Nandini Rajaram for AWS Community Builders

Posted on Jan 21, 2023 • Updated on Feb 28, 2023

Cook a recipe with AWS: A simple Web application which calls a webservice and displays result, using AWS Amplify

#webdev #javascript #microservices #aws

Static Website

A static website, as in contrast to a typical dynamic website, renders the webpage at the time of request and instead delivers pre-built HTML, CSS, and JavaScript files to a web browser.

Now, We are going to cook a simple static website using HTML and JavaScript which call the reverseStringCall api endpoint and Fetch the response, get it displayed on our website

Ingredient

Lambda Function (ReverseString)
Recipe: Cook a recipe with AWS: Simple and Easy Lambda Functions
REST API endpoint that triggers the Lambda Function ReverseString created using API Gateway
Recipe: Cook a recipe with AWS: A simple API using API-Gateway

Lets Jump to the recipe

Create an HTML page that calls a Rest API endpoint built using API Gateway and displays the API Response

Create a java script file that calls the API endpoint from API Gateway, fetch the result and get it displayed to HTML file

JavaScript is an extremely popular scripting language that may be used on both the client and the server. Our websites require JavaScript because it makes them interactive.
Here, We are going to add a JavaScript script code that makes an API call, retrieves the response, and displays it to the HTML form

Copy the below code to a notepad and save it as main.js

  form.addEventListener('submit', function(e) {
    // Prevent default behavior:
    e.preventDefault();
    // Create new FormData object
    const formData = new FormData(form);
    const formDataObject = Object.fromEntries(formData.entries());
    // Post the payload using Fetch:
    fetch('<Invoke URL>', {
      method: 'POST',
      body: JSON.stringify(formDataObject)
    }).then(res => res.json()).then(data => {
//log the response obtained to the browser console
      console.log(data);
// call to the function displayToHTML
      displayToHTML(data)
    })

    function displayToHTML(data) {
      const form = document.getElementById('form');
      document.getElementById("demo").innerHTML = ' < span > Reversed String is: '+data.reversed_string + ' < /span>';
    }
  })

Invoke URL
When you deploy your API, you deploy to a stage, a base URL is generated which is also called as the invoke URL

All APIs created with API Gateway will follow the same pattern as the invoke URL above, with the ID of the API and the Region in which it was created, followed by a stage, and then the resource and resource path you want to expose.

fetch('<Invoke URL>', {
Here, we have to specify the Invoke URL obtained from API Gateway

Create a CSS stylesheet file to beautify and format the html file.

CSS allows you to customize the color, font, text size, spacing between elements, how elements are positioned and laid out, what background images or background colors are to be used, different displays for different devices and screen sizes, and much more!

Here, We are going to create an external style sheet, with which you can change the look of an entire website by changing just one file!

Copy the below code to the notepad and save it as main.css

body {
        background-color: #FFFFFF;
        }
    label, button {
        color: #000080;
        font-family: Arial, Helvetica, sans-serif;
        font-size: 20px;
        margin-left: 40px;
        }
     input {
        color: #00BFFF;
        font-family: Arial, Helvetica, sans-serif;
        font-size: 20px;
        margin-left: 20px;
        }

      p {
        color: #000080;
        font-family: Arial, Helvetica, sans-serif;
        font-size: 20px;
        margin-left: 40px;
      }

Create an HTML page that calls a Rest API endpoint, Link the CSS and JS files to it

I am going to create a simple html page with a Text field which accepts the input string that needs to be reversed and a Submit button.

Open your favorite text editor on your computer.
Create a new file and paste the following HTML. Then, save the file as index.html

<!--- HTML form data --->
<html>
<head> 
<title> ReverseString Checker</title>
<!--- Linking the css file  --->
<link rel="stylesheet" href="main.css">

</head>

<body>
<form id='form'>
<label for="Input">Enter the String to be reversed</label>
    <input name="first_name" type="text">
    <button type="submit">Submit</button>
</form> 
<p id= "demo"></p>

<!--- linking the js file  --->
<script src="main.js"></script>

</body>

</html>

Yes, Our webpage is ready, Now lets get it deployed using AWS Amplify

Deploy a website using AWS Amplify

Now we are going to deploy the above html file as a webapplication using AWS Amplify

AWS Amplify

AWS Amplify is a set of products and tools that enable mobile and front-end web developers to build and deploy secure, scalable full-stack applications, powered by AWS.

Ingredient

The above html file saved as index.html

Prerequisites

Compress the files index.html, main.js and main.css and keep it ready

Log into AWS account with a valid user credentials (Root user not preferred)

Steps to create

Open the AWS Amplify service from aws console

Click Get Started button

Now Click Get Started button under Host your web app section , as we have already created the resources such as html, css and js files and we just need to deploy them

Now you will be navigated to Get started with Amplify Hosting page
Select without GIT Provider option, because we have saved the files local system and click Continue button
Note, GIT is a source code management system and we are not using it for this cooking this recipe now

You will be navigated to Manual Deploy Page where you need to Specify the App name and Environment name

Drag and drop option will be selected by default for Method, Leave it as it is

Here we are going to drag and drop our zipped file

Click Choose File and Select the Zipped folder
Make sure the folder name is correct.
Click Save and Deploy

A deployment process will automatically begin

Now wait for a couple of minutes and You will see a green bar, which indicates your deployment is completed
You can also see the application url link below Domain

Launch the Application

Click on the application url link and launch the web application
Yaay, Our application is ready

Now Give some input string and click Submit button, See Reversed version of your string is displayed on the Website

View the Network Tab browser console and ensure if the api endpoint called and response is generated

Right click on the webpage and click on Inspect option to launch the browser console and network tabs

Click Network and get into the Network tab
Click Submit button and observe the Network tab, You can see the API endpoint getting called once you click the Submit button and JSON Response is getting generated