A web application is an application that runs on a web server instead of a local system. Users can access web applications through a web browser using an active internet connection. Web apps are websites with enhanced functionality and interactive elements. Some common examples of web apps are Gmail, YouTube, and Facebook.
Web applications help businesses to communicate with customers, collaborate with employees, present information to the target audience, and capture and store all the necessary data. They use a combination of server-side scripts to manage the storage and retrieval of information and client scripts to present information to users.
While developing a web application, you need to keep in mind that the web application should:
- Be easy-to-use, simple, and aesthetically pleasing. It should address most of the customers’ problems.
- Stay aligned with a product or market fit.
- Be functional, scalable, and able to withstand heavy traffic loads.
All the above things are addressed in web application architecture.
This article aims to familiarize you with the web application architecture and explain how it works. Also, you will learn about the different layers of web application architecture, types of web application architecture, web application components, and the models of web application components.
What is Web Application Architecture?
Web application architecture is a type of software architecture that represents the relationship between components, databases, user interfaces, middleware systems, and servers in an application. In short, we can define web application architecture as the layout that logically describes the connection between the client and the server.
Any web application requires architecture to set a strong foundation. A well-thought-out web application architecture has the ability to adapt to changing business requirements and handle various loads to improve an application’s performance and provide a great user experience.
Also, web application architecture maintains the security of a web application by dividing it into several blocks, where each block is secured separately. This results in fewer security threats.
How Does Web Application Architecture Work?
Any typical web application consists of two different codes or sub-programs running simultaneously, namely client-side code and server-side code.
- Client-side code: It is popularly called frontend, where code is written in HTML, CSS, and JavaScript. This code is stored within the browser and responds to some user input.
- Server-side code: It is popularly called backend, where code is written in server-side programming languages, such as PHP, Java, Ruby and Python . It controls the business logic and responds to HTTP requests.
Along with client-side and server-side code, another major component of a web application is a database server. In general, a database server is responsible for transmitting the requested data to the server side.
The developer of a web application decides what the server-side code will do with respect to the client-side code or the code in the browser. The server-side code is responsible for rendering the page the user has requested. Also, end-users cannot access the server-side code of a web application.
On the other hand, the web browser parses the client-side code, and the end-users can see or modify it. The client-side code only reacts to user inputs and communicates with the server via HTTP requests.
Layers of Web Application Architecture
The architecture of web applications generally has four layers, namely, presentation, business, persistence, and database . However, the number of layers in a web application architecture can vary depending on the type of web application.If a web application is complex, it may have five to six layers, whereas a simple and small web application may have three layers.
Here is a brief overview of the four layers of web application architecture:
- Presentation Layer: This layer is built using HTML, CSS, and JavaScript. It facilitates user interaction by enabling communication between the application’s interface and browser.
- Business Layer: This layer defines the business logic and rules. It is responsible for processing browser requests, executing the business logic associated with requests, and sending the results of the execution of business logic to the presentation layer. The business layer is also referred to as Domain Logic or Application Layer.
- Persistence Layer: It is also called the Data Access Layer (DAL), which simplifies the access to data stored in persistent storage, like binary and XML files. In addition, it is also responsible for managing CRUD operations, i.e., create, read, update, and delete. The business layer and persistence layer are closely associated with each other.
- Database Layer: It is also referred to as the Data Service Layer (DSL). This layer is responsible for transmitting the data processed by the business layer to the persistence layer. It maintains all data and ensures data security by separating business logic from the client side.
Each layer of web application architecture works separately and independently. Components of each layer deal with the respective layer’s logic. For example, the components of the presentation layer deal with the presentation logic only. Such a layered architecture of a web application enables web developers to introduce changes in any layer without affecting the components of other layers.
Types of Web Application Architecture
There are three different types of web application architecture, namely single page, microservices, and serverless. Let us discuss each type of web application architecture in detail below:
1. Single Page Application Architecture
A Single Page Application or SPA is a web page or a website that dynamically rewrites the current web page with new content from the webserver for every new user action instead of loading a new page every time. In SPA, page refresh never takes place. Instead, all the necessary resources are dynamically loaded and added to the current web page, or the browser retrieves the CSS, JavaScript, and HTML code with a single page load.
2. Microservices Architecture
Microservices architecture is the best alternative to monolithic architecture and service-oriented architecture (SOA). It is a collection of loosely coupled services where we can develop, test, maintain, and deploy each service independently. These loosely coupled services communicate with each other via APIs.
The development of web applications using monolithic architecture is a cumbersome task. This is because the components of applications developed using monolithic architecture are tightly coupled. Unlike monolithic architecture, Microservices architecture divides a web application into several independent service components.
3. Serverless Architecture
The serverless architecture is an architecture where the cloud service provider takes care of the execution of the whole code. In other words, a web developer consults a third-party web service provider to outsource the server and infrastructure management. Therefore, applications built using the serverless architecture run without any manual interventions on the servers that are managed by the third-party cloud provider.
The primary benefit of the serverless architecture is that it enables applications to run the code logic regardless of the infrastructure-related tasks. In addition, this type of architecture lets a web developer concentrate on the quality of applications and make them highly scalable and reliable.
Components of Web Applications
There are two types of web application components, namely, user interface and structural. Let us briefly discuss both of these component types below.
- User Interface Components: These components are part of a web application’s visual interface and have no interaction with the architecture. The primary purpose of these components is to enhance the user experience. Some of the most common user interface components include dashboards, activity logs, notifications, configuration settings, widgets, statistics, etc.
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Structural Components:
Structural components are divided into two categories - client components and server components.
- The client components exist in the user’s web browser and are developed using JavaScript, HTML and CSS . They are the representation of the functionality of a web application with which the end-users interact.
- The server components are developed using Python, PHP, Node.js, Java, and many other programming languages. These components are bifurcated into two parts, namely app logic, and database. The app logic handles the business logic, and the database stores all the persistent data.
Models of Web Application Components
We can decide the model of any web application depending on the number of servers and databases used. In general, there are three models of web application components that are as follows:
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One Web Server, One Database
As its name suggests, this model uses only one web server and one database. It is the most basic web application component model. However, it has a major downside to it; that is, as soon as the server goes down, the web app also goes down. Therefore, this model is not very reliable. Furthermore, it is not employed in real-world web applications. Instead, it is widely used for running test projects and understanding the basics of web applications.
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Multiple Web Servers, One Database
This model employs multiple web servers and one database. A web server does not store any data in this type of model. When a web server receives data from a client, it processes the data and writes it to the database. The database in this model is managed outside the server. This model requires at least two web servers. It overcomes the drawback of the One Server, One Database model, where a web app goes down when the server goes down.
However, in this model, even if one server goes down, the other one will take charge and make sure the application keeps working. Therefore, the reliability of this model is better compared to the One Web Server, One Database model.
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Multiple Web Servers, Multiple Databases
The Multiple Web Servers, Multiple Databases model, is the most efficient one since it employs multiple web servers and databases, and they do not have a single point of failure.
This model offers two options for data storage. One is to store identical data in all the employed databases, and the other is to distribute it evenly among them. Both these options require normalized databases. But when there are more than five web servers or databases, it is recommended to install load balancers.
Conclusion
The success of modern web applications is closely associated with their architecture. In general, the robustness, reliability, scalability, and security of web applications are determined by the type of web application component model and the type of web application architecture that they use.
We hope this article has helped you to develop a better understanding of web application architecture and its various aspects. Also, if you have any queries or suggestions, feel free to share them in the comments section.
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