December 30, 2020
Monolithic vs Microservices Architecture
Thanks to rousing endorsements from the likes of Google, Amazon, and Netflix, microservices are continuing to rise in popularity. As a result, more and more companies are hopping on the bandwagon in hopes of finding their own success stories.
No longer are software monoliths able to meet the demands of today’s fast-paced competitive business landscape. Microservices offer agile, customizable software that allows for fast deployments, frequent updates, and increased scalability.
This article breaks down the core differences powering the monolithic vs. microservices discussion so that you can have a better understanding of what’s involved in a microservices initiative before diving in head-first.
What is the Difference Between Monolithic and Microservices Architecture?
Before we dig into the specifics of which is better–microservices or monolithic architecture, let’s first define each term. Here’s a quick overview of the characteristics that define each design:
What are Microservices?
Microservices are designed to combat the problems associated with monoliths by going in the complete opposite direction. Microservices are an architectural style where an application is broken into a series of modules, each associated with a specific business objective.
Because microservices are relatively new, there’s no universal definition that lays out what exactly a microservices architecture should look like.
However, all microservices share some commonalities:
- All services are independently deployable.
- They communicate using a network of lightweight technology-agnostic protocols.
- Services should be small in scope and focus on a single business goal.
- Each service is failure-resistant and fault-tolerant.
Many people first introduced to microservices confuse them with service-oriented architecture (SOA). While they do share some similarities, they differ on some fundamental levels.
For more information, read our article on the differences between microservices and SOA.
What is Monolithic Architecture?
Traditionally, applications were built on a monolithic architecture, a model in which all modules in an application are interconnected in a single, self-contained unit. All code exists inside a single codebase, which means that the entire application is deployed at the same time, and scaling is achieved by adding additional nodes.
The problem with monoliths isn’t so much that there’s an inherent problem with the architecture. In fact, simple applications with limited feature sets may benefit from this approach. The challenge comes when companies grow their applications–adding features and bug fixes on top of everything that came before.
Monolithic vs. Microservices: Which Architecture is Best?
While microservices have serious transformational potential and stand to accelerate development, it’s worth noting that they’re not the right fit for every organization.
Microservices work really well in organizations that have embraced Agile, DevOps, and CI/CD, and the decentralized decision-making culture that empowers small teams to move quickly.
Why are Companies Turning Their Backs on Monolithic Architecture?
The truth is, not all companies are.
Nor should they.
In fact, in some situations, a monolithic application is the best choice.
For example, when applications are small, adopting a distributed architecture like microservices before it’s necessary can result in an overly complex application and increased overhead.
Companies considering building a new app from scratch or developing a proof of concept may also benefit from embracing the monolith.
While it might seem counterintuitive, small monoliths are a cost-effective, uncomplicated solution. They’re easy to understand and simple to scale, test, and debug. And–just because we’re talking “traditional” architecture, that doesn’t mean monoliths are relegated to using the technologies of the past.
The key thing to remember here is, it isn’t until monoliths start to expand well beyond their original capabilities that it makes sense to make the migration. As a monolithic application grows, what initially made the architecture an appealing solution–low costs, simple development, etc.–now come at the expense of scale, flexibility, security, and of course speed.
Here’s a quick look at the key issues that microservices seek to address:
Utilize a Single Development Stack
Monolithic applications are tightly coupled and developed using a single stack. Down the road, organizations don’t have the flexibility you’ll find with microservices, which may cause delays or quality issues.
Within the monolithic architecture, developers don’t have the freedom to choose the best programming language or storage solution for each service. As monolithic applications grow, they start to collect an increasingly diverse dataset with varied processing requirements.
Difficult to Understand
Tight coupling and interconnected modules in monolithic applications can make it extremely difficult to learn the ins and outs of the codebase and all of the interdependencies at play.
New developers face a major hurdle during onboarding and must gain an understanding of how the entire application fits together. Additionally, even seasoned developers used to this system may have a hard time training their new colleagues.
Resiliency, Fault Tolerance & Isolation
Another advantage of microservices in the monolithic vs. microservices debate comes from its tight coupling and low cohesion. Any time you make a change to a monolithic application, it introduces a great deal of risk.
