Monolithic to Microservice Architecture, What is Microservice Architecture, Why Microservice Architecture

1. Introduction

With the development of the Internet and large-scale applications, software architecture has also undergone a continuous evolution from monolithic to microservices. Monolithic architecture used to be the mainstream development model, but as the scale of the system expanded and the functions became more complex, the monolithic architecture gradually exposed problems such as poor scalability, complex deployment, and high maintenance costs.

As a new architectural model, microservices have gradually become the first choice for many large Internet companies due to their advantages such as modularization and independent deployment. So, what are microservices? Why choose microservices? This article will discuss these issues in detail and intuitively show the comparison and evolution of the two architectures through architectural diagrams.

2. Overview of Monolithic Architecture

Monolithic architectureMonolithic Architecture refers to an architectural pattern that packages all functional modules of an application into a monolithic application for deployment. A typical monolithic application includes multiple functional modules, such as user management, order processing, payment system, etc. They share a code base, are compiled, packaged, and deployed together.

Features of Monolithic Architecture:

• Tight coupling: All functional modules are integrated into one code base and are highly dependent on each other.
• Unified deployment: Every time the application is updated, the entire system must be rebuilt, packaged, and deployed, even if it is just a small feature module change.
• Better performance: Since all functions run in the same process, internal calls are often direct function calls, which are faster.

Advantages and disadvantages of monolithic architecture:

• advantage:

  • It is simple and intuitive in the early stages of development and suitable for small applications.
  • The development tools and infrastructure are relatively simple, and the cost of building and debugging is low.
  • Deployment is relatively easy, and all features are released together.

• shortcoming:

  • Poor scalability: As the size and functionality of an application grows, the code base becomes large and complex, making it difficult to maintain and expand.
  • Low deployment efficiency: Even a small functional modification requires redeploying the entire application, which is time-consuming and risky.
  • Poor maintainability: Due to the high coupling between modules, a problem in one module may affect the entire system.

3. Definition of Microservices

Microservices ArchitectureMicroservices Architecture divides an application into a set of small, independent services, each of which runs and is deployed independently and communicates through network protocols such as HTTP/REST, gRPC, etc. Each microservice has its own independent database and business logic, which are decoupled from each other and can be developed and deployed separately.

Characteristics of microservices:

• Modularity and decoupling：Microservices divide complex systems into multiple independent services, each of which focuses on a specific business function.
• Standalone deployment: Each microservice can be deployed, updated, and scaled independently without relying on other services.
• Technology Heterogeneity：Microservices allow each service to use a different technology stack or programming language to best suit its functional requirements. For example, the user management service can be developed using Java, while the order processing service can be implemented using Node.js, communicating with each other through APIs or message queues.

Comparison between microservices and monolithic architecture:

Microservice architecture diagram

In this diagram, the application is decomposed into several services, each of which has an independent database and business logic. These services communicate through an API gateway or service discovery mechanism. The client does not need to directly access all services, but routes requests through the gateway. Each service can also be expanded and deployed separately.

4. Why choose microservices?

As the scale of applications grows and user needs change, more and more companies are choosing microservice architecture. The core value of microservice architecture is that it provides greater flexibility, scalability, and independence, especially when facing large distributed systems, which can significantly improve the maintainability and reliability of the system.

1. Scalability

Microservice architecture supportHorizontal Scaling, that is, resources can be scaled separately for different services. For example, if the traffic of the order service surges, we can only scale the number of instances of the order service without scaling the entire application. This on-demand scaling method greatly improves resource utilization.

2. Independent deployment and release

In a monolithic architecture, any feature update requires redeploying the entire application, which may cause system downtime or affect other functions. In a microservice architecture, each service canIndependent deployment and release, so the update of one service will not affect other services. This feature makesContinuous Integration and Continuous Delivery(CI/CD) becomes easier.

3. Technology heterogeneity and flexibility

Microservices allow each team to choose the most suitable technology stack according to specific needs. For example, some services may require high-performance computing and can use the Go language, while other services may be more suitable for Python development efficiency. This technology heterogeneity allows development teams to freely choose tools and avoid being locked into a certain technology.

4. Team independence and agile development

Due to the independence of microservices, different teams canParallel developmentDifferent services do not depend on each other. This team independence greatly promotes agile development and continuous delivery, making the development process more efficient.

Challenges of Microservices

Although microservices architecture brings many advantages, it also has its own challenges:

• Increased complexity：The distributed nature of microservices makes system operation and maintenance complicated. Additional tools and technologies are required to manage communication, monitoring, and fault handling between services.
• Data consistency issues: In a monolithic architecture, data consistency is relatively easy to manage because all modules share the same database. However, in microservices, each service often has an independent database, and maintaining data consistency becomes more difficult.
• Inter-service communication overhead：Since services communicate through the network, performance may be affected, especially in high-concurrency scenarios. How to optimize communication between services becomes a key issue.

5. Evolution path from monolith to microservices

The migration from a monolithic architecture to a microservices architecture is not a one-shot process.Incremental EvolutionHere are some common migration paths and strategies:

1. Modular Monolith

The first step is to transform the monolithic architectureModularity, the system is divided into multiple modules according to business functions. These modules are still in the same code base, but the degree of coupling is reduced through modular design, laying the foundation for future service-oriented development.

2. Split services

On the basis of modular monoliths, select the part that is most suitable for microservices and split it, and gradually separate some functions of the system. For example, you can first split the user management function into an independent service and communicate with other modules through APIs.

3. Service-oriented and API interface

As the decomposition progresses, more and more modules are converted into independent services. At this time, it is necessary to manage the communication between services through API gateway or service discovery mechanism. As the entrance of all requests, API gateway is responsible for request routing, authentication and authorization, load balancing, etc.

4. Finally, fully microservices

When most of the functions in the system are split into independent services and each service can be independently expanded and deployed, the system enters a fully microservice state.

Architecture diagram:

This diagram shows the process of the system being gradually split from a monolithic architecture to a microservice architecture. On the left is a complete monolithic application, and on the right are the independent services after the split.

6. Conclusion

The core concept of microservice architecture is toModularity, decoupling, independent deployment and expansion, making the system more flexible, scalable, and easy to maintain. Although microservices bring new challenges, especially in operation and data management, it provides a more resilient solution for large-scale and complex applications.

In the future, with the popularization of cloud computing, containerization technology (such as Docker, Kubernetes) and DevOps culture, microservice architecture will continue to evolve to help enterprises cope with growing demand. When choosing an architecture, each enterprise should weigh the pros and cons of monolithic architecture and microservice architecture according to its own business scale and technical requirements, so as to make the most suitable decision.