Understanding the Basics of Web Application Architecture
Welcome to an in-depth exploration of web app basics and how it functions under the hood. In this article, we'll break down the fundamental structure of a typical web application. Whether you're just getting started with web development or building your first project, this guide offers a clear introduction to the building blocks that power modern web apps.
The Three Core Components of a Web App
A typical web application is composed of three main parts:
Frontend
Backend (also called the web server or API server)
Database
Each plays a distinct role but works closely with the others to deliver the interactive experience users expect.
1. Frontend: The User Interface
The frontend is the part of the web app that runs in your browser. This is what users interact with directly — the buttons, forms, images, and text you see on the page. It’s responsible for capturing user input and displaying data fetched from the backend.
The front end communicates with the back end through protocols like HTTP or HTTPS. These are standard ways to send and receive data over the internet securely. You might hear the term API, short for Application Programming Interface, which is essentially a set of rules or protocols that allow the front end and back end to talk to each other.
2. Backend: The Server Side
The back end is the heart of the web application’s logic and data processing. It runs on a server and handles requests from the frontend. This is sometimes called the API server because it exposes APIs that the front end consumes.
Communication between the front end and back end typically happens over HTTP or HTTPS. The “S” in HTTPS stands for secure, meaning the data exchanged is encrypted to prevent eavesdropping or tampering.
While HTTP/HTTPS are the most common protocols, there are other advanced options like WebSockets that enable real-time, two-way communication. However, these are less common for standard web app interactions.
3. Database: The Data Store
The backend talks to a database to store and retrieve the application’s data. Think of the database as a supercharged spreadsheet that can hold millions or even hundreds of millions of records efficiently. It’s designed to support high performance and scale far beyond what a regular spreadsheet can handle.
Databases use a language called SQL (Structured Query Language) to manage data. SQL is a universal language understood by most databases, allowing the backend to execute queries that create, read, update, or delete data.
How These Components Work Together: A Real-World Example
To make these concepts more concrete, let’s look at an example: a web app built on Momen called Udamy. This app lets users browse different course categories and view course details. Understanding how the frontend communicates with the backend here will give you practical insight into web app workings.
Using Chrome DevTools to Inspect Communication
One of the best ways to understand how web apps communicate is by using Chrome DevTools (CDT). This tool lets you see the network traffic between the front end and back end, which is invaluable for debugging.
You can access CDT by right-clicking on a webpage and selecting “Inspect” or by pressing F12 (or Function + F12 on some Macs). When you open CDT, you’ll start in the “Elements” tab, which shows the HTML structure. But to see the communication, switch to the Network tab.
In the Network tab, you’ll see all the requests made by the frontend to the backend. These include fetching data, sending user input, and more. Initially, you might see all types of requests, but for many purposes, focusing on “fetch” requests is helpful because these commonly handle API calls.
Example: Fetching Course Data in UD Dami
Suppose you click on “Category 2” in Udamy to view its courses. This triggers a network request from the frontend to the backend asking for course data related to that category.
In the Network tab, you’ll see a request appear. Clicking on it reveals detailed information, including the payload — the data sent from the frontend to the backend — and the response — the data sent back.
Don’t be intimidated by the raw data; it can look complex at first. But this is how the frontend and backend exchange information behind the scenes.
Understanding the Payload and Response
Payload: What the Frontend Sends
The payload contains the request details, including the query parameters and variables. In Momen, we use GraphQL to structure these requests.
GraphQL is a query language for APIs that allows clients to request exactly the data they need. It’s more flexible and human-readable than some other protocols.
For example, the payload may specify that it wants a list of courses, with conditions like ordering, filtering, and limits on how many courses to return.
Here are some common parameters you might see in a GraphQL payload:
where: Conditions to filter the courses
order_by: How to sort the courses
distinct_on: To avoid repeated elements
limit: How many courses to return
offset: How many courses to skip (useful for pagination)
The payload also specifies which pieces of data to return for each course, such as the course ID, cover image, name, and price.
Response: What the Backend Returns
The response contains the data that matches the query. In the example, the back end sends back a list of courses with the requested fields.
The response can be viewed in different ways within Chrome DevTools. The “preview” tab is often easier to read than the raw JSON response.
For instance, you might see two courses returned, each with an ID, name, cover image URL, and price. This data is then rendered by the frontend to display on the page.
Why Understanding This Matters
Knowing what is a web app and how its components interact is crucial for developers and anyone interested in technology. It helps you understand:
How user actions in the browser translate to data requests
How secure communication protects user data
How data is stored and retrieved efficiently
How to debug issues by inspecting network traffic
For developers, these insights can streamline troubleshooting and improve app performance. For users, it fosters an appreciation of the complex systems working behind simple interfaces.
Conclusion
Understanding what is a web app involves grasping the interplay between the frontend, backend, and database. These components communicate through protocols like HTTP/HTTPS using APIs, often structured with technologies like GraphQL. Tools like Chrome DevTools empower you to peek behind the curtain and see these interactions in real time.
By mastering these basics, you set a strong foundation for exploring more advanced web development topics or simply appreciating the technology that powers everyday web experiences. Knowing how to utilize these principles effectively can significantly enhance your development experience with Momen.
FAQ: Common Questions About Web Apps
Q1: What exactly is a web app?
A web app is an application accessed through a web browser that interacts with servers and databases to provide dynamic content and functionality to users.
Q2: How does the front end communicate with the back end?
They communicate through protocols like HTTP or HTTPS, often using APIs. The front end sends requests, and the back end responds with data or actions.
Q3: What role does the database play?
The database stores all the data for the web app, such as user information, content, and settings. It uses SQL to handle data operations efficiently.
Q4: What is GraphQL and how is it different from REST?
GraphQL is a query language for APIs that allows clients to request exactly the data they need, making it more flexible and efficient than REST, which relies on predefined endpoints.
Q5: How can I inspect network communication in my browser?
You can use Chrome DevTools by right-clicking on a page and selecting “Inspect” or pressing F12, then navigating to the Network tab to see all requests between your browser and the server.
