# Java Ecosystem > Java 25 development patterns for the crypto-scout ecosystem including microservices, ActiveJ, and async I/O Use when this capability is needed. - Skill: `tomevault-io/java-ecosystem` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/java-ecosystem` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/java-ecosystem/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/java-ecosystem --- ## What I Do Provide comprehensive guidance for Java 25 development across the crypto-scout ecosystem, covering microservice patterns, ActiveJ framework usage, and async I/O operations. ## Core Architecture ### Launcher Pattern (ActiveJ) ```java public final class Service extends Launcher { @Override protected Module getModule() { return combine( JmxModule.create(), ServiceGraphModule.create(), CoreModule.create(), ServiceModule.create(), WebModule.create() ); } @Override protected void onStart() throws Exception { ConfigValidator.validate(); } @Override protected void run() throws Exception { awaitShutdown(); } public static void main(String[] args) throws Exception { new Service().launch(args); } } ``` ### Module Structure by Service | Module | Purpose | Services Using | |--------|---------|----------------| | CoreModule | Reactor and virtual thread executor | All services | | WebModule | HTTP server, clients, health routes | All services | | ClientModule | AMQP publisher lifecycle | crypto-scout-client | | CollectorModule | Repositories and services | crypto-scout-collector | | AnalystModule | Analysis services and transformers | crypto-scout-analyst | | BybitSpotModule | Bybit spot WebSocket consumers | crypto-scout-client | | BybitLinearModule | Bybit linear WebSocket consumers | crypto-scout-client | | CmcParserModule | CoinMarketCap parser | crypto-scout-client | ### Reactive Service Pattern ```java public final class MyService extends AbstractReactive implements ReactiveService { private final Executor executor; private volatile Resource resource; public static MyService create(NioReactor reactor, Executor executor) { return new MyService(reactor, executor); } private MyService(NioReactor reactor, Executor executor) { super(reactor); this.executor = executor; } @Override public Promise start() { return Promise.ofBlocking(executor, () -> { // Initialize resources resource = createResource(); }); } @Override public Promise stop() { return Promise.ofBlocking(executor, () -> { // Cleanup resources closeResource(resource); resource = null; }); } } ``` ### Stream Transformer Pattern (Analyst) ```java public final class AnalystTransformer extends AbstractStreamTransformer { @Override protected StreamDataAcceptor onResumed(final StreamDataAcceptor output) { return in -> { try { final var result = process(in); output.accept(result); } catch (final Exception ex) { LOGGER.error("Processing failed", ex); output.accept(new StreamPayload(in.stream(), in.offset(), null)); } }; } } ``` ## Code Style Essentials ### File Structure ``` 1-23: MIT License header 25: Package declaration 26: Blank line 27+: Imports (java.* → third-party → static) Blank line Class declaration ``` ### Import Organization ```java import java.io.IOException; import java.nio.file.Path; import java.time.Duration; import com.rabbitmq.stream.Environment; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import static com.github.akarazhev.cryptoscout.config.Constants.AmqpConfig.AMQP_RABBITMQ_HOST; ``` ### Naming Conventions | Element | Convention | Example | |---------|------------|---------| | Classes | PascalCase | `StreamService`, `AmqpPublisher` | | Methods | camelCase with verb | `waitForDatabaseReady` | | Constants | UPPER_SNAKE_CASE | `JDBC_URL`, `DB_USER` | | Locals | `final var` | `final var timeout` | | Tests | `Test` | `AmqpPublisherTest` | | Test methods | `should` | `shouldPublishPayload` | ### Error Handling ```java // Invalid state if (resource == null) { throw new IllegalStateException("Resource not initialized: " + name); } // Try-with-resources try (final var conn = dataSource.getConnection(); final var stmt = conn.prepareStatement(sql)) { // Use resources } catch (final SQLException e) { throw new IllegalStateException("Database error", e); } // Interrupt handling try { Thread.sleep(duration.toMillis()); } catch (final InterruptedException e) { Thread.currentThread().interrupt(); } ``` ## Exception Hierarchy (jcryptolib) ``` JCryptoLibException (base) ├── ApiException ├── CmcApiException ├── StreamException ├── CircuitBreakerException ├── RateLimiterException ├── HealthCheckException ├── ResilienceException └── ConfigurationException ``` Usage: ```java // In jcryptolib try { // operation } catch (final SomeException e) { throw new StreamException("Message", e); } // In services } catch (final SQLException e) { throw new IllegalStateException("Database operation failed", e); } ``` ## Testing Patterns ### JUnit 6 (Jupiter) ```java final class MyServiceTest { @BeforeAll static void setUp() { PodmanCompose.up(); } @AfterAll static void tearDown() { PodmanCompose.down(); } @Test void shouldServiceStartSuccessfully() throws Exception { final var service = createTestService(); assertTrue(service.start().isResult()); } } ``` ### Mock Data Usage ```java // Load test fixtures final var spotKlines = MockData.get( MockData.Source.BYBIT_SPOT, MockData.Type.KLINE_1 ); final var fgi = MockData.get( MockData.Source.CRYPTO_SCOUT, MockData.Type.FGI ); ``` ## Configuration Pattern ```java static final String VALUE = System.getProperty("property.key", "defaultValue"); static final int PORT = Integer.parseInt(System.getProperty("port.key", "5552")); static final Duration TIMEOUT = Duration.ofMinutes(Long.getLong("timeout.key", 3L)); ``` ## Key Classes Reference ### jcryptolib | Class | Purpose | |-------|---------| | `BybitStream` | WebSocket streaming with resilience | | `BybitParser` | REST API data fetching | | `CmcParser` | CoinMarketCap data parser | | `AnalystEngine` | Technical analysis indicators | | `Payload` | Stream data container | | `CircuitBreaker` | Resilience pattern | | `RateLimiter` | Rate limiting | | `JsonUtils` | JSON serialization | ### crypto-scout-client | Class | Purpose | |-------|---------| | `Client` | Service launcher | | `AmqpPublisher` | RabbitMQ Streams publisher | | `AbstractBybitStreamConsumer` | Base for Bybit consumers | | `CmcParserConsumer` | CMC data consumer | ### crypto-scout-collector | Class | Purpose | |-------|---------| | `Collector` | Service launcher | | `StreamService` | Stream consumer orchestrator | | `BybitStreamService` | Bybit data processor | | `CryptoScoutService` | CMC data processor | | `*Repository` | Database access | ### crypto-scout-analyst | Class | Purpose | |-------|---------| | `Analyst` | Service launcher | | `StreamService` | Stream processing orchestrator | | `DataService` | Async data processing | | `AnalystTransformer` | Stream transformer | | `StreamPublisher` | Output publisher | ## When to Use Me Use this skill when: - Writing new Java classes or services - Understanding ActiveJ patterns and lifecycle - Implementing reactive services with Promise/async - Organizing imports and file structure - Following error handling and logging conventions - Writing JUnit 6 tests with proper lifecycle - Configuring services via system properties - Implementing stream transformers - Working with jcryptolib abstractions --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/akarazhev) — claim your Tome and manage your conversions.