Microservices vs Monolithic Architecture

When building a new application or system, one of the key decisions a company must make is how it will be structured and organised. The decision is often made between the two common architecture models: Microservices vs Monolithic Architecture.

On one hand, an organisation may opt for a monolithic architecture: a design methodology in which an application is developed as a single unit or component. Conversely, they could choose to create an application within a microservices architecture, which requires the different parts – or services – within the application to be developed as separate components that are contained and deployed independently.

Let’s explore the differences between microservices vs monolithic architecture, the advantages and disadvantages of each developmental approach, and how to determine which methodology is best for your needs and circumstances.

What is a Monolithic Architecture?

A monolithic software architecture is the conventional approach to application development, in which an entire application is contained within a single codebase. Subsequently, this style of software development takes its name from the term monolith – which means large block or structure – as all the components, such as the user interface, business logic, databases, etc., are kept together in the same environment.

Because they’re in a single, self-contained ‘block’, the different components within a monolithic program architecture are tightly coupled, so changes made to one part of the software require amendments to its other connected parts. This can result in an increasing number of complex dependencies as the application grows over time. Similarly, a monolithic application will draw from a single pool of resources, e.g., databases, CPU, memory, bandwidth, etc.

Traditionally, before the advent and prolific rise in cloud computing, monolithic applications were stored on onsite servers. This meant that, as well as the software, organisations were responsible for maintaining the environment the application required to run.

What Are The Benefits of a Monolithic Architecture?

The advantages of a monolith architecture include:

Simple Development: with the application contained in a single code base, development doesn’t require as much initial planning, e.g., the architectural concerns that accompany microservices. Instead, you can just begin coding the application and add features when required.
Easier Deployment: developers only need to deploy one executable file or directory into a single environment.
Simplified Testing: because a monolithic application is held within a single, centralised unit, teams can perform end-to-end tests with greater speed and efficiency than with distributed software.
Quicker Debugging: subsequently, with all the application’s code in one place, it’s easier to find errors.

What Are The Drawbacks of a Monolithic Architecture?

The disadvantages of a monolith architecture include:

Scalability: because you can’t scale the individual components within monolithic software, you’re forced to deploy a new instance of the whole application to meet increased demand. This is not only more time-consuming but also consumes unnecessary resources, as only some parts of the application are running at peak capacity and require scaling.
Slower Development (as the Application Grows): now, while monolithic software architecture allows for faster initial development, this becomes slower and more cumbersome as the application grows larger. The increasing number of dependencies within the code means that developers have to spend more time cross-referencing and managing files and libraries to ensure they don’t unwittingly break the application.
Lack of Flexibility: any changes to the code affect the whole application, so amendments and updates can require significant time and resources.
Less Reliable: because of interdependency within the codebase, an error in one part of the software could render the entire application unavailable.
More Time to Redeploy: any changes to monolithic software, however small, require the retesting and redeployment of the entire application.

What is Microservices Architecture?

In the past, it was conventional for organisations to develop software within a monolithic architecture. However, as an application’s codebase became increasingly larger, development teams began dividing software into parts to make it more manageable and efficient.

First, software was rearranged into a multi-tier architecture, in which an application’s components were separated according to their functions. A common example is the three-tier architecture, where an application is divided into presentation, logic, and data layers. While this approach proved effective in some cases, it wasn’t a sufficient solution for the lack of scalability and increased interdependence that arose when a codebase grew too large – and organisations would often end up with “modular monoliths”.

Eventually, this evolved into the microservices architecture, in which the different layers of an application are further broken down into different services. In a microservices architecture, software is divided into modules according to its function, with each component having its own codebase and databases. Each service is held within a container that allows it to run independently and communicates with other parts of the application through APIs.

Additionally, rapid advancements in cloud computing have made microservices more feasible and economical. Instead of hosting a monolith application onsite, companies could rent server space from cloud service providers (CSPs) and deploy their containerised applications on virtual machines. This passes the responsibility of maintaining the infrastructure to the CSP, so organisations can concentrate on application development.

What Are The Benefits of a Microservices Architecture?

