quarkus-patterns

Quarkus-Entwicklungsmuster (Quarkus Development Patterns)

Quarkus 3.x-Architektur- und API-Muster für cloud-native, ereignisgesteuerte Dienste mit Apache Camel.

Wann zu aktivieren

• Erstellen von REST-APIs mit JAX-RS oder RESTEasy Reactive
• Strukturieren von Ressourcen → Service → Repository-Schichten
• Implementieren von ereignisgesteuerten Mustern mit Apache Camel und RabbitMQ
• Konfigurieren von Hibernate Panache, Caching oder reaktiven Streams
• Hinzufügen von Validierung, Exception-Mapping oder Paginierung
• Einrichten von Profilen für dev/staging/production-Umgebungen (YAML-Konfiguration)
• Benutzerdefiniertes Logging mit LogContext und Logback/Logstash-Encoder
• Arbeiten mit CompletableFuture für asynchrone Vorgänge
• Implementieren von bedingter Flussverarbeitung
• Arbeiten mit GraalVM-nativer Kompilierung

Service-Schicht mit mehreren Abhängigkeiten

@Slf4j
@ApplicationScoped
@RequiredArgsConstructor
public class OrderProcessingService {

    private final OrderValidator orderValidator;
    private final EventService eventService;
    private final OrderRepository orderRepository;
    private final FulfillmentPublisher fulfillmentPublisher;
    private final AuditPublisher auditPublisher;

    @Transactional
    public OrderReceipt process(CreateOrderCommand command) {
        ValidationResult validation = orderValidator.validate(command);
        if (!validation.valid()) {
            eventService.createErrorEvent(command, "ORDER_REJECTED", validation.message());
            throw new WebApplicationException(validation.message(), Response.Status.BAD_REQUEST);
        }

        Order order = Order.from(command);
        orderRepository.persist(order);

        OrderReceipt receipt = OrderReceipt.from(order);
        fulfillmentPublisher.publishAsync(receipt);
        auditPublisher.publish("ORDER_ACCEPTED", receipt);
        eventService.createSuccessEvent(receipt, "ORDER_ACCEPTED");

        log.info("Processed order {}", order.id);
        return receipt;
    }
}

Wichtige Muster:

• @RequiredArgsConstructor für Konstruktorinjektion über Lombok
• @Slf4j für Logback-Logging
• @Transactional auf Service-Methoden, die über Panache oder Repositories schreiben
• Validierung der Eingabe vor Persistenz oder Nachrichtenveröffentlichung
• Ereignisverfolgung für Erfolgs-/Fehlerszenarien
• Asynchrones Camel-Nachrichten-Publishing

Benutzerdefiniertes Logging-Kontext-Muster (Logback)

@ApplicationScoped
public class ProcessingService {

    public void processDocument(Document doc) {
        LogContext logContext = CustomLog.getCurrentContext();
        try (SafeAutoCloseable ignored = CustomLog.startScope(logContext)) {
            // Kontext zu allen Log-Anweisungen hinzufügen
            logContext.put("documentId", doc.getId().toString());
            logContext.put("documentType", doc.getType());
            logContext.put("userId", SecurityContext.getUserId());

            log.info("Starting document processing");

            // Alle Logs innerhalb dieses Gültigkeitsbereichs erben den Kontext
            processInternal(doc);

            log.info("Document processing completed");
        } catch (Exception e) {
            log.error("Document processing failed", e);
            throw e;
        }
    }
}

Logback-Konfiguration (logback.xml):

<configuration>
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="net.logstash.logback.encoder.LogstashEncoder">
            <includeContext>true</includeContext>
            <includeMdc>true</includeMdc>
        </encoder>
    </appender>

    <logger name="com.example" level="INFO"/>
    <root level="WARN">
        <appender-ref ref="CONSOLE"/>
    </root>
</configuration>

Ereignisdienst-Muster (Event Service Pattern)