Because a monolith is a single unit with many inter-dependencies, one bug that affects one tiny part of a single feature can cause problems in an unrelated area–or even bring the entire application down.
Due to the possible chain of faults that can occur, it is also difficult to isolate the root cause of any problems that might emerge.
Knowing this, developers must thoroughly test each module, as it may be impossible to predict the outcome of any change–no matter how small–to the codebase.
What’s more, recovering from failures is also a challenging, time-consuming endeavor. For example, once the bug has been isolated and resolved, the entire application needs to be rebuilt and redeployed.
Large monolithic applications take a very long time to develop and deploy. We’re talking months or even years. Slow deployments mean organizations fall behind competitors due to a lack of new feature releases, slow time to market, and an inability to incorporate user feedback as it comes in.
These are just some of the issues that organizations encounter with monolithic architectures.
Others include problems scaling, declining quality of code, and lack of flexibility caused by large development teams and traditional development methodologies like Waterfall.
Microservices Solve Monolithic Issues
Now that we’ve looked at the key differences between monoliths and microservices, as well as some of the primary reasons companies are moving away from monoliths, let’s look at how microservices can potentially help solve those problems we just mentioned.
Earlier, we discussed many of the issues that develop as monolithic applications increase in size and scope. Let’s look at those same pain points from the other side. Here’s how microservices can mitigate these issues:
Because microservices are loosely coupled and independently deployed, developers are free to choose a different technology stack for each service.
This provides an enormous amount of flexibility and allows developers to select the best programming language and storage solution based on the needs of a particular service.
Onboarding & Training Challenges
Because each microservice is smaller in both size and scope than monolithic architectures, training and onboarding is a much smoother experience for new hires and their trainers. Again, each service has a dedicated team, focused exclusively on that one service, eliminating the need to learn the ins, outs, and interdependencies of an entire monolithic application.
Resiliency, Fault Tolerance, & Isolation
Microservices don’t have the same resilience, fault tolerance, and isolation issues that plague monolith applications. Because microservices are loosely coupled, there’s little chance that a bug found in one microservice module will compromise other services in the application. That separation between microservices makes it easy to isolate and fix problems and redeploy.
Microservices are designed for rapid deployments. With smaller, dedicated teams focused on each service, developers can make changes and deploy the latest iteration of any service without worrying about the impact on other areas of the application.
Companies benefit further when they apply Agile, implement DevOps, and add CI/CD to their process, and layer automated functions like testing, monitoring, and deployment on top of those initial processes.
Monolithic vs. Microservices Architecture: A Quick Comparison
|Size||Single self-contained unit||Very small function-oriented independent services|
|Granularity||Tightly coupled with low cohesion||Loosely coupled with high cohesion|
|Ease of Deployment||Requires recreating and redeploying the entire application||Each service can be built and deployed independently|
|Remote Call Overhead||Low/None||High communication overhead due to an increase in remote calls|
|Speed of Deployment||Very slow deployment speeds||Rapid and continuous deployment|
|Persistence||All services in a monolithic application share data storage||Each service is free to choose its own data storage|
|Ease of On-Boarding||Can be difficult to onboard new developers||Easy to onboard new developers|
|Polyglot Programming||Utilize a single technology stack||Can utilize a different technology stack per service|
|Communication Method||Language-level or procedure calls||Communicates via API layer with lightweight protocols like REST|
|Scalability||Horizontally scalable, can be very challenging to scale as the application becomes larger||Vertically and horizontally scalable through the use of containers and the cloud|
Monolithic vs. Microservices Architecture: Which One is Right For You?
Unfortunately, there’s no one-size-fits-all answer when it comes to the old microservices vs. monolith debate.
As we’ve mentioned, in some cases, monolith applications are the best fit. While microservices offer a ton of promise, they don’t always square with every company’s culture, processes, and application. Nor are they some magical cure-all that delivers transformative benefits without putting in the work.
3Pillar Global draws on deep experience in using microservices as an integral part of the digital products we create for our clients. Contact us today to learn more.