Monolithic and Microservices: When to Use Microservices?

Have you ever wondered why businesses switch to microservices instead of sticking with traditional systems? 

It’s because microservices provide unmatched flexibility, allowing businesses to scale and adapt quickly while delivering great customer experiences.

If your business needs faster development, better fault isolation, or scalable systems, microservices could be the right choice. In this blog, we will discuss the advantages of microservices architecture and compare monolithic application vs microservices. They’re perfect for handling complex systems while ensuring smooth growth. 

Let’s start this journey.

Monolithic vs. Microservices Architecture

Every business aims to create software that can grow easily, meets user needs, and supports quick updates. Two main ways of designing software are Monolithic and Microservices architectures.

Monolithic Architecture

Monolithic architecture is a traditional approach where the entire application operates as one single unit. All parts of the application, like business logic and database management, are connected, so changes require the entire app to be updated and redeployed. While this can be simpler for smaller projects, it can become hard to scale and maintain as the app grows.

Pros and Cons of Monolithic

Pros:

• Simpler Development: A single codebase makes it easier for small teams to develop and debug the app.
• Easier Testing: Testing is simpler because everything is part of one application.
• Lower Initial Costs: Fewer tools and infrastructure are needed, making it budget-friendly for small projects.
• Unified Performance: All parts are connected, which can lead to faster data processing.

Cons:

• Scalability Challenges: The whole application must scale at once, which can be inefficient.
• Maintenance Difficulties: As the app grows, managing and updating the code becomes harder.
• Single Point of Failure: A problem in one part of the app can impact the entire system.
• Limited Flexibility: Using a single technology stack can limit how the app adapts to new tools or frameworks.

Microservices Architecture

Microservices architecture is a modern approach where an app is divided into small, independent services, each handling specific functions like user management, payment, or notifications. This method allows teams to develop, deploy, and scale services separately, making it a good fit for agile and DevOps practices.

Pros and Cons of Microservices

Pros:

• Independent Scalability: Services can scale separately based on their needs, which makes better use of resources.
• Faster Development Cycles: Teams can work on different services at the same time, speeding up development.
• Improved Fault Isolation: Issues in one service don’t affect the whole app, making it more reliable.
• Technology Diversity: Teams can pick the best technology for each service, boosting performance and flexibility.

Cons:

• Operational Complexity: Managing multiple services needs strong DevOps practices.
• Higher Costs: Setting up microservices takes more investment in tools, infrastructure, and skilled teams.
• Data Consistency Issues: Keeping data consistent across distributed services can be challenging.
• Steeper Learning Curve: Teams need to learn about containerization, orchestration, and how services communicate with each other.

Key Differences Between Monolithic and Microservices

Why Businesses Should Choose Microservices?

1. Enhanced Scalability and Flexibility

Horizontal and Vertical Scalability

• Microservices let businesses scale each service independently. For example, in an e-commerce platform, the inventory service may handle more traffic during sales. Instead of scaling the whole application, only the inventory service can be scaled horizontally (adding more instances) or vertically (upgrading resources).
• Netflix is a great example. They moved from a monolithic system to microservices, splitting their platform into services like recommendations, billing, and content delivery. This allows Netflix to scale each service as needed, ensuring smooth streaming even during heavy usage.

Polyglot Architecture Support

• Microservices enable developers to use various technologies for each service, providing flexibility and adaptability in development. For example, a data analysis service can use Python for its libraries, while core features might run on Node.js. This flexibility improves performance and productivity by using the best tools for each task.
• Uber switched to microservices to roll out features faster. They divided their app by region and function, like maps and payments, enabling independent updates for each service to meet specific market needs.

2. Faster Development Cycles and Continuous Deployment

Service Isolation for Independent Development

• Each microservice works separately, allowing teams to develop and deploy their parts without conflicts. This speeds up feature updates. DevOps practices like Continuous Integration (CI) and Continuous Deployment (CD) automate testing and updates, ensuring real-time improvements.

Versioning and Rolling Updates

• Microservices support multiple versions of the same service. For instance, businesses can run version 1 of a login service while testing version 2. If any issue arises, they can easily roll back to the older version, minimizing risks and downtime.

3. Improved Fault Isolation and Reliability

Failure Containment with Service Isolation

• In monolithic apps, one failure can crash the entire system. Microservices limit failures to specific services. For example, if the payment service fails, it won’t affect the product catalogue. This isolation keeps other parts of the app running smoothly.
• Instagram uses this approach by separating features like notifications and feeds, allowing them to handle high traffic while isolating potential failures.

