Springboot Microservices 

1: What is Spring Boot?

A: Spring Boot is an open-source framework used for building stand-alone, production-grade Spring-based applications. It provides a simplified configuration model, embedded web servers, and pre-built dependencies to enable developers to quickly build and run Spring-based applications.

2: What are microservices?

A: Microservices are a software architectural style that structures an application as a collection of small, independent services that communicate with each other through APIs. Each microservice is responsible for a specific task or feature and can be developed, deployed, and scaled independently of the other services in the application.

3: How does Spring Boot help in building microservices?

A: Spring Boot provides a number of features that make it easier to build microservices. These include a simplified configuration model, embedded web servers, pre-built dependencies, and auto-configuration of common infrastructure components like logging, security, and database access. Spring Boot also integrates well with other Spring projects, such as Spring Cloud, which provides additional tools for building microservices-based applications.

4: What is Spring Cloud?

A: Spring Cloud is a set of tools and frameworks that provide additional features for building microservices-based applications on top of Spring Boot. These include service discovery, distributed configuration, load balancing, and circuit breakers, among others.

5: What are the advantages of using Spring Boot for building microservices?

A: The advantages of using Spring Boot for building microservices include faster development time, simplified configuration, easier testing, and improved productivity. Spring Boot also provides built-in support for common infrastructure components like logging, security, and database access, which can reduce the amount of boilerplate code that developers need to write. Additionally, Spring Boot integrates well with other Spring projects and third-party libraries, making it easy to extend and customize.

6.What are microservices, and how do they differ from monolithic architectures?

Answer: Microservices are an architectural style that structures an application as a collection of small, independent services that communicate with each other through APIs. Each microservice is responsible for a specific task or feature and can be developed, deployed, and scaled independently of the other services in the application. In contrast, monolithic architectures typically involve a single codebase that handles all of the application's functionality.

7.How does Spring Boot simplify the process of building microservices?

Answer: Spring Boot provides a number of features that make it easier to build microservices-based applications. These include a simplified configuration model, embedded web servers, pre-built dependencies, and auto-configuration of common infrastructure components like logging, security, and database access.

8.What are some of the key features of Spring Boot?

Answer: Some key features of Spring Boot include:

• Simplified configuration model

• Auto-configuration of common infrastructure components

• Embedded web servers

• Pre-built dependencies

• Easy testing

• Production-ready monitoring and management

9.How do you configure a Spring Boot application?

Answer: Spring Boot applications can be configured using properties files, YAML files, environment variables, or command-line arguments. Configuration can also be done programmatically using the Spring Environment API or by creating custom configuration classes.

10.How does Spring Boot handle dependencies, and what is the purpose of the Starter POMs?

Answer: Spring Boot uses a dependency management system that provides a set of pre-built dependencies for common use cases, such as database access, web development, and testing. The purpose of the Starter POMs is to simplify the process of including these dependencies in a project by providing a single dependency that includes all of the necessary transitive dependencies.

11.How does Spring Boot support service discovery, and what are some of the options for implementing it?

Answer: Spring Boot supports service discovery through integrations with service registry systems like Eureka, Consul, or ZooKeeper. These integrations provide mechanisms for registering services, discovering other services, and handling failures.

12.What is an API gateway, and how does it fit into a microservices architecture?

Answer: An API gateway is a component that sits between clients and microservices and routes requests to the appropriate service. It can also handle tasks like authentication, rate limiting, and caching. An API gateway is typically used in microservices architectures to provide a single entry point for clients and to simplify the process of routing requests to the correct service.

13.How does Spring Boot support distributed tracing, and what are some of the available tools for implementing it?

Answer: Spring Boot supports distributed tracing through integrations with tracing systems like Zipkin or Jaeger. These integrations provide mechanisms for tracing requests across multiple services and capturing timing and metadata information.

14.How do you handle cross-cutting concerns like security and logging in a Spring Boot microservices architecture?

Answer: Spring Boot provides built-in support for common infrastructure components like security and logging. These components can be configured using properties files, YAML files, or by creating custom configuration classes. Spring Security is used for authentication and authorization, while logging is typically handled using the Logback or Log4j2 frameworks.

15.What are some of the challenges of building and deploying microservices-based applications, and how can they be addressed with Spring Boot?

