1. What are microservices, and how do they differ from monolithic architectures?
Answer:
Microservices are a software architectural style where an application is broken down into a collection of small, loosely coupled, independently deployable services. In contrast, monolithic architectures have a single, tightly integrated codebase. Microservices promote flexibility, scalability, and ease of maintenance.
2. What are the key advantages of using microservices architecture?
Answer:
- Scalability: Services can be scaled independently to handle varying loads.
- Technology Diversity: Each service can use the best-suited technology stack.
- Easy Maintenance: Small services are easier to maintain and upgrade.
- Fault Isolation: Failures in one service do not necessarily affect others.
- Rapid Development: Teams can work independently on services, speeding up development.
3. What are the challenges associated with microservices architecture?
Answer:
- Increased Complexity: Managing a network of microservices can be complex.
- Data Consistency: Maintaining data consistency across services can be challenging.
- Deployment and Monitoring: Managing deployments and monitoring services is crucial.
- Communication: Efficient inter-service communication is essential.
- Testing: Ensuring integration and end-to-end testing can be complex.
4. How can you handle inter-service communication in a microservices architecture?
Answer:
Inter-service communication can be managed using techniques such as RESTful APIs, gRPC, message queues, or event-driven architectures. API gateways are often used to manage and secure communication.
5. Explain the importance of service discovery and load balancing in microservices.
Answer:
Service discovery helps microservices locate and communicate with one another dynamically. Load balancing ensures even distribution of requests among instances of a service, improving performance and fault tolerance.
6. What is a container, and how does it relate to microservices?
Answer:
Containers, such as Docker, provide a lightweight, consistent environment for running applications. They are frequently used to package microservices, ensuring they run consistently across different environments.
7. What is the role of DevOps in a microservices environment?
Answer:
DevOps practices, such as automation, continuous integration, and continuous deployment, are essential for managing the rapid development and deployment of microservices. They help maintain consistency and reliability.
8. Explain the concept of service orchestration and choreography in microservices.
Answer:
Service orchestration is a centralized approach where a single service coordinates and controls the interactions between other services. Choreography, on the other hand, is a decentralized approach where services collaborate by emitting and consuming events. Both have their use cases in microservices.
9. What is a microservices API gateway, and why is it important?
Answer:
An API gateway is a single entry point for client requests to access multiple microservices. It handles routing, load balancing, authentication, and other cross-cutting concerns. It simplifies client access and security.
10. How can you ensure data consistency and transaction management in a microservices architecture?
Answer:
Techniques like the two-phase commit (2PC), the Saga pattern, and event-driven architectures can be used to manage data consistency and transactions in a distributed microservices environment.
11. What are microservices, and how do they differ from monolithic architectures?
Answer:
Microservices is an architectural approach where a large application is broken down into smaller, loosely coupled services. Each service focuses on a specific business capability and can be developed, deployed, and scaled independently. In contrast, monolithic architectures have all application functionality in a single codebase, making it harder to scale and maintain.
12. What are the key advantages of using microservices in software development?
Answer:
Microservices offer advantages such as improved scalability, better fault isolation, ease of deployment and updates, technology flexibility, and enhanced developer productivity. They also promote better resource utilization and the ability to use diverse programming languages and frameworks for different services.
13. Explain the concept of service discovery in a microservices architecture.
Answer:
Service discovery is a mechanism for microservices to find and communicate with each other in a dynamic environment. Services register themselves with a service registry, and clients can query the registry to locate services. This enables dynamic scaling, load balancing, and fault tolerance.
14. What is API Gateway in the context of microservices, and why is it important?
Answer:
An API Gateway is a central entry point for a microservices architecture. It handles tasks like authentication, routing, load balancing, and caching, providing a unified interface for clients. API Gateways simplify the client’s interaction with the microservices and protect them from the complexities of the underlying services.
15. What are the challenges and considerations when it comes to data management in a microservices architecture?
Answer:
Data management in microservices presents challenges like data consistency, data isolation, and data duplication. Microservices typically use their own databases, which can lead to complex synchronization and transaction management. Implementing event-driven architectures and using technologies like CQRS (Command Query Responsibility Segregation) can help address these challenges.
16. Explain the principles of fault tolerance and resilience in microservices.
Answer:
Fault tolerance and resilience in microservices involve designing services to withstand failures and recover gracefully. This can be achieved through strategies like redundancy, timeouts, retries, circuit breakers, and graceful degradation. The goal is to ensure that the failure of one service does not cause cascading failures across the system.
