In the context of ever-increasing competition in almost all areas of digital business, the speed and continuity of service delivery are becoming a key factor influencing the customer’s сhoice in favor of a particular solution. The widespread adoption of the DevOps philosophy to ensure continuity of delivery and updates without sacrificing quality is also a result of current market trends. In such a situation, there can be no trifles, and therefore the question of the code & app architecture was called into a debate. The result was a gradual shift away from the time-tested monolithic architecture in favor of a more agile microservices approach.
Monolithic vs Microservices comparison
In order to understand what is the difference between monolithic and microservices and why more and more companies prefer microservices, while monolithic architecture is still in demand, we need to compare both approaches in terms of their essence and purpose.
What is Monolithic architecture?
You can check monolithic architecture in a solid application with a single code base presented as a single file. Such a system works as a whole, solid product and it interacts with a single database. The client interface, database, front and back end, as well as the business logic of the application - all this is presented in one place, doesn’t interact through the API, and is definitely part of a single monolithic application. Hence the name.
This is the traditional approach to building applications that all of us have come across. Despite the fact that modern trends are forcing digital companies to increasingly make their choice in favor of a microservice architecture, the monolithic approach still has its advantages.
Ease of development. Monolithic architecture is a standard, long-studied approach that does not require any additional skills from developers.
Simplified deployment. The entire system is uploaded as a single file, and therefore engineers do not need to worry about unloading various services combined through the third-party API.
Higher productivity. A somewhat controversial point, but there is an opinion that the monolithic applications run faster due to the absence of a large number of microservices combined through the API. Nevertheless, it all depends on a number of additional parameters.
Simplified testing. Another advantage of a monolith structure - automated tests can be run with no worries about the need for a separate testing algorithm for each service.
Poor scalability. As the application grows, its size increases so it becomes more difficult to understand and scale.
Minor changes are harder to implement. You have to re-deploy the entire system even for small fixes, which is resource-intensive.
Future issues with speed. As an application grows in size, its deployment and launch times also increase.
Complicated onboarding. It is difficult for newcomers to understand a huge monolithic application, even if their tasks include working with only certain limited functionality. Over time and the growth of the application size, this problem only gets worse.
The application has a single tech stack. This means that the process of new technology implementation (in order to improve the work of some particular function) becomes extremely difficult.
Reliability. One of the main disadvantages of monolithic architecture. A critical error can possibly break down the entire system.
As you can see, despite a number of advantages, monolithic architecture has its significant drawbacks, so it is not surprising that companies increasingly prefer microservices architecture. However, this situation has its own nuances.
What is Microservices architecture?
In contrast to the monolithic approach, in the microservices architecture, the application structure is split into separate, small, independent services, which are often defined only by business logic and interact with each other through HTTP requests or third-party APIs. Each of these services has its own database, which allows you to ensure the continuity of the services delivery, their independence and prevent loss of quality and data. Microservices architecture is very important for those companies that are going to implement DevOps methodology, ensuring the continuity of delivery of their services. However, this architecture has its pros and cons.
Self-sufficiency. Each individual micro-service can be built to provide a specific business goal and work completely independently from the rest of the microservices.
Technical variety. Unlike monolithic architecture, where the selected stack is final and does not tolerate any changes, with the microservice architecture you will have the opportunity to select a separate stack for each service, improving productivity.
Scalability. One of the main advantages of microservices over monolithic, making it so popular these days. Due to the dispersed system of individual services, the system as a whole is extremely flexible and capable of expanding through changes in individual services.
High sustainability. Each of the microservices works autonomously, and therefore any errors in one of them will not affect the work of others, thereby increasing the reliability of the system as a whole.
Continuous delivery. Due to the autonomy of individual services and modules, customers can receive permanent value, while you can always make changes to specific services without stopping the system as a whole.
Minor changes are easier to implement. You don't need to stop and re-deploy the entire system for small changes.
Simplified onboarding. Newcomers can jump on a specific microservice and immediately get into work, so they do not need to examine the entire system.
More complicated approach. Developing a microservice architecture requires in-depth knowledge from software engineers, especially in terms of establishing connections between microservices.
Greater resource consumption. Microservices architecture often requires not only more effort but more development time and manpower, which may not suit some companies.
Complicated deployment. A large number of stand-alone services and connections between them require a greater effort from developers to deploy the app.
Complicated testing. Of course, a more complex system consisting of disparate services created using different tech stacks requires a more thorough approach to testing. Running a few automated scripts through the entire system will have no effect in such a situation.
As you can see, the main monolithic vs microservices difference is that 90% of the microservices’ advantages come from the monolithic architecture disadvantages and vice versa. That is exactly why both approaches coexist beautifully - each of them occupies its own niche. Let's find out when you should choose monolithic architecture or microservices and why.
When to opt for monolithic architecture?
