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Microservices Interview questions and answers aims to provide all the materials needed for interview; hopefully, this blog will be helpful for experienced and freshers.

Microservice architecture has become popular in software development, dividing monolithic applications into microservices.

These self-contained, responsive, loosely coupled components increase software design flexibility and scalability.

Microservices can be used to build more efficient and agile software systems, and thisblog will discuss Java microservices interview questions.

1. What is a microservice?

A software application built using a microservices architecture consists of multiple independent services that work together to perform a specific function.

2. What are some of the disadvantages of large and complex applications?

As the application size increases, it becomes difficult to understand and modify, leading to slow development and modularity breaking down over time.

Additionally, knowing how to implement changes correctly can be challenging, resulting in a decline in code quality.

3. What are some design patterns for creating applications using microservices?

Various design patterns for creating applications using microservices include the client-server pattern, the message-passing pattern, and the event-driven pattern.

4. What are some of the ways to secure microservices applications?

There are dfferent ways to secure microservices applications include authentication and authorisation, encryption, andcontainerisation.

5. What is monolithic architecture?

Monolithic architecture is a style of application design where the entire application is run as a single process or monolith, with all components and data tightly coupled.

6. What are the advantages of monolithic architecture?

It is famous for its scalability and reliability. each copy of an application instance has access to all data, making caching less effective and increasing memory consumption.

Different application components have additional resource requirements, making it challenging to scale each component independently.

7. What are the disadvantages of monolithic architecture?

Monolithic architecture has several disadvantages, including unsalability, unreliability, inflexibility, and a rigid design.

8. What are the main components of a microservice architecture?

The main components of a microservice architecture are management, service discovery, and A PI gateway, management is responsible for placing services on nodes, identifying failures, and rebalancing services across nodes.

Service discovery maintains a list of services and their nodes, enabling service lookup to find the endpoint for a service.

9. What are the three Maven projects that will be created to illustrate the concept of microservices?

The three Maven projects that will be created to illustrate microservices are the diagnosis, doctor, and patient microservices.

10. How does Microsoft’s architecture help businesses navigate the challenges of microservices?

Microsoft’s architecture presents various challenges, but understanding how to use these tools can help businesses navigate the challenges of microservices and improve their overall efficiency.

11. What are the challenges associated with Microsoft’s architecture?

The challenges associated with Microsoft’s architecture are acceptability, configuration management, debugging, consistency, and automation.

The architecture is characterised by numerous small components that must be deployed and maintained, making monitoring and identifying problems difficult.

12. How can configuration management be improved for Microsoft’s architecture?

To overcome configuration management challenges, great perceptibility around the components is essential. Centralised logging and dashboards can be helpful in debugging problems.

13. What are the challenges associated with debugging in Microsoft’s architecture?

Debugging is a significant challenge in Microsoft’s architecture because it becomes difficult to probe each service for errors.

14. What tools can maintain consistency in Microsoft’s architecture?

There is no decentralised governance around languages, platforms, technology, and tools for implementing or monitoring microservices, making maintaining consistency a significant challenge.

15. How can automation of components be improved in Microsoft’s architecture?

Building production-ready applications quickly becomes difficult due to the number of smaller components instead of a monolith.

Spring Boot offers a solution by enabling the creation of production-ready applications quickly and providing non-functional features.

16. What is the item catalogue application?

The item catalogue application is a Java file comprising several annotations, including the enable discovery client for registration in the eureka server, a spring boot application, and a main class responsible for item catalogue execution.

17. What does the entity class represent in the item catalogue application?

The entity class represents a table in a relational database, with each instance corresponding to a row in that table, the primary programming artefact of an entity is the entity class, which can also use helper classes.

18. What is the role of the repository, rest resource, and annotation in the item catalogue application?

The repository, rest resource, and annotation extend the item repository with a JPE repository and implement the command line runner interface, this interface is executed after the application context is loaded and before the spring application run method is completed.

19. How is the application built into the item catalogue application?

To build the application, clean it and run it using a maven build overhead type spring, hyphen boot colon run, and hit enter.

20. What are the details of the cloud properties file in the item catalogue application?

The cloud properties file includes the application name, non-secure port, metadata map to the instance, lease renewal interval in seconds, and default region registry fetch interval.

21. What is the role of each loop in generating key-value pairs in the item catalogue application?

Each loop generates key-value pairs overridden by the run method to print them.

22. What is monolithic architecture?

Monolithic architecture is a typical pattern used in large and complex applications, where all the application components are built as a single, integrated unit.

23. What are the problems with monolithic architecture?

Monolithic architecture can lead to slow development, unscalable components, and difficulty adopting new frameworks and languages.

