Monolithic vs. Microservices: Which is the Better Architecture for eCommerce App Development

The increasing business complexity and demand for highly scalable applications have brought a paradigm shift in how software applications are engineered. In the past few years, different software architectures are adopted by developers to reduce code complexity, improve fault isolation, and minimize time-to-market.

Software architecture defines and structures a solution in a way that it meets all the technical, operational and business requirements. It is a foundation for the attributes of an application, its elements, relationships, and properties, which ultimately impacts its scalability and performance.

Three of the popular software architecture approaches that developers prefer are:

1. Monolithic Architecture

2. Service-Oriented Architecture (SOA)

3. Microservices Architecture 

This blog discusses the fundamental differences between Monolithic VS Microservices Architecture and elaborates which approach works best for an eCommerce app development.

Monolithic vs. Microservices Architecture: An Introduction

A monolithic architecture is a unified model for designing a software solution. All components of software here are interconnected and interdependent. In such a tightly coupled architecture, each component and its related components must be functional for the code to be executed or compiled successfully.

Microservices architecture, on the other hand, is a modular approach for designing a software solution. Herein, a software application is built with an independent group of components that run each application process as a service. In such a loosely coupled architecture, a component is independent of the other one, can be written in different programming languages, use different data storages, and serves only one specific function.

Monolithic vs. Microservices Architecture: Differences

1) Fault Isolation

Since all services in a microservice architecture are independent of each other, any halt in a process will keep rest of the processes unaffected. For example, a memory leak in one service will only affect that single service. On the other hand, any misbehaving component in a monolithic architecture will bring the entire application down (since all services are interconnected and interdependent).

2) Technology Commitment

With microservices architecture, developers have the advantage of using different technologies (languages, frameworks, and OS) to build an application. This eliminates dependency and long-term commitment with a single technology stack. Whenever a new service is built or an existing service is updated, a new, better technology stack can be adopted. This also eliminates the dependency of the development team on a particular resource for building or updating service.

In a monolithic architecture, the development team is forced to stick to a single technology, which has its limitations. For example, if a framework that your application uses become obsolete with time, migrating to a newer, better framework can be challenging. Possibly, the development team has to rewrite the entire application in a new language, on a different framework, which involves some sure risks and is time-taking as well.  

3) Application Scaling

Once the codebase of an application reaches a certain size, it is a good practice to divide the development team to handle specific functional areas. For example, a UI team, an inventory management team, a product management team etc. In microservices architecture, all these services are developed as separate modules. Thus, teams can be divided to work independently, which helps them to change and update production, making it easy to scale application.

With a monolithic architecture, developers have a challenge in scaling. Since there is a single codebase accommodating all services, teams cannot work on different modules, independently. And even if they do, the team must coordinate during development and deployments.

4) Continuous Development and Deployment

In microservices architecture, each component of an application is developed, deployed, operated, and scaled independently. This means a change in one service of the application will keep other services unaffected. Moreover, the services in microservices do not share codebase or implementation of other services. Thus, continuous development and deployment of large, complex applications are easy with microservices architecture.

A monolithic architecture, on the other hand, has a large codebase with interdependent components. Such an application structure is an obstacle to frequent deployments because for updating a single component, the entire application has to be redeployed. This not only disturbs the tasks in the background but also impact the functioning of connected services. The risk associated with redeployments discourages frequent updates in the application.

5) Code Management

The size of a monolithic codebase is huge. The large monolithic codebase is difficult for developers to understand and manage, especially those who are new to the team. This, as a result, can slow down the development process. Microservices codebase, on the other hand, is divided into a group of small codes and thus is managed easily, compared to a monolithic application.

Monolithic vs. Microservices Architecture for eCommerce App Development

Let us understand which architecture works well for building a scalable, robust eCommerce app.

