as shown in figure.
• Name the class as “Product.cs”.

Here is the code for Product class.

public class Product
{
public int ProductID { get; set; }
public string ProductName { get; set; }
public string ProductCategory { get; set; }
public int Price { get; set; }
}

3. Adding Controller Class
Controller class plays an important role, because request coming from client hits the controller first. Then the controller decides which model to use to serve the incoming request. So, in order to add a controller:

• Right click on the “Controller” folder and choose “Controller” under “Add” from the context menu as shown in figure.
• Name the controller as “ProductsController”.

• Click the “Add” button, a new controller class will be added.

In order to make the things simple, we will load the model with data inside this controller instead of loading it from database. Following is the code for controller class.

public class ProductsController : ApiController
{
Product[] products = new Product[]
{
new Product { ProductID = 1, ProductName = “Product 1″, ProductCategory= “Category 1″, Price = 120 },
new Product { ProductID = 2, ProductName = “Product 2″, ProductCategory= “Category 1″, Price = 100 },
new Product { ProductID = 3, ProductName = “Product 3″, ProductCategory= “Category 2″, Price = 150 },
new Product { ProductID = 4, ProductName = “Product 4″, ProductCategory= “Category 3″, Price = 90 }
};

public IEnumerable GetProducts()
{
return products;
}
}

Don’t forget to add “using FirstWebAPIService.Models;” at the top of the controller class.

Now, it’s time to test your HTTP service using ASP.NET MVC Web API.
Run the application by pressing “CTRL+F5″, Welcome window will appear as follows:

In order to call our Product controller, change the URL as “http://localhost:XXXX/api/products”. You will see the results as shown in following output window.

Final output returned can be displayed differently by different browsers. Here is the output of google chrome version 29.0.1547.66.

Hopefully, this simple web development tutorial will be helpful for developers to code their first HTTP service