Answer: Some challenges of building and deploying microservices-based applications include service discovery, inter-service communication, and dealing with failures. Spring Boot provides integrations with common infrastructure components like service registry systems, API gateways, and circuit breakers to help address these challenges. Additionally, Spring Boot's embedded web server and simplified configuration model can make it easier to

16.What do you mean by Microservice?

Answer - Microservices, also known as Microservices Architecture, is basically an SDLC approach in which large applications are built as a collection of small functional modules. It is one of the most widely adopted architectural concepts within software development. In addition to helping in easy maintenance, this architecture also makes development faster. Additionally, microservices are also a big asset for the latest methods of software development such as DevOps and Agile. Furthermore, it helps deliver large, complex applications promptly, frequently, and reliably. Applications are modeled as collections of services, which are: 

• Maintainable and testable

• Loosely coupled

• Independently deployable

• Designed or organized around business capabilities

• Managed by a small team

17.Write main features of Microservices.

Some of the main features of Microservices include:

Decoupling: Within a system, services are largely decoupled. The application as a whole can therefore be easily constructed, altered, and scalable

Componentization: Microservices are viewed as independent components that can easily be exchanged or upgraded

Business Capabilities: Microservices are relatively simple and only focus on one service

Team autonomy: Each developer works independently of each other, allowing for a faster project timeline

Continuous Delivery: Enables frequent software releases through systematic automation of software development, testing, and approval

Responsibility: Microservices are not focused on applications as projects. Rather, they see applications as products they are responsible for

Decentralized Governance: Choosing the right tool according to the job is the goal. Developers can choose the best tools to solve their problems

Agility: Microservices facilitate agile development. It is possible to create new features quickly and discard them again at any time.

18. Write main components of Microservices.

Some of the main components of microservices include: 

• Containers, Clustering, and Orchestration 

• IaC [Infrastructure as Code Conception] 

• Cloud Infrastructure 

• API Gateway 

• Enterprise Service Bus 

• Service Delivery 

19. What are the benefits and drawbacks of Microservices?

Benefits: 

• Self-contained, and independent deployment module. 

• Independently managed services.   

• In order to improve performance, the demand service can be deployed on multiple servers.   

• It is easier to test and has fewer dependencies.  

• A greater degree of scalability and agility.   

• Simplicity in debugging & maintenance.  

• Better communication between developers and business users.   

• Development teams of a smaller size.

Drawbacks: 

• Due to the complexity of the architecture, testing and monitoring are more difficult.  

• Lacks the proper corporate culture for it to work.   

• Pre-planning is essential.  

• Complex development.  

• Requires a cultural shift.  

• Expensive compared to monoliths.   

• Security implications. 

• Maintaining the network is more difficult.  

•  Name three common tools mostly used for microservices.

• Three common tools used for microservices include: 

Wiremock 

Docker 

Hystrix 

20. Explain the working of Microservice Architecture.

Microservice architectures consist of the following components: 

• Clients: Different users send requests from various devices. 

• Identity Provider: Validate a user's or client's identity and issue security tokens. 

• API Gateway: Handles the requests from clients. 

• Static Content: Contains all of the system's content. 

• Management: Services are balanced on nodes and failures are identified. 

• Service Discovery: A guide to discovering the routes of communication between microservices. 

• Content Delivery Network: Includes distributed network of proxy servers and their data centers. 

• Remote Service: Provides remote access to data or information that resides on networked computers and devices. 

21. Write difference between Monolithic, SOA and Microservices Architecture.

Monolithic Architecture: It is "like a big container" where all the software components of an application are bundled together tightly.  It is usually built as one large system and is one code-base. 

SOA (Service-Oriented Architecture): It is a group of services interacting or communicating with each other. Depending on the nature of the communication, it can be simple data exchange or it could involve several services coordinating some activity.   

Microservice Architecture: It involves structuring an application in the form of a cluster of small, autonomous services modeled around a business domain. The functional modules can be deployed independently, are scalable, are aimed at achieving specific business goals, and communicate with each other over standard protocols. 

22. Explain spring cloud and spring boot.

Spring Cloud: In Microservices, the Spring cloud is a system that integrates with external systems. This is a short-lived framework designed to build applications quickly. It contributes significantly to microservice architecture due to its association with finite amounts of data processing. Some of the features of spring cloud are shown below:

Spring Boot: Spring Boot is an open-sourced, Java-based framework that provides its developers with a platform on which they can create stand-alone, production-grade Spring applications. In addition to reducing development time and increasing productivity, it is easily understood.

