10 Microservices Design Principles That Every Developer Should Know

Ever wondered, how big applications like Amazon, Netflix, etc. never face any major faults and are always up and running? Is it possible for such big and complex pieces of code to always be error and exceptions free? Well, that’s very hard to believe, right? But the answer is NO. They do face faults but are always running and serving millions of users without the services getting down. And that’s where Microservices come to play.

In this article, we’ll be going through the microservices design principles that every developer should follow in order to run an application efficiently. So, before that let’s understand what are microservices.

What are Microservices?

When a large application is broken down into a number of small, independent services that can communicate with each other over a network, this approach is known as Microservices. These services can each be created, deployed, and scaled independently. Each microservice carries out a particular business activity and interacts with other microservices via clear APIs.

This is why even if a piece of code fails, only that particular microservice gets affected making no major change to the whole application and that is how applications like Amazon and Netflix continue to serve their customers uninterruptedly.

Microservices can be developed in any programming language. They communicate with each other using language-neutral Application Programming Interfaces (APIs) such as Representational State Transfer (REST). 

For developing an optimal microservice architecture, you need to follow some design principles.

Microservices Design Principles

1. Independent and Autonomous/Self-governing services
2. API aggregation 
3. Flexibility
4. Scalability
5. Constant monitoring
6. Failure Isolation/ Failure resilience
7. Realtime Load balancing
8. Inclusion of DevOps
9. Versioning
10. Availability

Let’s take a deeper dive.

1. Independent and Autonomous/Self-Governing Services

Every microservice should be self-contained and should operate independently of all the other services in an application. Each service should have its resources to run including separate databases and business logic without relying on other services to perform any of its functions.

The main reason behind this principle is to ensure that each service can be developed, tested, as well as deployed independently without affecting the other part of the system. This also follows the idea of Decentralization which refers to the idea of not giving control to any central unit/ service, instead, each service should be responsible for its actions as well as should have the liberty to act independently.

Let us consider Amazon’s system, so in this system, each microservice would have its specific business function – product catalog, final cart, payment portal, etc. and every function would have its database as well as its performing logic without depending upon other services. Eventually, this will help in the scalability, resiliency, and maintainability of each microservice.

2. API Aggregation 

A developer should be able to design microservices in such a manner that they can communicate throughout the system with other microservices without having a programming language barrier. Most of the time different microservices belonging to the same system may be written in different programming languages but as the intercommunication among the microservices is important this is achieved with the help of API aggregation using different architectural approaches such as REST.

This principle emphasizes the use of well-defined and consistent APIs to enable communication between different microservices in the system.

Suppose the frontend part of Amazon is written in a particular language and its backend server is written in a different language then, To communicate between themselves, APIs are needed which help in fetching and sending, requests and responses.

3. Flexibility

The ability of a microservice to change or be changed easily according to the circumstances or the need of the time is referred to as the flexibility of a microservice. Assuming you added a feature that was criticized and was not successful, now that it needed to be taken out of the service, this can be done easily when you have made a flexible microservice. This principle makes your project more adaptable to possible future changes.

4. Scalability

It is a design principle that enables your application to get modified according to the increasing or decreasing traffic, data, and complexity without affecting the performance of the system.

Assume the festive season is going on and there is a high demand for supply due to which the level of traffic on the application drastically increases. At that time scalability plays its role by modifying the capacities of all the microservices needed such as databases, servers, etc. to serve the increasing traffic with high performance.

There are several ways to achieve scalabilities such as Service partitioning, Load balancing, Horizontal scaling, and Caching.

5. Constant monitoring

When numerous microservices are working in synchronization to successfully run an application there is a high possibility of faults occurring throughout the system. As the architecture becomes more complex, it becomes a tedious task to find and resolve these issues. To avoid this, constant monitoring is required so that the faults can be resolved at the earliest and your application can run smoothly.

Constant monitoring can be achieved by using these methods-

• Logging and metrics
• Distributed tracing
• Health checks 
• Alerting and notifications

6. Failure Isolation/ Failure Resilience

As a developer, you should always be prepared to encounter failures in your application, and to minimize these failures you should include fault-tolerant approaches during the designing of microservices. This principle helps to minimize the impact of failures on the whole system due to the failure of a particular system.

There are several techniques to make your application fault tolerant:

• Include Redundancy in order to have multiple instances present at the time of failure.
• Separation of Services in order to be isolated in case of failures.
• The microservices should Gracefully Degrade instead of crashing the whole service. 
• Each microservice should have Circuit Breakers in order to detect and isolate the failures.

7. Realtime Load Balancing

Sometimes it may happen when a client sends the request to the server then the database has to retrieve the data from multiple microservices at the same time. At that point, the Load balancer comes into the picture and it defines how much amount of the Central Processing Unit or GPU is to be used for a particular service to fetch the data and finally how the client request should be passed.

This whole process needs to be done in “Real-time” so that the client does not need to wait for the results.

Suppose you are at the payment portal, purchasing something on Amazon. At that time Amazon application is fetching multiple data like UPI integration, CC database, etc. With the help of real-time load balancing it gets easier for the application to perform multiple actions in less time.

8. Inclusion of DevOps

First of all, you need to know what is DevOps. DevOps is a set of techniques applied that is used to provide continuous support in order to collaborate, communicate and automate the development and operation with the help of operations teams. The inclusion of DevOps in a project promotes communication and collaboration between different microservices that in the end improves the efficiency and effectiveness of the software development process. DevOps helps microservices to achieve greater speed, high flexibility, and agility.

DevOps inclusion can be done using several services such as Automated Testing, Continuous Delivery, and Development as well as Continuous Monitoring that leads to faster time-to-market and best-quality software. Docker and Kubernetes are two common DevOps tools used for managing microservices.

9. Versioning

Isn’t it shocking for you that the applications like Amazon, and Netflix are always up to date and compatible with the latest software updates of the devices? This is possible through Versioning. Versioning is a term used for updating to the latest versions of the services according to the latest tech stacks that are being used in present.

Versioning helps to manage changes in the services over time and update them to the latest ones. This results in minimizing the disruption to the existing clients using the services. The versioning process includes updating version numbers, service interface, request, and response through URL versioning and the same in Header Versioning.

10. Availability

When businesses are serving worldwide then there are no chances that can be taken with downtime. Every minute can be proved to serve big losses if the services are down, thus availability is a very important design principle which states that all the services should be developed in such a manner that the services are up and working 24×7 or if not possible, they can at least be available for the maximum amount of time.
Availability straightway means the presence of microservices 24×7.

Conclusion

These are the top 10 design principles a developer should keep in mind while designing any microservice. All the design principles revolve around how the best solution available all the time can be served to the end customers without any failure or major downtimes. Everything from communication among the microservices to serving the end product of the application to the customers is smoothly possible only because of the usage of the microservice architecture. By adopting these design principles and embracing a microservices architecture, organizations can build software systems that can adapt and thrive in today’s fast-paced, constantly changing business environment.

FAQs

1. What is meant by microservices?

The approach of breaking down a large application into a number of small independent pieces that can communicate with each other is known as Microservices.

2. What are the major types of microservices?

Overall Microservices can be divided into two main parts-

• Stateless Microservices
• Stateful Microservices

3. What is the best technology used for microservices?

Currently, Docker and Kubernetes are the two best technologies that are being used for implementing Microservices.

4. What is the best language used for microservices?

Most of the Microservice developers are using three programming languages:

• Java
• Javascript
• Python

5. Which is the best microservice?

Most of the time Spring Boot with Spring Cloud is used as one of the major Microservice.