Several months ago, we explored how advantageous it is to couple microservices with the cloud. However, that blog post looked at the topic from the cloud’s perspective, listing the benefits a cloud environment can gain by leveraging microservices.
Now, we’ll delve deeper into microservices by comparing it to the monolithic architecture and determining whether it’s worth switching over to— even in a scenario where an organization is heavily entrenched in a monolith and is generally satisfied with it.
Monolithic vs. Microservices
Let’s see some basic definitions, followed by the listing of pros and cons for each architecture!
Monolithic
In the case of monolithic applications, they work with a single executable unit for the entire application. Thus, the whole application is packaged into one WAR or EAR file.
In the case of enterprise-level applications, it uses several components for different processes and purposes, meaning that each component could have connections with other components. When it comes to integrating components during the development of a monolithic application, we’ll have an easy time. However, adding bug fixing and requirement changes to the equation and changing the app becomes tricky.
Advantages when compared to Microservices
- Easy development process and simple integration testing thanks to the connected nature of each component.
- Seeing the exact dependencies and paths of component relationships makes monitoring easy.
Disadvantages when compared to Microservices
- Knowing the entire application with all its dependencies is virtually impossible.
- Even small changes are difficult to pull off.
- Exceptionally complex deployment; packaging of each component, application, and dependency must be done correctly, or the deployment will not succeed.
- The app is fully offline throughout the deployment.
- Due to the application’s highly connected and complex nature, frequent updates are neither feasible nor possible—delayed updates are common because of component dependencies.
- Much less scalable and reusable than a microservices architecture.
Microservices
Microservice architecture organizes an application as a collection of loosely coupled, independent services that follow a single responsibility principle. Although these services run as separate processes, their output is used as an input in a system of independent, communicating services.
The communication occurs through mechanisms, such as a container (e.g., HTTP resource API). In contrast to the monolithic, where the entire app is deployed, managed, scaled, and maintained in one package, microservices slices functions of an extensive application into smaller, manageable chunks that are managed independently during deployment and maintenance. Additionally, microservices applications can also be scaled much more quickly.
Advantages when compared to Monolithic
- Easy understanding of the codebase of components.
- Simple scalability: add, delete, and update functional units without affecting other parts of the application.
- The addition of features, maintenance, and bug fixes is much simpler than the monolithic architecture (dependent vs. independent components).
- Continuous delivery: with a microservice architecture, you can quickly update your software, meaning simplified troubleshooting and no downtime for users.
- High availability: microservices systems are dependable enough to operate continuously without failure—they are well-tested and sometimes equipped with redundant components.
- Fault Tolerance / Resilience: thanks to its decentralized, decoupled nature, service failure in a single container or workload won’t spiral out of control and compromise the others.
- Better support for hybrid technology stacks: microservices within a cluster can communicate with one another regardless of the language or technology used to build the specific services.
- Faster time to market: The easy addition and removal of components make development happen quickly without disrupting other resources.
Disadvantages when compared to Monolithic.
- More difficult component dependency management.
- The overview of the application is more complex, harder to track.
- Debugging is more complicated.
- More complicated integration testing: requires testing each API along the chain.
- More expensive*
* Sufficient hosting architecture with advanced security and maintenance support is needed to manage a microservices application properly. In addition, ensuring high availability across multiple services can lead to steeper prices.
What to Watch Out for in a Microservices Architecture?
Although its number of advantages over monolithic architecture outweighs those that monolithic has over microservices, there are still some common issues within a microservices architecture that must be considered at all times—and then swiftly overcome.
Avoidance of hardcoded values
Services usually contain configuration values, such as service names, hostnames, IP addresses, URLs, etc.; however, these can be changed at virtually any time. Therefore, when a service depends on another service and a configuration value is changed, it will generate redundant modifications and deployment in the first service. A service discovery tool is needed to circumvent this issue.
Versioning services
Due to the independent nature of microservices, an update to one service means that only that single service was updated. Therefore, it won’t spread over to the rest, leading to cases where services X and Z are at version 2.0, but service Y is still at 1.0. In this case, a suitable versioning mechanism (e.g., semantic versioning) is highly recommended.
Domain-driven design
If you don’t want to cause unnecessary headaches for yourself, a new application developed in a microservices architecture should be a fresh domain-driven design, where the domains are independent.
However, suppose a project that exists in a monolithic architecture must be migrated to a microservices one. In that case, the first step needs to be selecting domain-specific services and design, which can then be separated from the main project.
Fault Tolerance
Multiple services mean more possibilities for failures. If one service is about to fail and is not responding, that service must be made to fall quickly. Why? Because other services are trying to communicate with the failing service, many queries will form behind it. For an efficient fault tolerance mechanism, consider using the circuit-breaker pattern.
Our Verdict
There’s no doubt that the microservices architecture is the standard for today’s large-scale application architecture, with features such as loose coupling, lightweight services, distributed computing, and maintainable/testable code.
However, it’s still not mandatory for anyone to develop modern applications using the microservices architecture—and they will not fall behind their peers as a result.
There are quite a few scenarios where a monolith could provide better solutions and UX, while microservices would make both development and use overcomplicated for developer and user alike. Additionally, for enterprise clients who are already hosting their services as a monolith but are considering a complete migration to a microservices infrastructure, the initial investments of securing new resources and recruiting competent, microservices-savvy developers and DevOps engineers can be pretty pricey.
Microservices is an excellent solution for companies that need to service many thousands, maybe millions of customers simultaneously. Its ability for easy, flexible scaling, resilience, and availability makes it an incredibly versatile tool. But developers must be ready to fully understand and cope with the scope, timeline, and complexity of building applications in a microservices architecture. And then, management must be willing to invest in the needed resources to make it work.
How To Measure Readiness for Microservices?
Whether it’s an internal discussion about migration from a monolith to microservices, or you and a client discussing implementing a microservices architecture—or developing apps within it—, make sure you go through each of the questions below before committing to such. Going into any microservices-related project unprepared can lead to vast amounts of wasted money and time.
- Does the development timeline support the time needed to securely architect, build, and configure a complete microservices architecture?
- Is the budget for architecture, development, DevOps, maintenance, and management sufficient to finance the entire lifecycle of the application?
- How many users does the application need to service at once?
- Are these users invested in microservice topics like latency, scalability, availability, and improved security? Or would they be content and able to get by with a traditional? Monolithic architecture?
- What is the level of maturity of the dev and DevOps teams? Can they deploy, maintain, and scale multiple complex services continuously over the project lifecycle?
- Is it possible to organize dev teams into smaller teams that individually manage each microservice? Can they make the microservices synergize through direct lines of communication and improved operational flexibility?
If most of the answers are affirmative, the organization is ready to work with microservices and develop applications. However, if the application to be developed is enormous, complex, and needs direct control to service large numbers of users, microservices are the optimal solution that will yield the best results.
If it’s smaller and more compact, the monolithic architecture will be just as fine.
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