Monolith vs Microservices

The sudden interest in monoliths is largely due to the challenges that some organizations are facing with microservices. While microservices offer a range of benefits, they also introduce complexity in terms of deployment, management, and inter-service communication. Before we jump into the reasons, lets get the basics.

A microservices architecture is an approach where a software application is broken down into smaller, independently deployable services that communicate with each other through APIs. Each microservice focuses on a specific business capability and can be developed, deployed, and scaled independently. Microservices promote flexibility, agility, and easier maintenance, as changes to one service do not necessarily impact others.

A monolithic architecture is a traditional model where a software program is built as a single, unified unit. In a monolith, all business concerns are coupled together within one large code base. Making changes to a monolithic application involves updating the entire stack, which can be restrictive and time-consuming.

We look at pros and cons of microservices vs monolithic architectures

Microservices Architecture:

Pros:

• Modularity: Microservices break down applications into smaller, independent services (like LEGO bricks). Each service can be developed, deployed, and scaled independently.
• Scalability: Microservices allow fine-grained scaling. You can scale specific services based on demand.
• Flexibility: Different teams can work on different services, using technologies best suited for each.
• Fault Isolation: Failures in one microservice don’t affect others, improving system resilience.

Cons:

• Complexity: Managing multiple services, APIs, and inter-service communication introduces complexity.
• Operational Overhead: Each service requires its own infrastructure, monitoring, and deployment pipeline.
• Data Consistency Challenges: Distributed databases and eventual consistency can be tricky.
• Upfront Costs: Setting up microservices demands more resources initially, but this cost is often offset by long-term benefits.

Monolithic Architecture:

Pros:

• Simplicity: Monoliths are easier to understand and develop initially. They involve a single codebase, making it straightforward for small teams or simple applications.
• Cross-Cutting Concerns: Metrics, logging, configuration, and service registration are simpler to manage within a monolith since everything resides in one application instance.
• Faster Time to Market: For small teams working on straightforward apps, monoliths allow rapid development.

Cons:

• Scalability: Scaling monoliths becomes complex as they grow. Initially, they’re simpler to scale, but with enterprise-level demands, microservices offer better scalability.
• Data Consistency: In large monolithic applications, maintaining data consistency across various components can be challenging.
• Resource Intensiveness: Scaling a monolith can be expensive in the long run.

In recent times there is large interest in monoliths. Amazon Prime Video initially adopted a microservices architecture for its audio/video monitoring service, which analyzed the quality of audio and video streams in real-time. However, as the number of streams on the platform increased, this microservices infrastructure faced scaling bottlenecks and became costly. Amazon Prime Video’s move is akin to a hybrid architecture called Modulith.

Modulith combines the best of both worlds: a monolith broken down into loosely-coupled modules, each developed and deployed independently. Monoliths are simpler to develop, test, and deploy as they are composed as a single unit. They also eliminate the need for complex synchronization and message passing between services.

In addition, there's a growing realization that not all applications need to be broken down into microservices. In some cases, a well-structured monolith can be more effective and efficient.

However, it's important to note that both architectures have their place, and the choice between a monolith and microservices should depend on the specific needs and context of the project.