This article explores Spring Cloud Native Application Development, empowering you to build scalable and resilient microservices.
Rod Johnson’s book Expert One-on-One J2EE Design and Development lays the foundation for Spring, addressing the complexities of early J2EE specifications.
Challenges of Java Enterprise Edition (JEE later Jakarta EE) involved significant amounts of configuration and repetitive code, tight coupling of components, hindering portability and testing. It was difficult to test individual components in isolation due to tight coupling and reliance on the server environment.
In traditional coding, objects directly create and manage their own dependencies. This creates tight coupling. A change in one object’s dependency can ripple through its collaborators, requiring extensive code modifications. Testing becomes difficult, as tightly coupled objects are hard to isolate.
Spring provided a lightweight container, called Inversion of Control (IoC) for managing objects and dependencies and an application context for centralized configuration and resource access, streamlining application setup and configuration management.
With its Inversion of Control (IoC) container it offered a dependency injection(DI) paradigm which meant loose coupling between objects which greatly increased modularity and improved testability.
As a result spring framework emerged to simplify enterprise application development, and embrace open source collaboration. This transformed how developers managed dependencies and promoted a more adaptable code structure.
Spring Framework Principles
Shifting control from code to configuration, allows developers to define how objects collaborate without directly creating or managing their dependencies.
DI fosters loose coupling and modular code, making applications easier to test, maintain, and extend. This shifts the responsibility of managing dependencies from objects to Spring’s IoC container. The container injects the required dependencies into an object at runtime, based on its configuration. It allows you to define dependencies in configuration files or annotations, decoupling objects from their concrete implementations.
.Second big thing was object-relational mapping(ORM) which greatly improved converting database information to Java specific objects.
Aspect Oriented programming(AOP), empowered developers to implement cross-cutting concerns (like logging, security, and transactions) without cluttering core business logic, leading to cleaner code and better maintainability.
Providing pre-built modules and simplified configuration saved developers from writing code for common tasks. Configuration means what modules to be included and how objects interact and collaborate. Initially spring offered an XML file configuration approach, but with the introduction of the Annotations feature in Java language quickly adapted this approach.
Spring 4.0, released in 2014, marked a significant step forward for the framework, embracing modern Java features and refining core functionalities.
It marked a significant modernization and refinement of the Spring framework, embracing Java 8, enhancing core functionalities, and laying the foundation for future advancements like reactive programming.
Spring 5.0, released in 2017, was a major milestone for the framework, introducing significant novelties like Reactive Programming and Kotlin language support
Spring 6.0, released in November 2022, builds upon the foundations laid in Spring 5, offering various exciting new features and advancements like dedicated initiative for Observability and embrace for Java 17
Throughout its history, Spring has constantly adapted to address evolving industry trends and developer needs. From simplifying J2EE development to pioneering microservices development with Spring Boot, the framework has remained a cornerstone for building robust and efficient Java applications.
Spring embraced new technologies and paradigms like reactive programming and microservices, necessitating specialized modules with distinct lifecycles and dependencies.
Spring Landscape
As Spring grew and incorporated diverse functionalities, the monolithic core framework became increasingly complex and unwieldy. Separate projects allowed different modules to evolve at their own pace and integrate seamlessly with external libraries and frameworks.
At the heart of this modularity is Spring Core, the foundational module of the Spring Framework, providing the fundamental building blocks for developing Spring applications. It encapsulates core functionalities like:
Dependency Injection, data binding, type conversion, Spring Expresion Language(spEL) ,AOP, testing, Data Access, Spring MVC, Integration (JMS, JCA, JMX, scheduling, cache and observability), Language support (Kotlin, Groovy…).
Here’s an overview of some key modules from the diverse Spring ecosystem that have emerged over the years.
