Microservices are becoming increasingly popular among developers, and they are suitable for large-scale internet services that cater to a large number of users. If a failure occurs in one service, the others can continue to operate smoothly: this is very important for large and complex systems. When introducing innovations, it is easy to write a new service that seamlessly integrates into the whole system without dealing with compatibility issues. Moreover, several independent teams using different programming languages can be included in the work, as microservices enable this.
The microservice approach has both advantages and disadvantages. In this article, we will delve into the essence of microservice architecture, its differences from monolithic architecture, its advantages and disadvantages, as well as the specifics of operating applications built on the principle of microservices.
What is Microservice Architecture
Microservice architecture is a style of software development that involves breaking down the monolithic system into separate components that operate as independent services. Each individual service is tasked with performing relatively simple functions, and the application’s operation is tested in real-time by monitoring technical elements and business characteristics. Services have clear physical boundaries, making them scalable and allowing the use of different programming languages for development. Necessary changes are made without affecting the entire application.
Microservice Architecture vs. Monolithic
Monolithic systems combine all the application’s services into one process and then replicate this system across several servers. Microservice architecture packages each service separately, and they are stored on different servers in isolation, duplicated if necessary. This allows working with each functional element independently.
Advantages of Microservice Architecture
The advantages of microservices are compelling enough that major corporate players like Amazon, Netflix, and eBay have implemented them in their systems.
- High fault tolerance: If one service fails, the others remain operational. This way, issues in individual services do not disrupt the entire work process;
- Flexibility: It’s possible to try out a new technology with minimal effort. This will be significantly faster and, in case of failure, it is easy to roll back the changes. By locally changing one service, the risk to the entire system is minimized, and the time required for changes is reduced;
- Simplicity: The less code there is (as each individual service is a coherent system, it is unnecessary to deal with a large number of details unrelated to that particular function), the easier it is for programmers to understand how things work. Additionally, it takes less time;
- Ease of deploying written code: A small amount of code ensures rapid deployment;
- Scalability: The most necessary and important services can be supplemented and expanded when the need arises. The whole system remains as it is.
Compared to monolithic architecture, microservice architecture offers greater flexibility and the ability to independently scale individual services. It is easier to make local changes to the code without risking the entire system; however, this increases the complexity of interaction between services.
Disadvantages of Microservice Architecture
Despite the trendiness and numerous advantages of microservice architecture, it also has downsides.
- Communication between the services themselves is complex. Since each functional element is isolated, special care is needed to build proper communication between them, as they will inevitably need to exchange requests and responses. It’s clear that as the number of services increases, the complexity in building their communication will grow.
- The increase in the number of services also leads to an increase in the number of databases these services correlate with, as microservices use not one common database, unlike monolithic architecture.
- The complexity of testing is expressed in the need to first deal with each service individually and then test its correct interaction with other microservices.
- Microservices are less suitable for use within individual organizations; they may be unjustifiably complex for them, whereas they are excellent for large-scale internet services.
Specifics of Operating Applications with Microservice Architecture
- Monitoring
Over time, minor issues can lead to serious ones. Therefore, timely, and in the case of microservices, continuous monitoring is necessary. Setting up monitoring for microservice architecture is much more complex and requires more resources to maintain compared to monolithic applications. - Ensuring Fault Tolerance
Both monolithic and microservice architectures cannot avoid failures during application operation. An important principle when creating an application based on microservices is to assume that system failures will occur sooner or later. With this initial assumption, the application is developed.
Before releasing to production, the code must be thoroughly tested. Nevertheless, there is always the possibility that some error will be missed. For such cases, a chaos testing system was invented. Errors and problems are created automatically and intentionally — to study them in advance and devise a quick solution or prevention method. - Scalability
The cloud nature of microservices and the virtualization underlying them have scalability as their main advantage. Each service performs a specific function, all services are relatively small — these architectural characteristics make scaling simpler and less painful.
When to Use Microservice Architecture
Microservice architecture is particularly relevant for companies providing online services to a large number of users simultaneously. Such services include large online stores, streaming platforms, and social networks.
For these services, the ability to independently scale different system components is crucial. For example, during sales, the load on the order processing service increases significantly, while the other services operate in normal mode. Microservices allow flexible scaling of computational power and bandwidth specifically for the order processing service without affecting other subsystems.
For online services with a large audience, fault tolerance is also critical — if a particular service fails, the rest of the application should continue to operate normally. The separation into independent microservices ensures such isolation of failures.
Moreover, microservices are convenient for large distributed development teams — each team can work on its own service, which simplifies coordination and speeds up the release process.
At the same time, microservices may be an excessive solution for small projects or internal company systems. In such cases, it is preferable to use monolithic architecture due to its greater simplicity and lower cost in development and maintenance.
Examples of Using Microservice Architecture
Amazon
One of the first companies to start applying microservices. The entire Amazon infrastructure is built from hundreds of independent services — for the product catalog, user accounts, search, recommendations, and so on. This allows Amazon to easily scale resources under increasing loads and quickly launch new products thanks to microservice development.
Netflix
The streaming service Netflix is divided into more than 800 microservices. They handle video transcoding, recommendations, A/B testing interfaces, and other tasks. The flexibility of microservices allows Netflix to quickly expand its server fleet during traffic surges and experiment with UI/UX without risking the system.
Uber
The company uses hundreds of microservices — for geolocation, mapping, payment processing, logistics, and much more. This ensures system reliability and fault tolerance under enormous loads and allows Uber to quickly scale and enter new markets.
Conclusions
Microservices are less suitable for use as the architecture for developing corporate information systems. In such a case, we get an excessively complex system in terms of operation and maintenance. The increase in operational costs will not be compensated by the advantages of using microservice architecture, as they will not fully manifest within one, even large, organization.
The primary area of effective microservice application is large-scale internet services operating in real-time for a large number of users.
