Microservices architecture is a hot topic today and a common trend for many companies. It is driven by modern market influences and demands: flexibility, agility, scalability, a quick reaction to changes and customer-centricity. In this article, we will talk about the microservices architecture vs. monolithic architecture, compare their main features, advantages and disadvantages for software development. This will help you make a decision on which structure to choose for your enterprise.
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What is a monolithic architecture? Or, to be more precise, what is a monolith in the IT industry?
Monolithic architecture is a software development pattern in which an application is created with a single codebase, a single build system, a single executable binary and multiple modules for business or technical features. Its components work together, share the same memory space and resources. From the definition of monolithic, it follows that a monolithic application is a cohesive unit of code.
This approach has been used for years to develop enterprise apps, as the industry was focused on desktop devices with browsers that didn’t require application platform interfaces (APIs).
- The code for the whole system is stored in one database. Although the code may be divided into classes and packages and have a good structure, it is not split into modules for separate compilation, and functions as an isolated unit.
- The code, as soon as it is ready for release, is shipped in a single version to all nodes at the same time. To perform the allocation in a monolithic paradigm, it is often necessary to stop the whole system, roll out the software and then restart it.
- Components within an application can easily communicate with each other by using internal procedures.
- An application gets bigger in size with every iteration, becoming more difficult to manage and taking longer to start up.
- Scaling of one component requires the entire application scaling, as it is an integration of small parts that can’t function independently.
Almost any big and successful app we use today was started as a monolith since this architecture works well at the initial stage of the project. Let’s define monolithic benefits.
- Simple development. Monolithic architecture is well-known to any developer, as it’s a typical way the programs have been built for many years. The monolithic development process is easy to understand. You can take almost any existing tool, server, interface, framework or script, and it will be compatible with a monolithic app.
- Simple deployment. To deploy the packaged application, you just need to copy a single archive to one definite directory (to a server). The process is quite straightforward, though the time may vary.
- Simple testing. The application is deployed at once, therefore all the features are available as soon as it’s launched. Thus, it can be tested simultaneously, and there’s no need to wait for additional dependencies to begin testing, which greatly simplifies the process.
- Simple sharing. Since the code is stored in one base, it can be easily shared across all the stages of the development pipeline.
- IDE-friendly. Different development environments can be set up for monoliths, as they are typically designed for them.
In general, the advantages of monolithic architecture imply simplicity in every aspect.
There are lots of websites with millions of visitors that were built as one large monolith. Some of them will probably continue working in this mode for a couple of years, but most of the companies are striving to split up their products into microservices. This is happening because of some significant disadvantages of the monolithic applications. The difficulties become particularly noticeable when the service and the team expand.
- Difficult to understand and change. In the course of time, the solution is developing, the application scope is increasing and the overall structure becomes blurred. When the entire code looks like a lump of mud, it’s hard to discern some features, dependencies, or side-effects, especially for new developers that join the team. It’s also a challenge to make changes properly and quickly in a large and complicated app in which everything is tightly coupled and mutually dependent.
- Limited agility. Every small change requires full redeployment of the entire application, even if only one piece of functionality needs to be updated. It means that all the developers have to wait in order to see the impact of a tiny change. This is a great obstacle when multiple teams are working on the project. The team agility and the frequency of new deliveries are reduced.
- Barrier to new technologies. Adoption of a new technology may turn into a nightmare for a company, as it will affect the entire system, take a long time and cost too much. At the same time, an enterprise will definitely lose a position in the market without implementing new technologies.
- Barrier to continuous delivery/deployment/integration. Continuous delivery implies that software is incrementally developed and updated multiple times a day. In case of a monolith, it is almost an impossible task, as every change leads to the whole system redeployment. Today, a large company can’t be efficient enough and stay the course without CD implementation.
- Slowness. The large size of a codebase overloads IDE increases development time and slows down the start-up time.
- Poor reliability. One bug in the system can potentially stop the entire process, as all of the components are interconnected.
Lately, there has been a considerable paradigm shift from desktop to mobile devices. Today, customers want their service providers to be always on and available with the help of personal gadgets. This is why now it is time for mobile apps to flourish. Businesses need faster and more effective software delivery. Developers need to use API to expose data because legacy data exchange format is not compatible with the mobile applications. This is a driving force behind migration to microservices.
Microservices architecture is a collection of multiple loosely coupled services. It emerges from this definition that microservices vs. monolithic architecture represents a single large mobile application divided into a set of small, independent services deployed in personal archives. When brought together, they use standard lightweight communication and work as a cohesive solution.