Spring MVC (Model-View-Controller) module
It became a separate project in 2007. It is a popular web framework within the Spring ecosystem built on top of the Servlet API. It implements the MVC design pattern, separating the application logic (Model), presentation layer (View), and user interaction handling (Controller) into distinct components. This enables cleaner, more maintainable, and testable code for building web applications.
Central to this module is DispatcherServlet which acts as the central entry point for all web requests, directing them to the appropriate controller based on the URL pattern.
Spring Data Module
It emerged in 2008 and is a powerful umbrella project within the Spring ecosystem that aims to simplify data access and management for Spring applications. It provides abstractions and integrations for various data sources, libraries, and frameworks, allowing developers to work with databases, repositories, and persistence layers in a more convenient and consistent way.
Most important thing in this module is Object-Relational Mapping (ORM) which integrates with popular ORMs like JPA and Hibernate, simplifying object-persistence mapping and entity management. Developers can work with domain objects seamlessly without delving into intricate ORM details.
Spring Data offers additional functionalities like transactions, auditing, caching, and event-driven data access, further enhancing data management capabilities within Spring applications
Spring Security Module
Spring Security became a separate project in 2004. It is a powerful and comprehensive framework within the Spring ecosystem that provides essential security features for your Java applications. It helps you protect your applications from unauthorized access, data breaches, and other security threats, ensuring the integrity and confidentiality of your user data and business logic.
Spring security offers authentication ( including form-based login, basic authentication, token-based authentication and more), authorization( access control rules that determine which users or roles can access specific resources or functionalities within your application) and data encryption tools, both at rest and transit etc.
Spring Cloud Module
Is a suite of tools and libraries built on top of the Spring Framework, designed to facilitate the development and deployment of microservices architectures for Java applications. It provides a collection of pre-built components and patterns that address common challenges in distributed systems, such as service discovery( like Spring Cloud Eureka), configuration management( like Spring Cloud Config), load balancing (like Spring Cloud Ribbon).
Spring Cloud Stream enables communication between microservices using message queues and event buses, fostering asynchronous interactions and decoupling services.
Spring Cloud Gateway serves as a single entry point for your microservices API, simplifying routing and providing additional functionalities like security and rate limiting.
Spring Web Flow
Is a framework within the Spring ecosystem designed to manage the flow of user interactions within your web applications. It provides a structured way to define and control the sequence of steps a user goes through, offering advantages for complex workflows or multi-step user journeys.
Spring for Apache Kafka
Is a project within the Spring ecosystem that provides high-level abstractions and integrations for working with Apache Kafka, a distributed streaming platform, within your Spring applications. It aims to simplify Kafka development and utilization by leveraging the familiar Spring programming model and best practices.
Enables sending messages to Kafka topics using a Spring-style template object, similar to Spring’s JDBC template for database interactions. This simplifies sending messages and removes the need for low-level Kafka client API calls.
Provides support for additional functionalities like transactions, offsets management, and integration with Spring Security for securing Kafka interactions.
Spring Boot Module
It becomes clear that including and configuration of these libraries becomes a daunting task,
Spring Boot, introduced in 2014, revolutionized Spring adoption with its opinionated configuration and rapid application bootstrapping, becoming a separate project for faster evolution.
It uses the Convention over Configuration(CoC) pattern that aims to reduce the amount of explicit configuration code developers need to write. It achieves this by establishing sensible defaults and conventions that the framework or library adheres to, making common tasks easier and more intuitive.
Spring Boot has a set of auto-configuration classes, each responsible for configuring a specific feature or component. These classes have conditions attached to them, ensuring they only apply when the necessary dependencies and context are present. Developers can disable specific auto-configurations or provide your own bean definitions to take precedence.
Those properties make good fit for Spring Cloud Native Application Development.
Cloud Native Applications
Cloud native applications should be specifically designed for the cloud and have properties that take advantage of the cloud environment and the cloud computing model.
What does it mean to take advantage of “cloud computing”?
National Institute of Standards and Technology (NIST) defines cloud computing as follows:
Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.