17. What is the role of containerization and orchestration tools like Docker and Kubernetes in microservices?
Answer:
Containerization tools like Docker package microservices and their dependencies into isolated containers, ensuring consistency between development and production environments. Orchestration tools like Kubernetes manage the deployment, scaling, and lifecycle of containers, making it easier to manage and scale microservices in a dynamic environment.
18. How can you ensure security in a microservices architecture?
Answer:
Security in microservices involves practices like authentication, authorization, encryption, and monitoring. Implementing token-based authentication, role-based access control, and securing communication with HTTPS are common security measures. Additionally, continuous monitoring and auditing of microservices can help identify and mitigate security vulnerabilities.
19. What is the relationship between DevOps and microservices, and why is DevOps important in a microservices environment?
Answer:
DevOps is a set of practices that emphasize collaboration between development and operations teams to automate and streamline the software delivery process. DevOps is crucial in a microservices environment because it enables rapid deployment and continuous delivery, allowing teams to quickly respond to changing requirements and deliver updates to microservices.
20. What are the potential challenges in testing and debugging microservices, and how can they be addressed?
Answer:
Testing and debugging microservices can be challenging due to the distributed nature of the architecture. Challenges include service dependencies, network issues, and ensuring data consistency. To address these challenges, use techniques like contract testing, log aggregation, distributed tracing, and testing in isolation using mock services or containers.
21. What are the main components of Microservices?
Answer:
Following is the list of main components of Microservices or Microservice architecture:
- Containers
- IaC (Infrastructure as Code Conception)
- API Gateway
- Enterprise Service Bus
- Service Delivery
22. What are the three types of tests used in Microservices?
Answer:
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.
23. What is API versioning, and why is it important in microservices?
Answer:
API versioning is the practice of maintaining different versions of APIs to ensure backward compatibility and smooth transitions during updates.
24. How do you handle cross-cutting concerns like logging and authentication in microservices?
Answer:
Cross-cutting concerns are often addressed by using middleware or service meshes that provide common functionality across services.
25. What is the difference between REST and GraphQL in the context of microservices?
Answer:
REST is a set of rules that defines structured data exchange between a client and a server. GraphQL is a query language, architecture style, and set of tools to create and manipulate APIs. REST is good for simple data sources where resources are well defined.
26. What is API rate limiting, and why is it essential in microservices?
Answer:
API rate limiting restricts the number of requests a client can make to a microservice to prevent abuse and ensure fair resource utilization.
27. What are the common security threats in microservices, and how can they be mitigated?
Answer:
Threats include data breaches, API vulnerabilities, and DDoS attacks, and they can be mitigated through security best practices, such as authentication and authorization.
28. Explain the principles of the Twelve-Factor App and how they relate to Microservices.
Answer:
The Twelve-Factor App principles provide guidelines for building scalable and maintainable applications, many of which align with Microservices principles, like using stateless services, keeping configurations external, and using declarative formats.
29. What is Circuit Breaker pattern, and why is it important in Microservices?
Answer:
The Circuit Breaker pattern prevents repeated calls to a failing service, improving the stability of the system and reducing cascading failures.
30. What is Blue-Green Deployment in the context of Microservices?
Answer:
Blue-Green Deployment involves having two identical environments, one active (blue) and one inactive (green), allowing for smooth, risk-free updates.
31. Explain the CAP theorem and its relevance to Microservices.
Answer:
The CAP theorem states that a distributed system cannot simultaneously guarantee consistency, availability, and partition tolerance. Microservices often deal with trade-offs between these three factors.
32. How do you handle database per service vs. shared database in Microservices architecture?
Answer:
The choice depends on factors like data isolation, scalability, and team autonomy. Shared databases can lead to tight coupling, while database per service increases independence.
33. Explain the concept of Microservices Choreography vs. Orchestration.
Answer:
Choreography involves services collaborating independently through events, while orchestration centralizes control in one service to coordinate others.
34. What is the role of Domain-Driven Design (DDD) in Microservices architecture?
Answer:
Threats include data breaches, API vulnerabilities, and DDoS attacks, and they can be mitigated through security best practices, such as authentication and authorization.
35. How do you handle Microservices in a legacy system migration?
Answer:
Migrating from a monolithic system to Microservices requires careful planning, identifying bounded contexts, and gradual refactoring.
36. How do you ensure data privacy and compliance in Microservices architecture?
Answer:
Data privacy and compliance can be ensured through techniques like data encryption, access controls, auditing, and compliance with relevant regulations like GDPR.
37. How do you implement authentication and authorization in Microservices?
Answer:
Authentication can be implemented using techniques like JWT tokens or OAuth2. Authorization can be handled through role-based access control (RBAC) or attribute-based access control (ABAC).
38. What is the role of a service mesh in Microservices architecture?
Answer:
A service mesh is a dedicated infrastructure layer for handling service-to-service communication. It provides features like service discovery, load balancing, and security.
39. How do you ensure high availability in a Microservices environment?
Answer:
High availability can be achieved through techniques like load balancing, redundancy, failover strategies, and the use of stateless services.
40. What is the purpose of a canary release in Microservices deployment?
Answer:
A canary release is a technique where a new version of a service is released to a small subset of users to assess its performance and reliability before deploying it to the entire user base.
41. How do you handle configuration management in Microservices?
Answer:
Configuration management can be handled using tools like Spring Cloud Config Server, environment variables, or configuration files..
42. What is a Docker image?
Answer:
A Docker image is a lightweight, standalone, and executable package that contains everything required to run an application, including code, runtime, libraries, environment variables, and configuration.
43. What are the challenges of logging and monitoring in Microservices architecture?
Answer:
Challenges include distributed logging, tracking requests across services, and aggregating logs for comprehensive monitoring.
44. What is PACT in Microservices Architecture?
Answer:
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.
45. What are non-deterministic tests? What is the process to eliminate them?
Answer:
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
46. What is an anti-pattern in Microservices, and can you give an example?
Answer:
An anti-pattern is a design approach that should be avoided. An example is the “distributed monolith,” where Microservices become tightly coupled and interdependent.
47. How do you handle database migrations in a Microservices environment?
Answer:
Database migrations can be managed using tools like Flyway or Liquibase, and they should be coordinated with Microservices deployments.
48. What is the purpose of a “fallback” mechanism in Microservices?
Answer:
A fallback mechanism provides an alternative response or behavior when a Microservice is experiencing issues, ensuring that users still receive some level of service.
49. How do you maintain backward compatibility when making changes to Microservices APIs?
Answer:
Maintaining backward compatibility involves versioning APIs, avoiding breaking changes, and providing proper documentation for API consumers.
50. Why is there a need for a Domain-Driven Design (DDD)?
Answer:
- Mapping to a domain: We are mapping our architecture to a particular domain.
- Testability: Testing the application becomes easier.
- Maintainability: Maintaining the application also becomes easier because everybody is on the same page.
- Knowledge-rich design: These applications are very heavy on knowledge.
- Context focused: Very much focused on a particular domain.
Answer: This is explained in the table below:
| Advantages | Disadvantages |
|---|---|
| The liberty to use various technologies | Chances of troubleshooting is increased |
| Units that can be deployed individually are supported | Efforts of configurations including other efforts are increased |
| Software are released more frequently | Transaction safety isn’t easy to maintain |
| Each service security is ensured | It isn’t easy to track data from various service boundaries |
52. What is cohesion?
Answer:
cohesion refers to the degree to which the components or services within a Microservices system are focused on specific, well-defined responsibilities or functionalities. High cohesion means that a Microservice is highly specialized, performing a single, clear-cut task or business capability.
Achieving high cohesion in Microservices is important because it promotes better maintainability, flexibility, and scalability. Services with high cohesion are easier to develop, test, and maintain, and they are less likely to have unintended dependencies on other services. This ensures that each Microservice can evolve independently without negatively impacting the overall system, making it a fundamental principle in designing effective Microservices.
53. What is the full form of DRY? What is its usage in Microservices architecture?
Answer:
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.
54. What do you understand by Idempotence, and how is it used?
Answer:
Idempotence refers to the repeated performing of a task even though the end result remains the same. It is used mostly as a data source or a remote service in a way that when it receives the instruction more than once, it processes the instruction only once.
55. What are the uses of Reports and Dashboards in Microservices environments?
Answer:
Reports and Dashboards are generally used to monitor a system. For microservices Reports and Dashboards help to:
- Find which microservice support which resource.
- Find out the services that are impacted whenever changes in components are made/occur.
- Provide an easy point of access for documentation purposes.
Review versions of the deployed components. - Obtain compliance from the components.
56. What are the tools that can be considered for managing a microservice architecture?
Answer:
The main tools that can be used to build/manage a microservice architecture are:
- MongoDB: It is a document-based open-source distributed database. Here data is stored in JSON format with a different structure for different documents. It also supports a lot of programming languages like C, C++, C#, PERL, PHP, Python, Java, Ruby, Scala, etc.
- Elasticsearch: It is a full-text search engine.
- JENKINS: It is an automation tool that enables Continuous Integration and Continuous Development. It supports many plugins and easily integrates with almost every tool.
- DOCKER: The application development environment and application deployment environment are bound to vary in many aspects. This gives rise to deployment issues. Docker provides a static background for the application to run, thus avoiding deployment issues.
- KUBERNETES: With thousands of services running in an application, Kubernetes, as an engine orchestrates the entire process.
- JAEGER: It is an open-source end to end distributed tracing tool. Jaeger monitors distributed transactions, helps in performance optimization, and finds the dependencies between services. It also gives the root cause analysis.
57. Explain the usage of the @GetMapping annotation in Microservices.
Answer:
The @GetMapping annotation is used to map HTTP GET requests to specific methods in a Microservice.
58. What are some common patterns for inter-service communication in microservices?
Answer:
Common patterns for inter-service communication in microservices include:
- Request-response: Synchronous communication using HTTP/REST or gRPC for real-time and point-to-point interactions.
- Publish-subscribe: Asynchronous communication through message brokers like RabbitMQ or Apache Kafka, where services publish events and other services subscribe to relevant events.
- Choreography: Services communicate directly with each other based on events and state changes, without a centralized orchestrator.
- Orchestration: A central service (orchestrator) coordinates and controls the flow of requests and responses among multiple services.
59. Can you explain the concept of event-driven architecture in the context of microservices?
Answer:
Event-driven architecture (EDA) is an architectural pattern where services communicate by producing and consuming events. Events represent significant occurrences or state changes within the system. Microservices can publish events when something important happens, and other services can subscribe to those events to react accordingly. EDA enables loose coupling and scalability while supporting asynchronous and decoupled communication between services.
60. What is Eureka in Microservices?
Answer:
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.
61. What do you understand by Cross-functional testing?
Answer:
Cross-functional testing is the verification of non-functional requirements, i.e., the requirements that we cannot implement like a standard feature.
62. What is an Actuator in Microservices? Why is it used?
Answer:
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.
63. What is the use of Bounded Context in Domain-Driven Design?
Answer:
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.
64.How independent micro-services communicate with each other?
Answer:
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.
65. What Is Semantic Monitoring?
Answer:
The entire application is monitored and computerized tests are combined. Semantic Monitoring’s principal advantage is to discover out the qualities that make your business much more profitable. After a problem has been detected, it allows for faster insulation and bug triage, reducing the main repair time. After a problem has been detected, it allows for quicker insulation and bug emergency care, lowering the primary maintenance time. It tries to identify the transfers which are impacted by availability or lack of quality.
66. What is a Consumer Driven Contract (CDC)?
Answer:
Each consumer catches up with its supplier’s expectations in a separate contract in consumer-driven contracts. All these contracts are shared with the provider to provide an insight into the obligations that each individual customer has to fulfill. To validate these obligations, the provider can create a test suite. To validate such obligations, the provider can develop a test suite.
This allows them to remain agile and to make changes which do not affect consumers, as well as to identify consumers who will suffer the necessary changes for further planning and debate. Pacto helps to ensure that such commitments are fulfilled and decouples implementation obligations, so that customers and suppliers can be autonomously tested. For their testing, suppliers can also decouple consumers. Pacto may use contracts for provider testing to visualize consumers.
67. What is Confused Deputy Problem in security context?
Answer:
Assume that the customer sends the server name of the input and output file. The server builds and stores the input file in the output. Assume, too, the customer has fewer privileges than the server. Now also suppose there is a “restricted” file where the server doesn’t have authorization from the client. At that point, the server compiles the file and then write the server into a “restricted” file that overwrites the preceding content if the user sends an absurd input and a “restricted” as output file.The client had no “restricted” authorization here, but the server did.
The server is thus an administrator who has been used for a manipulative action. Such problems are known as Confused Deputy Problem.
68. What Are the Ways to Access RESTful Microservices?
Answer:
One of the commonly asked question in the Microservices interview is how to access RESTful Microservices. There are two ways to do it which are as follows:
- Use a REST template that is load balanced.
- Use multiple microservices.
69. What do you understand about Reactive Extensions in Microservices?
Answer:
Reactive extensions also called Rx is a design approach that enables us to call multiple services, collect their results or responses, and compile the combined result or response. The calls to services can be synchronous or asynchronous and blocking or non-blocking.
70. What is the role of a reverse proxy in Microservices architecture?
Answer:
The role of a reverse proxy in Microservices architecture is to act as a gateway for incoming client requests. It handles tasks such as load balancing, SSL termination, routing requests to the appropriate Microservices, and providing an additional layer of security, improving overall performance and scalability.
71. What is a “CQRS” pattern in Microservices, and when might you use it?
Answer:
The “CQRS” (Command Query Responsibility Segregation) pattern in Microservices is an architectural approach that separates the responsibility for handling write (command) and read (query) operations. This pattern is typically used when there’s a need for different optimization strategies, scalability, and performance requirements for read and write operations. It allows for specialized data models and storage systems for each type of operation, which can lead to improved performance and flexibility in complex systems.
72. What is the difference between synchronous and asynchronous communication in Microservices?
Answer:
Synchronous communication in Microservices involves immediate, blocking interactions where the client waits for a response before proceeding, much like traditional request-response mechanisms.
Asynchronous communication, on the other hand, allows the client to send a request and continue without waiting, receiving the response at a later time when it’s available. Asynchronous communication is often used for decoupling services, improving scalability, and handling long-running tasks.
73. How can you ensure that Microservices are stateless, and why is this important?
Answer:
You can ensure that Microservices are stateless by avoiding the storage of any client-specific data or session information within the service. Instead, all data is stored externally or passed explicitly through requests.
This is important because stateless Microservices are more scalable, as any instance of the service can handle any request without being tied to a specific user or session. It also simplifies failover and load balancing, as requests can be routed to any available instance of the service without concern for maintaining state.
74. What is “API-first” design, and why is it important in Microservices development?
Answer:
API-first design is an approach where you define and design the APIs (Application Programming Interfaces) of your Microservices before implementing the service itself. It is important in Microservices development because it promotes clear communication, collaboration, and alignment between teams working on different services.
API-first design ensures that all Microservices can interact effectively, making it easier to maintain and evolve the architecture as the application grows and changes.
75. How do you manage long-term storage and data archiving in Microservices?
Answer:
In Microservices, long-term storage and data archiving are typically managed by integrating Microservices with dedicated data storage services or archival solutions, ensuring that historical data is stored securely and can be accessed as needed while not cluttering the operational datastores.
76.Can you explain how Microservices architecture can support multi-tenancy?
Answer:
Microservices can support multi-tenancy by isolating tenant-specific data and configuration, allowing multiple tenants to coexist on the same infrastructure while maintaining data separation and security.
77. What is the use of Netflix Hystrix?
Answer:
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.
78. What do you understand by the Distributed Transaction?
Answer:
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.
79. What do you understand by end-to-end Microservices testing?
Answer:
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.
80. Why is Spring Cloud Bus used in a Microservices architecture, and what problem does it address?
Answer:
Spring Cloud Bus is used in Microservices architecture to address the issue of maintaining configuration consistency and triggering synchronized actions across multiple services. It helps propagate configuration changes and events across the entire distributed system in real-time, ensuring that all services are aware of updates and can respond accordingly. This eliminates the need for manual updates and helps maintain system stability and consistency.
81. What is Zipkin, and why is it used in a Microservices architecture?
Answer:
Zipkin is an open-source distributed tracing system that helps track and visualize requests as they flow across Microservices. It’s used to monitor and troubleshoot latency and performance issues.
82. What is the purpose of context propagation in request tracing with Zipkin?
Answer:
Context propagation ensures that trace data, including the trace ID and span ID, is passed from one Microservice to another to maintain a cohesive trace as the request flows through the system.
83. What is Zuul, and why would you implement a logging filter in it?
Answer:
Zuul is a gateway service that provides dynamic routing, monitoring, and security for Microservices applications. Implementing a logging filter in Zuul helps capture and log requests and responses, aiding in debugging, auditing, and monitoring.
84. What is the role of the Ribbon client in Microservices architecture?
Answer:
The Ribbon client is responsible for making routing decisions to determine which service instance to contact for a particular request. It provides load balancing and fault tolerance capabilities.
85. What is the role of an API Gateway in setting up a Currency Conversion Microservice?
Answer:
An API Gateway can serve as a central entry point for clients to request currency conversions. It can route incoming requests to the appropriate Currency Conversion Microservice instance.
86. What is Feign, and what is its primary purpose in a microservices architecture?
Answer:
Feign is a declarative web service client that simplifies making HTTP requests to other services. It is used in a microservices architecture to call remote services using a more concise and readable interface than traditional HTTP client libraries.
87. What annotations are commonly used in Feign interfaces?
Answer:
Common annotations include @FeignClient to declare the target service, @RequestMapping to define the HTTP methods and paths, and @RequestParam or @RequestBody for request parameters and payloads.
88. What are the main components of Eureka Naming Server?
Answer:
Eureka Naming Server primarily consists of the Eureka Server, which stores service instances, and Eureka Clients, which register and discover services.
89. What is the difference between an API Gateway and a Reverse Proxy?
Answer:
While both can route requests, a reverse proxy is typically focused on load balancing and forwarding requests to backend servers, whereas an API Gateway provides additional functionalities like authentication, authorization, and API composition.
90. What is Distributed Tracing?
Answer:
Distributed Tracing is a technique used to monitor and profile the flow of requests as they traverse through a distributed system. It helps in understanding the path and performance of requests across various microservices.
Answer: RabbitMQ is an open-source message broker server that acts as an intermediary for sending and receiving messages between distributed systems. Its primary purpose is to facilitate communication and decouple components in a system.
92. What is the difference between RabbitMQ and Kafka?
Answer: RabbitMQ is a traditional message broker focused on queuing and routing messages, while Kafka is a distributed streaming platform designed for high-throughput event streaming. RabbitMQ is more suitable for queuing and point-to-point messaging, whereas Kafka is used for log and event processing.
93. What is the role of the “RefreshScope” in Spring Cloud Bus?
Answer: The “RefreshScope” is a Spring Cloud component that enables beans to be refreshed automatically when a configuration change occurs. It’s essential for updating beans with changed configuration values.
94. How do you ensure visibility into Microservices when dealing with distributed systems?
Answer: Distributed tracing tools, such as OpenTracing or Jaeger, enable end-to-end visibility by tracing requests as they traverse through different services.
95. How does Microservices architecture impact the testing process compared to a monolithic architecture?
Answer: Testing in a Microservices architecture is more complex due to the need for comprehensive unit testing, integration testing, and ensuring that service interactions work correctly.
96. What is the purpose of the Hystrix dashboard, and how does it help in monitoring and troubleshooting?
Answer: The Hystrix dashboard provides real-time monitoring of the health and performance of Hystrix circuits. It helps in diagnosing issues, understanding service behavior, and making informed decisions about circuit configuration.
97. Explain the role of durable queues and exchanges in RabbitMQ.
Answer: Durable queues and exchanges are configured to survive server restarts. They ensure that messages and routing rules are not lost even if the server crashes.
98. What is the “poison message” problem in RabbitMQ, and how can it be mitigated?
Answer: The poison message problem occurs when a message repeatedly fails processing, potentially blocking a queue. It can be mitigated by using dead-letter queues to handle problematic messages.
99. Can you explain the concept of service orchestration in SOA?
Answer: Service orchestration involves coordinating the execution of multiple services to achieve a specific business process or workflow, often by defining a sequence of service invocations.
100. What is Spring Cloud Config Server?
Answer: Spring Cloud Config Server is a component of the Spring Cloud framework that provides a centralized configuration management system for distributed applications. It allows you to externalize and manage application configuration independently of the application code.
Answer:
- Wiremock
- Docker
- Hysrix
102. What do you understand by RESTful?
Answer: 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.
103. What is the use of PACT in Microservices architecture?
Answer: PACT is an open-source tool used for testing interactions between service providers and consumers. It increases the reliability of the Microservices applications.
104. What do you understand by end-to-end Microservices testing?
Answer: 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.
105. What do you understand by semantic monitoring in Microservices architecture?
Answer: 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.
106. What is unit testing, and why is it important in microservices architecture?
Answer: Unit testing is the process of testing individual components or functions of a software application in isolation. In microservices architecture, unit testing is crucial because it ensures that each service functions correctly on its own, helping to maintain the independence and reliability of services.
107. What is contract testing, and how does it apply to microservices?
Answer: Contract testing is a method for verifying that interactions between microservices conform to agreed-upon contracts, often defined through API specifications or messaging protocols. It ensures that service dependencies are met, even when different teams develop the services.
108. What tools or frameworks can be used for testing microservices written in Java?
Answer: Common tools and frameworks for testing microservices in Java include JUnit, TestNG, Mockito, RestAssured, WireMock, Pact, and Spring Cloud Contract.
109. Explain the concept of mocking and how it is used in microservices testing ?
Answer: Mocking is the practice of creating fake or simulated objects to replace real components during testing. In microservices testing, mocking is used to simulate the behavior of external dependencies (other services or databases) to isolate the service under test and verify its behavior in controlled conditions.
Answer: The test pyramid is a testing strategy that suggests having a broad base of unit tests, followed by a smaller number of integration tests, and even fewer end-to-end tests. In microservices testing, this pyramid emphasizes the importance of unit and integration tests to maintain a balance and ensure efficient testing.
Answer: Some popular Java Microservices frameworks are:
1) Jakarta EE
2) Micronaut
3) Spring Boot
4) Spark Java
5) Axon Framework
112. How does communication take place between Microservices?
Answer: This is one of the most common Java Microservices interview questions asked in technical interviews.
Communication takes place in two fashions: Synchronous Communication – Synchronous Communication can occur through HTTP, FeignClient, WebClient, and Ribbon, using the RestTemplate.
Asynchronous Communication – Asynchronous Communication occurs when the user doesn’t require an immediate response. This mode of communication can be achieved using Kafka, JMS Implementation, or RabbitMQ.
113. Why is Java a preferred language for Microservices?
Answer: Java is the most preferred language to write Microservices because its annotation syntax is the easiest to read among other OOP languages. Frameworks like Spring Boot and Angular make it easy to code Microservices applications.
114. Is Spring Boot built to write Java Microservice applications?
Answer: Although Spring Boot can be used to write Microservices, it isn’t built only to write Microservices applications. It can also be used to write advanced software programs in Java.
115. When does Contract Testing become useful in Microservices?
Answer: Contract testing is useful when multiple Microservices need to communicate with each other. It is mainly used to detect irregularities in application configuration and consumer workflow.
Answer: Dumb pipes mean that no further actions can be taken place in this communication means. It just carries the data across a channel, and it is replaceable. The infrastructure is dumb, i.e. it can only act as a message router, and it has no other functions.
117. What are reports and dashboards used for in Microservices?
Answer: Reports and dashboards monitor and upkeep services. They find out which microservices expose what services, services are impacted when changes in component occur, version of the components deployed, and a sense of compliance and maturity from the components.
118. What factors make one hesitant to use microservices?
Answer: Microservices require heavy investment and heavy architecture set up. They have autonomous staff selection and need excessive planning for handling operations overhead.
119. Tell one advantage and challenges faced while using Microservices.
Answer: Microservices is technologically diverse. It can be mixed with other libraries, databases and frameworks. As microservices rely on each other, there is a need for communication between them which poses a challenge.
120. Explain Microservices in layman terms.
Answer: Microservices or Microservices Architecture structures an application as small autonomous services modelled around a business domain as a honeycomb. The initial start is with a small section that builds a large structure that holds together a particular section; here, that is the business domain. Each cell is independent but correlated with the other cells. So damage to one cell does not impact the whole structure.
Answer: Microservice architecture is best suited for desktop, web, mobile devices, Smart TVs, Wearable, etc.
122. Explain three types of Tests for Microservices?
Answer:
123. Explain the use of PACT in Microservices architecture?
Answer: It is an open source tool which allows testing interactions between service providers and consumers. However, it is separated from the contract made. This increases the reliability of the Microservices applications.
124. What is End to End Microservices Testing?
Answer: End-to-end testing validates every process in the workflow is functioning correctly. It also ensures that the system works together as a whole and satisfies all requirements.
125. Why are Container used in Microservices?
Answer:Containers are easiest and effective method to manage the microservice based application. It also helps you to develop and deploy individually. Docker also allows you to encapsulate your microservice in a container image along with its dependencies. Microservice can use these elements without additional efforts.
Answer: 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.
127. What do you understand by Tasklet in Microservices?
Answer: The Tasklet is a simple interface with a method to execute. We can use it to perform single tasks like running queries, deleting files, etc. In Spring Batch, the Tasklet is an interface used to perform unique tasks like clean or set up resources before or after any step execution.
128. What is a ‘dumb pipe’ in Microservices?
Answer: Dumb pipes mean that no further actions can be taken place in this communication means. It just carries the data across a channel, and it is replaceable. The infrastructure is dumb, i.e. it can only act as a message router, and it has no other functions.
129. What are the three types of tests for Microservices?
Answer: The first test is the bottom level test that performs general test like unit and performance tests. At the middle level, experimental tests like usability and stress tests are there. Moreover, at the top level, acceptance testing takes place. Tests at all levels are automated.
130. Define reactive extensions in Microservices.
Answer: Reactive extensions or Rx is a design pattern that allows collecting results by calling multiple services and compiling a combined response. It is a popular tool working exactly opposite to legacy flows.
Answer:
132. What is auto-scaling?
Answer: Auto-scaling is a function that allows you to provision and launch new instances whenever there is a demand. It allows you to automatically increase or decrease resource capacity in relation to the demand.
133. What is geo-targeting in CloudFront?
Answer: Geo-Targeting is a concept where businesses can show personalized content to their audience based on their geographic location without changing the URL. This helps you create customized content for the audience of a specific geographical area, keeping their needs in the forefront.
134. Is there any other alternative tool to log into the cloud environment other than console?
Answer:
135. What are the native AWS Security logging capabilities?
Answer: Most of the AWS services have their logging options. Also, some of them have an account level logging, like in AWS CloudTrail, AWS Config, and others. Let’s take a look at two services in specific:
Answer: The Class class is used to obtain information about an object’s design.
137. The Class class is used to obtain information about an object’s design.
Answer: The Class class is used to obtain information about an object’s design.
138. The Class class is used to obtain information about an object’s design.
Answer: The Class class is used to obtain information about an object’s design.
139. The Class class is used to obtain information about an object’s design.
Answer: The Class class is used to obtain information about an object’s design.
140. The Class class is used to obtain information about an object’s design.
Answer: The Class class is used to obtain information about an object’s design.
Answer: Costs can be optimized during an AWS migration by utilizing AWS cost management tools, selecting appropriate EC2 instance types, leveraging AWS Reserved Instances, and implementing cost monitoring and optimization strategies.
142. How do you ensure minimal downtime during an AWS migration?
Answer: Minimal downtime during an AWS migration can be ensured by using techniques like blue-green deployments, leveraging AWS services like AWS Server Migration Service (SMS), and carefully planning the cutover process.
143. How do you validate the success of an AWS migration?
Answer: The success of an AWS migration can be validated through thorough testing of migrated applications, verifying data integrity, and monitoring performance and user acceptance after the migration.
144. What tools and services can be used for database migration in AWS?
Answer: AWS provides several tools and services for database migration, including AWS Database Migration Service (DMS), AWS Schema Conversion Tool (SCT), and AWS Database Discovery Service (DDS).
145. What is AWS CloudEndure, and how does it help with migration?
Answer: AWS CloudEndure is a service that simplifies migration and disaster recovery by enabling continuous replication of applications, databases, and servers from a source environment to AWS, minimizing downtime and data loss.
Answer: The SAGA design pattern is a pattern used in distributed systems and microservices architectures to manage complex and long-running transactions that span multiple services. It helps ensure data consistency and reliability in situations where traditional two-phase commit (2PC) transactions might be impractical or too restrictive. In a microservices architecture, services often need to collaborate to perform actions that require multiple steps, potentially involving multiple services and databases. In such cases, you may encounter scenarios where a transaction could fail at some point, and it’s important to handle this failure gracefully while maintaining data integrity. The SAGA pattern provides a way to address this challenge by breaking a complex transaction into a series of smaller, individual steps, each of which is represented by a service or a component. These steps are typically implemented as independent transactions. If a step fails, the SAGA pattern provides mechanisms to handle the failure, potentially by compensating for the failed step or by retrying it.
147. what is the use of circuit breakers
Answer: Circuit breakers are a software design pattern used in distributed systems and microservices architectures to improve the resilience and stability of an application or service. They are primarily used to prevent system overload, cascading failures, and to handle and recover from network or service failures. Circuit breakers work similarly to electrical circuit breakers, which open when there is an electrical fault to prevent further damage.
148. What is a monolithic architecture, and what is a microservices architecture?
Answer: Monolithic Architecture: In a monolithic architecture, an entire application is developed as a single, tightly integrated unit. All components and functionality are bundled together in one codebase and are often deployed as a single application.
Microservices Architecture: In a microservices architecture, an application is broken down into smaller, loosely coupled services. Each service focuses on a specific business capability and can be developed, deployed, and scaled independently.
149. What are the advantages of a monolithic architecture?
Answer: Simplicity: Monolithic applications are often simpler to develop, test, and deploy, making them a good choice for smaller projects. Easier Debugging: Debugging can be easier in monolithic systems since the code is all in one place. Stronger Consistency: Monolithic applications naturally provide strong data consistency because they have a single database.
150. When should you consider moving from a monolithic to a microservices architecture?
Answer: The decision to transition to microservices should be based on factors such as the project’s size, complexity, and long-term scalability needs. Consider moving to microservices when:
Your monolithic application is becoming difficult to maintain, scale, or update. Different parts of the application have varying resource demands.
You need to use different technology stacks for different components. You require faster development cycles and frequent updates.