Actually, the hype surrounding microservices is worth noticing, as this architectural model offers to build a loosely coupled infrastructure with the best user experience. Thus, it can be a great fit for some businesses. But keep in mind that a non-monolithic system is not suitable for every use case. To remain monolithic or to migrate — that is the question. You should know the requirements for adopting microservices in order to decide on the proper architecture for the system you are working on.
- The code of each microservice is stored in an isolated archive, runs its own memory space, and functions independently.
- Communication between services is a bit more complex since developers should use logic to connect them and deal with failures that sometimes occur.
- Multiple iterations don’t increase the application size.
- The scaling of one component is possible.
- A shared library can be used.
- Continuous delivery can be easily performed.
Microservices architecture is clearly organized. Decoupled units have their specific jobs, can be recomposed and reconfigured without affecting the whole structure. Advantages of microservices over monolithic systems are obvious.
- Variety. Developers are free to choose any programming languages. Multiple frameworks and technologies can be mixed within one service. It also enables rewriting some features using better tools, if necessary.
- Easy to understand and develop. Since the code base is small, an engineer can concentrate on one particular module and fully understand it. Thus, it is much easier to develop and maintain smaller services than a huge one.
- Scalability. Independent services can scale horizontally and vertically depending on their needs. Local changes can be easily deployed. In this case, they don’t impact the other stack, compared to a monolith.
- Reliability. A bug will only affect that small service in which it occurs, but will not bring down the entire application. This fact greatly enhances the reliability of the system and cybersecurity.
- Adoption of new technologies. Microservices allow you to easily adapt and take advantage of the latest emerging technologies.
- Flexible teams. Different microservices require different teams of developers, both in size and structure. Some services can be created by a couple of developers, others need the collaboration of a large group of various specialists. Company management is free to create mobile and versatile teams for better productivity.
In spite of all the positive aspects, microservices can’t solve all the software problems. They are certainly not so easy and some drawbacks exist.
- Difficult integration testing. Independent services within a microservices-based application may be tested in different environments. At the same time, testing the whole app can be more tedious compared to a monolithic app. The more modules there are, the more difficult it is to integrate services into one project and ensure its efficiency.
- Operational complexity. Management of multiple databases and transactions can be really cumbersome. The problem of operational complexity may be partially solved by the implementation of new configuration management tools (e.g. Docker, Ansible).
- Time-consuming. The development process of separate modules is much slower than a single code creation.
- Skill demands. A high level of expertise is a must while working with microservices. Each module requires its own team of specialists. Therefore, to achieve the goal of one project you should incorporate a multitude of professionals.
The initial cost of microservices is higher than in a monolithic architecture. Microservices require more complex and costly deployments, more difficult testing and maintenance. But using containers implies better hardware utilization and administrative simplification that results in reduced costs. They are also able to reduce technical debt.
Real Business Examples
Many global giants have moved their software to the cloud and adopted a modern microservices architecture. An American entertainment company Netflix is considered to be the pioneer in migration from a monolith to microservices. At that time, it was a risky move, but the company succeeded. Netflix paved the way and was later joined by Amazon, Google, IBM, LinkedIn, Nike, Nordstrom, Orbitz, PayPal, Spotify, Target, Twitter and many others.
However, the monolithic model is not fully dismissed yet. Many small companies are still using it and feel comfortable doing so. Moreover, some big players such as Etsy remain large monoliths. It is a great monolithic architecture example and it works! This proves that there are not only black and white solutions, but there’s a great variety of options.
Microservices is a modern trend, but it is not a solution that fits all cases. Switching to this model is challenging, painful but promising. Be careful while choosing the appropriate architecture for your business.
First of all, define the needs and the scale of your enterprise. Then compare monolithic vs. microservices considering the cons and pros of both options and decide when to use this or that one.
A traditional monolithic development approach relies on multiple teams each with its specific focus, e.g on databases, interfaces or server-based logic. Such a model is suitable for small applications that don’t require much logic, flexibility and independence.
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The microservices concept is client-based. It is most suitable when your service is quite large, and you work with big data and multiple cross-functional teams that have to perform different tasks and need real-time data processing.
In any case, if the software is based on proper engineering, it works well. SaM Solutions has experience in creating applications on the basis of both architectures. We can see significant advantages of dividing software into smaller pieces, adhere to the microservices model and help our customers succeed. Please contact our consulting experts for more information about our cloud-based software development and other solutions that can improve your business.