IT33541: USING THE INTEGRATION API TO STOP A MESSAGE FLOW FROM WITHIN A JCN IN THAT FLOW CAUSES A DEADLOCK

APAR status

• Closed as program error.

Error description

• A message flow cannot be stopped while it is currently
  processing a message. The stop request will wait for any
  message that is currently being processed to finish before
  performing the stop.
  
  The IntegrationAPI can be used to stop a
  message flow using the MessageFlowProxy object. A Java Compute
  node can be used to retrieve a MessageFlowProxy object that
  represents the message flow that the Java Compute node is
  deployed in. It is therefore possible to stop a message flow
  from within that same message flow.
  
  At v10 such requests from
  the IntegrationAPI are processed asynchronously by default,
  meaning that the message flow can continuing processing
  immediately after it has issue the stop request which will
  allow the stop request to be processed once the flow has
  finished.
  
  At v11 such requests are now synchronous, meaning
  they will block the message flow until a response has been
  returned for the request. This is an intentional change in
  behaviour as documented in the Knowledge Center. Since this
  request is now synchronous, it prevents the message flow from
  finishing until a response has been received. This leads to a
  deadlock where the flow cannot be stopped because it is waiting
  for itself to be stopped.
  
  Eventually the stop request will
  timeout and the flow will continue with an exception, after
  approximately 5 minutes.
  

Local fix

• Use a HTTPAsyncRequest node to manually invoke POST to the http:
  //hostname:adminPort/apiv2/servers/EG_NAME/applications/APP_NAME
  /messageflows/FLOW_NAME/teardown. Deploy an associated
  HTTPAsyncResponse node that is wired to any node, e.g. a Trace
  node, to make the deployment valid.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  All users of IBM App Connect Enterprise v11 who use the
  Integration API within a Java Compute Node to stop the message
  flow that the Java Compute Node is deployed in.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A message flow cannot be stopped while it is currently
  processing a message. The stop request will wait for any message
  that is currently being processed to finish before performing
  the stop.
  
  The IntegrationAPI can be used to stop a message flow using the
  MessageFlowProxy object. A Java Compute node can be used to
  retrieve a MessageFlowProxy object that represents the message
  flow that the Java Compute node is deployed in. It is therefore
  possible to stop a message flow from within that same message
  flow.
  
  At v10 such requests from the IntegrationAPI are processed
  asynchronously by default, meaning that the message flow can
  continuing processing immediately after it has issue the stop
  request which will allow the stop request to be processed once
  the flow has finished.
  
  At v11 such requests are now synchronous, meaning they will
  block the message flow until a response has been returned for
  the request. This is an intentional change in behaviour as
  documented in the Knowledge Center. Since this request is now
  synchronous, it prevents the message flow from finishing until a
  response has been received. This leads to a deadlock where the
  flow cannot be stopped because it is waiting for itself to be
  stopped.
  
  Eventually the stop request will timeout and the flow will
  continue with an exception, after approximately 5 minutes.
  

Problem conclusion

• The IntegrationAPI will now detect when a
  MessageFlowProxy.stop() call is being issued from within a Java
  Compute node and is targeting the same message flow that the
  node is deployed in. In such situations the REST API v2 stop
  request will be issued asynchronously and a dummy status code of
  200 will be returned.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v11.0      11.0.0.10
  
  The latest available maintenance can be obtained from:
  http://www-01.ibm.com/support/docview.wss?rs=849&uid=swg27006041
  
  If the maintenance level is not yet available,information on
  its planned availability can be found on:
  http://www-1.ibm.com/support/docview.wss?rs=849&uid=swg27006308
  ---------------------------------------------------------------
  

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

  APP CONNECT ENT

• Fixed component ID

  5724J0550

Applicable component levels