It can also make it difficult to understand and modify the application as it grows, and the large code base can block continuous development and make it unreliable due to tightly coupled components.

24. What is microservices architecture?

Microservices architecture is a solution that breaks down an extensive application into more minor, independent services that communicate with each other.

Each service runs on a different Docker container and has its own load balancer and execution environment.

25. What is an example of a microservice architecture?

An example of a microservice architecture is an e-commerce website, where clients from different devices use services like search, build, configure, and other management capabilities.

These services are separated based on their domains and functionalities and allotted to individual microservices.

26. What is the role of an API gateway in microservice architecture?

An API gateway is a central entry point for all requests to the microservices, it connects all internal points to the complete system and simplifies microservices management by providing a single interface for clients to access all the services.

27. What are the benefits of using microservices architecture?

Microservices architecture offers a more efficient and flexible approach to managing large and complex applications.

It allows for more efficient management of resources, reduces the need for multiple instances, and provides a more relaxed and adaptable solution for managing applications.

28. What is Docker?

It is a software that allows users to create an image, essentially a template for a virtual machine, and then run instances of that image in a container.

29. What are Docker images?

Docker images are read-only templates used to create containers, and it maintains a vast repository of images called the Docker app.

30. How do youpull images from the Docker hub?

Users can click on Docker pull Ubuntu to pull images from the Docker hub, which will check the local system for available images and remove them from the Docker hub.

31. How do youaccess the Docker hub?

Users can create an account for free and log in with their username and password to access Docker Hub.

32. What is Docker’s runtime isolation?

Docker’s runtime isolation allows for the efficiency and maintainability of running multiple API microservices on the same host.

33. How do you implement Docker in microservices?

To implement Docker in microservices, create two microservices, a user service, and a test database running on two containers using Docker compose.

34. How do you create a test database server in Docker?

To create a test database server in Docker, type the command Docker run, knife, name, and name. Give the name to your database and SQL password, and define a port and image.

35. How do you create a microservices application in node.js?

Navigate to the user service directory and the multiple folders and files, including package node.js, index dot j, API, config directory, repository directory, and server directory.

36. What should be written in the Docker Compose file?

All the Docker files you want to build and create an image, linking different Docker images or the Docker container.

37. What is the difference between Docker Compose and Docker Swarm?

Docker Compose orchestrates a single application with multiple containers, while Docker Swarm producesvarious applications across multiple nodes.

38. What is the difference between a microservice and a monolithic application?

A microservice is a software application built using a microservices architecture, while a monolithic application is a single, self-contained software application that performs all the necessary functions.

39. What is the difference between functional and infrastructure services in a microservices architecture?

A functional service is a fine-grained service that combines business, enterprise, and application services, while an infrastructure service refers to non-business operations such as ordering, scaling, and security.

40. What are infrastructure services in a business?

Infrastructure services handle non-business or non-technical operations like security, ordering, and logging in a business.

41. What is heterogeneous interoperability?

Heterogeneous interoperability means no software application must be developed in the same programming language.

42. What is the difference between microservices and SOA?

In microservices, the software is broken down into more minor features, and when operating involving multiple applications or services, those services are called by one another when needed.

43. What is component sharing in SOA?

In SOA, the same order service interacts with different smaller applications for customer management, warehouse management, and order fulfilment, each application has its order service, accesses its database, and stores data in other databases.

44. What is the difference between middleware and API layer in SOA and microservices?

In SOA, middleware is used for communication, while in microservices, an API layer is used for communication.

45. What are some typical applications found in e-commerce portals?

Typical applications in e-commerce portals include a shopping cart, product catalogue, and user account applications, these applications provide various tasks, such as adding or removing products, checking taxes, and managing quantities.

46. What issues can arise when changes to the code in these applications are made?

When changes are made to the code in the applications, it can cause issues such as bugs, failure, or errors.

47. How can these issues be avoided?

These issues can be avoided by testing each application separately after changing the code and updating the required details.

48. What is the time-consuming and effort-intensive process of deploying each application separately?

Deploying each application separately is time-consuming as it involves testing and deploying each application individually.

49. What is real-time load balancing in microservices?

Real-time load balancing helps manage the allocation of resources for different services, allowing clients to receive outputs within seconds.

50. What is the availability of microservices?

Availability ensures that services are available 24/7, allowing users to use them as much as they want.

51. What is continuous delivery through DevOps integration in microservices?

Continuous delivery through DevOps integration allows for continuous delivery of outputs, which can be achieved by collaborating with DevOps.

52. What is the aggregator design pattern?

The aggregator design pattern involves sending requests to two or more services with unique IDs, collecting data from individual services, and applying business logic.

