Software architecture defines the quality attributes of an application. When planning a software architecture behind an application project managers are met with the task of comparing microservices vs. monolithic architecture.
Choosing the right architecture is crucial to the stability, performance, scalability and security of the application. A right architecture also helps with cost optimization, reduced time to delivery, and customer satisfaction. Since applications are an integral part of the business ecosystem today the choice of architecture behind them is equally crucial.
The Monolithic Approach to Application Development
Monolithic means all components in one piece. Monolithic applications bundle all the functionalities of an application within a single codebase. The application is built in several layers and then all the code is deployed into a single platform as a single program.
The layers of a monolithic application consists of:
User Interface (UI)
The front-end or client-side code responsible for rendering the user interface and interacting with users. This comprises of HTML, CSS, JavaScript, and related frameworks/libraries.
Application logic
Contains the core business logic of the application, including algorithms, workflows, and business rules. This logic is tightly integrated within the monolithic application.
Database layer
The data storage and retrieval component, where data is stored in a centralized database. The database layer typically uses a relational database management system (RDBMS) like MySQL, PostgreSQL, or Oracle.
Integration layer
Handles communication with external systems or APIs, if needed.
Integrates with third-party services or legacy systems.
Utilities and libraries
Common utilities, libraries, or in-memory functions used throughout the application. This is a shared resource across different components within the monolith.
Deployment unit
The entire application is packaged and deployed as a single unit.
Deployment involves deploying the application on a server or cloud platform.
The key characteristics of a monolithic architecture are:
Single unit
The entire application is built as a single unit, making it easier to develop, test, and deploy.
Tightly coupled components
Components of the application are tightly integrated and share a common codebase, making it challenging to isolate and modify specific components without affecting others.
Consistent technology stack
Monolithic applications typically use a consistent technology stack throughout the entire application since they are built as a single unit.
Deployment and scaling
Deployment involves deploying the entire application at once, and scaling involves replicating the entire application to handle increased load.
Microservice Based Architecture
In microservice based architecture the software is composed of small self contained services which communicate with each other over APIs.
Here are the key principles and approaches associated with microservices architecture:
Single Responsibility Principle (SRP)
Each microservice should have a specific and clearly defined business function or capability. It should focus on doing one thing and doing it well. SRP leads to domain driven design (DDD). Each microservice is organized around a specific business domain to align with the organization’s business capabilities and models.
Decentralized data management
Each microservice manages its own data and database. This ensures that each service has control over its data and can choose an appropriate data storage technology.
Inter-Process Communication (IPC)
Microservices communicate with each other through well-defined APIs, such as RESTful APIs, messaging queues, or gRPC. This allows for loose coupling and flexibility in technology choices.
DevOps and CI/CD automation
Automated deployment and continuous integration through CI/CD pipelines are an important characteristic of microservice based architecture. This enables the rapid change and deployment of microservices and safely as per need. The microservice based architecture is well managed through the DevOps practices of infrastructure automation, comprehensive monitoring and logging, CI/CD etc.
Event-Driven Architecture (EDA)
Event-driven architecture is often used in microservices to enhance scalability and responsiveness. Events enable asynchronous communication and improve decoupling between services.
CQRS (Command Query Responsibility Segregation)
The read and write operations are separated to optimize for different performance, scalability, and functional requirements.
Comparing Microservices Vs. Monolithic
Microservice based architecture can be compared to monolithic depending on various properties and characteristics.
Scalability and performance
Microservices are decoupled from each other and can be individually scaled based on demand. This allows them to act as on-demand service leading to efficient resource utilization and improved performance. When it comes to scaling a monolith it has to happen in entirety. This leads to several performance issues like introducing glitches or slowing down the application.
Flexibility and agility
Microservices offer flexibility in terms of scaling, technology selection, and deployment. It allows small teams to adopt agile practices and deploy frequently adapting to changing business requirements without affecting the entire application. Monolithic applications on the other hand are difficult to scale or deploy without affecting the entire codebase and involving a large part of the development team. The development approach of monolith is typically a waterfall method and lacks the speed with which a microservice can be deployed.
Technology heterogeneity
Microservices based applications use a heterogeneous array of tools, services, database schema from various service providers. This allows technological and financial flexibility to choose whatever fits best for the software product development. Monolithic applications have a constrained tech stack and the codebase is rigid due to this. However, having limited frameworks and technologies reduces the complexity of a codebase.
Fault isolation and resilience
Failure in one microservice does not necessarily affect the entire application. Isolation of failures to individual services ensures the system remains resilient, and the impact on users is minimized. Monolithic applications on the other hand crashes entirely even due to a single glitch.
Easier maintenance and updates
Smaller, isolated microservices compared to one large monolithic codebase are easier to understand, maintain, and update without the risk of unintended consequences on other parts of the application. This simplifies testing and reduces the potential for regression issues.
Autonomous development and deployment teams
Each microservice can be developed and deployed independently by dedicated teams, promoting parallel development and faster time-to-market for new features and updates.
Smaller, focused development teams can work on specific microservices, enhancing productivity, collaboration, and specialization, as they can fully understand and manage a smaller codebase.
Optimized resource utilization
Microservices allow efficient use of resources by enabling containerization and orchestration platforms like Kubernetes, making it easier to manage and optimize resource allocation for each service.
Advantages of monolithic applications
Simplicity of development and deployment
Developing and deploying a monolithic application is simpler and may be more suitable for small projects or applications with straightforward requirements.
Simpler testing and debugging
Debugging and testing in a monolith can be more straightforward due to the cohesive nature of the application, making it easier to trace issues.
Less operational overhead
Managing a single application is less complex in terms of deployment, monitoring, and operational activities compared to managing a distributed microservices architecture.
Conclusion
As we compare microservices vs. monolithic applications we see a lot of advantages for microservice based applications over monolithic. While monolithic architecture may be well suited for small applications when it comes to large scalable enterprise grade applications, microservices are the way to go.
