A web application consists of three layers at the very least: client-side (frontend), server-side (backend), and database (persistence layer). You might find different developers for each layer of web applications, but one who works on all of the three layers is a full-stack developer.
The frontend development consists of HTML, CSS, and JavaScript along with JavaScript’s frameworks and libraries. Working on the backend involves server-side scripting programming languages such as Java, .Net, PHP, Go, Python, Ruby, and more. Lastly, the persistence layer comprises one or more SQL or NoSQL databases, although the advent of Big Data has enabled non-conventional databases to store data.
Some technologies are more popular than others among these three web application layers. However, when technologies cover the frontend, the backend and database layer is called “a stack”. Some of the popular stacks that are being used by full-stack developers include:
Read: The Ultimate Guide to FullStack Development
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MEAN: MongoDB, Express, AngularJS and Node.js.
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MERN: MongoDB, Express, ReactJS and Node.js
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LAMP/LEMP: Linux, Apache/ Nginx (pronounced engine-x), MySQL and PHP
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Django Stack: Django, python and MySQL
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Ruby on Rails: Ruby, PHP and MySQL
Single-page applications (SPAs) and progressive web applications (PWAs) have become the norm in full-stack development and server-side rendering (SSR) have appeared to overcome their limitations. Moreover, the web applications’ frontend needs to work with the backend to offer smooth functionalities and features to the users. To address this issue, the concept of the backend for the frontend has come into view and helps developers to align the backend with the frontend using APIs.
What is an API?
Application Programming Interfaces (APIs) are the set of definitions and protocols that help two software components to communicate. It acts as a middleman between services without having to know how they are implemented. By allowing apps to exchange functions and data securely, APIs simplify the app development process.
Read: 7 Best Practices for Testing APIs
Put simply, API allows businesses to open up the features and data of the application to external business partners, third-party developers and internal departments of the company. API uses a documented interface to enable products and services to communicate with each other and use data and functionalities from each other. A document that describes how such an interface can be built or used is called an API specification.
Here’s how APIs work:
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A client initiates an API call to retrieve data from the application - also known as a request. Leveraging the API’s URI (Uniform Resource Identifier), this request is then processed from the application to the web server and includes headers, a request verb and occasionally a request body.
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After the API receives a valid request it makes a call to the external program or web server.
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The web server sends the requested information as a response to the API.
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Finally, API sends the response to the client application.
Now that we have a basic understanding of what APIs are, we are going to introduce you to Spring Boot - a Java framework that helps in developing backend APIs.
What is Spring?
Spring has been widely adopted by developers to build scalable applications. From web apps to big data, configuration to security - whatever the application’s infrastructure needs, there’s a Spring project to help. Some of the Spring projects are Spring Boot, Spring Framework, Spring Cloud, Spring Cloud Data Flow, Spring Data, Spring Integration, Spring Batch, Spring Control, Spring Security and more.
Although Spring MVC can be used to create REST API, the configurations are manual and each dependency needs to be defined separately, so, it can be time-consuming and overwhelming for new developers.
Read: Microservices vs API
To solve this problem, we have Spring Boot. Spring Boot is a Spring framework module that creates a complete production-ready environment that can be fully configured using its prebuilt codebase. It allows developers to create REST APIs with minimal configuration.
Spring boot is better suited for building REST APIs because:
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It has an embedded tomcat server to run applications
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It doesn’t require complex XML configurations.
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It includes an auto-configuration feature that configures an application for certain dependencies automatically.
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It can also auto-configure Spring libraries and third-party libraries.
Building REST API with Spring Boot
REST has become the de facto standard for developing APIs on the web as they are easy to build and use. To create REST API with Spring Boot, we will also use Spring Initializr which creates the structure of Spring Boot projects for you.
But why should we create a REST API?
As REST embraces the rules of the web including its benefits, architecture and more. By building on top of HTML, REST APIs help in building scalable services, evolvable APIs, backward compatible APIs, stateless to stateful services, and securable services. One thing to notice before moving ahead is that REST is not a standard but an approach that can help in developing web-scale applications.
Read: API VS Web Services VS Microservices
To create REST API, we need to:
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Create the Spring Boot Project
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Configure JPA, Spring Data Source and Hibernate
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Create an Entity Class
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Create JPA (Java Persistence API) Data Repository layer
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Create Rest Controllers and map API requests
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Build and run the Project
Create the Spring Boot Project
To begin, go to Spring Initializr and create a project with the below settings:
Web: Provides support for building web applications, including RESTful services, using Spring MVC and Apache Tomcat.
SQL: Java Persistence API with Spring Data and Hibernate is used to persist data in SQL stores.
Developer Tools: It allows you to restart applications quickly, perform LiveReloads, and configure the environment for better development.
Ops: Spring Boot Ops is a community project which manages and monitors your applications. It also offers a user interface on top of the Spring Boot Actuator endpoints.
After creating a project, generate, download and import it to the development environment.
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Configure JPA, Spring Data Source and Hibernate
We are using MySQL database as datasource, where spring.datasource.username & spring.datasource.password are username and passwords of MySQL.
Hibernate is used by Spring Boot for implementation of Spring Data JPA and generates better SQL for the database that is why we configure spring.jpa.properties.hibernate.dialect.
spring.jpa.hibernate.ddl-auto, automatically exports or validates schema DDL to the database as part of SessionFactory creation.
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Create an Entity Class
Create JPA (Java Persistence API) Data Repository layer
Create Rest Controllers and map API requests
Build and run the Project
Summary
We hope that this article might have helped you in building backend APIs using Spring Boot. Now you know that the first step in creating an API is to create a project on Spring Initializr. After that only you can define the database configurations, define entity class, and build the JPA repository layer. After achieving this, the last two steps include mapping API requests while creating the Rest controller and finally, building and running the project.
Read: How Docker Container Works
However, if you are a business owner who wants to transform their web app idea into reality with the help of experts, then you should hire developers with years of hands-on experience in the same area.