 23 What is the role of actuator in spring boot?

A spring boot actuator is a project that provides restful web services to access the current state of an application that is running in production. In addition, you can monitor and manage application usage in a production environment without having to code or configure any of the applications.

24.. Explain how you can override the default properties of Spring boot projects.

By specifying properties in the application.properties file, it is possible to override the default properties of a spring boot project.  

Example: 

In Spring MVC applications, you need to specify a suffix and prefix. You can do this by adding the properties listed below in the application.properties file. 

For suffix – spring.mvc.view.suffix: .jsp 

For prefix – spring.mvc.view.prefix: /WEB-INF/ 

25. What issues are generally solved by spring clouds?

The following problems can be solved with spring cloud:   

Complicated issues caused by distributed systems: This includes network issues, latency problems, bandwidth problems, and security issues. 

Service Discovery issues: Service discovery allows processes and services to communicate and locate each other within a cluster. 

Redundancy issues: Distributed systems can often have redundancy issues. 

Load balancing issues: Optimize the distribution of workloads among multiple computing resources, including computer clusters, central processing units, and network links. 

Reduces performance issues: Reduces performance issues caused by various operational overheads. 

26. What do you mean by Cohesion and Coupling?

Coupling: It is defined as a relationship between software modules A and B, and how much one module depends or interacts with another one. Couplings fall into three major categories. Modules can be highly coupled (highly dependent), loosely coupled, and uncoupled from each other. The best kind of coupling is loose coupling, which is achieved through interfaces. 

Cohesion: It is defined as a relationship between two or more parts/elements of a module that serves the same purpose. Generally, a module with high cohesion can perform a specific function efficiently without needing communication with any other modules. High cohesion enhances the functionality of the module.

27. What do you mean by Bounded Context?

A Bounded Context is a central pattern in DDD (Domain-Driven Design), which deals with collaboration across large models and teams. DDD breaks large models down into multiple contexts to make them more manageable. Additionally, it explains their relationship explicitly. The concept promotes an object-oriented approach to developing services bound to a data model and is also responsible for ensuring the integrity and mutability of said data model. 

28. Write the fundamental characteristics of Microservice Design.

Based on Business Capabilities: Services are divided and organized around business capabilities. 

Products not projects: A product should belong to the team that handles it.  

Essential messaging frameworks: Rely on functional messaging frameworks: Eliminate centralized service buses by embracing the concept of decentralization.  

Decentralized Governance: The development teams are accountable for all aspects of the software they produce.  

Decentralized data management: Microservices allow each service to manage its data separately.  

Automated infrastructure: These systems are complete and can be deployed independently.   

Design for failure: Increase the tolerance for failure of services by focusing on continuous monitoring of the applications. 

29. 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 heavy infrastructure setup. 

• Need Heavy investment. 

• 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. 

30. Explain PACT in microservices.

PACT is defined as an open-source tool that allows service providers and consumers to test interactions in isolation against contracts that have been made to increase the reliability of microservice integration. It also offers support for numerous languages, such as Ruby, Java, Scala, .NET, JavaScript, Swift/Objective-C. 

31. Explain how independent microservices communicate with each other.

• Communication between microservices can take place through: 

• HTTP/REST with JSON or binary protocol for request-response 

• Websockets for streaming.  

• A broker or server program that uses advanced routing algorithms.  

• RabbitMQ, Nats, Kafka, etc., can be used as message brokers; each is built to handle a particular message semantic. You can also use Backend as a Service like Space Cloud to automate your entire backend. 

32. What do you mean by client certificates?

The client certificate is a type of digital certificate that generally allows client systems to authenticate their requests to remote servers. In many mutual authentication designs, it plays a key role in providing strong assurance of the requestor's identity.

33. Explain CDC.

As the name implies, CDC (Consumer-Driven Contract) basically ensures service communication compatibility by establishing an agreement between consumers and service providers regarding the format of the data exchanged between them. An agreement like this is called a contract. Basically, it is a pattern used to develop Microservices so that they can be efficiently used by external systems.

34. Name some famous companies that use Microservice architecture.

Microservices architecture has replaced monolithic architecture for most large-scale websites like: 

• Twitter 

• Netflix 

• Amazon, etc. 

