Spring MVC vs Spring Web Flux: Top Differences

For creating Java-based projects and applications, developers usually have to choose between Spring MVC and Spring WebFlux when using the Spring framework to create web apps. To pick the best framework for their project, developers need to know how each one is different and what features they have.

Each framework has its own benefits compared to the others. In this article, we will learn about the main differences between Spring MVC vs Spring WebFlux so that developers can pick the best one based on their specific requirements. In this article, we will learn about the main differences between Spring MVC vs Spring WebFlux so that the developers can pick the best one for their projects.

What is Spring MVC?

Spring MVC is a classic web framework that has been widely used for creating Java web apps for a long time. It follows the model-view-controller (MVC) pattern, where the app is divided into three parts: the model (data), the view (UI), and the controller (logic).

In Spring MVC, when a request comes in, it goes to the Dispatcher Servlet first. This servlet sends the request to the right controllers. These controllers deal with the requests, work with the data, and send back the right response. Spring MVC works one request at a time, which means each request is handled by one thread. This can cause delays when there are lots of requests at once.

What is Spring WebFlux?

Spring WebFlux, on the other hand, is a reactive web framework that was introduced in Spring 5. It’s good for apps that have to do a lot of things at once and respond fast because it’s designed to handle tasks that can happen simultaneously without waiting. Spring WebFlux is made using Project Reactor, which helps with a way of programming where tasks can happen at the same time and don’t have to wait for each other.

In Spring WebFlux, the request processing flow is non-blocking, meaning that threads are not tied to individual requests. Instead, requests are dealt with one after the other, allowing the server to manage many requests at the same time using only a few threads. This makes Spring WebFlux perfect for apps that need to handle lots of users or tasks that take a long time, like streaming data or real-time analytics.

Spring MVC vs Spring WebFlux

Now that we have understood about Spring MVC and Spring WebFlux. Let’s compare both of them on various constraints like performance, programming model, Integration and more.

Performance Comparison

When you compare how Spring MVC and Spring WebFlux work, it’s important to think about how each one deals with requests, works with data, and handles lots of work.

Spring MVC

• Spring MVC basically follows a traditional synchronous model, where each incoming request is generally handled by a dedicated thread from the server’s thread pool.
• In scenarios with a moderate number of multiple requests, Spring MVC performs well and can effectively handle the workload.
• However, under heavy loads or when dealing with long-running operations, Spring MVC’s synchronous nature can lead to thread exhaustion which automatically increases the response times.
• The synchronous model can limit scalability, especially when dealing with I/O-bound operations, as threads may spend significant time waiting for I/O operations to complete.

Spring WebFlux

• Spring WebFlux, being a reactive framework, works on a non-blocking, asynchronous model.
• Requests in Spring WebFlux are generally handled in asynchronous manner in order to allow a small number of threads to handle a large number of concurrent requests.
• This non-blocking model is very well-suited for scenarios with high concurrency, as it can efficiently use system resources and handle a large number of concurrent connections without the problem of maintaining a thread per request.
• For applications that require streaming data, real-time updates, or persistent connections—where managing numerous concurrent connections effectively is critical—Spring WebFlux is generally very helpful.
• Furthermore, because of its reactive design, Spring WebFlux works well with applications that need low latency and responsive client interactions.

Programming Model

The manner in which developers engage with a framework, including the control of concurrency, handling of requests, and data flow inside the system, is determined by its programming model. In the context of Spring MVC and Spring WebFlux, their programming models differ significantly due to their underlying architectural paradigms.

Spring MVC

• In general, Spring MVC follows the traditional synchronous model, where each incoming request is typically handled by a alloted thread from the thread pool of the server.
• Controllers in Spring MVC are basically responsible for processing incoming requests, interact with the model in order to retrieve or update data, and select the appropriate view to render the responses.
• The synchronous nature of Spring MVC means that threads are mainly blocked while waiting for I/O operations to complete, such as reading from a database or making an HTTP calls or request to another service.
• This programming model is well-suited for applications with having a request-response nature, where each request is comparatively short-lived and does not require extensive concurrent processing.

Spring WebFlux

• Spring WebFlux follows a reactive programming model, which is generally based upon the principles of reactive streams and non-blocking I/O.
• In Spring WebFlux, requests are generally handled asynchronously using non-blocking I/O operations that allows a small number of threads to handle a large group of multiple requests simultaneously.
• Instead of blocking threads, Spring WebFlux uses reactive streams to process data asynchronously that allows for more efficient use of system resources and usually good for better scalability.
• The reactive programming model is very well-suited for applications that require high concurrency, real-time updates, or handling long-lived connections, as it can handle these scenarios more efficiently than the synchronous model.

Use Cases and Best Fit

Choosing between Spring MVC and Spring WebFlux depends on the specific requirements of the particular application which included factors like expected traffic volume, type of interactions with clients, and the need for real-time updates or streaming data. A well-informed decision can be made by developers if they are aware of the use cases and optimal fit for each framework.

Spring MVC Use Cases

• Spring MVC is well-suited for traditional web applications that follow a request-response model.
• Applications with moderate traffic volumes and somewhat steady usage patterns are a suitable fit for it.
• Use cases include where this is used are content management systems, apps for businesses, online stores, and other similar online apps. They all involve showing HTML pages with forms for users to interact with.

Best Fit for Spring MVC

• Applications with a straightforward request-response flow.
• Applications where the majority of interactions are synchronous and do not require handling a large number of concurrent requests.
• Scenarios where developers are more familiar with the synchronous programming model and prefer a more traditional web development approach.