@Slf4j
@ApplicationScoped
@RequiredArgsConstructor
public class EventService {
    private final EventRepository eventRepository;
    private final ObjectMapper objectMapper;

    public void createSuccessEvent(Object payload, String eventType) {
        Objects.requireNonNull(payload, "Payload cannot be null");
        Event event = new Event();
        event.setType(eventType);
        event.setStatus(EventStatus.SUCCESS);
        event.setPayload(serializePayload(payload));
        event.setTimestamp(Instant.now());

        eventRepository.persist(event);
        log.info("Success event created: {}", eventType);
    }

    public void createErrorEvent(Object payload, String eventType, String errorMessage) {
        Objects.requireNonNull(payload, "Payload cannot be null");
        if (errorMessage == null || errorMessage.isBlank()) {
            throw new IllegalArgumentException("Error message cannot be blank");
        }
        Event event = new Event();
        event.setType(eventType);
        event.setStatus(EventStatus.ERROR);
        event.setErrorMessage(errorMessage);
        event.setPayload(serializePayload(payload));
        event.setTimestamp(Instant.now());

        eventRepository.persist(event);
        log.error("Error event created: {} - {}", eventType, errorMessage);
    }

    private String serializePayload(Object payload) {
        try {
            return objectMapper.writeValueAsString(payload);
        } catch (JsonProcessingException e) {
            throw new IllegalStateException("Failed to serialize event payload", e);
        }
    }
}

Camel-Nachrichten-Publishing (RabbitMQ)

@Slf4j
@ApplicationScoped
@RequiredArgsConstructor
public class BusinessRulesPublisher {
    private final ProducerTemplate producerTemplate;

    public void publishSync(BusinessRulesPayload payload) {
        producerTemplate.sendBody(
            "direct:business-rules-publisher",
            payload
        );
    }
}

Camel-Routen-Konfiguration:

@ApplicationScoped
public class BusinessRulesRoute extends RouteBuilder {

    @ConfigProperty(name = "camel.rabbitmq.queue.business-rules")
    String businessRulesQueue;

    @ConfigProperty(name = "rabbitmq.host")
    String rabbitHost;

    @ConfigProperty(name = "rabbitmq.port")
    Integer rabbitPort;

    @Override
    public void configure() {
        from("direct:business-rules-publisher")
            .routeId("business-rules-publisher")
            .log("Publishing message to RabbitMQ: ${body}")
            .marshal().json(JsonLibrary.Jackson)
            .toF("spring-rabbitmq:%s?hostname=%s&portNumber=%d",
                businessRulesQueue, rabbitHost, rabbitPort);
    }
}

Camel-Direkt-Routen (In-Memory)

@ApplicationScoped
public class DocumentProcessingRoute extends RouteBuilder {

    @Override
    public void configure() {
        // Fehlerbehandlung
        onException(ValidationException.class)
            .handled(true)
            .to("direct:validation-error-handler")
            .log("Validation error: ${exception.message}");

        // Hauptverarbeitungsroute
        from("direct:process-document")
            .routeId("document-processing")
            .log("Processing document: ${header.documentId}")
            .bean(DocumentValidator.class, "validate")
            .bean(DocumentTransformer.class, "transform")
            .choice()
                .when(header("documentType").isEqualTo("INVOICE"))
                    .to("direct:process-invoice")
                .when(header("documentType").isEqualTo("CREDIT_NOTE"))
                    .to("direct:process-credit-note")
                .otherwise()
                    .to("direct:process-generic")
            .end();

        from("direct:validation-error-handler")
            .bean(EventService.class, "createErrorEvent")
            .log("Validation error handled");
    }
}

Camel-Dateiverarbeitung

@ApplicationScoped
public class FileMonitoringRoute extends RouteBuilder {

    @ConfigProperty(name = "file.input.directory")
    String inputDirectory;

    @ConfigProperty(name = "file.processed.directory")
    String processedDirectory;

    @ConfigProperty(name = "file.error.directory")
    String errorDirectory;

    @Override
    public void configure() {
        from("file:" + inputDirectory + "?move=" + processedDirectory +
             "&moveFailed=" + errorDirectory + "&delay=5000")
            .routeId("file-monitor")
            .log("Processing file: ${header.CamelFileName}")
            .to("direct:process-file");

        from("direct:process-file")
            .bean(OrderProcessingService.class, "processFile")
            .log("File processing completed");
    }
}

Camel-Bean-Aufruf

@ApplicationScoped
public class InvoiceRoute extends RouteBuilder {

    @Override
    public void configure() {
        from("direct:invoice-validation")
            .bean(InvoiceFlowValidator.class, "validateFlowWithConfig")
            .log("Validation result: ${body}");

        from("direct:persist-and-publish")
            .bean(DocumentJobService.class, "createDocumentAndJobEntities")
            .bean(BusinessRulesPublisher.class, "publishAsync")
            .bean(EventService.class, "createSuccessEvent(${body}, 'PUBLISHED')");
    }
}

REST-API-Struktur

@Path("/api/documents")
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
@RequiredArgsConstructor
public class DocumentResource {
  private final DocumentService documentService;