Cloud Native Applications Properties
The Cloud Native Computing Foundation(CNCF) identifies five main properties that cloud native applications. That is:
Scalability – the ability of a system to handle a growing amount of work or workload while maintaining its performance and efficiency.
Loose coupling – Components in a loosely coupled system rely on each other as little as possible, meaning a change in one component has minimal impact on the others
Resilience – the ability to withstand, adapt to, and recover from unexpected disruptions, errors, or external threats
Observability – the ability to gain deep insights into the internal state and health of your system based on its external outputs.
and
Manageability – the ability to effectively control, operate, and maintain a cloud-native system throughout its entire lifecycle.
Cloud Native Topologies
These goals were achieved with the help of several principles called Cloud Native Topologies. That is:
Containers – lightweight and isolated software packages containing everything an application needs to run: code, runtime, system tools, settings, and libraries.
Spring Boot‘s embedded servers (Tomcat, Jetty, Undertow) eliminate the need for external server installations, making applications self-contained and easier to package as containers. DI pattern decouples components and simplifies testing and maintenance thus It becomes easier to manage dependencies within containers, reducing conflicts and promoting portability.
Those features and capabilities that seamlessly align with containerization practices, makes it a perfect choice for building cloud-native applications.
Orchestration – automated management and coordination of containerized applications and their underlying infrastructure.
Spring Framework offers seamless integration with orchestration tools such as Kubernetes.
This is possible with tools like: Spring Cloud Netflix Eureka for service discovery, Spring Cloud Config server for automatic configuration and Spring Boot Actuator for health checks and observability.
Developers can leverage these integrations to seamlessly deploy and manage containerized Spring applications within an orchestrated environment.
Serverless – It moves away from the traditional notion of managing and maintaining servers, allowing developers to focus solely on writing and deploying code.
While Spring Framework wasn’t designed specifically for serverless, it offers capabilities that align well with serverless principles and cloud-native environments.
Spring Cloud Function project features include function definition annotations, flexible function binding, and integration with popular serverless platforms like AWS Lambda, Azure Functions, and Google Cloud Functions.
Spring supports reactive programming paradigms like Project Reactor and Spring WebFlux, which align well with the event-driven nature of serverless functions.
This enables building responsive and scalable functions that can handle high volumes of events efficiently.
Cloud Native Applications Architecture
Cloud Native Applications are built using modern architecture styles that leverage cloud native properties.
Lets see how Spring Cloud Native Application Development fits here:
Microservices – a fundamental architectural approach where large applications are broken down into smaller, independent services.
Spring Framework plays a crucial role in building and managing microservices in cloud-native environments. Its focus on modularity, agility, and cloud-native integration makes it a go-to choice for developing robust and scalable microservices applications.
Service Based Architecture(SBA) – it’s about building an entire system around the concept of well-defined, independent services that collaborate to deliver functionality.
Spring offers flexible dependency management options like annotations, XML configuration, and external servers.This allows services to manage their dependencies effectively without impacting other services, upholding the principle of loose coupling.
Spring Cloud Netflix Hystrix and other tools offer circuit breaker patterns and resilience mechanisms.These features ensure that failures in one service don’t cascade to others, maintaining uptime and application stability, crucial for robust SBA implementations.
Conclusion
Spring Framework and cloud-native technologies form a powerful alliance for building and deploying agile, resilient, and scalable Spring Cloud Native Application in the modern cloud.
Spring’s modularity, flexibility, and cloud-native integrations equip developers with a comprehensive toolbox to embrace. Whether you’re building microservices, serverless functions, or API gateways, Spring offers the tools and flexibility to craft cloud-native applications that can thrive in the ever-evolving landscape of the digital age.
This isn’t just a technology match; it’s a paradigm shift, empowering developers to deliver innovative and reliable solutions that scale with ease and adapt to the ever-changing demands of the cloud.