Apache Camel FTP error

Question

I am working on a piece of code that routes from FTP input to a bean process and then to FTP output. The process takes about 15 minutes to complete and when it finishes, the Camel tries to delete a input file from FTP input route. Currently the FTP server throws an error:

13 Jan 2015 18:21:26 DEBUG org.apache.camel.component.file.remote.FtpOperations.deleteFile - Deleting file: ../flex-brazil/Portal_Forn/request_appr/364/NF_4.txt
13 Jan 2015 18:21:26  WARN org.slf4j.helpers.MarkerIgnoringBase.warn - Error during commit. Exchange[org.apache.camel.component.file.GenericFileMessage@3207779]. Caused by: [org.apache.camel.component.file.GenericFileOperationFailedException - File operation failed: 421 Timeout (900 seconds): closing control connection.
FTP response 421 received.  Server closed connection.. Code: 421]
org.apache.camel.component.file.GenericFileOperationFailedException: File operation failed: 421 Timeout (900 seconds): closing control connection.
FTP response 421 received.  Server closed connection.. Code: 421
at org.apache.camel.component.file.remote.FtpOperations.getCurrentDirectory(FtpOperations.java:701)
at org.apache.camel.component.file.remote.FtpOperations.deleteFile(FtpOperations.java:224)
at org.apache.camel.component.file.strategy.GenericFileDeleteProcessStrategy.commit(GenericFileDeleteProcessStrategy.java:71)
at org.apache.camel.component.file.GenericFileOnCompletion.processStrategyCommit(GenericFileOnCompletion.java:124)
at org.apache.camel.component.file.GenericFileOnCompletion.onCompletion(GenericFileOnCompletion.java:80)
at org.apache.camel.component.file.GenericFileOnCompletion.onComplete(GenericFileOnCompletion.java:54)
at org.apache.camel.util.UnitOfWorkHelper.doneSynchronizations(UnitOfWorkHelper.java:100)
at org.apache.camel.impl.DefaultUnitOfWork.done(DefaultUnitOfWork.java:228)
at org.apache.camel.util.UnitOfWorkHelper.doneUow(UnitOfWorkHelper.java:61)
at org.apache.camel.processor.CamelInternalProcessor$UnitOfWorkProcessorAdvice.after(CamelInternalProcessor.java:613)
at org.apache.camel.processor.CamelInternalProcessor$UnitOfWorkProcessorAdvice.after(CamelInternalProcessor.java:581)
at org.apache.camel.processor.CamelInternalProcessor$InternalCallback.done(CamelInternalProcessor.java:240)
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:173)
at org.apache.camel.component.file.GenericFileConsumer.processExchange(GenericFileConsumer.java:401)
at org.apache.camel.component.file.remote.RemoteFileConsumer.processExchange(RemoteFileConsumer.java:99)
at org.apache.camel.component.file.GenericFileConsumer.processBatch(GenericFileConsumer.java:201)
at org.apache.camel.component.file.GenericFileConsumer.poll(GenericFileConsumer.java:165)
at org.apache.camel.impl.ScheduledPollConsumer.doRun(ScheduledPollConsumer.java:187)
at org.apache.camel.impl.ScheduledPollConsumer.run(ScheduledPollConsumer.java:114)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.commons.net.ftp.FTPConnectionClosedException: FTP response 421 received.  Server closed connection.
at org.apache.commons.net.ftp.FTP.__getReply(FTP.java:367)
at org.apache.commons.net.ftp.FTP.__getReply(FTP.java:294)
at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:483)
at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:608)
at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:582)
at org.apache.commons.net.ftp.FTP.pwd(FTP.java:1454)
at org.apache.commons.net.ftp.FTPClient.printWorkingDirectory(FTPClient.java:2658)
at org.apache.camel.component.file.remote.FtpOperations.getCurrentDirectory(FtpOperations.java:697)
... 25 more

There are any parameter to teach the Camel to send keepalives to FTP server to avoid this situation?

Answer 1

I suggest to split the whole process into two routes:

1. Reader Route: Only reads the file from the FTP server.
2. Process and Writer Route: This route processes the incoming message and writes a response to the FTP server

The advantage is, that the connection will be closed after reading and deleting without exception. When a new message will be written back to server a new connection will be created.

The first route can only close the connection, when the process is asynchronous. For this purpose you can use queues for reading and writing e.g. seda or jms.

Answer 2

You may consider to set a bigger timeout option - the default is 30s.

To set the timeout to 15 minutes: ftp://user@host?timeout=900000

Keep in mind, however, that the connection may be closed by the FTP server.