Talking in terms of computing, a web application or a web app can be termed as a client–server computer program where the client, including the user interface and client-side logic, runs in a web browser. Some of the most common types of web applications are webmail, online retail sales, online banking, and online auctions among many others.
One cannot clearly differentiate between a dynamic web page of any kind and a ‘web application’. Those websites which are referred to as “web applications” are the ones which have similar functionality to a desktop software application, or to a mobile app.
With HTML5, came the explicit language support which makes applications that are loaded as web pages, but can also store data locally and still keep on functioning while offline.
How did web applications originate?
In earliest versions of computing models where client–server model was used, you would see that the processing load for the application was shared between code on the server and code installed on each client locally.
Earlier applications had their own pre-compiled client program that used to serve as its user interface and had to be separately installed on each user’s personal computer.
If one upgraded the server-side code of the application, they would also typically require an upgrade to the client-side code installed on each user workstation. This would in turn add to the support cost and decrease productivity as well.
Also, the client and server components of the application were closely bound together at that time to a specific computer architecture and operating system and porting them to others was significantly important, where the users took a blow to their pockets for all but the largest applications.
You can consider web applications as a specific variant of client–server software in which the client software is downloaded to the client machine when requesting a web page, using standard procedures such as HTTP.
In this case, the client web software updates commence each time the user visits a web page. At the time of the session, the web browser understands and displays the pages, and becomes the universal client for any web application.
During the the early days of the web, when we had static single page websites, each individual web page was delivered to the client as a static document. Even then, the sequence of pages could still provide an interactive experience.
This is because the user input returned through web form elements embedded in the page markup. As a matter of fact, every significant change to the web page needed a round trip back to the server to refresh the entire page.
Components of web applications
Any web application, big or small, contains these major components:
View Layer:- When you consider an MVC application, the View layer component gives an interface to the application. Regardless if it is for users with a browser or for another application using Web services. View layer is the bridge for getting the data in and out of the application.
It does not have business logic, like calculating interest for a banking application or storing items in a shopping cart for an online catalog. It also does not contain any code for existing data to or retrieving data from a data source. Business logic is managed by the Model layer. View layer is more focused on the interface.
Business Layer:- It is also known as Business Logic or Domain Logic or Application Layer. The function of the business layer is to accept user requests from the browser, processes them, and determine the routes through which the data will be accessed. The workflows by which the data and requests travel through the back end lay encoded in a business layer.
Data Access Layer:- This layer is built to keep the code you use to pull data from your data store like database, flat files, or web services separate from business logic and presentation code. So even if you have to change data stores, you don’t end up rewriting the whole thing.
There are many ORM frameworks that are blending the DAL with other layers which makes development easy during web application development services.
Error handling, security, logging:- When you build a web application, people generally tend to focus on the end-goal, building and testing only for situations when things go right. Alas! things rarely go right all the time in the real world.
This is where error handling is a vital part of any application’s user experience. And, if it is done well, it can leave your users feeling informed and properly considered.
Types of Web Applications
In simple terms, a web application architecture or a type of web application is a pattern of interaction between various web application components that we discussed above. The “type” of web application architecture is directly proportional to how the application logic is distributed among the client and server sides.
Three primary types of web application architecture are:
Serverless Architecture — A serverless architecture is a simple way to build and run applications and services without having to manage infrastructure. The application you deploy runs on servers, but all the server management is done by a third-party service provider like AWS. You don’t need to provision, scale, and maintain servers in order to run your applications, databases, and storage systems.
Single-Page Applications — A single-page application or SPA is a type of web application architecture which interacts with the user by dynamically rewriting the current page rather than loading entire new pages from a server. By this way, one can avoid interruption of the user experience between successive pages which makes the application behave more like a desktop application.
Microservices — They can be called small and lightweight services which are responsible for executing a single functionality. The Microservices Architecture framework allows the developers working with it to not only enhance productivity but also speed up the entire deployment process.
Along with technology, the architecture of web applications is also evolving and growing day-by-day. The overall effectiveness, responsiveness, and agility of a web application is defined by the type of model one chooses. It is highly recommended that you take time to consider all your business requirements before initiating the development process.