                                       Example: An eCommerce App built using Microservices Architecture

The example demonstrates how to build an eCommerce application using microservices architecture, powered by Consule, Docker, Spring, React.JS, MongoDB, Redis and more. The above example includes functional microservices (Product catalogue, cart microservice) and infrastructure microservices (global configuration microservice, Service Registration & Discovery microservice) only. These microservices are deployed independently and are organized around business capabilities.

                                       Example: An eCommerce App built using Monolithic Architecture

The same eCommerce application when built using monolithic architecture has all the services tightly-coupled, uses limited technology stack and have a single database. Such an architecture brings several challenges as the application scales.

Monolithic vs. Microservices Architecture: Real-Life Examples

Monolithic Architecture

Example: Shopify

Shopify, a popular eCommerce platform, started as a monolithic application. In the early stages, when the platform's features were relatively simple and the user base was small, a monolithic architecture was a suitable choice. The centralized control and ease of development allowed Shopify to rapidly build and deploy its platform. However, as the platform grew and the user base expanded, Shopify encountered challenges related to scalability and maintenance.

Factors Influencing Monolithic Architecture:

• Monolithic architecture is often preferred for small to medium-sized eCommerce businesses with straightforward requirements. 
  
  
• This architecture can be more cost-effective for startups and businesses with limited budgets, especially in the early stages of development.
  
  
• For rapid prototyping and quick iterations during the development phase, monolithic architectures offer simplicity and speed.
  
  
• Efficient when the product range is limited and the features are relatively stable.
  
  
• Suitable for platforms that require few external integrations, as managing integrations is generally simpler.
  
  
• Ideal for platform that experiences consistent traffic patterns without significant fluctuations.

Microservices Architecture

Example: eBay

eBay, one of the world's largest online marketplaces, has transitioned to a microservices architecture. They have progressively moved from a monolithic architecture to a more decentralized, service-oriented architecture. By breaking down their system into smaller, manageable services, eBay has been able to scale different parts of their platform independently, allowing for better performance, scalability, and flexibility in adding new features.

Factors Influencing Microservices Architecture:

• Platforms with varying traffic demands, such as flash sales or seasonal spikes, benefit from microservices. They enable scaling specific services during peak times without affecting the entire system.
  
  
• For global eCommerce platforms catering to diverse regions and languages, microservices facilitate localization and customization specific to each region, ensuring a tailored user experience.
  
  
• Suitable for eCommerce businesses that heavily reliant on multiple third-party services (payment gateways, shipping providers, analytics tools, etc.). As each integration can be encapsulated within a service, enhancing modularity and maintainability.

Cons of Monolithic Architecture

• The large monolithic codebase has manageability issues.
• Larger the codebase, slower is the IDE, which makes developers less productive.
• Interdependent and interconnected services make continuous deployment of new features challenging.
• Scaling an application with a large codebase include obstacles.
• A failure in one part can bring down the entire system due to tight integration.
• Comprehensive testing is difficult due to the inability to isolate specific components.
• Implementing changes requires thorough testing of the entire system, leading to slower development.
  
  

Pros of Microservices Architecture

• Microservices allow parallel development, speeding up the overall development process as teams can work independently on different services.
  
• If a service fails, the system can reroute traffic, allowing the application to continue functioning, albeit with potentially reduced capacity, ensuring continuous service.
• There is less dependency on a specific resource for building a module (due to technology stack flexibility).
• Development teams can be structured around specific services, allowing for smaller, specialized teams that can be easily scaled based on project needs.
• Microservices enable efficient resource allocation, ensuring that each service can be deployed on appropriate hardware, maximizing resource utilization and cost-efficiency.
  
  

ALSO READ: Benefits of Building Cloud-Native Application using Microservices

Building an eCommerce Application

Ultimately, the choice between monolithic and microservices architectures is a critical decision, but it's not a permanent one. With a thorough understanding of your project’s needs, consultation with experts, and a willingness to adapt, you can make an informed decision that aligns with your current requirements. Stay open to reevaluation as your eCommerce business evolves, ensuring your architecture continues to support your growth and innovation.