In this post we explore two distinct approaches to software architecture: Monolithic and Microservice.

We'll break down their characteristics, weigh their pros and cons, and provide practical examples from our storage ecosystem. Let's dive into how these architectures work and consider our own journey from a monolithic setup to a microservice-based approach.

The difference between a Monolithic and Microservice Architecture

Consider a grand piano, where a broken string can render the entire instrument out of tune. This is like a monolithic architecture, unified but overall vulnerable to a single flaw. Now imagine an orchestra, composed of many musicians; if one instrument fails, the music plays on with minimal disruption. This is much like a microservice architecture, composed of autonomous, adaptable parts that make the overall system more resilient.

Advantages of Monolithic Architecture

1. Simpler Development: It's less complex to develop since all components exist together.
2. Easier Testing: Testing is straightforward as there’s only one piece to test.
3. Efficient Communication: Components communicate efficiently due to tight coupling.
4. Simple Deployment: The entire codebase is deployed as one release.
5. Shared Memory Access: All components share the same memory, making it more efficient.

Disadvantages of Monolithic Architecture

1. Difficult Maintenance: Upkeep is tough because all components are interlinked.
2. Limited Scalability: Scaling is challenging since you need to scale the entire system, not just parts.
3. Slow Deployment: Updating or adding new features means redeploying the entire application.
4. Hard Fault Isolation: Isolating faults is difficult because if one part fails, it can bring down the whole system.
5. Changes Affect Entire System: Any modification can impact the entire system, potentially leading to unexpected issues.

Advantages of Microservice Architecture

1. Accelerated Scalability: Deploying services across multiple servers can mitigate the performance impact of individual components.
2. Improved Fault Isolation: If one service fails, it’s easier to identify and fix the issue without affecting the entire system.
3. Enhanced Productivity: Focus on one small piece of the system at a time.
4. Quick Development & Deployment: Only small bits of code are deployed, reducing deployment time.
5. Cost-Effective: Localizing services reduces overall development and maintenance costs.

Disadvantages of Microservice Architecture

1. Increased Complexity: Developers need to write extra code for smooth communication between modules.
2. Deployment & Versioning Challenges: Coordinating deployments and managing versions across multiple services can be complex.
3. Testing Complexity: Requires setup to test microservices, though containerization (e.g., using Docker) can mitigate this.
4. Data Management: Managing data consistency and transactions across multiple services can be complex.

Real-World Application

Example of Monolithic System In a monolithic system, a user accesses the system through a web application that interacts with an API and a database. This setup creates a single point of failure; if the API is down, the entire system is down.

Example of Microservice System In a microservice system, the application is broken into multiple services, each with its own database. If one service fails, the rest of the application can still function, eliminating single points of failure and enhancing system robustness.

Our Current System

Currently, our system is a hybrid between monolithic and microservice architecture. We have multiple front-end applications but a monolithic API. This means if the API goes down, all applications go down. Extending our legacy code is challenging and often results in breaking other systems.

Proposed Microservice Design

We are planning to transition to a microservice architecture. This involves splitting the current monolithic API into smaller, independent services. Each service will have its own database and communicate with others as needed. This design aims to improve fault isolation and scalability while reducing single points of failure.

Implementation Strategy

We plan to use the Strangler Fig Pattern for transitioning. This involves incrementally migrating from the legacy system to the new system by building new microservices alongside the existing system and gradually phasing out the old code.

Handling Service-to-Service Calls

We are exploring Dapr (Distributed Application Runtime) to handle service-to-service communication and other microservice challenges. Dapr acts as a sidecar to your application, simplifying the development of scalable microservices by managing infrastructure concerns. Stay tuned as we continue to share our experiences and insights on this journey of transition over our architecture!