In this article, we will compare microservices and monolithic architecture, what type of architecture we should use, and take a look at their advantages and disadvantages.
Let’s understand both of them first.
The monolithic architecture is considered to be a traditional way of building applications. A monolithic application is built as a single and indivisible unit. Usually, such a solution comprises a client-side user interface, a server side-application, and a database. It is unified and all the functions are managed and served in one place.
Normally, monolithic applications have one large code base and lack modularity. If developers want to update or change something, they access the same code base. So, they make changes in the whole stack at once.
A microservices architecture breaks it down into a collection of smaller independent units. These units carry out every application process as a separate service. So all the services have their own logic and the database as well as perform the specific functions.
Within a microservices architecture, the entire functionality is split up into independently deployable modules which communicate with each other through defined methods called APIs (Application Programming Interfaces). Each service covers its own scope and can be updated, deployed, and scaled independently.
Let’s discuss each point in details.
With Monolith apps, you can set your deployment once and adjust it based on ongoing changes you have.
However, there is also only a single point of failure during the deployment process and, if everything goes wrong, it could break entire project.
In comparison, microservices require much more work. For example, you need to deploy each microservice independently, worry about orchestration tools, and try to unify the format of your ci/cd pipelines to reduce the a amount of time required for doing it for each new microservice.
One advantage of microservices over monolith is that if something goes wrong, you will only break one small microservice. It’s also much easier to rollback one small microservices than and entire monolith app.
To use a microservices architecture, you need a Dev-Ops for your team. Because not every developer will be familiar with Docker or orchestration tools, such as Kubernetes, Docker Swarm, Mesosphere.
You will need someone who can monitor and maintain the functioning state of your CI configuration for each microservice and the whole infrastructure.
Well, we just discussed the failure part in both and Microservices architecture is the obvious winner here.
Breaking one microservice affects only one part and causes issues for the clients that use it, but no one else.
For example, if you’re building a financial app and the microservice responsible for money withdrawal is down, then it won’t affect the whole app, which is a huge relief.
For scalability, microservices are again better.
Monolith apps are hard to scale because, even if you run more workers, every worker will be on the single, whole project, an inefficient way of using resources. Also, you might write code whihc can’t be scaled horizontally.
With microservices, your resources can be used more carefully and allow you to scale only that parts that require more resources.
Monolith architecture is cheaper in some scenarios, but not in others.
For example, with the better scalability of microservices, you could set up an auto-scale and only pay for that when the volume of users really requires more resources.
At the same time, to keep that infrastructure up and running you need a devops that needs to be paid.
With a small monolith app, you could run on a $5-$20 host but with a larger monolith app, you may host a very expensive instance because you can’t share it over multiple small, cheap hosts.
It’s simple. The more code you need to write/manage, the more trickier it gets. More microservices, more code and hard to manage.
On the other hand, when you develop one microservice, you may have a case in which you don’t need to run other parts of the application at all.
Doing code review and QA is simpler with microservices; you may even be able to write microservices in different languages.
What’s easy to release? Small parts of code and small apps. Microservices that are smaller and with a proper architecture of microservices communication allow you to release new features faster by reducing QA time, build time, and tests execution time.
Monolith apps have a lot of internal dependencies that could not be broken up.
Let’s make a list of strengths and weaknesses for both.
Strengths of the Monolithic Architecture
In a monolithic application, this area of functionality concerns only one application so it is easier to handle it.
Monolithic applications are much easier to debug and test. Since a monolithic app is a single indivisible unit, you can run end-to-end testing much faster.
When it comes to monolithic applications, you do not have to handle many deployments – just one file or directory.
Simple to develop. As long as the monolithic approach is a standard way of building applications, any engineering team has the right knowledge and capabilities to develop a monolithic application.
Weaknesses of the Monolithic Architecture
When a monolithic application scales up, it becomes too complicated to understand, to code as well as to manage.
It is harder to implement changes in such a large and complex application with highly tight coupling. This makes the overall development process much longer.
You cannot scale components independently, only the whole application.
It is extremely problematic to apply a new technology in a monolithic application because then the entire application has to be rewritten.
Strengths of the Microservice Architecture
All the services can be deployed and updated independently, which gives more flexibility.
As I have mentioned earlier, a bug in one microservice has an impact only on a particular service and does not influence the entire application.
It is much easier to add new features to a microservice application than a monolithic one. It is easier to understand and manage as well.
Each element can be scaled independently and in this sense, it’s cost- and time-effective
We can easily apply various technologies and frameworks in each microservice. So it gives flexibility.
Weaknesses of the Microservice Architecture
You have to choose and set up the connections between all the modules and databases, which is complex task as well. Also, as long as such an application includes independent services, all of them have to be deployed independently.
A multitude of independently deployable components makes testing a microservices-based solution much harder.â€‹â€‹â€‹â€‹â€‹â€‹â€‹
What should you choose then?
A monolithic architecture works best in following scenarios:
If you are a startup and your team is small, you may not need to deal with the complexity of the microservices architecture. A monolith can meet all your business needs so there is no emergency to follow the hype and start with microservices.
If you want to make a simple and small application which do not demand much business logic, superior scalability, and flexibility work better with monolithic architectures.
Microservices require profound expertise to work well and bring business value. If you want to start a microservices application from scratch with no technical expertise in it, most probably, it will not pay off.
If you want to develop your application and launch it as soon as possible, a monolithic model is the best choice.
If you don’t have lots of money to spend as microservices will require expert devops and you will end up paying a lot.â€‹â€‹â€‹â€‹â€‹â€‹â€‹
A microservices architecture works best in following scenarios:
If you have microservices expertise because without proper skills and knowledge, building a microservice application is extremely risky. You need to have Dev-Ops and Containers experts since the concepts are tightly coupled with microservices. Also, domain modeling expertise is a must. Dealing with microservices means splitting the system into separate functionalities and dividing responsibilities.
If you are concerned about the scalability and reliability of your product. The microservices architecture will make scaling and adding new capabilities to your application much easier. So if you plan to develop a large application with multiple modules and user journeys, a microservice pattern would be the best way to handle it.
If you don’t have a tight deadline; microservices require you to research and architecture planning to ensure it works.
If you have an existing monolith app and see problems with parts of your application that could be split across multiple microservices.