The software development landscape has been evolving rapidly over the last two decades. Digital transformation has fueled the progress of app development environments and made the process of building apps and developing various types of software much more efficient, scalable, and distributed.
During the legacy days, the applications were developed in an environment which we now refer to as monolithic. These monolithic apps are planned and designed in systems that encompass all the required process components and features in an all-in-one manner, with a goal to maximize the server capacity usage. Though many of the well-known apps we all use and love today were made within monolithic architectures, this type of framework is becoming outmoded due to a plethora of constraints that are intrinsic to this model.
This is where microservices come in with their container-based approach to deployment that solves a vast majority of issues monolithic architectures weren’t able to mitigate. The microservice-based system disassembles the architectural patterns of monolithic architecture and leverages modern technological solutions such as containerization, virtualization, and the cloud. Microservices basically break down a system into smaller components that are, due to their modularity and flexibility, much more suitable for fast-paced and business-focused software development environments.
The monolithic vs microservices battle is still an ongoing one, as both approaches have their own set of advantages and disadvantages. However, we are currently experiencing a paradigm-shifting trend whereby the global cloud microservices market is growing at a rate of 22.5% (27.4% in the US), with 61% of organizations stating they have used microservices for between 1 and 5 years. According to Linux.com, 90% of all applications will be developed using microservices architecture by 2022.
That said, let us delve deeper into the differences between these two models.
Monolithic vs Microservices: Monolithic Architecture Explained
Monolithic architecture is a traditional software development approach wherein the entire system functions as a single, autonomous, and indivisible unit, which is why it is analogous with a monolith – composed all in one piece, large, and unable to be changed or modified.
Monolithic apps are single-tiered software pieces where the user interface and data access code are coupled together into a single program from a single platform, with all functions being managed and served in one place. A monolithic app doesn’t depend on other computing applications, and its components don’t require API to communicate.
Advantages of Monolithic Apps
Developing monolithic apps using legacy systems is a very simple and straightforward process:
build → test → deploy → troubleshoot → scale
The benefits of using monolithic architecture to build applications include:
Easier Implementation – Monolithic architecture is a much less complex structure than microservices, which means it is easier to implement. It also features a simpler business logic implementation as its component orchestration is less convoluted.
No API – Monolithic apps do not involve API for the communication between components, which means they can have higher performance when compared to microservice apps.
Easier Automated Testing – Since it is a single unit, it is easier to perform automated testing and debugging as you can do it without taking into account different run-time environments.
Simple Deployment – You can do it simply by using a script that loads your module and launches the application.
Less Cross-cutting Issues – With a single application in place, you will have much fewer concerns with caching, logins, memory management, and allocation, etc.
Disadvantages of Monolithic Apps
The pitfalls of using monolithic architecture to build applications include:
Tight Coupling – Monolithic apps involve tightly coupled processes, which means that their codebase gets much more complex as the app grows. The services are much harder to isolate, therefore impeding independent scaling and code support.
Low Flexibility – Mutual dependency of elements and components is high. Any changes and updates that you perform require deployment and affect the whole network, which is why these processes are very time-consuming, costly, and need to be carefully coordinated.
Extremely Low Scalability – Monolithic apps are not impossible to scale, but the scaling process can only be done as a whole because the scaling of individual components is not possible.
The biggest issues and challenges with monolithic apps emerge when the app starts and continues to grow and evolve. Each new iteration causes the development process to go into the notorious “fear cycle.” The fear cycle is a state in which the app architecture ends up being too complex, with each new change causing unnecessary, time-consuming, and expensive side effects. This often leads to crashes and downtime (triggered by a single unstable component due to the tight coupling of app components) and involves the inevitable architectural erosion.
Monolithic vs Microservices: Microservice Architecture Explained
Microservice-based software development architecture involves business logic that divides the components into lightweight, single-purpose stand-alone units where each microservice is a self-sufficient component that encompasses its own code and data, with no dependencies on other components. Deployment is done within separate software containers that are managed by container orchestrators.
With this type of infrastructure that resembles collection modules, each microservice deals with and is responsible for a specific business goal, enabling the architecture to be broken down into multiple modules. The communication and interaction between these stand-alone components are being conducted through APIs, message queues or event stream processing.
The environment that is based on microservices allows each component to be deployed, upgraded, restarted, and scaled with no influence whatsoever on other microservices within the same app. This type of system automation enables frequent updates and changes to be made within live applications. There is no downtime, no issues caused to other components, and no impact on the end-user.
Advantages of Microservices Architecture
Autonomy – Microservice-based environment allows you to create independent and cross-functional teams for individual business goals, which means that the features each team deploys aren’t affecting other components and services.
Agility and Accessibility – You can use various storage technologies or languages for different functions. Microservice-based apps are also capable of functioning on any type of device, through both Cloud and legacy on-prem servers.
