Why microservices exist - Why It Works This Way

Overview - Why microservices exist

What is it?

Microservices are a way to build software by splitting a big application into many small, independent parts. Each part does one job and can work on its own. This helps teams build, test, and update software faster and more safely. Instead of one big program, you have many small programs working together.

Why it matters

Without microservices, software often becomes a huge, tangled mess that is hard to change or fix. When one part breaks or needs updating, the whole system can slow down or stop. Microservices let companies deliver new features quickly and keep their systems running smoothly, which is important for users and businesses.

Where it fits

Before learning why microservices exist, you should understand what a monolithic application is and the basics of software architecture. After this, you can learn about how to design microservices, how they communicate, and how to manage them in production.

Mental Model

Core Idea

Microservices exist to break big software into small, manageable pieces that can be built, changed, and scaled independently.

Think of it like...

Imagine a big department store where every product is in one giant room versus a mall with many small shops. Each shop can change its products or open longer hours without affecting the others.

┌───────────────┐   ┌───────────────┐   ┌───────────────┐
│  Microservice │   │  Microservice │   │  Microservice │
│      A        │   │      B        │   │      C        │
└──────┬────────┘   └──────┬────────┘   └──────┬────────┘
       │                   │                   │
       └───────┬───────────┴───────────┬───────┘
               │                       │
          ┌────▼────┐             ┌────▼────┐
          │  Client │             │ Database│
          └─────────┘             └─────────┘

Build-Up - 6 Steps

1

Foundation

Understanding Monolithic Applications

Concept: Learn what a monolithic application is and its limitations.

A monolithic application is built as one single unit where all parts are tightly connected. For example, the user interface, business logic, and database access are all in one program. This makes it simple to start but hard to change or grow because everything depends on everything else.

Result

You see why big applications can become slow to update and hard to fix.

Understanding the limits of monoliths helps explain why breaking software into smaller parts can be better.

2

Foundation

Basics of Software Scalability

Concept: Learn why software needs to handle more users and data over time.

As more people use an app, it needs to work faster and handle more data. Scaling means making the software bigger or faster. Monoliths often scale by copying the whole app, which can be expensive and inefficient.

Result

You understand why scaling a big app is hard and costly.

Knowing scalability challenges shows why smaller parts can be scaled separately and more efficiently.

3

Intermediate

Introducing Microservices Architecture

🤔Before reading on: do you think splitting an app into parts makes it simpler or more complex to manage? Commit to your answer.

Concept: Microservices split a big app into small, independent services that each do one job well.

Instead of one big program, microservices are many small programs. Each service can be built, tested, and deployed on its own. They communicate over the network using simple messages. This separation helps teams work independently and speeds up development.

Result

You see how microservices can make software easier to build and change.

Understanding that independence between parts reduces risk and speeds up updates is key to why microservices exist.

4

Intermediate

Benefits of Microservices Over Monoliths

🤔Before reading on: do you think microservices improve deployment speed or just add complexity? Commit to your answer.

Concept: Microservices improve flexibility, scalability, and fault isolation compared to monoliths.

With microservices, teams can deploy updates to one service without touching others. If one service fails, it doesn't crash the whole app. Each service can be scaled independently based on demand, saving resources.

Result

You understand the practical advantages microservices bring to software projects.

Knowing these benefits explains why many companies choose microservices despite added complexity.

5

Advanced

Challenges That Led to Microservices

🤔Before reading on: do you think microservices were invented to solve technical or organizational problems? Commit to your answer.

Concept: Microservices address both technical limits and team coordination problems in large software projects.

As apps grew, teams became large and needed to work independently. Monoliths made coordination hard and slowed releases. Microservices let teams own services end-to-end, improving speed and quality. They also help manage complex systems by isolating failures.

Result

You see microservices as a solution to both code and team challenges.

Understanding the organizational reasons behind microservices reveals why architecture and team structure are linked.

6

Expert

Trade-offs and Why Microservices Exist Today

🤔Before reading on: do you think microservices always improve software or sometimes add new problems? Commit to your answer.

Concept: Microservices exist because their benefits outweigh their complexity in many modern systems, but they introduce new challenges.

Microservices add network communication, data consistency, and deployment complexity. They require automation and monitoring tools. However, for large, fast-changing systems, these trade-offs are worth it. The rise of cloud computing and containers made microservices practical and popular.

Result

You appreciate why microservices are not a silver bullet but a strategic choice.

Knowing the trade-offs helps you decide when microservices are the right solution and prepares you for their operational challenges.

Under the Hood

Microservices work by running many small, independent programs that communicate over networks using APIs or messaging. Each service has its own database or data store to avoid tight coupling. They deploy separately, often in containers, and use service discovery to find each other. This setup isolates failures and allows independent scaling.

