In this post, we'll build the Web API, use MVC 5 to access it, and use Web API 2 to send emails.

Let's begin gradually:

• Work with a web application by creating an ASP.NET web application.
• Including a model
• Including a controller
• Including a Helper class
• Using JavaScript and JQuery to Call the Web Api (test web API)
• To call the API and send an email notification, use the Rest client (Install Fiddler).

Select a template Web API.

Add a model class
A model is an object that represents the data in your application. In this case, the only model is a TeamA item.

Add a class file “TeamA.cs”.

Replace the generated code with:
    namespace EmailNotification.Models  
    {  
        public class TeamA  
        {  
            public int Id  
            {  
                get;  
                set;  
            }  
            public string Name  
            {  
                get;  
                set;  
            }  
            public string Type  
            {  
                get;  
                set;  
            }  
            public decimal Price  
            {  
                get;  
                set;  
            }  
        }  
    }  

Add a controller

In the Add Scaffold wizard, select the Web API 2 Empty Controller: Name it EmailNotifier.

In the Add Controller dialog, name the controller "EmailNotifierController " and click Add.

Replace code with the following controller.
    public class EmailNotifierController: ApiController  
    {  
        TeamGroupA[] teamA = new TeamGroupA[]  
        {  
            new TeamGroupA  
            {  
                Id = 1, Name = "zing", Type = "Cricket", Price = 1  
            },  
            new TeamGroupA  
            {  
                Id = 2, Name = "Yo-yo", Type = "Football", Price = 3.75 M  
            },  
            new TeamGroupA  
            {  
                Id = 3, Name = "soft", Type = "Software", Price = 16.99 M  
            }  
        };  
        // Run the application  
        public IEnumerable < TeamGroupA > GetAllTeams()  
        {  
            return teamA;  
        }  
    }  

To keep the example simple, TeamGroupA has stored in a fixed array inside the controller class. But, in a real application, you would get it from the Data access layer or use some other external data source.

The controller defines two methods that return products:
The GetAllTeams method returns the entire list of products as an IEnumerable<TeamGroupA> type.

As we are working with Web API it may contain one or more methods.

Now add new model for AdpaterResponsebase for another API method as SendEmailNotification.cs.

AdapterResponseBase.cs

Replace model code with the following code:
    using System;  
    using System.Collections.Generic;  
    namespace EmailNotification.Models  
    {  
        public class ResponseBase  
        {}  
        public class RequestBase  
        {}  
        public class RequestBase < T > : RequestBase  
        {  
            public RequestBase()  
            {}  
            public RequestBase(T data)  
            {  
                Data = data;  
            }  
            public T Data  
            {  
                get;  
                set;  
            }  
        }  
    }  

Add new Helper class file EMailHelper.cs to folder named Helpers.

    using System;  
    namespace EmailNotofication.Models  
    {  
        public class EmailInput  
        {  
            public string UserName  
            {  
                get;  
                set;  
            }  
            public string EmailId  
            {  
                get;  
                set;  
            }  
        }  
    }  

Now we will start with UI part.

Calling the Web API with Javascript and jQuery
Here we will add an HTML page that uses AJAX to call the web API. We'll use jQuery to make the AJAX calls and also to update the page with the results.
In Solution Explorer, right-click the project and select Add, then select New Item.

In the Add New Item dialog, select the Web node under Visual C#, and then select the HTML Page item. Name the page "index.html".

Replace everything in this file with the following:
    <!DOCTYPE html>  
    <html xmlns="http://www.w3.org/1999/xhtml">  
      
    <head>  
        <title>Notification App</title>  
    </head>  
      
    <body>  
        <div>  
            <h2>All Teams</h2>  
            <ul id="teams" /> </div>  
        <script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-2.0.3.min.js"></script>  
        <script>  
            var uri = 'api/EmailNotifier/GetAllTeams';  
            $(document).ready(function()  
            {  
                // Send an AJAX request  
                $.getJSON(uri).done(function(data)  
                {  
                    // On success, 'data' contains a list of teams.  
                    $.each(data, function(key, item)  
                    {  
                        // Add a list item for the teams.  
                        $('<li>',  
                        {  
                            text: formatItem(item)  
                        }).appendTo($('#teams'));  
                    });  
                });  
            });  
      
            function formatItem(item)  
            {  
                return item.Name + ': $' + item.Price;  
            }  
        </script>  
    </body>  
      
    </html>  

Getting a List of Teams
To get a list of teams, send an HTTP GET request to "/api/GetAllTeams".

Set index.html as start page:

Run the project,
Yippee! Here we got success for calling Web API using Ajax. Now let’s add method for Email Notification.

We will call SendEmailNotification API using RestClient.

Add the following method to controller:
    [HttpPost]  
    public async Task < IHttpActionResult > SendEmailNotification(EmailInput data)  
    {  
        ResponseBase updateResponse = new ResponseBase();  
        var updateRequest = new RequestBase < EmailInput > (data);  
        try  
        {  
            EMailHelper mailHelper = new EMailHelper(EMailHelper.EMAIL_SENDER, EMailHelper.EMAIL_CREDENTIALS, EMailHelper.SMTP_CLIENT);  
            var emailBody = String.Format(EMailHelper.EMAIL_BODY);  
            if(mailHelper.SendEMail(data.EmailId, EMailHelper.EMAIL_SUBJECT, emailBody))  
            {  
                //   
            }  
        }  
        catch(Exception ex)  
        {}  
        return Ok(updateResponse);  
    }  

You need to add extension for RestClient to your chrome browser to call API. Pass the parameter and do necessary changes to call API from rest client as in the following:

http://localhost:21084/api/EmailNotifier/SendEmailNotification

HTTPPOST
    Content-Type: application/json  
    {  
       "UserName": "xyz",  
       "EmailId" : "[email protected]",  
    }  

Once you click on send button, you can verify input parameter by adding debug point to API in controller

After successful execution we will get response as follows:

Note: To send email you need to add actual email id and credential so that it will work as expected.