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Modular Architecture in Mobile Development: Pros and Cons


10 min read

Modular architecture, as a software design technique when an application is structured as a collection of distinct, self-contained modules, has existed for more than 73 years already. Despite it being well-established, lots of apps are built using traditional, monolithic development patterns. 

It’s possible to observe that mobile software solutions become more complex as the capabilities of mobile platforms evolve. The modular architecture is exactly what can help here due to the scalability, flexibility, maintainability, and reusability it has to offer.

In this post, I’ll delve deeper into the concept of modular architecture, review implementation details, discover the major advantages and limitations of this software design, and share my top tips for working with modular apps. 

What is Modular Architecture?

Let’s get started by defining modular architecture:

Modular architecture is a software design approach where a system is divided into a set of smaller, independent software modules. Each module is responsible for a distinct aspect of the system’s functionality and can be developed, tested, and maintained separately.

In contrast, traditional app design, often referred to as monolithic architecture, involves developing an application as a single, indivisible unit. You can review the visual representations of two app designs in the infographics below:

Modularity and decomposition are foundational concepts in software engineering. Let’s get an understanding of them before proceeding:

Decomposition is the process of breaking down a complex system into smaller, manageable parts, i.e., modules. 

This approach follows the principles of modularity:

Modularity is when each part or software module encapsulates a specific functionality or a set of closely related functions. 

Modularity, enabled by decomposition, makes the system more understandable, maintainable, and adaptable to changes over time.

Implementation of the Modular Software Design

You may have a monolithic application that you intend to rework into a modular one. Alternatively, you may be starting modular application development from scratch. Both ways, the steps you will have to go through to implement modular software design are shown below:

  1. Requirement analysis. Understand and outline the software’s requirements to identify functionalities for separate modules.
  2. Modular architecture planning. Create an architecture dividing the software into modules, each for specific or related functionalities.
  3. Defining interfaces. Set clear interfaces for modules, specifying their communication methods and data exchanges.
  4. Development of modules. Independently develop each module, ensuring self-contained functionality.
  5. Module integration. Integrate the developed modules based on the architecture, focusing on their interactions and adherence to interfaces.
  6. Testing modules. Test each module individually for functionality, followed by integration testing to ensure cohesive operation.
  7. Documentation and maintenance. Thoroughly document each module’s functionality, interfaces, and dependencies for future reference and maintenance.

The stages of modular planning and modular coding are heavily involved with decomposition, the concept that is explained in the above section. As a result of the implementation process, you should have a modular software solution that can be used and maintained error-free. 

The Benefits of Modular Mobile Applications Architecture

Breaking down complex software systems into smaller, more manageable modules has proven beneficial in lots of software solutions, which are listed in the below sections. But first, let’s get to know the main benefits that modular architecture design has to offer:

Better Scalability and Flexibility

Scalability isn’t just about handling more data or users, it’s also about accommodating new functionalities seamlessly. Modular design makes it possible to plug in new features or services as separate software modules. It helps to maintain the integrity of the existing system. 

This flexibility extends to experimenting with new features or making changes based on user feedback, ensuring the application remains dynamic and responsive to changing needs.

So, modular architecture enables easy expansion and modification of applications by adding or updating individual modules without the need to rework the entire system. This approach is particularly beneficial in the rapidly evolving tech sphere, where adapting quickly to new technologies or market demands is crucial.

Simplified Maintenance and Update

One of the standout advantages of a modular approach is the ease of maintenance and updating. In a module system, each component is isolated, meaning updates or fixes can be applied to one module without the risk of inadvertently impacting others. 

This isolation simplifies the debugging process, as developers can focus on a specific module where an issue arises rather than combing through a monolithic codebase.

With modular architecture software, regular updates and maintenance tasks become more efficient, reducing downtime and improving overall system stability. Additionally, this approach allows for continuous delivery and integration practices, enabling regular, incremental improvements without disrupting the system’s overall functionality.

Enhanced and Streamlined Collaboration Between Development Teams

Modular architecture allows multiple teams to work in parallel on different modules without any negative impacts on the system. This parallel development accelerates the overall fintech software development process, as teams can focus on specific areas without waiting for others to complete their parts. 