The collected data is then published to the rest of the endpoints and consumed by the services that require it.

53. What is the API Gateway design pattern?

The API Gateway design pattern addresses developers’ problems when breaking an application into small autonomous services, it can be considered a proxy service to root a request to their concerned microservice.

A PI Gateway is the entry point for the client’s request and can send requests to multiple services and aggregate results back to the composite or consumer service.

54. What is the event sourcing design pattern?

The event sourcing design pattern creates events regarding changes in the application state, which are stored as a sequence of events to help developers track changes made when and by home.

55. What is the branch pattern?

The branch pattern is a design pattern that allows simultaneous processing of requests and responses from two or more independent microservices in a single or multiple chains.

56. What is scalability in microservices?

Scalability allows for scaling a specific service individually without scaling the others. For example, in an e-commerce application, if there are four services: customers, orders, and products, the customer service can be scaled without scaling the orders of the product service.

57. What is decentralisation in microservices?

Decentralisation divides control into individual services, ensuring that the complete application doesn’t go down even if one service is down.

58. What is the composition design pattern?

The composition design pattern enables developers to break down large applications into smaller, autonomous units. Decomposition patterns can decompose an application based on business capabilities or subdomains, such as in an e-commerce application.

59. What are microservices tools?

Microservices tools are a collection of various tools and technologies with different functionalities, they are used in multiple stages of building an application and help developers work with ease.

These tools come with predefined functions, algorithms, and a user-friendly JY to ensure developers can quickly develop their applications.

60. What are the different tools used in microservices?

Different tools used in microservices include operating systems, programming languages, API management and testing, messaging tools, architectural frameworks, orchestrations, monitoring tools, and serverless tools.

61. What is Spring Boot?

Spring Boot is a framework that simplifies the creation of rest-based microservices, it provides a range of features such as auto-configuration, embedded term gaps, containers, Jetty, and a wide range of APIs for monitoring and managing applications.

62. Why is API management and testing important in microservices?

API management and testing are essential in microservices because each microservice can have its API to communicate with other servers, proper management and testing of all APIs in the system are required to get the desired results.

63. What is Postman?

Postman is an API development suite that allows for easy UI-driven tests, allowing for easy exploration of RESTful API resources.

It integrates with the software development lifecycle, provides features to design APIs, maintains multiple API versions, and supports collaboration by saving related API endpoints into collections.

64. What is API Fortress?

API Fortress is a code-free tool that automates load testing, health monitoring, and functional testing processes, it is highly interoperable with any platform and validates API’s built-in management platforms.

It simplifies test creation and execution by providing a drag-and-drop interface, aiming to simplify end-to-end testing by generating functional tests and storing tests and reports in a collaborative environment.

65. What is Apache Kafka?

Apache Kafka is a distributed published subscribe messaging system developed at LinkedIn and later became part of the Apache project.

It is scalable, agile, and distributed by design, offering high throughput for publishing and subscribing messages, ensuring stable performance, zero downtime, and data loss.

66. What is RabbitMQ?

RabbitMQ is a messaging system that simultaneously utilises patterns to communicate between microservices and scale applications.

It offers reliability, delivery acknowledgements, publisher confirmations, higher availability, and routing of messages through exchanges before arriving at the queues.

67. What is Fabric 8?

Fabric 8 is a platform-as-a-service tool that helps developers provide configuration management systems through Git, handles port mapping, and addresses complexity.

It provides results for faster application creation and continuous delivery pipelines, on-premise kit repository hosting, and a developer console for building managed microservices with deep visualisation into projects, applications, and environments.

68. What is Seneca?

Seneca is a tool kit for building message-based microservices processes, helping to write clean and organised code with systematic business logic.

It provides plugins that look after the foundation of the application, allowing users to write code without worrying about which database to use or how to structure components. Seneca also has a decoupled engine and plugins to implement custom DSLs and generate arbitrary outputs.

69. What is Kubernetes?

Kubernetes is an open-source container management order that handles container deployment scaling, descaling, and container load balancing, and it can help deploy and update secrets and application configuration without rebuilding the image or exposing secrets in the stack configuration.

70. What is Prometheus?

Prometheus is a monitoring tool that visualises monitoring information and supports time-based tracking for animalist patterns.

It is an open-source tool that gathers monitoring information, provides a flexible query language, and offers distributed storage and autonomous server nodes.

Conclusion

Finally, microservices are a widespread software architecture; they are more flexible, scalable, and resilient than monolithic architectures.

By breaking an application into more minor, independent services, developers can build and deploy features faster and improve user experience.

I hope you find these microservices interview questions and answers helpful, it will help you achieve your future goals.