  @GET
  public Response list(
      @QueryParam("page") @DefaultValue("0") int page,
      @QueryParam("size") @DefaultValue("20") int size) {
    List<Document> documents = documentService.list(page, size);
    return Response.ok(documents).build();
  }

  @POST
  public Response create(@Valid CreateDocumentRequest request, @Context UriInfo uriInfo) {
    Document document = documentService.create(request);
    URI location = uriInfo.getAbsolutePathBuilder()
        .path(String.valueOf(document.id))
        .build();
    return Response.created(location).entity(DocumentResponse.from(document)).build();
  }

  @GET
  @Path("/{id}")
  public Response getById(@PathParam("id") Long id) {
    return documentService.findById(id)
        .map(DocumentResponse::from)
        .map(Response::ok)
        .orElse(Response.status(Response.Status.NOT_FOUND))
        .build();
  }
}

Repository-Muster (Panache Repository)

@ApplicationScoped
public class DocumentRepository implements PanacheRepository<Document> {

  public List<Document> findByStatus(DocumentStatus status, int page, int size) {
    return find("status = ?1 order by createdAt desc", status)
        .page(page, size)
        .list();
  }

  public Optional<Document> findByReferenceNumber(String referenceNumber) {
    return find("referenceNumber", referenceNumber).firstResultOptional();
  }

  public long countByStatusAndDate(DocumentStatus status, LocalDate date) {
    return count("status = ?1 and createdAt >= ?2", status, date.atStartOfDay());
  }
}

Service-Schicht mit Transaktionen

@ApplicationScoped
@RequiredArgsConstructor
public class DocumentService {
  private final DocumentRepository repo;
  private final EventService eventService;

  @Transactional
  public Document create(CreateDocumentRequest request) {
    Document document = new Document();
    document.setReferenceNumber(request.referenceNumber());
    document.setDescription(request.description());
    document.setStatus(DocumentStatus.PENDING);
    document.setCreatedAt(Instant.now());

    repo.persist(document);

    eventService.createSuccessEvent(document, "DOCUMENT_CREATED");

    return document;
  }

  public Optional<Document> findById(Long id) {
    return repo.findByIdOptional(id);
  }

  public List<Document> list(int page, int size) {
    return repo.findAll()
        .page(page, size)
        .list();
  }
}

DTOs und Validierung

public record CreateDocumentRequest(
    @NotBlank @Size(max = 200) String referenceNumber,
    @NotBlank @Size(max = 2000) String description,
    @NotNull @FutureOrPresent Instant validUntil,
    @NotEmpty List<@NotBlank String> categories) {}

public record DocumentResponse(Long id, String referenceNumber, DocumentStatus status) {
  public static DocumentResponse from(Document document) {
    return new DocumentResponse(document.getId(), document.getReferenceNumber(),
        document.getStatus());
  }
}

Exception-Mapping

@Provider
public class ValidationExceptionMapper implements ExceptionMapper<ConstraintViolationException> {
  @Override
  public Response toResponse(ConstraintViolationException exception) {
    String message = exception.getConstraintViolations().stream()
        .map(cv -> cv.getPropertyPath() + ": " + cv.getMessage())
        .collect(Collectors.joining(", "));

    return Response.status(Response.Status.BAD_REQUEST)
        .entity(Map.of("error", "validation_error", "message", message))
        .build();
  }
}

@Provider
@Slf4j
public class GenericExceptionMapper implements ExceptionMapper<Exception> {

  @Override
  public Response toResponse(Exception exception) {
    log.error("Unhandled exception", exception);
    return Response.status(Response.Status.INTERNAL_SERVER_ERROR)
        .entity(Map.of("error", "internal_error", "message", "An unexpected error occurred"))
        .build();
  }
}

CompletableFuture-Asynchrone-Vorgänge

@Slf4j
@ApplicationScoped
@RequiredArgsConstructor
public class FileStorageService {
    private final S3Client s3Client;
    private final ExecutorService executorService;

    @ConfigProperty(name = "storage.bucket-name")
    String bucketName;

    public CompletableFuture<StoredDocumentInfo> uploadOriginalFile(
            InputStream inputStream,
            long size,
            LogContext logContext,
            InvoiceFormat format) {

        return CompletableFuture.supplyAsync(() -> {
            try (SafeAutoCloseable ignored = CustomLog.startScope(logContext)) {
                String path = generateStoragePath(format);

                PutObjectRequest request = PutObjectRequest.builder()
                    .bucket(bucketName)
                    .key(path)


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