Spring Integration - 处理陈旧的 sftp 会话

Question

我已经实现了以下场景：

1. 一个queueChannel以字节[]的形式保存消息
2. MessageHandler，轮询队列通道并通过 sftp 上传文件
3. 一个 Transformer，监听 errorChannel 并将从失败消息中提取的有效负载发送回 queueChannel（被认为是处理失败消息的错误处理程序，因此不会丢失任何内容）

如果 sftp 服务器在线，一切正常。

如果 sftp 服务器关闭，则作为转换器到达的错误消息是：

org.springframework.messaging.MessagingException: Failed to obtain pooled item; nested exception is java.lang.IllegalStateException: failed to create SFTP Session

转换器对此无能为力，因为有效负载的 failedMessage 为 null 并且本身会引发异常。转换器丢失了消息。

如何配置我的流程以使转换器获得正确的消息以及未成功上传文件的相应负载？

我的配置：

  @Bean
  public MessageChannel toSftpChannel() {
    final QueueChannel channel = new QueueChannel();
    channel.setLoggingEnabled(true);
    return new QueueChannel();
  }

  @Bean
  public MessageChannel toSplitter() {
    return new PublishSubscribeChannel();
  }

  @Bean
  @ServiceActivator(inputChannel = "toSftpChannel", poller = @Poller(fixedDelay = "10000", maxMessagesPerPoll = "1"))
  public MessageHandler handler() {
    final SftpMessageHandler handler = new SftpMessageHandler(sftpSessionFactory());
    handler.setRemoteDirectoryExpression(new LiteralExpression(sftpRemoteDirectory));
    handler.setFileNameGenerator(message -> {
      if (message.getPayload() instanceof byte[]) {
        return (String) message.getHeaders().get("name");
      } else {
        throw new IllegalArgumentException("byte[] expected in Payload!");
      }
    });
    return handler;
  }

  @Bean
  public SessionFactory<LsEntry> sftpSessionFactory() {
    final DefaultSftpSessionFactory factory = new DefaultSftpSessionFactory(true);

    final Properties jschProps = new Properties();
    jschProps.put("StrictHostKeyChecking", "no");
    jschProps.put("PreferredAuthentications", "publickey,password");
    factory.setSessionConfig(jschProps);

    factory.setHost(sftpHost);
    factory.setPort(sftpPort);
    factory.setUser(sftpUser);
    if (sftpPrivateKey != null) {
      factory.setPrivateKey(sftpPrivateKey);
      factory.setPrivateKeyPassphrase(sftpPrivateKeyPassphrase);
    } else {
      factory.setPassword(sftpPasword);
    }
    factory.setAllowUnknownKeys(true);
    return new CachingSessionFactory<>(factory);
  }

  @Bean
  @Splitter(inputChannel = "toSplitter")
  public DmsDocumentMessageSplitter splitter() {
    final DmsDocumentMessageSplitter splitter = new DmsDocumentMessageSplitter();
    splitter.setOutputChannelName("toSftpChannel");
    return splitter;
  }

  @Transformer(inputChannel = "errorChannel", outputChannel = "toSftpChannel")
  public Message<?> errorChannelHandler(ErrorMessage errorMessage) throws RuntimeException {

    Message<?> failedMessage = ((MessagingException) errorMessage.getPayload())
      .getFailedMessage();
    return MessageBuilder.withPayload(failedMessage)
                         .copyHeadersIfAbsent(failedMessage.getHeaders())
                         .build();
  }

  @MessagingGateway 
  public interface UploadGateway {

    @Gateway(requestChannel = "toSplitter")
    void upload(@Payload List<byte[]> payload, @Header("header") DmsDocumentUploadRequestHeader header);
  }

谢谢..

更新

@Bean(PollerMetadata.DEFAULT_POLLER)
@Transactional(propagation = Propagation.REQUIRED, isolation = Isolation.READ_COMMITTED)
  PollerMetadata poller() {
    return Pollers
      .fixedRate(5000)
      .maxMessagesPerPoll(1)
      .receiveTimeout(500)
      .taskExecutor(taskExecutor())
      .transactionSynchronizationFactory(transactionSynchronizationFactory())
      .get();
  }

  @Bean
  @ServiceActivator(inputChannel = "toMessageStore", poller = @Poller(PollerMetadata.DEFAULT_POLLER))
  public BridgeHandler bridge() {
    BridgeHandler bridgeHandler = new BridgeHandler();
    bridgeHandler.setOutputChannelName("toSftpChannel");
    return bridgeHandler;
  }

Answer 1

null failedMessage 是一个错误；转载INT-4421。

我不建议在这种情况下使用QueueChannel。如果您使用直接渠道，您可以配置retry advice 以尝试重新投递。当重试次数用尽时（如果这样配置），异常将被抛回调用线程。

将建议添加到SftpMessageHandler 的adviceChain 属性。

编辑

您可以通过在可轮询通道和 sftp 适配器之间插入桥接来解决“丢失”失败消息：

@Bean
@ServiceActivator(inputChannel = "toSftpChannel", poller = @Poller(fixedDelay = "5000", maxMessagesPerPoll = "1"))
public BridgeHandler bridge() {
    BridgeHandler bridgeHandler = new BridgeHandler();
    bridgeHandler.setOutputChannelName("toRealSftpChannel");
    return bridgeHandler;
}

@Bean
@ServiceActivator(inputChannel = "toRealSftpChannel")
public MessageHandler handler() {
    final SftpMessageHandler handler = new SftpMessageHandler(sftpSessionFactory());
    handler.setRemoteDirectoryExpression(new LiteralExpression("foo"));
    handler.setFileNameGenerator(message -> {
        if (message.getPayload() instanceof byte[]) {
            return (String) message.getHeaders().get("name");
        }
        else {
            throw new IllegalArgumentException("byte[] expected in Payload!");
        }
    });
    return handler;
}