Microservices Interview Questions For 15 Years Experience

Why Do People Hesitate In Using Microservices

I have seen many of us fumble over this question. After all, we are appearing for microservices interview question to be hired as a Microservices architect, so acknowledging cons could always be a little tricky. Here is the answer:

• Requires heavy investment Microservices demand a great deal of collaboration. Since your teams are working independently, they should be able to synchronize well at all times.
• Heavy architecture set up The system is distributed, the architecture is heavily involved.
• Excessive planning for handling operations overhead You need to be ready for operations overhead if you are planning to use Microservices architecture.
• Autonomous staff selection Skilled professionals are needed who can support microservices that are distributed heterogeneously.

What Is Auto Configuration In Spring Boot

AutoConfiguration is a process by which Spring Boot automatically configures all the infrastructural beans. It declares the built-in beans/objects of the spring specific module such as JPA, spring security and so on based on the dependencies present in your applications class path.

For example: If we make use of Spring JDBC, the spring boot autoconfiguration feature automatically registers the DataSource and JDBCTemplete bean.This entire process of automatically declaring the framework specific bean without the need of writing the xml code or java config code explicity is called Autoconfiguration which is done by springBoot with the help of an annotation called @EnableAutoconfiguration alternatively @SpringBootApplication.

How To Handle 404 Error In Spring Boot

Consider a scenario, where there are no stockDetails in the DB and still, whenever you hit the GET method you get 200 even though the resource is not found which is not expected. Instead of 200, you should get 404 error.So to handle this, you need to create an exception, in the above scenario StockNotFoundException.

GetMapping  public Stock retriveStock    

Now, create a Constructor from Superclass.

Right-click on the file -> Go to Source -> And generate constuctors from superclass-> and check the RuntimeException-> and generate.

And add an annotation called @ResponseStatus which will give you 404 error.

package com.greatlearning   import org.springframework.http.HttpStatus import org.springframework.web.bind.annotation.ResponseStatus   @ResponseStatuspublic class StockNotFoundException extends RuntimeException     }  

Now, you can hit the same URL again and there you go, you get a 404 error when a resource is not found.

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What Are The Challenges That One Has To Face While Using Microservices

The challenges that one has to face while using microservices can be both functional and technical as given below: Functional Challenges:

• Require excessive planning to handle or manage operations overhead.

Technical Challenges:

• Microservices are always interdependent. Therefore, they must communicate with each other.
• It is a heavily involved model because it is a distributed system.
• You need to be prepared for operations overhead if you are using Microservice architecture.
• To support heterogeneously distributed microservices, you need skilled professionals.
• It is difficult to automate because of the number of smaller components. For that reason, each component must be built, deployed, and monitored separately.
• It is difficult to manage configurations across different environments for all components.
• Challenges associated with deployment, debugging, and testing.

What Are The Three Types Of Tests Used In Microservices

We can categorize the tests used in Microservice architecture into three main categories:

• Bottom Level Test: The bottom-level tests perform general tests such as performance tests and unit tests. These kinds of tests are entirely automated.
• Middle-Level Tests: The middle-level tests are used to perform exploratory tests such as the stress test and usability test.
• Top Level Tests: The top-level tests are used to conduct acceptance tests, mostly fewer in numbers. These types of tests make stakeholders know about different software features.

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What Is The Easiest Way To Deploy A Spring Boot Application In Production What Other Options Are There

The simplest way to deploy your Spring Boot application is as a .jar file with an embedded servlet container, to any server or platform that has a JRE installed. For organizational and historical reasons, you can also deploy your Spring Boot application as a .war file, into an existing servlet container or application server.

Last but not least, you can, of course, also put your .jar file into a Docker image and even deploy those with Kubernetes.

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Mention The Different Issues Handled By The Spring Cloud

The spring cloud is an important system in the Microservices architecture because it can handle several issues such as load balancing, service delivery, redundancy, and performance issues. In handling service delivery issues, it allows processes and services to communicate and locate one another easily. It attempts to solve all the operational overheads that may affect performance on performance issues.

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What Is Canary Releasing

Hiring managers often ask questions that require specific knowledge, problem-solving application and clear communication. Asking about a specific process or procedure like Canary Testing requires that you use a variety of skills to explain yourself.

