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Natobotics

Java Microservices Kafka

Natobotics
Ireland · Full-time · Entry
Job title: Java Microservices Kafka

Job location: Dublin, Ireland

Job mode: Onsite

Job type: Contract

Jd

The focus will be on Java microservices (6+ years), Kafka (3+ years), private cloud, and hands-on implementation skills.

⸻

🧩 1. Core Java & Advanced Concepts

Be prepared for implementation-based and scenario-driven questions.

Strings & Immutability

  • Difference between String, StringBuilder, and StringBuffer.
  • Why is String immutable in Java?
  • How to create a custom immutable class (implement step by step).
  • Memory allocation for Strings (String Pool vs Heap).

Serialization

  • What is serialization and deserialization?
  • How to make a class serializable?
  • transient and serialVersionUID usage.
  • How serialization impacts performance and when to avoid it.

Concurrency & Multithreading

  • Explain synchronized, volatile, and ReentrantLock.
  • What is the Lock interface and how it differs from synchronized.
  • Difference between BlockingQueue, ConcurrentHashMap, and traditional collections.
  • What is a deadlock and how to prevent or detect it (practical scenario).
  • Thread pool and ExecutorService usage in microservices.
  • Callable vs Runnable.

⸻

☁️ 2. Microservices Architecture

  • Explain what microservices are and where you have implemented them.
  • Describe real project(s) where microservices were used (especially in Mastercard-like environments).
  • How microservices communicate (REST, gRPC, message queues).
  • How to manage configuration, scaling, and deployment on a private cloud.
  • Explain how you handle inter-service communication, fault tolerance, and circuit breakers (Hystrix, Resilience4j).
  • API Gateway and service registry (Eureka, Consul, etc.).
  • Authentication & Authorization in microservices (OAuth2, JWT, Spring Security).

⸻

🔄 3. Kafka (3+ Years Expected)

  • Explain how you used Kafka in your projects (data pipelines, async communication, event sourcing, etc.).
  • Kafka Producer–Consumer model.
  • Partitions, offsets, and consumer groups.
  • How you ensure exactly-once delivery or handle duplicates.
  • Kafka Streams and message ordering.
  • Integration of Kafka with Spring Boot microservices (Spring Kafka).
  • Performance tuning and troubleshooting Kafka lag.

⸻

⚙️ 4. Frameworks & Tools

Spring Framework (Core + Boot)

  • Spring Boot annotations (@RestController, @Configuration, @Component, @Service, etc.).
  • Dependency Injection & Inversion of Control.
  • RESTful APIs and exception handling.
  • Spring Data JPA & transaction management.
  • Spring Security (Authentication & Authorization).
  • Profiles and property management for different environments (private cloud setups).

Executive Framework (if referring to frameworks like ExecutorService or Spring Task Executor)

  • Thread management via Executor framework.
  • Asynchronous task execution.

⸻

💡 5. Design Patterns & Architecture

  • Common patterns used in your implementation:
  • Singleton, Factory, Builder, Prototype, Strategy, Observer, etc.
  • Microservice-related: Circuit Breaker, Gateway Aggregation, Saga, CQRS.
  • When and why you used each.
  • Have you implemented any custom design pattern or reusable utility component?

⸻

🧠 6. Problem-Solving / Scenario-Based Questions

  • How would you search or filter based on multiple criteria (e.g., search customers by ID, name, location)?
  • How to optimize search (indexes, pagination, caching).
  • How you handle failed transactions or partial updates.
  • How to debug microservice issues in distributed systems.

⸻

👥 7. Agile & Team Collaboration

  • Are you following Agile Scrum? Describe sprint cycles, ceremonies (daily stand-up, retrospective, grooming).
  • How do you understand user stories and break them into technical tasks?
  • How do you estimate tasks and manage backlog?
  • How do you handle technical debt and backlog cleanup?

⸻

🧰 8. Project & Work Environment

  • Describe day-to-day activities (development, review, deployment, production support).
  • Team size and roles.
  • Tools used: Git, Jenkins, JIRA, SonarQube, etc.
  • CI/CD pipeline experience.
  • Monitoring & logging (ELK, Splunk, Prometheus, Grafana).

⸻

🔐 9. Security

  • Difference between authentication and authorization.
  • How to secure REST APIs (OAuth2, JWT).
  • How to manage secrets/configurations in private cloud (Vault, KMS, config server).
  • HTTPS/SSL setup in Spring Boot.

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🧭 10. Personal & Role-Fit

  • This role is for a sound technical person who can work independently → Be ready with examples showing ownership.
  • How you handle ongoing projects, backlog work, and production issues.
  • How you contribute to team improvement (code reviews, mentoring, refactoring).

Key Skills

Ranked by relevance

microservices kafka cloud java spring boot design patterns fault tolerance design pattern restful apis prometheus jenkins splunk vault scrum grpc cicd jira git elk
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Country Guide

Ireland

English-speaking EU tech hub

Posted
Nov 07, 2025
Type
Full-time
Level
Entry
Location
Dublin
Company
Natobotics

Industries

IT Services IT Consulting

Categories

Engineering Information Technology

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