• Microservices Interview Questions for Experienced

35. What do you mean by Semantic Monitoring?

The semantic monitoring method, also called synthetic monitoring, uses automated tests and monitoring of the application to identify errors in business processes. This technology provides a deeper look into the transaction performance, service availability, and overall application performance to identify performance issues of microservices, catch bugs in transactions and provide an overall higher level of performance. 

36. Explain continuous monitoring.

Continuous monitoring involves identifying compliance and risk issues in a company's financial and operational environment. It consists of people, processes, and working systems that support efficient and effective operations.

37. What do you mean by Domain driven design?

DDD (Domain-Driven-Design) is basically an architectural style that is based on Object-Oriented Analysis Design approaches and principles. In this approach, the business domain is modeled carefully in software, without regard to how the system actually works. By interconnecting related components of the software system into a continuously evolving system, it facilitates the development of complex systems. There are three fundamental principles underlying it as shown below: 

Concentrate on the core domain and domain logic. 

Analyze domain models to find complex designs. 

Engage in regular collaboration with the domain experts to improve the application model and address emerging domain issues. 

38. Explain OAuth.

Generally speaking, OAuth (Open Authorization Protocol) enables users to authenticate themselves with third-party service providers. With this protocol, you can access client applications on HTTP for third-party providers such as GitHub, Facebook, etc. Using it, you can also share resources on one site with another site without requiring their credentials.

39. What do you mean by Distributed Transaction?

Distributed transactions are an outdated approach in today's microservice architecture that leaves the developer with severe scalability issues. Transactions are distributed to several services that are called to complete the transaction in sequence. With so many moving parts, it is very complex and prone to failure. 

40. Explain Idempotence and its usage.

The term 'idempotence' refers to the repeated performance of a task despite the same outcome.  In other words, it is a situation in which a task is performed repeatedly with the end result remaining the same. 

 Usage: When the remote service or data source receives instructions more than once, Idempotence ensures that it will process each request once. 

41. What do you mean by end-to-end microservices testing?

Usually, end-to-end (E2E) microservice testing is an uncoordinated, high-cost technique that is used to ensure that all components work together for a complete user journey. Usually, it is done through the user interface, mimicking how it appears to the user. It also ensures all processes in the workflow are working properly. 

42. Explain the term Eureka in Microservices.

Eureka Server, also referred to as Netflix Service Discovery Server, is an application that keeps track of all client-service applications. As every Microservice registers to Eureka Server, Eureka Server knows all the client applications running on the different ports and IP addresses. It generally uses Spring Cloud and is not heavy on the application development process. 

43. Explain the way to implement service discovery in microservices architecture.

There are many ways to set up service discovery, but Netflix's Eureka is the most efficient. This is a hassle-free procedure that doesn't add much weight to the application. It also supports a wide range of web applications. A number of annotations are provided by Spring Cloud to make its use as simple as possible and to hide complex concepts.

44. Explain the importance of reports and dashboards in microservices.

Monitoring a system usually involves the use of reports and dashboards. Using reports and dashboards for microservices can help you:  

• Determine which microservices support which resources.   

• Determine which services are impacted whenever changes are made or occur to components. 

• Make documentation easy to access whenever needed.   

• Review deployed component versions.  

• Determine the level of maturity and compliance from the components.

45. What are Reactive Extensions in Microservices?

A reactive extension, also known as Rx, is basically a design approach that calls multiple services and then generates a single response by combining the results. The calls can either be blocking or not blocking, synchronous or asynchronous. A popular tool in distributed systems, Rx works exactly opposite to legacy flows.

46. Explain type of tests mostly used in Microservices.

As there are multiple microservices working together, microservice testing becomes quite complex when working with microservices. Consequently, tests are categorized according to their level:

Botton-level tests: The bottom-level tests are those that deal with technology, such as unit tests and performance tests. This is a completely automated process.  

Middle-level tests: In the middle, we have exploratory tests such as stress tests and usability tests.   

Top-level tests: In the top-level testing, we have a limited number of acceptance tests. The acceptance tests help stakeholders understand and verify the software features.   

47. What do you mean by Mike Cohn’s Test Pyramid?

Mike Cohn's Test Pyramid explains the different types of automated tests needed for software development. The test pyramid is basically used to maximize automation at all levels of testing, including unit testing, service level testing, UI testing, etc. The pyramid also states that unit tests are faster and more isolated, while UI tests, which are at the top, are more time-consuming and are centered around integration. 

