Top Microservices Interview Questions and Answers

In this article, we are going to cover top microservices interview questions with descriptions. These interview questions will help you to prepare for the interview from basic to advance level and these questions will also help you to enhance your technical skills.

Microservices Interview Questions

1- Explain Microservices Architecture

Microservices architecture is an architectural development style that is used to build an application as a collection of narrowly focused services developed for a business domain.

Note:- Build Microservices using Asp Net Core 5

2- what is a monolithic architecture?

Monolith architecture is an architectural development style in which all the software components of an application are clubbed within a single autonomous unit.

3- What are the advantages of microservices?

There are some advantages of using microservices:

• It is very easy to build and maintain.
• Smaller and faster deployment.
• Technology diversity. It means it is very easy to use different technologies.
• Independent deployment.
• Ease of understanding.
• It helps to divide an application into smaller parts.

4- What are the Disadvantages of Microservices?

There are below some disadvantages of Microservices:

• Communication between services is very complex. In case if your application consists of hundreds or thousands of microservices, then the application becomes really complex. Especially when the services talk to each other.
• More resources are needed to use multiple services.
• Debugging is harder.
• Testing is harder.
• Cascading of problems to other services.
• Handling the messages in the queue is very hard.
• Latency: every call to another service adds some latency and the user has to wait longer until the result comes.
• Separate deployment of each service.

5- What are the main differences between microservices and monolithic architecture

There are below differences between microservices architecture vs monolithic architecture.

Microservices Architecture	Monolith Architecture
In microservices architecture, we build an application as a collection of narrowly focused services developed for a business domain	All the software components of an application are clubbed within a single autonomous unit.
It is very easy to scale up and down based on demand.	It is not easy to scale up and down based on demand.
Each Microservice has its own database.	It has a shared database.
A failure of one service doesn’t affect the other services.	One failure may cause the whole system to go down.
Smaller and faster deployment. Each service can be deployed individually.	You need to Deploy an entire system once.
You can use different technologies to build different services for different business needs. Because every service or module is independent from other services or modules.	Impossible to implement different technologies or programming languages. Because everything is tightly coupled.
Communication between services is very complex. In case if your application consists of hundreds or thousands of microservices, then the application becomes really complex. Especially when the services talk to each other.	Secure data processing and transferring is easier at the system level.
You need to test each service individually.	Test is very easy.

6: What are the challenges faced while using microservices?

• Microservices depend on each other. So, communication between services is challenging. Because if your application consists of hundreds or thousands of microservices, then the application becomes really complex.
• Individually testing each service is a complex task. 
• You need to deploy each service individually. So, the deployment of multiple services is very complicated.
• Cascading of problems to other services.
• Handling of the messages in the queue is very hard

7: When to go with microservice architecture?

• If you want to build a large-scale application then you must go to Microservices architecture.
• If you want to use different technologies or programming languages in your solution then you must go to microservices architecture.
• If you want to build multiple independent teams that would work on different functions of your solution then you must go to microservices architecture.

8:What are the key differences between SOA and Microservices architecture?

There are some differences between SOA (Service Oriented Architecture) and Microservices Architecture.

SOA vs Microservices

9- What are the characteristics of microservices?

There are some below characteristics of microservices:

• It is responsible for a single capability.
• It is individually deployable.
• It consists of one or more processes.
• It owns its own data store.
• It is replaceable.
• A small team can maintain a handful of Microservices.

10- What are the three broad categories of tests in Microservices.

There are below three broad categories of tests in microservices.

• System Test (Top-level test): In this category, tests that span the complete system of microservices and are usually implemented through the GUI.
• Service Test (Middle-level test): In this category, we perform tests against one, but only one, complete microservice.
• Unit Test (Bottom level test): In this category, we test one small piece of functionality in a microservice. 

11- What is end-to-end Microservices testing?

In this end-to-end testing, we validate every process of the workflow and ensure that the system works together as a whole, and validate all the requirements.

12- How independent microservices communicate with each other?

It totally depends on the needs of the project. So, microservices communicate with each other using well-known communication styles like single-receiver communication with synchronous HTTP/HTTPS protocols or they can use messaging protocols for asynchronous communication.

13- What is the use of PACT in Microservices architecture?

PACT is an open-source tool that allows us to test interactions between service providers and consumers in isolation against a contract. It is an automated suite to test this interaction that increases the reliability of microservices integration.

14- Why do we use containers for Microservices ?

Containers are the easiest alternative to manage a microservices architecture based application. It helps us to deploy individually. E.g. Docker is a container and it helps us to encapsulate the microservice in the image without any additional dependencies or efforts.  

15- What is semantic monitoring in microservices architecture?

Semantic monitoring combines automated tests with monitoring of the entire application. It helps us to find out the factors which are more profitable to our business.

16- What are reactive extensions in Microservices?

Reactive Extensions is a design pattern in which we collect the results by calling the multiple services and then compile a combined response. It is also known as Rx. It works opposite to legacy flows and is very popular in distributed systems. 

17- What is a client certificate?

The client certificate is a digital certificate that is usually used by client systems for making an authenticated request by a remote server.

18- What is a CDC?

CDC (Consumer-Driven Contract) is a pattern for developing microservices so that external systems can use them.

19- What is a spring cloud?

Spring Cloud is an integration software that provides integration with external systems. In the microservices framework, it allows building applications that perform finite amounts of data processing.

20- What is a RESTFul?

REST (Representational State Transfer)/REST is an architectural style for providing standards between computer systems on the web and making it easier for systems to communicate with each other. So, using these web services, microservices are easier to understand and implement.