Modular app architecture also encourages specialization, where teams or individuals can develop expertise in certain modules, leading to higher quality and more innovative solutions. This clear division of work helps in managing large-scale projects more effectively, reducing overlaps and confusion, and promoting a more organized development workflow.

High Reusability Potential

The modular design offers high reusability in the matter that modules developed for one project can be easily repurposed or integrated into other projects. This module reuse not only saves time and resources but also ensures consistency across different applications. 

Developers can create a library of modules for common functionalities that can be plugged into new projects as needed to maximize reuse. This approach promotes the creation of higher-quality, tested modules that can be shared across teams, leading to more robust software. 

Reusability also extends to leveraging open-source software modules or third-party integrations, where external functionalities can be integrated into the application with minimal effort.

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The Limitations of Modular Mobile Applications Architecture

As with all software architectural patterns, modular app design is not deprived of limitations. Here are the main considerations to keep in mind:

Increased Complexity

The proliferation of modules can lead to a situation where managing and understanding the interconnections and dependencies becomes a challenge. This complex logic affects not just in terms of coding but also in the management of the development process.

At some point, ensuring consistent communication across modules, maintaining uniform standards, and keeping track of numerous smaller components can be more demanding than managing a monolithic structure. 

Furthermore, the complexity can escalate when integrating modules developed by different teams or individuals, as each software module may have its own unique characteristics and requirements.

Steep Learning Curve and Lengthy Start-Up Period

Understanding how to break down a whole system into modules effectively, establish communication between them, and manage their dependencies can be troublesome for new teams. 

Modular software architecture requires a thorough understanding of the technology stack as well as the specific design principles that govern modular systems.

This learning process extends the start-up period for software development, as more time is initially required for planning and structuring the large project appropriately. Furthermore, the need to establish robust and well-defined interfaces between modules adds to the initial workload, potentially delaying the start of actual development.

Integration Issues 

While each module is designed to function independently, they must work in unison. Issues can arise when integrating modules that have been developed independently or in parallel. 

Differences in the following software aspects can lead to integration issues:

  • Module interfaces
  • Data formats
  • Communication protocols
  • Security protocols
  • Technology stacks  

Additionally, ensuring that the integrated software modules perform optimally and do not introduce performance bottlenecks or reliability issues requires careful design and lots of integration tests, which can be a complex and time-consuming process.

Higher Investments May Be Needed

The upfront effort and investment in designing a modular system, establishing standards and protocols, and ensuring all team members are trained can be substantial. Furthermore, the expenses of maintaining several modules over time might be higher than those of a simpler, monolithic system. 

While modular design can provide long-term benefits in terms of maintainability and scalability, the initial investment and continuing expenditures of operating a more complicated system can be considerable, especially for smaller teams or organizations with limited resources.

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Examples of World-Wide Known Apps that Use Modular Architecture

Modular software architecture, as an approach to development, is fairly widespread. Here is the list of famous apps that utilize modular architecture and the list of respective features enabled by modules:

  • Facebook

Facebook is a social networking platform that connects people worldwide. It uses a modular software architecture to enable features like News Feed, Messenger, and Notifications. Each of these modules handles specialized functions such as user interactions, communications, and real-time changes, which improves maintainability and scalability.

  • Uber

Uber is a ride-hailing service that connects riders with drivers. Its modular structure includes separate software modules for user location tracking, payment processing, ride matching, and driver/rider interfaces. They facilitate the smooth integration of complex functionalities and easier updates.

  • Instagram

Instagram is a photo- and video-sharing social networking service. It employs modular architecture in components like the feed, stories, direct messaging, and camera filters. These modules are in charge of various parts of the app’s operation, such as enhancing the user experience and developing new features.

  • PayPal

PayPal is a globally recognized digital payment platform. Its modular architecture is critical in handling distinct functions like user account management, payment processing, fraud detection, and currency conversion. This separation of modules allows PayPal to efficiently manage diverse payment operations, enhance security measures, and introduce new features or services while ensuring a seamless user experience across different regions and currencies.