In accordance with the pyramid, the number of tests should be highest at the first layer. At the service layer, fewer tests should be performed than at the unit test level, but greater than that at the end-to-end level.

48. Explain Container in Microservices.

Containers are useful technologies for allocating and sharing resources. It is considered the most effective and easiest method for managing microservice-based applications to develop and deploy them individually. Using Docker, you may also encapsulate a microservice along with its dependencies in a container image, which can then be used to roll on-demand instances of the microservice without any additional work. 

49. What is the main role of docker in microservices?

Docker generally provides a container environment, in which any application can be hosted. This is accomplished by tightly packaging both the application and the dependencies required to support it. These packaged products are referred to as Containers, and since Docker is used to doing that, they are called Docker containers. Docker, in essence, allows you to containerize your microservices and manage these microservices more easily.

Conclusion:

Microservices architecture is a method of developing a large-scale application as a collection of small autonomous services developed for a business domain. Since its debut in 2011, microservices have become a popular technology, especially among organizations building forward-thinking applications. This list of Microservices interview questions was carefully constructed to assist the development community in their interviews. Hope these Microservices Architect Interview Questions would be helpful for your interview. 

50. What are Microservices? / What do you understand by Microservices?

Microservices are an architectural approach or style that is used to build applications. The microservice architecture provides a rapid, frequent and reliable delivery of large and complex applications. It is distributed and loosely coupled, so it won't break the entire app if you make changes in one team.

Microservices are also known as the microservice architecture, a variant of the service-oriented architecture (SOA) structural style and used to structure an application as a collection of services that have the following features:

• Distributed and loosely coupled

• Highly maintainable and testable

• Independently deployable

• Organized around business capabilities

• Owned by a small team

50  What are the most significant benefits of using microservices?

The most significant benefit of using microservices is that it builds an application to collect small autonomous services developed for a business domain. So, if the business needs to change constantly, the development teams can rapidly build new apps components to meet the requirement.

Each microservice runs a unique process and communicates through a well-defined, lightweight mechanism, such as a container, to serve a business goal. It also makes an organization capable of evolving its technology stack.

51. What are the three commonly used tools for Microservices?

Following are the three commonly used tools for Microservices:

• Wiremock

• Docker

• Hysrix

52 What are the main components of Microservices?

Following is the list of main components of Microservices or Microservice architecture:

• Containers, Clustering, and Orchestration

• IaC (Infrastructure as Code Conception)

• Cloud Infrastructure

• API Gateway

• Enterprise Service Bus

• Service Delivery

53. How does a Microservice architecture work?

The Microservice architecture of an application can be simplified into multiple modules that independently perform the single precise standalone task. Let's see how Microservice architecture works:

• An application is fragmented into loosely coupled various modules, each of which performs a distinct function.

• It is distributed across clouds and data centers.

• Each application module is an independent service/process that can be replaced, updated, or deleted without disrupting the rest of the application.

• Under microservice architecture, an application can grow along with its requirements.

54.What are the main advantages of using Microservices?

Following is a list of some most important advantages of using Microservices:

• Microservices provide great technology diversity. You can mix it easily with other frameworks, libraries, and databases.

• Microservices support fault isolation as it collects small autonomous services or processes, so a process failure should not bring the whole system down.

• It provides excellent support for the minor and parallel team.

• It reduces the deployment time significantly.

• Independent deployment

55. What do you understand by Monolithic Architecture?

Monolithic architecture is like a big container that contains all the software components of an application. These applications are clubbed inside a single package within the application.

56.What are the biggest challenges in Microservice deployment?

We can specify the biggest challenges in Microservice deployment in two ways, i.e., technical and functional.

The main challenges from the business point of view:

• Microservices require a heavy investment.

• It requires a heavy infrastructure setup also.

• We need excessive planning for managing operations overhead.

• It cost a lot in staff selection and maintenance.

• The main challenges from a technical point of view:

• The components in microservices always rely on each other, so; it requires communication between them in the application.

• There are also a lot of challenges in deployment.

• Testing and Debugging are very challenging.

• It requires complete component automation and application maintenance.

• It receives heavy operations overhead.

• It requires skilled professionals to support heterogeneously distributed microservices.

57.What do you understand by Spring Cloud?