Why designed this way?

Microservices were designed to overcome the rigidity and scaling limits of monoliths. By decentralizing data and logic, teams can work independently and deploy faster. The design balances independence with the need for communication, using lightweight protocols to keep services connected but loosely coupled.

┌───────────────┐     ┌───────────────┐     ┌───────────────┐
│ Microservice  │◄───►│ Microservice  │◄───►│ Microservice  │
│     A         │     │     B         │     │     C         │
└──────┬────────┘     └──────┬────────┘     └──────┬────────┘
       │                     │                     │
┌──────▼─────┐         ┌─────▼─────┐         ┌─────▼─────┐
│ Database A │         │ Database B│         │ Database C│
└────────────┘         └──────────┘         └──────────┘

Myth Busters - 4 Common Misconceptions

Quick: Do microservices always make software simpler to manage? Commit yes or no.

Common Belief: Microservices always simplify software management by breaking it into parts.

Reality: Microservices add complexity in communication, deployment, and data consistency that must be managed carefully.

Why it matters: Ignoring this leads to systems that are harder to debug and maintain than monoliths.

Quick: Do microservices eliminate the need for coordination between teams? Commit yes or no.

Common Belief: Microservices let teams work completely independently without coordination.

Reality: Teams still need to coordinate APIs, data contracts, and deployment schedules to avoid conflicts.

Why it matters: Underestimating coordination causes integration failures and delays.

Quick: Do microservices always improve performance? Commit yes or no.

Common Belief: Microservices always make applications faster and more scalable.

Reality: Network calls between services add latency; improper design can hurt performance.

Why it matters: Assuming automatic speed gains can lead to poor user experience.

Quick: Are microservices a new invention from the last few years? Commit yes or no.

Common Belief: Microservices are a brand-new concept invented recently.

Reality: The idea of splitting software into smaller parts has existed for decades; microservices formalized and popularized it with modern tools.

Why it matters: Knowing the history helps avoid hype-driven decisions and appreciate foundational principles.

Expert Zone

1

Microservices require careful API versioning to avoid breaking dependent services during updates.

2

Data consistency across services often uses eventual consistency, which changes how developers think about transactions.

3

Operational complexity grows with microservices, demanding advanced monitoring, logging, and automated deployment pipelines.

When NOT to use

Microservices are not ideal for small or simple applications where the overhead outweighs benefits. In such cases, a monolithic or modular monolith approach is better. Also, if the team lacks DevOps maturity or automation, microservices can cause more harm than good.

Production Patterns

In production, microservices often use container orchestration platforms like Kubernetes, API gateways for routing, and service meshes for secure communication. Teams adopt continuous integration and continuous deployment (CI/CD) pipelines to manage frequent releases safely.

Connections

Modular Programming

Microservices build on the idea of modular programming by applying it at the system level.

Understanding modular programming helps grasp how breaking software into independent parts improves maintainability and reuse.

Supply Chain Management

Both microservices and supply chains break complex systems into smaller units that operate independently but must coordinate.

Seeing microservices like supply chains highlights the importance of clear interfaces and coordination to avoid bottlenecks.

Cellular Biology

Microservices resemble cells in biology, each performing specialized functions and communicating to keep the organism alive.

This connection shows how complex systems thrive by dividing work into specialized, autonomous units.

Common Pitfalls

#1 Trying to convert a small app into microservices too early.

Wrong approach:

Splitting a simple app into many microservices before it grows:
Service A: handles users
Service B: handles orders
Service C: handles payments
All deployed separately from day one.

Correct approach:

Start with a monolith or modular monolith and split into microservices only when the app grows and needs it.

Root cause:

Misunderstanding that microservices add overhead and are not always the best first step.

#2 Ignoring data consistency challenges between services.

Wrong approach:

Each microservice updates its own database without coordination, assuming data is always in sync.

Correct approach:

Design services with eventual consistency and use messaging or events to synchronize data changes.

Root cause:

Assuming microservices share a single database like monoliths do.

#3 Not automating deployment and monitoring.

Wrong approach:

Manually deploying each microservice and checking logs by hand.

Correct approach:

Use CI/CD pipelines and centralized monitoring tools to manage many services efficiently.

Root cause:

Underestimating operational complexity introduced by microservices.

Key Takeaways

Microservices exist to break large software into small, independent parts that can be developed and scaled separately.

They solve problems of monolithic apps like slow updates, scaling limits, and team coordination challenges.

Microservices bring benefits but also add complexity in communication, deployment, and data management.

Choosing microservices requires understanding trade-offs and having the right tools and team practices.

Microservices connect deeply to ideas in modular design, organizational structure, and complex system management.