Monolithic vs Microservices: What Architecture To Choose For Your Project
By Mariana Demchuk, Kostya Zgara | June 20, 2022 | Web Development
Almost any company, even if it is not IT, has its digital services. They need to be released on time, and then updated: add improvements, fix problems, close vulnerabilities, and launch new features.
That said, when an application is updated, it needs to keep running as if nothing is happening.
This need for speed of updates and flexibility of applications has changed software architecture: developers are increasingly having to move from monoliths to microservices. What is it and what is the difference?
To put it simply, in the case of a monolith, all the components of an application are in one block, while in the case of a microservice, parts of the application are scattered over different blocks, with usually one function or component of the application being in one block.
Monolithic and microservice architectures are two very different approaches. One advantage of a microservice architecture is that parts of the application can be developed and updated independently - for example, you can update just one block and not change the rest. In a monolith, you have to rebuild and resolve conflicts every time, because you can say that the application forms a whole.
In this article, we will overview the main features of different types of project architecture, as well as what to consider to find the best solution for your business.
What is Monolithic Architecture?
The monolithic architecture approach is considered a classic and assumes that all components of one program are implemented on a single code base. This is a full-fledged module that works autonomously and independently of other applications.
With this approach, all components of the program are interconnected and interchangeable - this helps to develop the program as self-sufficient. At the same time, removing one element inevitably causes changes throughout the system.
As you add new features and changes to the same code base, it will grow over time. This approach is well suited for small development teams and has the corresponding benefits. A monolith usually has a server application, a user interface, and a single database. All functions are managed and serviced in one place, which is an advantage in some cases.
Advantages of Monolithic Architecture
- Simplified development and deployment. There are many tools that you can integrate to make development easier. In addition, all actions are performed with a single directory, which simplifies deployment. With a monolithic kernel, developers don't have to deploy changes or updates individually, as they can do it all at once and save a lot of time.
- Fewer end-to-end problems. Most applications depend on many cross-component tasks such as audit trails, logging, rate-limiting, etc. Monolithic applications deal with these issues much more easily due to their single code base. It is easier to connect components to these tasks when everything works in one application.
- Better performance. When built correctly, monolithic applications tend to perform better than microservices-based applications. For example, an application with a microservice architecture might need to make 40 API calls to 40 different microservices to load each screen, which results in a performance hit. Monolithic applications, in turn, enable faster communication between software components by sharing code and memory
Disadvantages of Monolithic Architecture
- Codebase becomes unwieldy over time. Over time, most products continue to develop and grow in scope, and their structure becomes blurred. The codebase starts to look unwieldy and becomes difficult to understand and change, especially for new developers. It also becomes increasingly difficult to find side effects and addictions. With the growth of the code base, the quality deteriorates and the IDE is overloaded.
- Difficulty in adopting new technologies. If some new technology needs to be added to your application, developers may encounter barriers to implementation. Adding new technology means rewriting the entire application, which is costly and time-consuming.
- Limited Flexibility. In monolithic applications, every small update requires a complete redeployment. Thus, all developers must wait until this is done. When multiple teams work on the same project, flexibility can be greatly reduced.
When it is better to choose a monolith architecture
The monolith is suitable for startups that need to develop and release a product as soon as possible. Monolithic software architecture can be useful if your team is in the early stages of development, you are creating an untested product, and you have no experience with microservices.
What are Microservices?
As an alternative to a monolithic architecture, microservices act as a distributed system of simple and easily replaceable modules. They are responsible for one elementary function, while microservices are not built hierarchically, but symmetrically.
Services communicate with each other and with clients using lightweight protocols such as HTTP. The result is an easy-to-configure system that is easier to update regularly. The key idea of a microservice is independence from the environment and a high level of reuse.
So, the failure of one service does not lead to a shutdown of the system as a whole. Once the bug is fixed, the required change can be deployed to the relevant service only, instead of reconfiguring the entire application. True, for this, at the design stage, it is required to think over the links between the services to achieve maximum independence from each other. In the event of an error, users should receive correct notifications about the temporary unavailability of a particular service without affecting the entire system.