Spring cloud is an Integration software used to integrate with external systems. It allows a microservices framework to build applications that perform restricted amounts of data processing.

58  In which cases microservice architecture is best suited?

The microservice architecture is best suited for all tech devices such as desktop, web, mobile devices, Smart TVs, Wearable devices, etc.

59.What are the most significant advantages and disadvantages of using Microservices?

Following is the list of the most significant advantages and disadvantages of using Microservices:

Advantages of Microservices

• Provide improved scalability

• Increased Agility

• Localized Complexity

• Provide fault isolation

• Debugging & Maintenance are easy and simplified.

• Communication between developers with business users is accessible and better.

• Smaller development teams

• You can easily upgrade the technology.

Disadvantages of Microservices

• As a whole project, it isn't easy because it uses multiple components in the application.

• It requires accurate pre-planning before use.

• It uses modular dependencies that are hard to calculate.

• The third-party applications are hard to control.

• Modular interdependencies are challenging to track.

• More opportunities for malicious intrusions.

• Complete end-to-end testing is complex.

• Deployment Challenges.

60. Which are some famous companies that are using Microservice architecture?

Most large-scale software companies and websites such as Twitter, Netflix, Amazon are using microservices architecture instead of monolithic architecture.

61.What do you understand by RESTful?

REST or RESTful stands for Representational State Transfer. The RESTful web service is an architectural style that helps computer systems to communicate over the internet. These web services make microservices easier to understand and implement.

62.What are the different strategies used in Microservices deployment?

Following strategies are used in Microservices deployment:

• Multiple Service Instance per Host: It is used to run single or multiple service instances of the application on a single or multiple physical/virtual hosts.

• Service Instance per Host: It is used to run a service instance per host.

• Service Instance per Container: It is used to run each service instance in its respective container.

• Serverless Deployment: It packages the service as a ZIP file and uploads it to the Lambda function. The Lambda function is a stateless service that automatically runs enough micro-services to handle all requests.

63.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.

64.What is the main difference between SOA and the Microservices Architecture?

SOA stands for Service Oriented Architecture. It is a collection of services used to communicate with each other through simple data passing or activity coordination. On the other hand, the Microservices Architecture is a collection of small functional modules that are independently deployable, scalable, target specific business goals, and communicate over standard protocols.

65.What is a Client certificate? What is its usage?

A client certificate is a digital certificate used to make authenticated requests to a remote server. A certificate is generated for each microservice.

66.What do you understand by Domain-Driven Design?

Domain-Driven Design is an architectural style based on Object-Oriented Analysis Design concepts and principles. It is used to develop a complex system by connecting the related components of the software system into a continuously evolving system. Domain-Driven Design is based on three principles:

• Focus on the core domain and domain logic.

• Base complex designs on models of the domain.

• Collaborate with the domain experts to improve the application model and resolve any emerging domain-related issues regularly.

67.What is the use of PACT in Microservices architecture?

PACT is an open-source tool used for testing interactions between service providers and consumers. It increases the reliability of the Microservices applications.

68.What do you understand by OAuth?

OAuth stands for Open Authorization protocol. This protocol allows you to access the client applications on HTTP for third-party providers GitHub, Facebook, etc. It also facilitates us to share resources stored on one site with another site without their credentials.

69.What is Spring Boot? Why is it used?

Spring Boot is an open-source, Java-based framework that provides developers an excellent platform for developing a stand-alone and production-grade spring application. It is easy to understand, reduces development time, and increases productivity. It automatically configures a claim based on the added dependencies of an application.

70.What is the method to override a Spring Boot project's default properties?

We can do it by specifying the properties in application.properties. The Spring MVC applications need the suffix and the prefix to be specified. This can be done by:

For suffix:mvc.view.suffix: .jsp

For prefix:mvc.view.prefix: /WEB-INF/

71.What do you understand by end-to-end Microservices testing?

End-to-end testing is used to validate that every process in the workflow is functioning correctly. It also ensures that the system works together as a whole and fulfills all the requirements.

72.What is the difference between Coupling and Cohesion?

Difference between Coupling and Cohesion

Coupling: Coupling is specified as a relationship between module A and another module B. There are mainly three types of coupling. Any module can be highly coupled (highly dependent), loosely coupled, and uncoupled with other modules. The best coupling is the loose coupling which can be achieved through interfaces.