Scalability – Unlike it is the case with monolithic architectures where you have to scale the entire system, the containers let you change only one system component.
High Reliability – Due to high autonomy levels, an issue or a failure in one module will not cause other modules to malfunction.
Reusable Modules – Microservices offer an ecosystem of modules wherein each component can be reused and reprofiled for other purposes and tasks.
Simple Continuous Delivery – Teams can build and test specific system elements without causing disruption within the entire app.
Disadvantages of Microservices Architecture
Potential Challenges With the Distributed System Design – Building a microservice-based infrastructure involves creating the often complex network of connections within the distributed system, a process that can be quite challenging for certain teams and companies – especially if they try to do it themselves without any outside assistance.
Requires More Resources and Time (Initially)– Building the environment based on microservices may involve heftier budget spending and is typically a more time-consuming process when compared to monolithic infrastructures. However, as you scale up, the project requires less time and resources
Potentially More Cross-Cutting Issues – These types of concerns are more common with microservices as each service involves a great deal of logging, caching, and other similar elements that require tight management strategies.
Increased Operational Complexity – With the increased number of modules comes higher operational complexity and the deployment process becomes more convoluted when compared to monolithic architectures. This challenge ensues because the developers are required to manage numerous autonomous services, as well as take care of interactions and testing across all of them. This also includes testing.
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Monolithic vs Microservices: Direct Comparison
- Monolithic: you perform a one-off deployment of an entire system once and make adjustments as needed
- Microservices: you can deploy and rollback each microservice independently
- Microservices: you need to master the following: DevOps, Docker, Kubernetes, Lambda, etc
- Monolithic: your entire system can crash due to a single failure
- Microservices: a failure of one service doesn’t affect other services so your app won’t crash
- Monolithic: low, both horizontal and vertical
- Microservices: high, both horizontal and vertical
- Monolithic: you cannot implement new technologies, programming languages, etc
- Microservices: teams can use various new technologies and different languages for various business needs and goals
- Monolithic: all teams are involved in the development process at the same time
- Microservices: all teams are stand-alone units capable of developing different app elements
- Monolithic: initial – low, requires more resource spending as you add more instances
- Microservices: initial – high, requires fewer resources as you add more instances
- Monolithic: slow updates due to internal dependencies and other teams/developers working simultaneously
- Microservices: fast updates because each module/service is autonomous
- Monolithic: you can perform end-to-end testing
- Microservices: complex, you need to test each component individually
Time to Market
- Monolithic: due to internal dependencies and size of the architecture, monoliths are much harder to deploy, which results in suboptimal TTM
- Microservices: TTM is substantially increased due to seamless rollouts, continuous testing, and minimal internal dependencies
- Monolithic: as the number of team members and communication channels grows, so does the number of communication bottlenecks
- Microservices: reduced communication channels and bottlenecks (by a factor of 10 in some scenarios)
- Monolithic: data transfers and processing is easier
- Microservices: some security issues can occur due to the communication between services
When to go With a Monolithic Architecture?
Monolithic architectures should be considered when you are building a small app that doesn’t require team growth. Microservices account for a system that can be too complex to design and manage by small teams, which is often not optimal for developing small-scale apps.
If your project is still at the early stages of your Software Development Life Cycle, at the ideation phase for example, and your app has the potential to grow in later stages, you may consider opting for the monolithic model as it supports fast iterating.
Teams that are building an MVP (minimum viable product), should consider going with monolith infrastructures as it enables you to get first-user feedback very quickly.
When to go With Microservices?
In the monolithic vs microservices battle, the microservice-based architecture comes out as the winner for a vast number of big companies that face a significant increase in customer demand. Most modern companies (including Amazon, PayPal, Spotify, etc) are en masse switching to containers and microservices as it allows them to build a large-scale solution that is easily scalable and optimized in terms of resource usage and real-time demand.
This type of scalability is essential for the projects that see the growth of development teams, as well as operational departments, especially if the app and/or your workflow require the use of different languages for different elements, which is quite often the case with large-scale software projects.
Microservices are also extremely useful for the projects that require:
- multiple independent teams working on different app functions
- 24/7 reliability
- the ability to withstand big load peaks
- 10+ developers
- the ability to break down business domain into smaller ones
- operations that are short-lived or expressed as REST calls or queue events
- minimal or no specific or strict cross-service transactional requirements
The projects that are still fresh and at the early validation stages should perhaps start with a monolithic approach in order to develop a simple and lightweight solution. This will allow the team to build, change, deploy, and test their app much easier.
On the other hand, if you are building a complex app that is bound to evolve and grow, we recommend microservices as a much more suitable long-term solution. These cloud-native architectures enable streamlined workflow, high scalability, and much more effective management in terms of handling a multi-tiered system consisting of different functions and services. However, the complexity of these infrastructures could be overwhelming (and often counter-productive) for inexperienced teams, especially if tackled without adequate microservices expertise.