What is the request-response cycle?
The request-response cycle is a fundamental concept in software development that describes the communication process between a client application and a server. This cycle is initiated when the client application makes a request to the server to access specific resources. These resources can vary widely, including web pages, data files, or any information the server is set up to provide. To illustrate this concept, I wrote a narrative about Mike, a developer making a web application. Through Mike’s journey, we’ll explore the utilization of the request-response cycle both in a local development setting — referred to simply as “development” — and later, as he transitions his project onto the wider internet for public accessibility, a stage known as “production.”
Request-Response Cycle Locally (Development)
Mike embarked on a journey to create a website that could be accessible to everyone on the internet. His first step involved writing the website’s program using HTML, CSS, and JavaScript. Each piece of the website was developed in separate files, which Mike wrote and tested on his computer, locally. Running a website locally means that the website files are stored on one’s own computer, and the site can only be accessed by that same computer, not from the wider internet.
When you work locally, what’s happening is your computer’s private IP address is being used to interact with the software or services running on your own machine. This private IP address is unique within your local network but not across the internet. It allows your computer to communicate with other devices on your home or office network, such as printers, other computers, or internet-connected devices, but it is not directly accessible from the internet. This setup is useful for testing, development, or running applications that don’t need to be accessed outside of your local network. It provides a layer of security, as devices on the internet cannot directly access your computer unless specific configurations, like port forwarding, are set up on your router.
In the depicted scenario, Mike is developing a web application using HTML, CSS, and JavaScript, all of which he authors within a popular code editor called Visual Studio Code (VS Code). To streamline his development process, Mike employs an extension for VS Code known as Live Server. This tool automatically serves his files directly to his default web browser, Google Chrome, allowing for immediate viewing and interaction with his project.
Live Server operates by translating the URL of Mike’s project — a URL that, in essence, represents an IP address — from its numeric form into a more human-readable format (such as www.example.com). However, during development, instead of using a global IP address, Live Server utilizes a loopback address, an address that devices use to refer to themselves sometimes called localhost. This special address directs requests back to Mike’s own device, allowing his browser to communicate directly with the local server established by Live Server. Note: most devices have a local, global, and loopback address
As Mike makes changes to his code, or as he navigates between different pages of his site (for instance, from the homepage to an “About” page), Live Server dynamically updates the content shown in Chrome. This is made possible by the loopback address, which ensures that all requests and responses during the development phase are contained within Mike’s local environment, enabling a seamless and efficient workflow.
Request-Response Cycle Publicly (Production)
When Mike decided to take his locally developed website or web application and make it available on the internet, he opted for GitHub as a straightforward hosting solution, given its simplicity and direct integration with his development workflow. By pushing his project to a GitHub repository, Mike effectively leveraged GitHub’s servers, which are configured to serve web content globally.
Upon activating GitHub Pages for his repository, Mike’s project was instantly hosted on GitHub’s infrastructure. This meant his website was now accessible through a unique URL provided by GitHub, essentially assigning his project a global reach. This URL is similar to a global IP address in that it allows anyone, anywhere, to access Mike’s site by entering this address into their web browser, such as Chrome or Firefox.
The magic behind serving Mike’s site to anyone in the world starts when a request is made to this URL. GitHub’s servers, acting as the backbone for GitHub Pages, receive the request for Mike’s website. These servers then look up the necessary files in Mike’s repository — whether they’re HTML, CSS, or JavaScript files — and send them back to the requesting browser. This response allows the browser to render Mike’s site for the viewer.
Conclude:
Mike’s journey from local development to global production showcases how his browser, specifically Google Chrome, requests and displays the files he coded to create his website. This process involves:
- Google Chrome sending requests for the necessary files, which are stored either locally during development or on a hosting service’s server in production.
- The server then responds (live server or Github), providing the files for Chrome to render Mike’s website for viewing.