The advantages of a microservices architecture include:

Enhanced Scalability: if a particular part of an application is at capacity, development teams can quickly deploy a new container with the corresponding microservice – instead of having to deploy an instance of the whole application. This is considerably more efficient and economical than scaling the entire application.
Independent Deployability: because each microservice is held in an individual container, it can be deployed independently, allowing for faster software updates and the efficient introduction of new features. This allows for faster and more frequent release cycles, like those required in continuous integration/continuous deployment (CI/CD) pipelines and other iterative development practices.
Technological Flexibility: on a similar note, as microservices are self-contained, the various development teams working on an application can use the coding language, tools, and technologies they deem best for the task at hand. They aren’t constrained by the use of a single set of technologies and processes as with a monolithic architecture.
More Robust Applications: microservices allow you to deploy changes for a specific software component, without potentially bringing the entire application offline. Additionally, microservices can test fixes and new features – and simply roll them back if they don’t work as intended.
Faster Time to Market: companies that produce digital products can release them quicker by employing a microservices architecture. Similarly, organisations in any industry can achieve their digital innovation goals – and the increased productivity and efficiency that accompanies them – in less time. In either case, this gives companies an edge in an increasingly competitive marketplace.
Lower Costs: all the above advantages contribute to more cost-effective application development. This is especially true as the application increases in size and complexity.

What are the drawbacks of a microservices architecture?

The disadvantages of a microservices architecture include:

Increased Developmental Complexity: microservice architectures demand more design and planning and design before implementation. A development team must identify which functions warrant their own microservice, which can be packaged together, and which components need to communicate with each other through APIs. Insufficient design considerations can result in too many microservices (often referred to as nanoservices) which constrains development speed and the application’s performance.
More Complicated Debugging: with different codebases running in different environments – and each microservice having its own set of logs, debugging a microservices-based application can prove time-consuming and complex if it’s not architected efficiently
Lack of Clear Ownership: similarly, with the potential for different microservices to be managed by separate teams, it can become difficult to establish who’s responsible for a particular software component and, subsequently, who to contact for support. What’s more, the more features added to the application, the greater the number of teams responsible for developing and maintaining the corresponding microservices.
Additional Organisational Overhead: all the disadvantages described above require additional protocols and processes, increased communication between business units, and perhaps the hiring of additional personnel and new team formation. Not to mention – personnel and processes to manage and coordinate it all. This all results in an additional organisation overhead that must be accounted for.

Microservices vs Monolithic Architecture: Which One is Best For You?

When weighing up microservices vs monolithic architectures for a digital innovation project, here are the most important factors to consider:

Application Size and Scope: while a monolithic architecture may be more suited to the development of a simple application – or a prototype, microservices are better for more complex, feature-rich software. As discussed earlier, a microservice architecture requires planning and forethought, which may be overkill for a small project.

Business Goals: while evaluating the pros and cons of microservices vs monolithic architectures, it’s important to also assess your organisation’s growth objectives. A monolithic application may suffice in the short term, but if you plan to expand soon, it could quickly grow complex and difficult to scale. If you have expansion plans, it’s worth investing the extra time required upfront to properly plan and design your application as microservices.

Team Competency: crucially – do you have personnel with the necessary skills and expertise to design and create a microservices architecture? Developing with microservices requires a different skillset and mindset than for a monolithic application. This includes an understanding of distributed architecture design, cloud environments, containerisation, and APIs.

Infrastructure: microservices are a cloud-native technology, so your organisation needs to have migrated, at least partially, to a cloud environment or have plans to do so. If your IT infrastructure is hosted on-premises and you don’t plan to change that in the near future, a monolithic application will be the best option.

Conclusion

Microservices vs Monolithic Architecture: In Summary

A monolithic architecture is the conventional approach to application development, in which an entire application is contained within a single codebase.
A microservices architecture sees the different parts – or services – of an application developed as separate components that are contained and deployed independently.

Pros and Cons of Monolithic Architecture

Pros

Simple Development
Easier Deployment
Simplified Testing
Quicker Debugging

Cons

Scalability
Slower Development (as the Application Grows)
Lack of Flexibility
Less Reliable
More Time to Redeploy

Pros and Cons of a Microservices Architecture