IT12287: IMPROVE THE WAY MANAGED FILE TRANSFER PROTOCOL BRIDGE AGENTS HANDLE FTP REPLY CODES

APAR status

• Closed as program error.

Error description

• MQ Managed File Transfer protocol bridge agents currently treat
  FTP Reply Codes as being the result of unrecoverable errors. If
  a file server returns an FTP Reply Code indicating that a
  problem has occurred while trying to write the last piece of
  file data,
  then the  protocol bridge agent will mark the managed transfer
  as
  "Failed".
  
  The FTP Specification states that FTP Reply Codes in the range
  4xx represent Transient Negative Completion replies, and that
  the action which resulted in the FTP Reply Code being generated
  should be retried.
  
  This APAR is being raised to add new logic to the protocol
  bridge agent to ensure that it will retry a managed transfer if
  a file server returned an FTP Reply Code in the 4xx range just
  after
  the last piece of file data has been written.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This new function affects users of MQ V8.0 Managed File Transfer
  protocol bridge agents that connect to file servers using either
  the FTP or FTPS protocol.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When an MQ Managed File Transfer protocol bridge agent is acting
  as a Destination Agent in a managed transfer, and is connecting
  to a file server using either the FTP or FTPS protocol, it will
  establish two connections to the file server:
  
  - A control connection. This is used by the Protocol Bridge
  Agent and the file server to initiate file transfers, and
  monitor their state.
  - A data connection, which is used to send the file data to the
  file server.
  
  If a file transfer is in progress, and the file server
  encounters an issue, it will send an FTP reply code indicating
  the nature of the issue to the protocol bridge. FTP reply codes
  in the 4xx range represent transient issues, while FTP reply
  codes in the 5xx range represent a permanent issues which will
  prevent the managed transfer from completing.
  
  APARs IT08384 and IT09538 introduced logic to the protocol
  bridge agent to ensure that if a file server sent either FTP
  reply code 425 or 426 to the agent after the last piece of file
  data had been written to the file server, the agent put the
  managed transfer into recovery. However, if a file server sent
  any other FTP reply code in the 4xx range, or the 5xx range, to
  the protocol bridge agent, the agent incorrectly assumed that
  the reply code had already been handled, and so ignored it. As a
  result of this, the transfer item that was being transferred
  when the issue occurred was marked as as being "Successful",
  even though the file was not successfully written by the file
  server.
  

Problem conclusion

• The logic that was introduced to the protocol bridge agent as
  part of APARs IT08384 andIT09538 has been expanded to handle the
  other FTP reply codes in the 4xx range. These FTP reply codes
  are shown below:
  
  421 	Service not available, closing control connection. This
  may be a reply to any command if the service knows it must shut
  down.
  430 	Invalid username or password
  434 	Requested host unavailable.
  450 	Requested file action not taken.
  451 	Requested action aborted. Local error in processing.
  452 	Requested action not taken. Insufficient storage space
  in system. File unavailable (e.g., file busy).
  
  If a file server returns any of these FTP reply codes after the
  last piece of the file data has been written to the file server,
  the protocol bridge agent will put the managed transfer into
  recovery.
  
  The protocol bridge agent has also been updated so that, if the
  file server returns an FTP reply code in 5xx range after the
  last piece of file data has been written, the managed transfer
  is marked as "Failed". The FTP reply codes in the 5xx range that
  will cause a managed transfer to be marked as "Failed" in this
  situation are shown below for reference:
  
  501 	Syntax error in parameters or arguments.
  502 	Command not implemented.
  503 	Bad sequence of commands.
  504 	Command not implemented for that parameter.
  530 	Not logged in.
  532 	Need account for storing files.
  550 	Requested action not taken. File unavailable (e.g.,
  file not found, no access).
  551 	Requested action aborted. Page type unknown.
  552 	Requested file action aborted. Exceeded storage
  allocation (for current directory or dataset).
  553 	Requested action not taken. File name not allowed.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v8.0       8.0.0.5
  
  The latest available FTE maintenance can be obtained from
  'Fix List for WebSphere MQ File Transfer Edition 7.0'
  http://www-01.ibm.com/support/docview.wss?uid=swg27015313
  
  The latest available MQ maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  WMQ MFT V8.0

• Fixed component ID

  5724H7252

Applicable component levels

• R800 PSY

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