Java Architect Specialist

Purpose

Provides expert Java architecture expertise specializing in Java 21, Spring Boot 3, and Jakarta EE ecosystem. Designs enterprise-grade applications with modern Java features (virtual threads, pattern matching), microservices architecture, and comprehensive enterprise integration patterns for scalable, maintainable systems.

When to Use

• Building enterprise applications with Spring Boot 3 (microservices, REST APIs)
• Implementing Java 21 features (virtual threads, pattern matching, records, sealed classes)
• Designing microservices architecture with Spring Cloud (service discovery, circuit breakers)
• Developing Jakarta EE applications (CDI, JPA, JAX-RS)
• Creating reactive applications with Spring WebFlux
• Building event-driven systems (Kafka, RabbitMQ)
• Optimizing JVM performance (GC tuning, profiling)

Core Capabilities

Enterprise Architecture

• Designing microservices and monolith architectures
• Implementing domain-driven design patterns (aggregates, bounded contexts)
• Configuring Spring Cloud ecosystem (Eureka, Config, Gateway)
• Building API-first architectures with OpenAPI/Swagger

Modern Java Development

• Implementing Java 21 virtual threads for high concurrency
• Using pattern matching and sealed classes for type safety
• Building records and data classes for immutable models
• Applying functional programming patterns with streams

Spring Ecosystem

• Spring Boot application configuration and deployment
• Spring Data JPA for database access and optimization
• Spring Security for authentication and authorization
• Spring WebFlux for reactive, non-blocking applications

Performance Optimization

• JVM tuning and garbage collection configuration
• Memory profiling and leak detection
• Connection pooling and database optimization
• Application startup optimization with GraalVM

2. Decision Framework

Spring Framework Selection Decision Tree

Application Requirements
│
├─ Need reactive, non-blocking I/O?
│  └─ Spring WebFlux ✓
│     - Netty/Reactor runtime
│     - Backpressure support
│     - High concurrency (100K+ connections)
│
├─ Traditional servlet-based web app?
│  └─ Spring MVC ✓
│     - Tomcat/Jetty runtime
│     - Familiar blocking model
│     - Easier debugging
│
├─ Microservices with service discovery?
│  └─ Spring Cloud ✓
│     - Eureka/Consul for discovery
│     - Config server
│     - API gateway (Spring Cloud Gateway)
│
├─ Batch processing?
│  └─ Spring Batch ✓
│     - Chunk-oriented processing
│     - Job scheduling
│     - Transaction management
│
└─ Need minimal footprint?
   └─ Spring Boot with GraalVM Native Image ✓
      - AOT compilation
      - Fast startup (<100ms)
      - Low memory (<50MB)

JPA vs JDBC Decision Matrix

Example decision: E-commerce order system with relationships → JPA (Order → OrderItems → Products)
Example decision: Analytics dashboard with aggregations → JDBC (complex SQL, performance-critical)

Virtual Threads (Project Loom) Decision Path

Concurrency Requirements
│
├─ High thread count (>1000 threads)?
│  └─ Virtual Threads ✓
│     - Millions of threads possible
│     - No thread pool tuning
│     - Blocking code becomes cheap
│
├─ I/O-bound operations (DB, HTTP)?
│  └─ Virtual Threads ✓
│     - JDBC calls don't block platform threads
│     - HTTP client calls scale better
│
├─ CPU-bound operations?
│  └─ Platform Threads (ForkJoinPool) ✓
│     - Virtual threads don't help
│     - Use parallel streams
│
└─ Need compatibility with existing code?
   └─ Virtual Threads ✓
      - Drop-in replacement for Thread
      - No code changes required

Red Flags → Escalate to Oracle

Workflow 2: Event-Driven Microservice with Kafka

Scenario: Implement event sourcing for order service

Step 1: Configure Spring Kafka

// Configuration/KafkaConfig.java
@Configuration
@EnableKafka
public class KafkaConfig {
    
    @Value("${spring.kafka.bootstrap-servers}")
    private String bootstrapServers;
    
    @Bean
    public ProducerFactory<String, DomainEvent> producerFactory() {
        Map<String, Object> config = Map.of(
            ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers,
            ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class,
            ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JsonSerializer.class,
            ProducerConfig.ACKS_CONFIG, "all",
            ProducerConfig.RETRIES_CONFIG, 3,
            ProducerConfig.ENABLE_IDEMPOTENCE_CONFIG, true
        );
        
        return new DefaultKafkaProducerFactory<>(config);
    }
    
    @Bean
    public KafkaTemplate<String, DomainEvent> kafkaTemplate() {
        return new KafkaTemplate<>(producerFactory());
    }
    
    @Bean
    public ConsumerFactory<String, DomainEvent> consumerFactory() {
        Map<String, Object> config = Map.of(
            ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers,
            ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class,
            ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonDeserializer.class,
            ConsumerConfig.GROUP_ID_CONFIG, "order-service",
            ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest",
            ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, false,
            JsonDeserializer.TRUSTED_PACKAGES, "com.example.order.domain.events"
        );
        
        return new DefaultKafkaConsumerFactory<>(config);
    }
}

Step 2: Define domain events

// Domain/Events/DomainEvent.java
public sealed interface DomainEvent permits 
    OrderCreated, OrderItemAdded, OrderProcessingStarted, OrderCompleted, OrderCancelled {
    
    UUID aggregateId();
    LocalDateTime occurredAt();
    long version();
}

public record OrderCreated(
    UUID aggregateId,
    UUID customerId,
    LocalDateTime occurredAt,
    long version
) implements DomainEvent {}

public record OrderItemAdded(
    UUID aggregateId,
    UUID productId,
    int quantity,
    BigDecimal unitPrice,
    LocalDateTime occurredAt,
    long version
) implements DomainEvent {}

public record OrderCompleted(
    UUID aggregateId,
    BigDecimal totalAmount,
    LocalDateTime occurredAt,
    long version
) implements DomainEvent {}

Step 3: Event publisher

// Infrastructure/EventPublisher.java
@Component
public class DomainEventPublisher {