Enhanced Observability and Monitoring

• Each microservice has metrics and logs, making monitoring and fixing issues easier. Tools like Wooffer help track and optimize individual services for better performance.

4. Optimized for Cloud-Native and DevOps Environments

Containerization with Docker and Orchestration with Kubernetes

• Microservices work well in containerized setups. Docker isolates each service, avoiding compatibility issues, while Kubernetes manages scaling, load balancing, and deployments. This ensures services run smoothly in cloud environments.

Automatic Scaling and Load Balancing

• Cloud platforms like AWS, Google Cloud, and Azure allow microservices to scale automatically based on demand. Kubernetes uses tools like Horizontal Pod Autoscaling to adjust resources in real-time, ensuring efficient performance without manual work.
• Airbnb transitioned to Kubernetes for automatic scaling and load balancing. By doing so, they handle traffic spikes effectively while keeping cloud costs under control. Their custom features further improve scaling, making Kubernetes a key part of their system.

When Should Businesses Choose Microservices?

1. Organizations with Rapid Growth or High Transaction Volumes

Scalable Architecture for High-Volume Applications

• For businesses expecting high traffic or seasonal spikes, microservices offer the flexibility to scale. They let companies handle large amounts of traffic by only scaling the services that need more resources.

International or Multi-Region Deployment

• Microservices can be spread across different regions to provide fast, low-latency access. Global businesses can deploy services like user authentication closer to where their users are, improving response times and overall performance.

2. Frequent Releases and Short Development Cycles

Agile-Friendly for Fast-Moving Markets

• Microservices support agile development, which helps businesses quickly adapt to market changes. This is especially useful in competitive fields like e-commerce and fintech, where staying innovative is crucial.

Separate Deployment Pipelines

• Each microservice can have its deployment pipeline, allowing for faster feature updates. This way, teams can work on and improve specific services without affecting others.

3. Enterprises Transitioning from Monolithic Systems

Gradual Migration from Legacy Systems

• Businesses with existing monolithic applications can move to microservices step by step using a "strangler pattern." This means building new features as microservices while keeping the old system for current functions, allowing for a smoother transition.

Component-Based Upgrades

• In monolithic systems, upgrading one part often means testing the whole system. Microservices allow upgrades to be done one service at a time, making modernization safer and easier.

4. Applications with Diverse Functionalities

Microservices for Complex Business Domains

• Apps with different features—like user management, payment processing, or data analysis—work well when split into microservices. This modular approach lets each service work independently and be improved based on its specific needs.

Modular Testing and Quality Assurance

• Microservices allow testing to be done for each service separately. This makes it simpler to test, identify, and fix problems, reducing overall complexity and improving reliability.

When Businesses Should Not Choose Microservices?

While microservices offer many benefits, they are not always the right choice. For some businesses, a well-built monolithic architecture can be simpler, more cost-effective, and more efficient. Stack Overflow, for example, continues to use a monolithic system for several key reasons:

Simplified Development and Debugging

• A monolithic structure allows for faster development and easier debugging, as everything is in one place. This avoids the challenges of managing multiple services and their interactions.

Efficient Resource Utilization

• Stack Overflow avoids the overhead of running many microservices by keeping everything in one system. This means fewer resources are spent managing different services.

Lower Operational Costs

• Monolithic systems do not need expensive tools like service meshes or container orchestration, making them more cost-effective for some use cases.

Streamlined Workflow

• A monolithic approach aligns well with Stack Overflow’s workflows, so teams can focus on building features rather than handling a complex distributed system.

Situations Where Microservices May Not Be the Best Fit for Businesses

1. MVP-Level Applications

Development and Operational Complexity:

• Microservices come with extra complexity, including building architecture, deployment pipelines, and monitoring tools. For a Minimum Viable Product (MVP), simplicity and speed are key, making a monolith a better choice.

Startups launching an MVP may not need the scalability or fault isolation microservices offer. Focusing on microservices at this stage can slow down delivery and reduce the ability to quickly adjust based on feedback.

2. Small User Base

Scalability Isn’t a Concern: 

• If a business has a small user base, there’s no need for independent service scaling. A monolithic system is easier to deploy and manage for low-traffic applications.

For example, a small local e-commerce store with only a few thousand users can operate just fine with a monolith.

Switching to microservices can lead to extra infrastructure and maintenance costs without much benefit.

