Building modern day software requires upfront and considerable thought about maintainability, security, scalability, observability, performance in the long run. Beyond these qualitative and quantitative measures, it is also important as developers and software engineers to look at how this is all put together when it comes to testing and improving the system over time. This is where a comparison between choosing a microservice or a monolith architecture. Microservices and monoliths are two different architectural approaches for designing and building software applications. In this short post, we will look at both pros and cons when it comes to choosing either the next time you need to build your next web, native, progressive web, e-commerce, or even a console application.
Understanding the microservices architectural approach
Microservices are built using an architectural method in which a series of services are deployed independently of each other. Each service has its own database, middleware configurations, and business logic. Each service has a specific purpose and goal. A good example is an e-commerce web application in which there is a Customers service to manage customer information, a Products service to manage product details, a Tax service to determine taxes to be applied to products, and a Payments service to manage payments. Every single one of these services operate on its own, yet makes up and is aimed at fulfilling one specific function of the e-commerce web application.
Ultimately, while microservices might not reduce complexity, they make any complexity visible and more manageable by separating tasks and functions into smaller processes that function independently of each other and contribute to the overall function of the parent system. Updating, testing, deployment, and scaling occur within each service. By contrast, breaking one service will definitely sever the interaction from the other services but will not necessarily cause the system to be unavailable. For example, if the Tax service goes down, the user can still navigate the Products page and even add items to their cart.
Understanding the monolith architectural approach
A monolith is a single, self-contained application where all components and functionalities are tightly integrated. That is, unlike having multiple independent services, using the e-commerce system illustration from the illustration above, we would have one single application where the Product, Customer, Tax, and Payment modules would be part of the same application, invoked by function calls that handle each of those functionalities. As a result, it is clear that it is easier to develop and deploy a monolith application, at least initially.
What to know when it comes to choose one for your next big application project?
- Initial deployments: Monolith applications can easily be deployed since most of the code will be in one directory where it is running. In a microservices architectural approach, each service is running independently and should be monitored directly. Therefore, during a deployment, there are multipoint to check that everything is running smoothly. (Advantage: Monolith architectural approach).
- Maintenance: Monolithic applications can evolve into a situation where more than one developer is needed to maintain, improve, and scale the application. That is, no single developer can realistically understand and manage the application. By contrast, in a microservices application, since services are fairly small, they are easily managed by one or a handful of developers. (Advantage: Microservices architectural approach).
- Scalability: Scaling becomes a tall task for a monolith application whereas it is a matter of independently scaling a service or maybe 2 at a time for a microservices application. (Advantage: Microservices architectural approach).
- Interdependency: Interdependency between services need to be closely monitored in a microservices architectural approach, whereas in a monolith, connection between functions and modules are simply handled by function calls. (Advantage: Monolith architectural approach).
- Debugging: Microservices add more complexity compared to a monolith architecture, since there are more services in more places coo be maintained by multiple teams. Furthermore, each service has its own set of logs, which makes debugging more complicated. (Advantage: Monolith architectural approach).
- Reusability: Reusability is better supported in a microservices architectural approach since each service can be consumed and reused by other services and applications without direct coupling through language bindings or shared libraries. This is nearly impossible in a monolith architectural approach without making necessary code changes. This is due to the fact that monolith applications use a single development stack, therefore decoupling a single module from the application become a nearly impossible task. (Advantage: Microservices architectural approach).
- Technology flexibility: Operational agility is harder to achieve in the repeated deployment of monolithic application artifacts. (Advantage: Microservices architectural approach).
Which one should you choose?
The choice between using either a microservices or monolith architectural approach depends on factors like the size of your project, team capabilities, scalability requirements, and expected changes over time. What to keep in mind is that as a service architecture, the microservices architecture has become increasingly popular, not all business specific use cases and needs are the same. Therefore it is critical to evaluate against the above pros and cons, whether an approach is critical, or even essential, to that use case and specific business needs, and then go with that particular approach. For a lightweight application, a monolithic system often suits better. For a complex, evolving application with clear domains, the microservices architecture will be the better choice.