Example:”Canary Testing is a common process used by microservices developers to implement new software or updated software without the risk of a large-scale problem. When Canary Testing, new or updated software is provided to a small group of users as a test. Once it’s clear that the software is working well, the developers release it to all users.”

What Are The Main Features Of Microservices

Microservices have various features that help DevOps teams in their software development cycles. They include decoupling, which helps in easy construction, alteration, and scalability of applications team autonomy which empowers every developer to work independently of the other continuous delivery that allows systematic software development through automation agility, thus allowing the expeditious creation and elimination of features and decentralized governance that allows developers to pick the best tools to solve different problems. Microservices are also quite simple and only focus on a singular service. Lastly, they have a feature, which means that the independent components can be easily upgraded and exchanged.

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What Is The Use Of Containers In Microservices

Containers are the easiest and effective method to manage microservice-based applications. They are like a software development platform. They also help us to develop and deploy individually. A Docker is an example of a container. It is an open-source software development platform that allows us to encapsulate our microservice in a container image along with its dependencies. Microservice can use these elements without additional efforts.

Q8 How To Tell An Auto

To instruct an auto-configuration class to back off when a bean already exists, we can use the @ConditionalOnMissingBean annotation.

The most noticeable attributes of this annotation are:

• value the types of beans to be checked
• name the names of beans to be checked

When placed on a method adorned with @Bean, the target type defaults to the methods return type:

@Configurationpublic class CustomConfiguration }

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How To Nail Your Next Tech Interview

Microservices are a key concept discussed in technical interviews for software engineers. Java Microservices interview questions are typically asked of experienced software engineers during coding and design interviews. In this article, we’ll look at frequently asked Java Microservices interview questions for fresher and experienced developers to help you ace your tech interview.

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Letâs look at some popular Java Microservices interview questions that frequently feature in technical interviews.

Q20 What Are The Advantages Of Microservices

There are various advantages of using Microservices. They are as follows:

• The tiny base of code is quite easy to maintain
• It is quite easy to scale as it has only an individual component
• It also supports the phenomenon of independent implementation
• It drastically reduces the installation time
• It renders good support for the parallel and the support teams
• Another main advantage of this Microservices is in the form of the fact that it has the ability to facilitate technological diversity

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Mention The Advantages Of Spring Boot

Advantages of Spring Boot

What Are The Advantages Of Microservices

Here, are some significant advantages of using Microservices:

• Technology diversity, e., Microservices can mix easily with other frameworks, libraries, and databases
• Fault isolation, e., a process failure should not bring the whole system down.
• Greater support for smaller and parallel team
• Independent deployment
• Deployment time reduce

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You Have Mentioned That There Is A High Level Of Interdependence In Microservices How Do These Services Communicate With One Another

Microservices constantly communicate through three main ways: web sockets used for streaming, broker or server programs that utilize technical routing algorithms, and HTTP/ REST with JSON. They can also perform the request-response operation via a binary protocol. Other proven means include backend as a service that will automate the entire backend. Additionally, one can use RabbitMQ as a message blocker.

Questions 1: How Do You Avoid Deadlock In Java

If you know, a deadlock occurs when two threads try to access two resources which are held by each other, but to that happen the following four conditions need to match:

You can avoid deadlock by breaking the circular wait condition. To do that, you can make arrangements in the code to impose the ordering on the acquisition and release of locks.

If lock were acquired in a logical order and released in just opposite order, there would not be a situation where one thread is holding a lock that is received by others and vice-versa.

You can further see my post, how to avoid deadlock in Java for the code example, and a more detailed explanation.

I also recommend, Applying Concurrency and Multi-threading to Common Java Patterns By José Paumard on Pluralsight for a better understanding of concurrency patterns for Java developers.

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Is Rest Scalable And/or Interoperable

Yes, REST is scalable and interoperable. It doesnt mandate a specific choice of technology either at the client or server end. You can use Java, C++, Python, or JavaScript to create RESTful web services and consume them at the client end. I suggest you read a good book on REST API, like RESTful Web Services to learn more about REST.