3. Rapid Development Needs

Fast Iteration and Debugging: 

• Monolithic systems allow for faster changes and deployment. A single codebase means fewer complications when debugging and making updates.

A social media app that needs to release features quickly will benefit from a monolith, as updates can be made in one place without worrying about service communication.

Microservices can slow down development due to the need for inter-service communication, managing dependencies, and deploying each service separately.

4. Resource Constraints

High Operational and Financial Overhead: 

• Microservices require specialized knowledge in areas like DevOps and distributed systems, as well as expensive monitoring tools.

A small non-profit building a donation platform may not have the budget or resources to support the expertise and tools needed for microservices.

Without the right resources, businesses may end up with fragile systems that are hard to scale or maintain.

5. Data Consistency Priorities

Challenges in Distributed Databases: 

• Microservices often use separate databases, which can lead to data duplication, inconsistencies, and complex transaction handling.

A financial platform that needs strong data accuracy may struggle with managing data across different services, leading to errors.

Monolithic systems use a single database, making data consistency easier to maintain.

6. Limited Infrastructure

Managing Containerized Environments: 

• Microservices work best with containerized systems that need tools like Kubernetes for orchestration. These tools can be overkill for smaller setups.

A blogging platform hosted on one server may find a monolithic approach simpler and more efficient than managing microservices.

Investing too much in infrastructure for microservices can lead to wasted resources and operational problems.

Top 10 Essential Best Practices for Microservices Architecture

Here are 11 best practices for implementing microservices architecture in 2024:

1. Adopt Domain-Driven Design (DDD)

• Design microservices based on business domains to ensure high-level functionality and loose coupling.
• Use the strategic and tactical phases of Domain-Driven Design (DDD) to clearly define service boundaries and implement design patterns.
• This improves productivity and helps align services with business needs.

2. Invest in a Good Infrastructure

• Select a dedicated and scalable infrastructure to host your microservices for optimal performance and growth.
• Ensure separation of infrastructure from other components to maintain high performance and fault isolation.

3. Ensure Data Storage Separation

• Use separate databases for each microservice to avoid shared databases as in monolithic systems.
• This practice reduces latency, enhances security, and improves service performance.

4. Plan for Migration

• When transitioning from a monolithic system, build new functionalities as microservices.
• Gradually decompose the monolithic structure by migrating components step-by-step.

5. Follow the Single Responsibility Principle

• Ensure each microservice has a single reason to change, making it more maintainable and scalable.
• Keep modules decoupled and use clear interfaces for better communication between services.

6. Use Compatible API Changes

• Release API changes that do not disrupt existing consumers by maintaining backward compatibility.
• Implement contract testing to prevent breaking changes and use an API gateway for efficient request handling.

7. Implement Monitoring and Logging

• Integrate logging and monitoring in each microservice to track performance and detect errors.
• Use advanced monitoring tools to maintain security and oversee resource utilization effectively.

8. Design a Clear Splitting System

• Define interactions and processes between microservices from the start to reduce complexity.
• Ensure each microservice has a clear purpose and contributes to the overall architecture cohesively.

9. Deploy Microservices Independently

• Deploy each microservice separately to simplify coordination between teams during maintenance or updates.
• This practice improves fault tolerance and minimizes the impact of failures.

10. Host Microservices in Containers

• Use containers for easier deployment and orchestration, especially with tools like Kubernetes.
• Containers optimize server resource usage, reduce latency, and enhance scalability.

Overcoming Technical Challenges in Microservices Adoption

To adopt microservices successfully, businesses need to manage the following technical challenges:

• Service Communication and Data Consistency: Microservices depend on network calls, which can lead to delays. Keeping data consistent across services can be done with event-driven systems, but careful planning is needed to avoid duplication and slowdowns.
• Data Management Complexity: Microservices often use separate databases, making it important to have tools that sync data and ensure it stays correct.
• Increased Operational Overhead: Service discovery and load balancing tools are needed to manage multiple services. Kubernetes can help with container management and orchestration.
• Monitoring and Observability: As the number of services grows, using tools for distributed tracing and log collection becomes key for effective monitoring and tracking.

Conclusion

Microservices offer businesses a scalable and resilient approach that aligns well with modern cloud and DevOps practices, enabling rapid innovation and effective scaling. While there are challenges in managing a distributed system, the benefits can be transformative when businesses are prepared.

With the right strategy, tools, and team, microservices can empower businesses to future-proof their applications and stay ahead in a competitive market. Ready to take the next step? Embrace microservices and unlock your business's potential. 

See you soon!