IV99246: A MQ Java send exit is only invoked for the last TSH packet sentover TCP/IP when sending a message larger than 32KB

APAR status

• Closed as program error.

Error description

• A MQ classes for JMS or MQ classes for Java application sends a
  message to a queue, where the message size (including message
  headers) is larger than 32KB, over a TCP/IP CLIENT connections,
  a configured channel send exit is only invoked for the final
  transmission segment sent to the queue manager.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the:
  
    - WebSphere MQ V7.1 classes for JMS
    - WebSphere MQ V7.1 classes for Java
    - WebSphere MQ V7.1 JCA Resource Adapter
  
    - WebSphere MQ V7.5 classes for JMS
    - WebSphere MQ V7.5 classes for Java
    - WebSphere MQ V7.5 JCA Resource Adapter
  
    - WebSphere Application Server V8.5 MQ messaging provider
  
  who have applications that are configured as follows:
  
  (a) Create CLIENT mode transport connections to a queue manager
  
  (b) Have configured one or more channel send exits
  
  (c) Send messages that are greater than the maximum transmission
  segment size for the connection
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When an MQ classes for JMS or MQ classes for Java application
  connects to a queue manager using the CLIENT transport mode, the
  unit of data that is transmitted in a single flow between the
  client and queue manager message channel agents (MCAs) is called
  a transmission segment.  A transmission segment has a maximum
  allowable size, negotiated when the MQ Java/JMS classes connect
  to the queue manager.
  
  When an application sends a message which combined size (message
  headers plus the body size) is larger than the negotiated
  maximum size of the single transmission segment, the message is
  segmented and transmitted using multiple transmission segment
  flows.
  
  If the application had configured a channel send exit to run on
  the transmitted data, then the exit would have only been invoked
  on the last transmission segment flow required to complete the
  sending of the entire message.  The exit would not have been
  invoked for any of the preceding transmission segments.
  
  For example, if a single message was broken up into five
  transmission segments in order to not exceed the maximum
  transmission segment size, the configured send exit would not
  have been invoked for the first four transmission segments.  The
  exit would have only been invoked for the final, fifth,
  transmission segment.
  
  
  Note: The maximum transmission segment size is negotiated
  between the client and queue manager when a TCP/IP connection is
  initially established.  For non-secure TCP/IP connections the
  value negotiated is in the region of 32KB.  For TLS secured
  connections, the maximum size of a TSH flow is in the region of
  16KB.
  

Problem conclusion

• The WebSphere MQ Java clients have been updated to ensure that
  channel send exits are called for each Transmission Segment
  Header (TSH) flow required to send a message that is larger the
  maximum allowable size for a single TSH.
  
  The problem addressed by this APAR does not affect the MQ V8 or
  MQ V9 Java/JMS applications.  However, this APAR has been used
  to deliver some serviceability improvements on these versions of
  the product.  The product code changes delivered to the MQ V8
  and MQ V9 Java clients are therefore not functional changes.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.5       7.5.0.9
  v8.0       8.0.0.9
  v9.0 CD    9.0.5
  v9.0 LTS   9.0.0.3
  
  The latest available 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 LIN X86 V7

• Fixed component ID

  5724H7224

Applicable component levels

• R710 PSY

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