Cohesion: Cohesion is the relationship between 2 or more parts within a module. The high cohesion within a module specifies that the module can perform a specific task with maximum efficiency on its own, without the need to communicate with other modules. High cohesion increases the functional strength of the module.

73.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.

74.What is Spring Cloud? What problems can be solved by using Spring Cloud?

Spring Cloud is a collection of tools used by developers to quickly build some of the common patterns in distributed systems such as configuration management, circuit breakers, service discovery, intelligent routing, micro-proxy, control bus, one-time tokens, global locks, leadership election, distributed sessions, cluster state, etc.

We can use spring cloud to solve the following problems:

We can solve network issues, latency overhead, bandwidth issues, security issues, and other issues occurred in distributed systems.

We can also solve redundancy issues that occur in distributed systems.

We can balance the distribution of load between resources like network links, CPU, clusters, etc.

We can solve the performance issues that occurred because of operational overheads.

We can resolve the service discovery issues to make smooth communication possible between services in a cluster.

75.What do you understand by semantic monitoring in Microservices architecture?

Semantic monitoring is used to combine the automated tests by monitoring the application. It is used to find out the reasons why your business is not getting more profits.

76.What do you understand by the Distributed Transaction?

A distribution transaction is a type of transaction that has two or more engaged network hosts. In this transaction, a transaction manager takes care of developing and handling transactions. If the transaction involves more than one peer, the transaction managers of each peer communicate with each other using subordinate or superior relationships. In the same way, the resource manager handles the resources and coordinates with the distributed transaction coordinator for transaction atomicity and isolation.

77.What is the full form of CDC? What is its usage?

The full form of CDC is a Consumer-Driven Contract. It is a pattern used for developing Microservices so that the external systems can use them efficiently.

78.What is Reactive Extension in Microservices?

Reactive Extension is a design pattern that allows collecting results by calling multiple services and then compiles a combined response. It is also called Rx. Rx is a popular tool in distributed systems that works opposite to legacy flows.

79.How can you configure Spring Boot application login?

We can configure the Spring Boot application login by specifying the logging.level in the application.properties file. Generally, it is pre-configured as console output.

80.What do you understand by the term 'Continuous Monitoring'?

The term continuous monitoring is used to specify a method used to search compliance and risk issues associated with a company's operational and financial environment. This method contains human processes and working systems that support efficient and actual operations.

81.What is Mike Cohn's Test Pyramid?

Mike Cohn's Test Pyramid is used to maximize automation at all levels of testing, such as unit testing, service level testing, UI testing, etc. This pyramid specifies that while unit tests are faster and more isolated, UI tests, which are at the highest level, take time and focus on integration.

82.How independent micro-services communicate with each other?

We can make our micro-services communicate with each other according to our project needs. In most cases, developers use HTTP/REST with JSON or Binary protocol while using any communication protocol.

83.How can you implement a Spring Security in a Spring Boot Application?

We can quickly implement a Spring Security in a Spring Boot Application by using the following method:

By adding the spring-boot-starter-security in the file pom.xml

By creating a Spring config class that will override the required method while extending the WebSecurityConfigurerAdapter to achieve security in the application

84.What do you understand by ubiquitous language?

Ubiquitous Language or UL is a common language used by developers and users of a specific domain to explain that domain easily. The ubiquitous language has to bring all the team members on the same page and be translated so that a machine can understand.

85.What is the difference between Rest and Microservices?

There are multiple ways to implement microservices. REST over HTTP is one of them. REST is also used in other applications such as web apps, API design, and MVC applications to serve business data.

On the other hand, in microservices architecture, all the system components are put into individual components, which can be built, deployed, and scaled individually. Microservices provide certain principles and best practices that help in building a resilient application. So, we can say that REST is a medium to build Microservices.

86. What do you understand by Idempotence? Where is it used?

Idempotence is a property that facilitates us to do something twice so that the result will remain the same always in such a way that if it had been done once only. Usage of Idempotence: Idempotence is used at the remote service or data source so that, when it receives the instruction more than once, it only processes the instruction once.

87.What is an Actuator in Microservices? Why is it used?

Actuator is a sub-project of Spring Boot. It brings in production-ready features into an application and is mainly used to expose operational information about the running application's health, metrics, info, dump, env, etc. It uses HTTP endpoints or JMX beans to interact with it.