Define Domain Driven Design

The main focus is on the core domain logic. Complex designs are detected based on the domains model. Involves collaboration with domain experts constantly to resolve issues related to the domain and improve the model of the application. While answering this microservices interview question, you will also need to mention the core fundamentals of DDD. They are

• DDD focuses mostly on domain logic and the domain itself.
• Complex designs are completely based on the domains model.
• To improve the design of the model and fix any emerging issues, DDD constantly works in collaboration with domain experts.

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Q9 What Are The Key Differences Between Soa And Microservices Architecture

The key differences between SOA and microservices are as follows:

There Are Three Main Types Of Tests Used In Microservices Mention Them

Microservices testing is a complicated but important aspect, given the interdependence of these services. Tests are generally grouped depending on their level. At the top of the pyramid, we have system tests, integration tests, and unit tests. The unit tests at the bottom of the pyramid deal with technology-related components and issues. It is similar to performance testing, which is all automated processes.

The middle-level or integration tests consist of exploratory tests such as usability tests. In contrast, the top-level tests at the top of the pyramid consist of a small collection of acceptance tests. They are used to understand and verify software features by developers.

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Interview Questions With Sample Answers

It’s often helpful to understand why a hiring manager might ask specific questions when preparing for an interview. Review these few common microservices interview questions with explanations and answers to more deeply understand how to best prepare for your next interview:

• What is microservices architecture?

• What are the features of microservices architecture?

• What’s the difference between monolithic architecture and microservices architecture?

• Explain what Canary Releasing is.

• What does end-to-end testing do in microservices?

Is It A Good Idea To Share A Common Database Across Multiple Microservices

In a microservices architecture, each microservice shall own its private data which can only be accessed by the outside world through owning service. If we start sharing microserviceâs private datastore with other services, then we will violate the principle of Bounded Context.

Practically we have three approaches –

Microservices Architecture can become cumbersome & unmanageable if not done properly. There are best practices that help design a resilient & highly scalable system. The most important ones are

• Partition correctly

Get to know the domain of your business, that’s very very important. Only then you will be able to define the bounded context and partition your microservice correctly based on business capabilities.

• DevOps culture

• Design for stateless operations

• Design for failures

• Design for versioning

• Design for eventual consistency

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How To Fetch Data From Database In Spring Boot

You can use the following steps to connect your application with MySQL database.1. First create a database in MySQL with create DATABASE student 2. Now, create a table inside this DB:CREATE TABLE student) 3. Create a SpringBoot application and add JDBC, MySQL and web dependencies.4. In application.properties, you need to configure the database.

spring.datasource.url=jdbc:mysql://localhost:3306/studentDetailsspring.datasource.username=system123 spring.datasource.password=system123 spring.jpa.hibernate.ddl-auto=create-drop 

5. In your controller class, you need to handle the requests.

package com.student import org.springframework.web.bind.annotation.RequestMapping import org.springframework.beans.factory.annotation.Autowired import org.springframework.jdbc.core.JdbcTemplate import org.springframework.web.bind.annotation.RestController @RestControllerpublic class JdbcController }

6. Run the application and check the entry in your Database.

Q23 What Are Different Types Of Tests For Microservices

While working with microservices, testing becomes quite complex as there are multiple microservices working together. So, tests are divided into different levels.

• At the bottom level, we have technology-facing tests like- unit tests and performance tests. These are completely automated.
• At the middle level, we have tests for exploratory testing like the stress tests and usability tests.
• At the top level, we have acceptance tests that are few in number. These acceptance tests help stakeholders in understanding and verifying software features.

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What Does Coupling Mean In Microservice Architecture

This is a relatively specific question about microservices, but you may have experience in coupled modules from other software architect methods. You may likely receive this question because coupling is typically an essential aspect of microservices. There are usually three variations or coupling states, which are highly coupled, loosely coupled and uncoupled. In a microservice architecture, loosely coupled modules are typically the most prominent. It may be a good idea to focus your answer on loose coupling.

Example answer:’Coupling generally refers to the level of dependency between software modules. Modules may either be highly dependent, slightly dependent or independent. In a microservice architecture, the most prominent form of coupling is loose coupling, which involves slightly dependent modules. In a loosely coupled application, individual software modules only depend on other modules through interface functions rather than actual software objects. This means a development team can change, improve and remove an individual software module without deploying or affecting every module in the application.’

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