Despite the growing demand for microservices architecture, the monolithic approach still makes sense if:
The app will be small. It will be easier and faster to develop a monolithic architecture for a small product.
There are no team and product expansion plans in your mind. The expanding process is expensive and undesirable with a monolithic architecture.
Your product isn’t developed yet and you’re at the start-up stage. Developing a monolithic architecture will take less time than creating many microservices.
You need a minimum viable product (MVP) with a key value to validate your idea and collect feedback - monolithic architecture is your choice.
When to opt for microservices architecture?
Microservices are the choice of large companies and businesses that want to expand and meet the growing needs of their customers. Tech giants like Amazon and Spotify have long since switched to microservices architecture. This approach is also suitable for you if:
The future product will be large and will have a lot of features and services.
The team has time to thoroughly study and map out the entire development process.
The team and product will expand in the future, implementing new specialists and technologies.
The use of different tech-stacks for specific services is crucial.
The budget is not an issue. You aren't afraid of higher costs and want to create a feature-rich product that will have separate teams working on it.
Monolithic vs Microservices architecture comparison
To finalize monolith vs microservices pros and cons, we formalized them in the form of a table.
Single deployment process, changes require re-deployment
Flexible deployment of each of the individual services without stopping the entire system
Any error affects the entire system and can cause serious issues
Any error can be resolved locally without disrupting the operation of other services
The selected tech stack is final and new technologies are not implemented
There are no technology restrictions - new technologies are constantly being introduced
One team develops a classic solution
Development requires sophisticated knowledge from engineers - connections between services are developed using separate APIs
Updated can take time and may require the entire application to be stopped
Updates can be delivered continuously and without disrupting the system, so that the user does not notice anything due to the autonomous nature of the individual services
Testing & Bug-fixing
End-to-end testing is possible, as well as single automated scripts for the entire system, which makes the testing process easier
Each separate service is responsible for a separate business task, and therefore needs an individual approach to testing. In addition, services can be written using different technologies. All this complicates the process of testing the application.
At the system level, data is stored in a single database and transmitted over a single secure channel, and therefore the process of monitoring security is easier
The interaction of services with each other via API causes additional concerns regarding security and requires extra attention
Over time, onboarding becomes more difficult as the application grows and it is difficult for a newcomer to deal with a complex system
The onboarding process is agile and simpler, since new specialists do not need to deal with the operation of the entire system, but only with the microservice
Microservices vs Service-Oriented architecture: what’s the difference?
Service-oriented architecture (SOA) is often confused with microservices and this is not surprising. This concept appeared at the beginning of the 21st century and was the answer to the problems that were found in the products using monolithic architecture. So, using SOA, a monolithic application can be divided into several separate services. However, communication between them was weak and they continued to use a single database.
Microservices architecture is the next step and is a more advanced SOA approach. Microservices within the system communicate with each other directly, interact with separate databases, can be written using different technologies, and so on. Until now, you can find the opinion that these two concepts are synonymous, but the truth is that SOA is just a previous stage in the development of the Microservices idea.
How to migrate from monolithic to microservices architecture?
First, ask yourself if you need it. Despite the growing popularity and manufacturability of microservices, the monolithic approach is still used due to the presence of several undeniable advantages. A young product and a young team of specialists will make their choice in favor of a monolithic structure and they will be right. The same goes for startups.
Ready-made monolithic product migration to microservices is a difficult and time-consuming task. You only need to decide on this when you are 100% sure that you need to expand and become more flexible. At the same time, a thorough study must be carried out of what costs will be needed for migration and what benefits the company will receive in the end.
This complex process includes a complete analysis of the entire current structure of the application and its functions, breaking them down into separate services, elaboration, and analysis of which technologies should be used for each individual service, as well as thinking over and developing connections between them. The best option, if you have decided to migrate to microservices, is to contact professionals who have experience in this area, since it can be extremely problematic to assemble such an extensive team of specialists on your own.
Both approaches have a number of advantages and disadvantages, and this question can only be answered from the point of view of a specific example. Monolithic architecture is more suitable for small companies and startups that do not plan for expansion and flexibility in the near future. Microservices architecture is suitable for large companies with large budgets who want to make their product more flexible.
Monolithic architecture is a single complex system in which all services interact with a single database and are represented by a single codebase. Microservices is a system that includes many separate autonomous and self-sufficient services that interact with individual databases and with each other through dedicated APIs.
Each of the architectures provides speed bonuses depending on the type and complexity of the product. A monolithic product will work faster if it is a small app with a small set of functions. In the opposite situation, a monolithic architecture can backfire and slow down the application. Microservice architecture, on the other hand, will slow down a small application, but it will provide faster operation of a complex product with many functions.
The choice in favor of a monolithic architecture should be made in a situation if:
- The app will be small
- There are no team and product expansion plans in your mind
- Your product isn’t developed yet and you’re at the start-up stage
- You need a minimum viable product (MVP)