88. What is the use of Bounded Context in Domain-Driven Design?

The Bounded Context is a central pattern in Domain-Driven Design. It is the core of Domain-Driven Design's strategic design section, which deals with large models and teams. It is used to divide the large models into different Bounded Contexts and being explicit about their inter-relationships.

89/ What is PACT in Microservices Architecture?

The contract between a consumer application and a provider application is known as a PACT. Each PACT is a collection of interactions. It is an open-source tool that can be used to implement the Consumer-Driven Contract in Microservices.

90/ What do you understand by Two Factor Authentication? What are the different types of credentials used in Two Factor Authentication?

Two-factor authentication enables the users to fulfill the second level of authentication to an account login process. If a user has to enter only a username and password at the time of login, it would be considered a single-factor authentication. But in Two-factor authentication, the user has to enter more information than the login password.

Mainly three types of credentials are used in Two-factor authentication:

Something you know: In this authentication step, you have to enter a PIN, password, or a pattern.

Something you have: This authentication step requires an ATM card, phone, or OTP.

Something you are: In this authentication step, you have to enter your biometric fingerprint or voice print.

91.What is the need for Reports and Dashboards in Microservices?

Reports and dashboards are mainly used to monitor microservices. There are multiple tools used for this purpose.

Following is the list of some usages of Reports and dashboards in microservices:

Reports and dashboards are used to find out which microservices expose what resources.

It is also used to specify the services which are impacted whenever we make changes in a component.

It provides an easy point to access whenever documentation is required.

It specifies the versions of the components which are deployed.

It is also used to obtain a sense of maturity and compliance from the components.

92.What do you understand by Canary Releasing?

Canary releasing is a technique used to introduce new software versions by rolling out the updated version or new code/features to a subset of users as an initial test before making the entire infrastructure available to everybody. This technique is called canary release because it is based on canary releases in coal mines to alert miners when the toxic gases reach dangerous levels.

93.Why do many developers hesitate in using Microservices? / What are the biggest cons of using Microservices?

There are some cons of Microservices that can make developers hesitate in using Microservices:

Microservices require heavy investment: It requires a great deal of collaboration. Since your teams are working independently, they should be able to synchronize well at all times.

The architecture setup cost is high: The Microservices system is distributed, so the architecture is heavily involved and costly.

Handling operations overhead is complex: Using Microservices may lead to overhead so, you need to be ready for operations overhead if you are planning to use Microservices architecture.

Autonomous staff selection: It requires skilled professionals to support Microservices that are distributed heterogeneously.

94.What are non-deterministic tests? What is the process to eliminate them?

Non-deterministic tests or NDT are unreliable tests that sometimes pass and sometimes fail. When these tests fail, they are re-run again. We can use the following ways to eliminate non-determinism from Non-Deterministic tests.

• Quarantine

• Asynchronous

• Remote Services

• Isolation

• Time

• Resource Leaks

95.What is the usage of WebMvcTest annotation in Spring MVC applications?

WebMvcTest annotation is used for unit testing in Spring MVC Applications in cases where the test objective is to focus on Spring MVC Components.

See the following code:

@WebMvcTest(value =ToTestController.class, secure = false):

Here, we want to launch only the ToTestController. All other controllers and mappings will not be launched until this unit test is executed.

96.What is Eureka in Microservices?

Eureka or Eureka Server is an application that holds the information about the client-service applications. Microservices have to register into the Eureka server, and the Eureka server knows all the client applications running on each port and IP address. Eureka Server is also alternatively known as the Netflix Service Discovery Server. It uses Spring Cloud and is not heavy on the application development process.

97.What is the full form of DRY? What is its usage in Microservices architecture?

The full form of DRY is Don't Repeat Yourself. It is used to promote the concept of reusing the code. This makes things easy in developing and sharing the libraries, which in turn result in tight coupling.

98,How can you balance the server-side load by utilizing Spring Cloud?

We can use the Netflix Zuul to balance the server-side load by utilizing Spring Cloud. It is also known as a JVM-based router.

99,What do you understand by Cross-functional testing?

Cross-functional testing is the verification of non-functional requirements, i.e., the requirements that we cannot implement like a standard feature.

100.What is the use of Netflix Hystrix?

Hystrix is an error tolerance and latency library. It is mainly used to isolate the access points. It also ensures that all 3rd party libraries and services are restricted. So, the application runs efficiently and avoids the kind of failures that occur in distributed systems.