From Monolithic to Microservices: Architecture Basics for Web Developers

Are you ready to take your web development skills to the next level? If you already know the basics of how the web works and have built a few projects, it’s time to dive deeper into software architecture. Two key patterns often dominate these discussions: monolithic architecture and microservices architecture. In this guide, we’ll break down both, explore their pros and cons, and share tips on how to migrate from one to the other.

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What Is a Monolith?

In a monolithic architecture, your application is packaged as a single, unified codebase (often following the MVC pattern) and typically shares one database. All features and modules are interconnected and run as a single deployment unit.

Advantages of a Monolith

• Simpler Development: With everything in one place, it’s straightforward to build and debug smaller projects.
• Easy Deployment: You typically deploy just one application, so updates and versioning are relatively painless.
• Streamlined Debugging: Troubleshooting is often simpler because you only need to look into a single codebase.

Disadvantages of a Monolith

• Limited Scalability: You can’t easily scale individual features; you usually scale the entire application—even if only one module needs it.
• Complex Maintenance: As the codebase expands, keeping track of all functionalities in one place can become overwhelming.
• Slower Feature Development: Large monoliths can hamper development speed once they become unwieldy.

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Enter Microservices Architecture

Microservices architecture breaks your application into smaller, independently deployable services. Each service has its own database and communicates with other services via lightweight APIs. Popular patterns like Domain-Driven Design (DDD) guide how microservices are structured around business domains.

Advantages of Microservices

• Independent Scalability: Scale individual services as needed, saving resources and optimizing performance.
• Flexibility in Tech Stacks: Different services can use different technologies, enabling teams to pick the best tools.
• Distributed Complexity: Bugs and feature changes are confined to smaller codebases, making it easier for new developers to onboard.

Disadvantages of Microservices

• Complex Communication: Ensuring all services reliably talk to each other can be challenging (think message queues, network configurations, etc.).
• Infrastructure Management: Deployment pipelines and monitoring for multiple services require more effort.
• Higher Latency: Each inter-service call adds overhead; poor design can lead to performance bottlenecks.

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A Hybrid Approach: Tools That Bridge the Gap

Some platforms aim to combine the simplicity of monolithic development with the scalability of microservices. One example is Encore, which lets you call a microservice from within another service with minimal hassle, almost like working in a single codebase. These platforms strive to provide the developer experience of a monolith alongside the scaling power of microservices.

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Choosing the Right Architecture

When deciding which architecture to use, consider your project’s complexity, growth potential, and team size.

Architecture	Key Benefits	Main Drawbacks	Best For
Monolithic	Simple to develop, deploy, and debug	Scaling can be complex as the app grows	Small-to-medium projects or MVPs (e.g., DEV.to reportedly uses a monolith)
Microservices	Independently scalable parts, flexible tech choices	More complex management and communication	Large-scale apps with multiple teams (e.g., Netflix operates with numerous microservices)

If you’re unsure, starting with a monolith is often wise. It’s easier to split a monolith later than to merge multiple services if you over-engineer too early.

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Migrating From a Monolith to Microservices

If you do decide to break up a monolithic application, here are two common strategies:

1. Greenfield Replacement
   Build an entirely new system from scratch (the “green field”). This avoids legacy constraints but may take substantial time and planning.
2. Brownfield Replacement
   Let new and old systems coexist while gradually refactoring. A popular tactic here is the Strangler Fig Pattern: wrap parts of the old system with new microservices, slowly phasing out legacy components to minimize risk and downtime.

Typical Migration Steps

1. Identify Boundaries: Determine which parts of the monolith can function independently.
2. Extract Services: Move less critical features or modules first to reduce overall risk.
3. Implement New Features Separately: Keep new development within microservices, preventing old code from expanding.
4. Refactor & Support: Modify the monolith to communicate with the new services.
5. Test & Monitor: Use thorough testing strategies to ensure reliability during and after the transition.

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Final Thoughts

Software architecture is rarely one-size-fits-all. Monolithic architectures work best for smaller, simpler applications or MVPs where speed and ease of development are key. Microservices shine in complex, large-scale environments that require flexibility and independent scalability.

No matter which path you choose, understanding both architectures is crucial for making informed decisions. With the right strategy in place—and a plan for refactoring—you’ll be well-equipped to handle the evolving needs of your project.

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Thank you for reading! If you have insights or questions about these architectures, share them in the comments. Remember, start small, plan for growth, and adopt the architectural style that best suits your project’s needs.