Modernising legacy monolithic applications

Tech Community • 4 min read

Monolithic applications are in the past.

Modular, manageable and scalable services are the future.

In software development, the shift from monolithic applications to modular, scalable services is becoming pivotal. While monolithic applications have played a big historical role, their limitations prompt a reevaluation. 

This blog explores the challenges of monolithic architectures, guiding developers toward adaptive, forward-thinking decisions. And we look at the constraints, aiming for flexibility and scalability amidst evolving technologies. 

Exploring the challenges of monolith applications

Monolithic applications have played a big role and served their purpose well in the history of software development. But they come with a set of their limitations that you really need to grasp to make informed architectural decisions. 

Understanding the problems inherent in monolithic architectures can guide developers toward more flexible and scalable solutions, ensuring their software remains adaptive in the face of evolving technological landscapes.

Here’s some of the key limitations of monolithic applications:

Unclear boundaries of services: At some point the business requirements get blurred.

Scalability: Legacy monoliths often struggle to scale to meet increasing demands.

Maintenance burden: They require extensive maintenance and are hard to modify.

Old Technology: Dependency on outdated technologies and libraries.

Resistance to adapt new tech: Inflexibility of the application makes it resistant to change.

Before starting the break down process

Before we start breaking apart the monolith, we need to understand the overall requirements and business domain of the application and its key features. 

This means we have to consider the business capabilities and not the technical layer of the application while separating the application parts. Identify dependencies between modules and consider how changes in one can affect the others. 

The same rule applies to the databases - how to break down the databases into independent and normalised small databases. The technology world is moving incredibly fast, so thinking through re-architecting the applications to take advantage of new technologies. 

Here are some key points to be considered:

Goals and requirements: Key features and functionality need to keep and enhanced

Architecture evaluation: Identify the pain points and performance issues.

Impact analysis: Identify the areas which affect the users and crucial functionalities while transitioning the applications.

Database analysis: Determine the databases and how the shared data will be used by new services.

High availability and scalability: Load and down time need to be handled by application.

Deployment model: Containerised applications can be deployed in local or cloud environments.

Security analysis: Review the security and compliance standard requirements.

Monitoring and logging: Distributed monitoring and logging is required for distributed and scalable services.

Embracing a microservices future

As microservices continue to evolve, adopting advanced practices becomes crucial for staying competitive in the fast-paced world of software development. Explore the event-driven architectures, container orchestration, service mesh, serverless computing, and observability to unlock the full potential of microservices. 

By mastering these advanced strategies, development teams can build resilient, scalable, and high-performing systems that meet the demands of modern applications.

What does this really look like? An example

Picture a monolithic application of transportation web sites. all aspects of the system are tightly integrated into a single, cohesive unit. This application serves as a platform catering to diverse user needs within the world of transportation. 

Users, ranging from passengers to service providers, interact with a unified system that encompasses various modes of transport booking options.

The user management system is a pivotal component, handling authentication and authorisation processes to ensure secure and controlled access. Users, based on their roles and permissions, can seamlessly navigate through the application, accessing features like route planning, booking, and real-time tracking. 

The monolithic structure also incorporates databases to store and manage vast amounts of data related to users, bookings, routes and transaction histories. This centralised approach simplifies the development process, as all functionalities, from user registration to transport bookings, are tightly coupled within the same codebase.

Now, we want to break down this application into new manageable microservices based on business requirements. For that I’d suggest the following approach:

1. Consider moving the authentication and authorisation part first to a new service or library.

2. Move the user management part to the next new service.

3. Move the route management to the new service.

4. Move the booking management to the new service.

5. Transaction management is the next part to move the service.

During this transition, we have to keep the both systems up and running but the API gateway/load balancer will redirect the requests to newly created services as and when they are deployed in production. 

Embracing microservices is not just a technological evolution; it's a strategic move to stay competitive in the ever-changing landscape of software development. It is a way of future-proofing architecture where agility, scalability, and innovation define the core principles of software setup. If you have any questions, go ahead and use the form below or find out more about our application modernisation services here.

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Ilja Summala
Ilja’s passion and tech knowledge help customers transform how they manage infrastructure and develop apps in cloud.
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