Monolith vs. Microservices: When to use one or the other
Discussing trade-offs is crucial in system design, as it demonstrates a deep understanding of the subject. This article explores a frequent system design dilemma: choosing between Monolithic and Microservices Architecture. It provides guidance on selecting the appropriate approach for system design and real-world application development.
Monolithic vs Microservice Architectures
Monolithic architecture
Monolith — Something that is large and often rigid (like a stone)
A monolithic architecture is a traditional software development model that uses one code base to perform multiple business functions.
⚠️ It’s restrictive and time-consuming to modify monolithic architecture as small changes impact large areas of the code base.
Microservice architecture
Microservices are an architectural and organizational approach to software development where software is composed of small independent services. These services are owned by small, self-contained teams.
This makes applications easier to scale and faster to develop, enabling innovation and accelerating time-to-market for new features.
Key Differences (pros and cons)
In the Development process
the development process involves stages such as requirements gathering, planning, design, implementation, testing, debugging, deployment, and maintenance.
Monolith:
- 🟩👍 Easier to start with.
- 🟥👎 Challenging to update or change over time.
Microservices:
- 🟥👎 Requires more planning and design before starting.
- 🟩👍 Make changes and find bugs is faster.
- 🟩👍 Code reusability also increases over time.
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In Deployment
is the process of releasing and making software available for use, typically involving the installation, configuration, and activation of the application in a production environment.
Monolith:
- 🟩👍 Is more straightforward.
Devs install the entire app code base and dependencies in a single environment.
Microservices
- 🟥👎 Is more complex.
Each microservice is an independently deployable software package.
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In Debugging
is a software process to identify coding errors that cause the application to behave erratically.
Monolith:
- 🟩👍 Devs can trace data movement or examine code behavior within the same programming environment.
Microservices:
- 🟥👎 Requires looking at multiple loosely coupled individual services.
Several developers might be responsible for many microservices.
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In Modifications
Monolith:
- 🟥👎 A small change in one part of a monolithic application affects multiple software functions.
When developers introduce new changes, they must retest and redeploy the entire system on the server.
Microservices:
- 🟩👍 Instead of modifying all the services, developers only change specific functions.
Ability to make small changes without affecting the system’s stability.
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In Scaling
refers to adapting a system’s capacity to handle increased load, either by adding resources or optimizing performance, to ensure responsiveness and efficiency as demands grow.
Monolith:
- 🟥👎 The entire application must be scaled as requirements change.
This results in resource wastage because not all parts of the application are at peak capacity.
Microservices:
- 🟩👍 Supports distributed systems.
- 🟩👍 Resources can be scaled independently.
Each software component receives its own computing resources in a distributed system.
Operational Impact
Monolithic:
- Innovate faster: 🟥👎 Delays your org in adopting modern tech trends.
- Reduce risks: 🟥👎 A minor error in the code can cause the whole app to fail.
- Accelerate time to market: 🟥👎 Development effort increases exponentially as code complexity grows.
- Reduce total cost of ownership: 🟥👎 Companies must upgrade memory and processing power for the app as a whole which is more expensive.
Microservices:
- Innovate faster: 🟩👍 Allows businesses to innovate more quickly.
- Reduce risks: 🟩👍 If a microservice fails, other microservices remain operational.
- Accelerate time to market: 🟩👍 Each developer focuses on a smaller chunk of code instead of a large one.
- Reduce total cost of ownership: 🟩👍 You only have to add resources for the individual service, not the entire application.
When to use one or the other
✍️ Friendly reminder: It’s important to understand that microservices don’t reduce the complexity of an application. Instead, the microservices structure reveals underlying complexities and allows developers to build, manage, and scale large applications more efficiently.
Approach more suitable when:
Monolithic:
- 1️⃣ designing a simple application or prototype. — app size
- 2️⃣ the team has limited experience in development and design thinking .— team competency
- 3️⃣ it’s ok to run the app on a single server. — infrastructure
Microservices:
- 1️⃣ building a complex system. — app size
- 2️⃣ the team has strong skills in development and design thinking. — team competency
- 3️⃣ need to ensure scalability, fault tolerance, and HA. — infrastructure
Mono-repo vs Multi-repo
A repository is the place where all the files of a project are stored, organized and maintained. They contain a change history, giving teams transparency and control over different possible versions.
Nowadays, repositories are commonly used with Git, through providers like Github, GitLab, and Bitbucket. These can store a wide variety of file types.
A mono-repo is not a monolith. It’s a software development strategy in which all the codebase is stored in a single repository.
A multi-repo is a software development approach where different projects or components of a larger application are stored and managed as separate repositories.
Comparing Mono-repo and Multi-repo from Technical Standpoint
Symbology:
- ✅ (Benefit) = Represents something obtainable without much effort.
- ⚠️ (Attention) = Represents something not easily obtainable.
- ❌ (Challenge) = Represents something difficult to obtain.
Comparing Mono-repo and Multi-repo from Cultural Standpoint
Symbology:
- ✅ (Benefit) = Represents something obtainable without much effort.
- ⚠️ (Attention) = Represents something not easily obtainable.
- ❌ (Challenge) = Represents something difficult to obtain.
Recap
This article delves into the important considerations when choosing between Monolithic and Microservices Architectures, highlighting their respective strengths and weaknesses in various aspects of software development.
Monolithic Architecture is characterized by a single, unified codebase that can be simpler to start with but becomes increasingly difficult to manage and scale as the application grows. It’s generally easier to deploy and debug within a single environment but poses challenges in making modifications and scaling resources efficiently.
Microservices Architecture, on the other hand, involves building applications as a collection of small, independent services. This approach enables faster innovation and scalability, allowing different components to be developed, deployed, and scaled independently. However, it requires careful planning and design upfront and can be more complex to manage due to the need to coordinate multiple services.
The article also discusses the operational impacts of both architectures, such as innovation speed, risk management, time to market, and total cost of ownership. While Monolithic Architecture may lead to slower innovation and higher risk due to its tightly coupled nature, Microservices can offer quicker time-to-market and reduced risks through isolated services.
Additionally, the concept of Mono-repo vs. Multi-repo is explored, comparing the management of codebases in single versus multiple repositories. This comparison covers technical and cultural aspects, outlining the benefits and challenges of each approach.
Conclusions
Monolithic and microservices architectures each have their strengths and weaknesses. The optimal choice depends on the specific requirements of your project.
- For small, simple applications or rapid prototyping, a monolithic architecture might be sufficient.
- For complex systems that demand scalability, fault tolerance, and independent development teams, a microservices architecture is often the preferred approach.
It’s essential to carefully evaluate the trade-offs in development, deployment, debugging, modification, and scaling when making a decision. Additionally, consider the expertise of your team and the available infrastructure.
Deep Dive: Related Resources
- 🎥 Myself Presenting at Python Barcelona Meetup: ‘Launch Your Own Python Library Within the Company’.
- 📖 Top 6 Books to Learn Microservices in Depth
- 📖 What are Microservices? | AWS
- 📖 Monolithic vs Microservices — Difference Between Software Development Architectures- AWS
- 📖 Monorepo vs. multi-repo: Different strategies for organizing repositories