  • Square

Square, known for its payment processing solutions, leverages a modular architecture in its app. This design separates modules for point-of-sale transactions, inventory management, analytics, and customer relationship management. Such a structure enables Square to provide tailored services for various business types, from retail to restaurants, facilitating seamless payment processes, easy tracking of sales, and effective customer engagement strategies.

  • Revolut

Revolut, a global neobank that has a digital banking app, incorporates modular software architecture to offer a wide range of financial services. Its modules include personal banking, currency exchange, stock trading, and cryptocurrency services. This modular approach allows Revolut to efficiently manage different financial services within one platform, ensuring a cohesive user experience while enabling rapid expansion and adaptation to new financial trends or regulatory changes.

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My Tips for Modular App Architecture Design

I am a mobile development team lead with over 8 years of diverse experience in programming and mobile app architecture. I specialize in crafting mobile applications for business needs. From my experience, following software architecture best practices is extremely helpful. Also, in the process, every development team finds what works best for them. With respect to modular software architecture, here are some bits of knowledge I’d like to share:

  1. Start with a good plan. Before everything else, think about what each part of your app will do. Draw diagrams or other visual representations if you find them helpful. This enables a better understanding of how different parts will work together and what each part must be responsible for. 
  2. Keep modules independent. Each module should work on its own, without other modules involved in any way. Why is it so? Independent modules are easier to update and fix. If a single module experiences an issue, it won’t break the whole app but rather just make a part of its functionality temporarily unavailable. 
  3. Use clear interfaces between modules. From a certain point of view, an interface is like a contract. It says how modules will communicate with each other. With clear interfaces, you can change the inside of a module without affecting the work of others. As well as keeping modules independent, using clear interfaces makes updates safer and easier 
  4. Make modules reusable. Design software modules so you can use them in different parts of your app or even in multiple apps. This saves loads of time and resources. The best thing about modular software architecture is that by featuring it, you don’t have to write the same or similar code again for another feature or app.
  5. Test modules separately. Check each module by itself to make sure it works right. Once again, this approach makes it easier to find and fix technical issues. You will know which module is troubled for sure.
  6. Document everything well. Write clear explanations for each module, including what it does, how it works, and how it connects with others. Good documentation helps other developers understand your code. This is really helpful for big teams or when onboarding new developers.
  7. Plan for module size and complexity. Don’t implement too big or too complicated modules. As per the best modularity and composition principles, break big tasks into independent parts. Smaller modules are easier to manage, update, and understand. They also make the app run faster.

The listed tips, combined with standard practices for modular programming, are a good starting point. You and your team will find what works best for you and your software solution in the process. 

Final Take

Modular architecture in mobile development offers a compelling blend of advantages, notably in scalability, maintainability, and development speed. It allows for efficient handling of complex applications by breaking them down into manageable, reusable, and independently functioning modules. 

However, it’s important to acknowledge the potential challenges, such as the initial complexity of setting up a modular system and the need for meticulous planning and coordination among different modules.

Partnering with a trusted team specializing in modular software development is half the battle. Here at DashDevs, we have been providing fintech services for more than 12 years, assisting businesses worldwide. 

Contact us to book your free strategy session. Let’s discuss the modular architecture in mobile development and other IT opportunities for your business.

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Table of contents
How can modular coding help when designing a large project?
In large-scale projects, modular coding allows for better organization, easier maintenance, simpler debugging, scalable development, and more effective collaborative work.
Can modular architecture be integrated with other development approaches, like Agile or DevOps?
Yes, the development of an app with a modular architecture supports Agile and DevOps practices, complementing these methodologies by enhancing flexibility and efficiency in development processes.
Is modular architecture suitable for all types of mobile applications?
The modular architecture is mainly suitable for large-scale apps, apps requiring frequent updates, cross platform mobile development, and projects where multiple teams are involved. It’s not suitable for small-scale apps or rapid prototyping.
As a startup owner, should I use modular architecture?
As a startup owner, using modular architecture can be beneficial, particularly if you anticipate your application will grow and evolve over time. This development approach will make future expansions and updates more manageable.