Microservices Mania: Are Moduliths the Saner Path to Scalable Architectures?

Introduction

Lately, microservices have become extremely popular in software design. They offer the ability to scale, deploy updates independently and use different technologies. However, it's easy to forget how complex microservices can be to manage. Inspired in part by the introduction of Spring Modulith, a top-level Spring project aimed at helping developers create evolvable applications, this blog post takes a fresh look at the concept of modularity. 

Could moduliths offer a simpler and more practical path for many development teams?  We'll explore scenarios where moduliths provide a more pragmatic and manageable architectural approach, highlighting the potential advantages they hold over a pure microservice-based architecture.

What are Moduliths?

Unlike microservices, which are independently deployed units communicating over a network, moduliths are highly-encapsulated modules residing within a single application.  Moduliths have their own individually-defined responsibilities and interfaces, but they share a common codebase and are deployed as a unit. Think of these modules as building blocks within a larger structure, offering a balance between the rigidity of a traditional monolith and the distributed complexity of microservices.

The Case for Moduliths

The monolithic versus microservice debate can sometimes leave developers feeling like there's no comfortable middle ground. Moduliths offer an appealing alternative, especially when considering their strengths:

Reduced Overhead: When scaling a system with microservices, each new component adds to the network complexity, increases the need for robust service discovery and can lead to potential distributed tracing headaches. Moduliths minimize these overheads, offering smoother administration, especially in early-stage projects.

Developer-Friendly: While microservices excel in isolation, sometimes it may be ore beneficial to have everything under one roof. For example, debugging and testing become more easily manageable. For smaller teams, or those tackling less complex projects, this streamlined workflow can significantly boost productivity compared to the intricacies of a microservice landscape.

Project Evolution: Moduliths serve as a smooth transition towards microservices. Start by building a well-organized, modular monolith. This approach allows you to identify components that would benefit from the microservice architecture and gradually extract them as the project grows and requirements evolve.

Performance: A Matter of Perspective:  Network latency inside a monolith is practically non-existent, with concerns about potential performance woes under a monolith being often overstated. Splitting functionality into microservices too early can introduce communication delays that may be worse than any perceived bottleneck in a monolithic architecture.

Microservices: Power with Purpose

Let's be clear, microservices aren't inherently bad. They excel under specific circumstances, such as:

Tech Stack Freedom: Microservices let you break free from the constraints of a single monolithic language or framework. This is highly beneficial when distinct parts of your system have extremely different technological needs (think a Python backend alongside a real-time Node.js component).

Giants and Their Needs: Tech titans, like Google and Amazon, operate at a scale where independent scaling is a must-have. Microservices ensure that a surge in demand for one tiny feature doesn't bring down the whole system or unnecessarily require scaling resources for unrelated components.

Resilience by Design:  When any downtime is unacceptable, the isolation provided by microservices can be a lifesaver. If one component fails, properly designed microservice architectures prevent this failure from cascading through the entire application.

It's Not Black and White

The best part about software architecture is how flexible it can be. Sticking too strictly to one style, like microservices or monoliths, can limit your project's potential. A context-based, nuanced approach that takes into account the following points, offers a better solution.

Hybrid Architectures: The Power of Combination 

Imagine your system as a well-organized city. The core downtown area, where stability and efficiency are paramount, could be built as interconnected moduliths. The  outlying suburbs, where rapid change and experimentation are more likely,  could rely on a collection of targeted microservices. This approach grants you flexibility while managing complexity.

The Right Tool for the Job: Practicality Over Trends  

The latest industry buzzwords shouldn't be your primary guide. Ask yourself critical questions: Does your project genuinely demand the overhead of full-blown microservices? Would the scalability benefits outweigh the complexity? Could a well-structured modular monolith evolve into microservices when the need arises? Let the answers to these questions, rather than the latest trends, shape your architectural choices.

Embracing Evolution 

Software systems are rarely static. What makes sense today might need to adapt in the future. Building with modularity in mind, whether in a monolith or a hybrid approach, allows you to make changes more easily when those future needs arise.  Consider moduliths and potential microservice extraction points as an investment in your system's adaptability.

Conclusion

Moduliths offer a pragmatic solution for many use cases, promoting maintainability and scalability without introducing excessive complexity. The intrinsic flexibility of Jakarta EE means you can confidently employ monoliths, microservices or a strategically chosen hybrid approach as your project demands.

Furthermore, solutions like Payara Services' range of products can cater to your chosen architecture. Need the speed and convenience of a lightweight runtime for microservices? Payara Micro is at your service. Want to leverage a comprehensive application server for a modular monolith or a hybrid system? Payara Server is there. Feeling adventurous about cloud-native deployments? Payara Cloud is ready to help. Assess your project's specific needs before blindly decomposing into a multitude of microservices – the right tools and frameworks are there to support your intended application.