Spring

Modern enterprise tools designed for building resilient cloud architecture and getting that scale.

Explore Ecosystem Java 21+ Knowledge Hub

VOLUME I—FRAMEWORK MODULES

Spring Framework Ecosystem

Curated deep dives into the essential blocks powering modern production systems.

SECTION IFramework Core

Spring Boot 3.3 & Core Framework

The backbone of modern enterprise Java applications, offering opinionated auto-configuration, GraalVM native image generation, Ahead-Of-Time (AOT) processing, and comprehensive Actuator telemetry.

GraalVM Native Compilation
Virtual Thread Execution
Structured Logging & Metrics
Custom Starters & Auto-config

Java SnippetSpring 6+

@SpringBootApplication
public class PrimaveraApplication {
    public static void main(String[] args) {
        SpringApplication.run(PrimaveraApplication.class, args);
    }
}

Explore Architecture Specs

SECTION IIIdentity & Access

Spring Security 6.3

Enterprise-grade authorization and authentication framework. Provides seamless integration for OAuth2 Resource Servers, OIDC, Passkeys, JWT validation, and Method Security annotations.

OAuth2 / OpenID Connect
Passkey & WebAuthn Support
Reactive Security WebFilter
CSRF & CORS Controls

Java SnippetSpring 6+

@Bean
public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
    return http
        .authorizeHttpRequests(auth -> auth
            .requestMatchers("/api/public/**").permitAll()
            .anyRequest().authenticated())
        .oauth2ResourceServer(oauth -> oauth.jwt(Customizer.withDefaults()))
        .build();
}

Explore Architecture Specs

SECTION IIIMicroservices

Spring Cloud Native

Architectural tooling for microservice patterns: API Gateway routing, Resilience4j circuit breakers, distributed tracing with Micrometer, and declarative REST clients with OpenFeign.

Spring Cloud Gateway
Resilience4j Circuit Breakers
Distributed Tracing (Zipkin/OTel)
Eureka & Consul Discovery

Java SnippetSpring 6+

@Bean
public RouteLocator customRoutes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route("payment_route", r -> r.path("/payments/**")
            .filters(f -> f.circuitBreakers(c -> c.setName("payCB")))
            .uri("lb://PAYMENT-SERVICE"))
        .build();
}

Explore Architecture Specs

SECTION IVPersistence Layer

Spring Data JPA & R2DBC

Unified repository abstractions for both synchronous relational databases via Hibernate 6 and asynchronous non-blocking storage via R2DBC and Spring Data Redis.

Derived Query Methods
R2DBC Reactive Storage
Redis & Mongo Aggregations
Auditing & Entity Callbacks

Java SnippetSpring 6+

@Repository
public interface OrderRepository extends JpaRepository<Order, UUID> {
    @Query("SELECT o FROM Order o WHERE o.status = :status")
    List<Order> findActiveOrders(@Param("status") OrderStatus status);
}

Explore Architecture Specs

SECTION VHigh Throughput

Reactive WebFlux & Netty

Non-blocking event-loop architecture powered by Project Reactor. Enables extreme throughput and concurrency handling with Mono and Flux reactive publishers on top of Netty.

Publisher (Mono & Flux)
Backpressure Management
Server-Sent Events (SSE)
Non-blocking HTTP Client

Java SnippetSpring 6+

@GetMapping(value = "/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
public Flux<TelemetryEvent> getLiveStream() {
    return telemetryService.getEventStream()
        .delayElements(Duration.ofMillis(100));
}

Explore Architecture Specs

SECTION VIGenerative AI

Spring AI Ecosystem

Portable AI abstractions for integrating Large Language Models (LLMs), Vector Databases (PgVector, Pinecone), RAG workflows, and Function Calling with Java safety.

Multi-Model Portability
Vector Store Embeddings
Retrieval-Augmented Generation
Tool & Function Calling

Java SnippetSpring 6+

@RestController
public class AIController {
    private final ChatClient chatClient;
    
    public AIController(ChatClient.Builder builder) {
        this.chatClient = builder.build();
    }
    
    @GetMapping("/ai/prompt")
    public String ask(@RequestParam String query) {
        return chatClient.prompt().user(query).call().content();
    }
}

Explore Architecture Specs

VOLUME II — LANGUAGE INNOVATION

Modern Java 21+ Platform

Open Full Java 21+ Portal

SECTION VIIJava 21 LTS

Virtual Threads (Project Loom)

High-throughput, lightweight threads managed by the JVM instead of OS threads. Million-thread concurrency with traditional synchronous thread-per-request code.

Code SpecificationJava 21 LTS

try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
    IntStream.range(0, 10_000).forEach(i -> {
        executor.submit(() -> {
            Thread.sleep(Duration.ofSeconds(1));
            return i;
        });
    });
}

SECTION VIIIJava 21 LTS

Generational ZGC (Low-Latency)

Scalable zero-pause garbage collector capable of handling terabyte heaps with sub-millisecond maximum pause times.

Code SpecificationJava 21 LTS

# Enable Generational ZGC in Java 21+
java -XX:+UseZGC -XX:+ZGenerational -jar primavera-app.jar

SECTION IXJava 21 LTS

Pattern Matching & Record Patterns

Deconstruct records directly in switch expressions with guards, enabling safe functional programming and algebraic type handling.

Code SpecificationJava 21 LTS

static String formatValue(Object obj) {
    return switch (obj) {
        case Point(int x, int y) -> "Point at (%d, %d)".formatted(x, y);
        case String s when s.length() > 5 -> "Long string: " + s;
        case Integer i -> "Number: " + i;
        default -> "Unknown";
    };
}

SECTION XJava 17 / 21

Sealed Classes & Exhaustive Switches

Restrict subclassing to known permits, guaranteeing compile-time safety and eliminating the need for fallback default cases in switch statements.

Code SpecificationJava 21 LTS

public sealed interface PaymentMethod permits CreditCard, Crypto, BankTransfer {}

public record CreditCard(String cardNumber) implements PaymentMethod {}
public record Crypto(String walletAddress) implements PaymentMethod {}
public record BankTransfer(String iban) implements PaymentMethod {}