What are MicroServices? When & Why is it used? | Monolithic vs Microservices Architecture

Summary of the Video (Microservices vs Monolith)

Goal

The video explains:

• What microservices are
• What a microservices architecture means
• When/why microservices are used
• How microservices differ from monolithic architecture

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Why Microservices Exist

Microservices are presented as a solution to common monolith disadvantages, particularly around:

• Redeployment
• Scaling
• Dependency/versioning

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Monolithic Architecture (As Described)

Key Characteristics

• Single unit design: The entire application is built and deployed as one codebase/repository.
• Single tech stack assumption: If the backend uses Java, the rest of the app (e.g., payments, authentication, listings) also uses Java.
• Single CI/CD pipeline: One pipeline for the whole application.

Pros

• Easier to develop and manage because everything is centralized.

Cons

1. Redeployment problem: A small change (e.g., authentication) forces redeploying the entire application.
2. Scaling inflexibility: You cannot scale only one component (e.g., authentication); you must scale the whole app.
3. Tight dependencies / version lock: Shared packages/modules often require consistent versions across features (e.g., authentication and listings can’t use different versions).

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Microservices Architecture (As Described)

Core Idea

A monolith is broken into independent services, where each microservice handles a single responsibility.

Independence

Microservices emphasize:

• Separate code bases and repositories
• Independent deployment
• Loosely coupled services

No Fixed Number Rule

There’s no hard rule for how many microservices to create—it depends on business logic/business needs.

Examples mentioned:

• Separate payments logic into its own microservice.
• Separate authentication logic with its own database.

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Benefits of Microservices

1. Independent deployment / versioning
   • Update only the affected service (e.g., authentication) and deploy a new version (e.g., v2) while other services stay on older versions.
2. Flexible scaling
   • Scale only the required services (e.g., listings) without scaling the entire system.
3. Technology flexibility
   • Different services can use different technologies (example mentioned: authentication could be in Python).

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How Microservices Communicate (3 Methods)

1. Synchronous communication via APIs

   • One service calls another using HTTP requests to the target service’s API endpoint.
   • Example: payment service calls listings service, and listings returns an HTTP response.

2. Asynchronous communication via message brokers

   • Services publish messages to a broker, which forwards them to the appropriate microservice.
   • Examples mentioned: RabbitMQ, MQ, and Apache Kafka (appeared as “Achi Kafka” due to subtitle errors).

3. Service mesh (for Kubernetes deployments)

   • Mentioned as common when microservices run on Kubernetes (referred to as “Kube Networks”).

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Disadvantages / Tradeoffs of Microservices

• More complexity (“textured”): Requires coordination across multiple teams and services.
• Higher management overhead: More platforms/services to manage.
• Higher infrastructure cost:
  • Each microservice typically has its own CI/CD pipeline and runs in independently managed containers.
• Not ideal for small teams/startups: Overhead and cost can outweigh benefits.
• Preferred by large organizations: Benefits are more compelling at scale.

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Main Sources / Speakers

• Single narrator/speaker (no named person shown in the subtitles).