Spring WebFlux Use Cases

• For apps that generally need to be responsive, have higher concurrency, and able to manage persistent connections, Spring WebFlux is just perfect.
• It is very good for applications that need to support a large number of multiple simultaneous users or handle streaming data, real-time updates, or event-driven architectures.
• Use cases include real-time analytics dashboards, social media feeds, chat applications, IoT (Internet of Things) platforms, and any application that benefits from a reactive, non-blocking programming model.

Best Fit for Spring WebFlux

• Applications with a high volume of concurrent requests or long-lived connections.
• Applications that demand streaming data, event-driven behaviour, or real-time changes.
• Scenarios where developers are interested in adopting a reactive programming model and want to use the benefits of non-blocking I/O and reactive streams.

Integration

Developers must take into account a framework’s environment and integration because these factors dictate how well the framework works with other tools, libraries, and components to create a finished application. In the context of Spring MVC and Spring WebFlux, their integration capabilities and ecosystem support can influence developers’ choices when selecting a framework for their projects.

Spring MVC Integration

• Spring MVC has been a core part of the Spring ecosystem for a longer duration of time and is well-integrated with other Spring projects and libraries.
• It is smoothly integrated with Spring’s inversion of control (IoC) and dependency injection (DI) containers that enables the developers to take advantage of Spring’s features for managing configurations, dependencies, and beans.
• Other Spring modules like Spring Data for data access, Spring Security for authentication and authorization, and Spring Boot for quick application development and deployment are also integrated with Spring MVC.

Spring WebFlux Integration

• Spring WebFlux is designed to work well within the broader Spring ecosystem and is compatible with other Spring projects and libraries.
• Building user-to-user reactive applications is only made possible by its integration with libraries for reactive data access, such as Spring Data R2DBC and Spring Data MongoDB.
• In order to secure reactive apps, Spring WebFlux can be combined with Spring Security, Cloud, and other Spring technologies that enables cloud-native application development.

Testing Support

Testing and debugging are crucial steps in the software development process since they ensure that the programmes are trustworthy, effective, and error-free.Developers may guarantee the quality and stability of their applications by knowing the testing and debugging capabilities of Spring MVC and Spring WebFlux.

Spring MVC Testing:

• Through the usage of the Spring Test framework, which consist tools for unit testing, integration testing, and end-to-end testing of MVC controllers and components, Spring MVC offers strong support for testing.
• Unit tests for Spring MVC controllers can be written using JUnit or other different testing frameworks, by using Spring’s testing annotations and utilities in order to set up the Spring application context and mock dependencies.
• Integration tests can be performed using tools like Spring’s MockMvc to mimic HTTP requests and verify the behavior of MVC controllers in a controlled environment.
• End-to-end testing of Spring MVC applications can be performed using tools like Selenium for browser automation and tools that can make HTTP requests and validate ASP.NET MVCmultiple responses.

Spring WebFlux Testing:

• Spring WebFlux provides similar testing capabilities as Spring MVC but with a focus on testing reactive components and handling asynchronous operations.
• Unit tests for Spring WebFlux controllers and handlers can be done using multiple testing frameworks like JUnit and Mockito, with support for testing reactive streams and publishers.
• Integration testing of Spring WebFlux applications can be performed using tools like WebTestClient, that basically allows for testing HTTP endpoints in a reactive and non-blocking manner.
• Because reactive applications are asynchronous, testing reactive components in an integrated environment can be very difficult, however there is support for this kind of testing with tools like the Spring Test framework.

Learning Curve and Adoption

The learning curve and adoption of a framework are important factors to consider when choosing between Spring MVC and Spring WebFlux. These elements may affect how fast and broadly a framework is adopted by the development community, as well as how productively developers may work with it.

Spring MVC Learning Curve

• Spring MVC follows a traditional synchronous programming model, which is similar to developers who have experience with other web frameworks such as JavaServer Faces (JSF), Struts, or ASP.NET MVC.
• Developers with experience in Java and web development can quickly adapt with Sping MVC and they can start working with Spring MVC, as it uses the familiar concepts such as controllers, views, and models.
• Spring MVC’s learning curve is comparatively simple for developers who are already knows with Java language and have some experience in building web applications using traditional MVC frameworks.
• Spring MVC has been a part of the Spring ecosystem for a long time so that it has a large and established user base. It has strong community support and is commonly utilised in the business.

Spring WebFlux Learning Curve

• Spring WebFlux initially introduces a reactive programming model, which may have a steeper or difficult learning curve for developers who are new in the field of reactive programming concepts.
• In Sping WebFlux, developers generally need to understand reactive streams, asynchronous programming, and non-blocking I/O in order to effectively work with it.
• While the learning curve for Spring WebFlux can be steep initially, developers having a good experience in reactive programming or having a strong foundational understanding of asynchronous programming paradigms may find it easier to understand.
• Although it is a more recent addition to the Spring framework, Spring WebFlux is becoming more and more popular, particularly when it comes to the domain like microservices and reactive designs.
• The growing popularity of reactive programming, the demand for high concurrency, and the use of architectures based on micro-services could all have an impact on the world-wide adoption of Spring WebFlux.

Conclusion

At Last, Spring is a powerful framework for creating web apps with Spring MVC and Spring WebFlux.Which one to choose depends on what the project needs. Spring MVC is good for regular web apps, while Spring WebFlux is better for apps that need to do many things at once, have long-lasting tasks, or work with reactive data.