Main characteristics of microservice architecture:
- modules can be replaced at any time: they are simple and independent in the deployment and update processes;
- modules are organized around functions - thus the microservice performs only one elementary function;
- for modules, you can use different programming languages and frameworks that run in different environments using different operating systems on various hardware platforms;
- microservice architecture is symmetrical, not hierarchical.
Advantages of Microservice Architecture
- High system stability. When one of the services crashes, the rest remain in working order. Thanks to this, one faulty service does not affect the operation of the others. However, at the design stage of microservices, attention should be paid to how the unavailability of services affects the user experience.
- Scalability. The microservice architecture allows you to scale each service separately without affecting the rest of the system. While vertical scaling can be limited by the bandwidth of each service, horizontal scaling is unlimited. In addition, it can be fully automated and work with microservices dynamically.
- Easy to develop and maintain. Each service is designed, built, tested, and deployed independently. This speeds up development and release. Since developers release individual services, rather than the entire application, the risks of releasing a piece of software that will disrupt the entire system are reduced.
- The technology stack is unlimited. In microservices, we can intelligently choose the technology stack based on the characteristics of the business and the project team.
Disadvantages of Microservices Architecture
Despite all the advantages of building a project based on a microservice architecture, this approach is not universal. Don't opt for microservices just because you see other organizations using them successfully. The microservices approach is not suitable for all business needs and does not magically eliminate development and maintenance complexity. The main weaknesses of microservices are:
- The growth of the development process. Microservices are more complex than monolithic architectures, as more and more teams are created in different places. If growth is not properly controlled, it slows down development and reduces operational efficiency.
- Requirements for maintenance are high. In a monolithic architecture, it is necessary to guarantee the normal operation of only one application; while in microservices it is necessary to guarantee normal work and joint work of tens or even hundreds of services that create huge problems.
- Higher costs. More services mean more investment in operation and maintenance. Each new microservice can have its own cost of a set of tests, deployment instructions, hosting infrastructure, monitoring tools, etc.
- Debugging problems. Each microservice has its own set of logs, which complicates debugging. In addition, additional difficulties may arise when one business process runs on multiple machines.
- Support issues. As new services emerge, the number of teams working on them increases. At a certain point, it becomes more difficult to determine which services the team uses and who to contact for support.
When microservices are a good option for your business
Microservice architecture is your option if the team plans to develop a medium-sized web application that consists of a set of modules. At the same time modules are weakly connected or isolated from each other.
Also, the choice of microservice architecture may be due to business requirements to constantly make changes to the product and speed up the development process. This architecture is suitable for projects that require point scaling and changes at various points in the application.
Microservices are also applicable to products that involve different technologies, such as multiple languages. It is also planned to integrate with external services, such as payment systems and banks.
Monolithic vs Microservices: Main Differences
Monolith vs Microservices: Which One To Choose?
First of all, you need to understand that there is no universal solution. To choose the optimal architecture for the project, pay attention to the project parameters: subject area, team qualifications, release dates, project workload, and many external systems with which the application should communicate.
Ideally, the software architecture is determined at the design stage. That is, even before the start of development it is known what the finished result will look like, the size of the project, and all the necessary functionality. But this is not always the case. Often, at first glance, a small project later scales up and expands its functionality, and this requires new integrations.
That is why at mobile and web development company Seedium we often use a hybrid model of development. In this approach, the project is divided into separate modules, and monolithic architecture is programmed within such a structure. In essence, one database with individual modules is stored, and the role of the connecting element is performed by Apache Kafka.
This project architecture is properly scalable for business growth, makes it easier to maintain changes in the project, and if necessary allows you to connect a clean microservice architecture. In addition, it can significantly increase the speed of development, reduce the cost of maintenance and improve the quality of software.
The microservice architecture of the application is becoming increasingly popular. However, to solve a particular business problem, evaluated in the light of the pros and cons listed above, it is important to determine whether you should start with a monolith or microservices.
If your program does not need an extended scale, and the complexity of the components is predicted in advance, the monolithic architecture is the best choice. For a complex, ever-evolving application with specific domains, microservice architecture will be a better option.
But the main things that you should focus on are the specific needs of your business and how many resources will be involved in the project development and maintenance. In particular, how product features will be coupled in the codebase and what kind size of the team will be working on the project. This will help avoid unnecessary complexity when developing applications.