Restful API In ASP.NET: Introduction of REST & Web API

In the previous article Getting Started in Web API, we have learned the basic infrastructure of API and multiple clients which can consume API. Now, we will discuss here the architecture of Restful API and we will also get an overview of ASP.NET Web API introduction.

What is REST

REST is the acronym that stands for: Representational State Transfer. REST is an architectural style of distributed system. It is based upon the set of principles that describes how network resources are defined and addressed. These set of principles was first described by “Roy Fielding” in 2000. REST is bigger than Web Services.

RESTful services uses HTTP (Hyper Text Transfer Protocol) to communicate. REST system interface with external systems as web resources identified by URIs (Uniform Resource Identifiers).

Constraints of REST

A Restful system should follow the constrains so it can be called Restful. There are 5 and 1 optional constraints of REST.

HTTP Verbs

Http verbs plays a very important role in the Restful Web API. The most common Http verbs are GET, PUT, POST and DELETE and these correspond to CRUD (Create, Read, Update and Delete) operations respectively.

The following Http Verbs exists:

• Get
• Post
• Put
• Delete
• Trace
• Options
• Connect
• Patch

I will discuss here the most common used verbs and we will also see that how we can use these verbs in my next articles in which we will perform database operations with the help of the above Http verbs.

So, the following are the description of most common used Http verbs:

GET

As the name specifies, this verb is used to retrieve the data or information. It does not have any other effect except getting data.

Syntax

[HttpGet]

We can use the above syntax to define the method as a GET method. If we are retrieving the data from the database or displaying the data, then we can use this attribute to get the data.

Use

Let’s see an example of a GET method:

In the above example there is a method named GetInfo which is defined as GET method. ActionName attribute is used to define the name of an action method.

Call

http://localhost:56828/api/sample/GetInfo

By the help of above Requested URI, we can get the information. Sample is the controller name.

POST

This verb is used to generate or create the resource. For example, If we have to add some information to the database then we must define the method as a POST method. The most common form to submit the data into the POST method is to pass the data into any entity object.

Syntax

[HttpPost]

We can use the above syntax to define the method as a POST method.

Use
In the above example there is a method named PostInfo which is defined as POST method. We have to assign the data to the properties of the entity (Result class).

PUT

This verb is used to update the existing resource. For example, If we have to update some information to the database then we can define the method as a PUT method. We can send the data in the form of object as well as in a parameter too.

Syntax

[HttpPut]

We can use the above syntax to define the method as a PUT method.

Use
In the above example there is a method as named UpdateInfo which is defined as PUT method. We can assign the id to update the info.

DELETE

This verb is used to delete the existing resource. For example, If we have to delete some information to the database then we can define the method as a DELETE method. We can send the data in the form of object as well as in a parameter too.

Syntax

[HttpDelete]

We can use the above syntax to define the method as a DELETE method.

Use
In the above example there is a method named DeleteInfo which is defined as DELETE method. We can assign the id to delete the info.

Demo

In the above section you have learned all the basics of RESTtful architecture and Web API. Now, in this section we will create the demo application in which we will perform the database operations from the ASP.NET Web API Application.

Prerequisites

If you want to create the demo then you must have Visual Studio 2012 or later version to do this. I am using here Visual Studio 2015.

Getting Started

Let’s create an ASP.NET Web API app in which we will perform the CRUD operations and later we will publish it into the Azure API. Now, just follow the procedure below to create the application.

Creating Web API Application

In this section, we will create the ASP.NET Web API application by following the steps below:

Step 1: Open the Visual Studio as an Administrator and click on “New Project”.


Figure 1: Visual Studio Start Page

Step 2: Select the Web tab from the left pane and then select ASP.NET Web Application to create the project.


Figure 2: Creating New Application

Step 3: In the next ASP.NET wizard select the Web API Project Template.


Figure 3: Web API Project Template

Now, Web API application is created successfully.

Perform Database Operations

In this section, we’ll perform database operation in which we will create the stored procedures to perform CRUD operations. I have created the database and tables with the record and stored procedures too. You can create the whole database from the following script or you can create your own database records. So, just follow the steps below:

Step 1: Just create the database from the following script:

CREATE DATABASE [Cricketer]

Step 2: Now from the following script the whole database is created with the tables and records and stored procs:
Perform CRUD Operations

In this section we will add new projects to associate the database with the Web API application. So, start with the following steps:

Step 1: Just add a new Solution Folder in your application named “Models”


Figure 4: Adding New Solution Folder

Step 2: Add a “New Project” in the Models folder


Figure 5: Adding New Project

Step 3: Select Class Library template to add a new project and name it “BestCricketers.Models”.


Figure 6: Adding Class Library

Step 4: Add a new class named “CricketerProfile” and replace the code with the following code: