Caspex Corp Senior Java Developer Interview Questions and Answers

I would assess the legacy system's data exchange formats and communication protocols, then design a seamless integration plan.

• Analyze the data exchange formats used by the legacy system and determine compatibility with Java application

• Identify the communication protocols utilized by the legacy system and ensure they can be integrated with Java

• Design a middleware layer or API to facilitate communication between the lega...read more

Designing a concurrency model for a high calling java application to ensure thread safety and maximize throughput while minimizing deadlock risks.

• Use a combination of thread pools and executor services to manage concurrent requests efficiently.

• Implement synchronization mechanisms such as locks, semaphores, or atomic variables to ensure thread safety.

• Utilize non-blocking algorithms and data structures to reduce contenti...read more

Design a reliable messaging system using Kafka and RabbitMQ for communication between distributed components.

• Use Kafka for high-throughput, low-latency messaging with strong durability guarantees.

• Implement RabbitMQ for reliable message queuing and delivery.

• Integrate Kafka for real-time event streaming and RabbitMQ for asynchronous communication.

• Leverage Kafka Connect to easily connect Kafka with external systems and Ra...read more

Setting up CICD pipeline for Spring Boot microservices using Jenkins/GitLab

• Configure Jenkins/GitLab to listen for changes in the repository

• Set up build steps to compile the code, run unit tests, and perform integration tests

• Use Docker for containerization and Kubernetes for container orchestration

• Deploy artifacts to Artifactory and promote to production environment

• Automate the entire process with appropriate triggers a...read more

Optimize microservice performance with caching strategies like Spring Cache and distributed caching solutions.

• Implement Spring Cache Abstraction to cache method results, reducing database calls.

• Use annotations like @Cacheable, @CachePut, and @CacheEvict for fine-grained control over caching.

• Consider distributed caching solutions like Redis or Hazelcast for scalability across multiple instances.

• Cache external API respon...read more

Implement service discovery and load balancing using Netflix Eureka for microservices communication.

• Use Netflix Eureka as a service registry where microservices can register themselves and discover other services.

• Each microservice will have a Eureka client that registers its instance with the Eureka server upon startup.

• Eureka server provides a REST API for services to query for available instances of other services.

• Loa...read more

Implement secure authentication and authorization using Auth or JWT token to prevent security vulnerabilities.

• Use HTTPS to encrypt communication between client and server to prevent eavesdropping.

• Implement strong password policies and use password hashing to securely store user credentials.

• Use JWT tokens with short expiration times and refresh tokens to prevent token theft.

• Implement role-based access control to ensure ...read more

Designing a microservices architecture on AWS ECS involves containerization, service decomposition, and orchestration strategies.

• Identify and decompose the monolithic application into microservices based on business capabilities.

• Create Docker images for each microservice, ensuring they are lightweight and include only necessary dependencies.

• Use Docker Compose for local development to manage multi-container applications...read more

Choose AWS for flexibility and customization, choose Dynamo DB for simplicity and scalability

• Consider AWS if you need more flexibility and customization in your data storage solution

• Choose Dynamo DB if you prioritize simplicity and scalability for your mission critical application

• AWS offers a wide range of services and configurations for high availability and scalability, while Dynamo DB is a fully managed NoSQL databa...read more

Implementing circuit breaker pattern in Spring Boot to handle failures in a distributed environment

• Use Spring Boot's resilience4j library to implement the circuit breaker pattern

• Configure the circuit breaker to monitor the external service dependency and trip open when failures exceed a certain threshold

• Handle the circuit breaker state transitions (OPEN, HALF_OPEN, CLOSED) appropriately in your code

• Implement fallback m...read more

Analyzing database schema and query execution to identify performance issues

• Review database schema for normalization and indexing

• Analyze query execution plans for inefficiencies

• Consider optimizing data access patterns and query structure

• Use database profiling tools to identify bottlenecks

• Implement caching mechanisms for frequently accessed data

Default methods in Java 8 allow interfaces to have method implementations.

• Default methods were introduced in Java 8 to allow interfaces to have method implementations.

• Default methods are used to provide a default implementation for a method in an interface.

• Default methods are useful when adding new methods to existing interfaces without breaking the classes that already use them.

• Default methods can be overridden by cla...read more

Identify and diagnose memory leaks in Java using profiling tools, heap dumps, and code analysis.

• Use a profiling tool like VisualVM or YourKit to monitor memory usage and identify memory leaks.

• Analyze heap dumps with tools like Eclipse MAT to find objects that are not being garbage collected.

• Check for common memory leak patterns, such as static collections holding references to objects.

• Review code for improper use of li...read more

Meta space is a memory space in Java 8 and later versions that replaces PermGen for storing class metadata.

• Meta space is a part of the native memory and is used to store class metadata, such as class structures and method information.

• Unlike PermGen, meta space is not part of the Java heap and is not subject to the same memory limits.

• Meta space automatically resizes based on the application's demand, unlike PermGen whic...read more

Amazon S3 provides high availability and low latency through data replication and global edge locations.

• Amazon S3 replicates data across multiple availability zones within a region to ensure high availability.

• Global edge locations cache frequently accessed data closer to users, reducing latency.

• Amazon S3 uses a content delivery network (CDN) to deliver content quickly to users worldwide.

Stopping an EC2 instance puts it into a stopped state, while terminating an EC2 instance permanently deletes it.

• Stopping an EC2 instance preserves the data on the instance's EBS volumes

• Terminating an EC2 instance deletes the instance and all associated data

• Stopped instances can be started again, while terminated instances cannot be recovered

• Stopping an instance does not incur charges, but terminating an instance does

Method referencing is a way to refer to methods without invoking them directly.

• Used to simplify lambda expressions in Java

• Commonly used in functional interfaces

• Types of method referencing include static, instance, and constructor referencing

Request mapping is a general annotation used for mapping web requests to handler methods, while Get mapping is a specific type of request mapping used for mapping HTTP GET requests.

• Request mapping is a more general annotation that can be used for mapping various types of HTTP requests, while Get mapping specifically maps HTTP GET requests.

• Get mapping is a shortcut for @RequestMapping(method = RequestMethod.GET), making...read more

Enable debugging log in Spring Boot application

• Add 'logging.level.root=DEBUG' in application.properties file

• Use '@Slf4j' annotation in the Java class to enable logging

• Set 'logging.level.org.springframework=DEBUG' for Spring framework debugging

Yes, we can override or replace the embedded tomcat server in Spring Boot.

• You can override the embedded Tomcat server by excluding the Tomcat dependency in the pom.xml file and adding a different embedded server dependency like Jetty or Undertow.

• You can also customize the embedded server configuration by creating a bean of type EmbeddedServletContainerCustomizer in a @Configuration class.

• For example, to replace Tomcat ...read more

findFirst returns the first element in a stream, while findAny returns any element in a stream.

• findFirst is deterministic and will always return the first element in a stream, while findAny is non-deterministic and can return any element.

• findAny is useful for parallel processing as it can return any available element without the need to search for the first one.

• findFirst is typically used when the order of elements mat...read more

Monolithic SOE is a single large application while Microservices architecture breaks down the application into smaller, independent services.

• Monolithic SOE is a single, self-contained application where all components are tightly coupled.

• Microservices architecture breaks down the application into smaller, independent services that communicate through APIs.

• Monolithic SOE is easier to develop and test but can be harder to...read more

Recovery Time Objective (RTO) and Recovery Point Objective (RPO) are key metrics in disaster recovery planning in AWS.

• RTO is the maximum acceptable downtime for restoring services after a disaster.

• RPO is the maximum acceptable data loss in case of a disaster.

• RTO and RPO help in determining the appropriate backup and recovery strategies.

• For example, if RTO is 4 hours and RPO is 1 hour, it means services should be restor...read more