com.ibm.wsspi.batch.parallel.logicalTX
Class Synchronization

java.lang.Object
  extended by com.ibm.websphere.grid.spi.SPI
      extended by com.ibm.wsspi.batch.parallel.logicalTX.Synchronization
All Implemented Interfaces:
java.lang.Comparable

public abstract class Synchronization
extends com.ibm.websphere.grid.spi.SPI

Synchronization is the abstract base class for the ParallelJobManager logical transaction Synchronization System Programming Interface (SPI). Use the Synchronization SPI to receive callbacks that demarcate the lifecycle of a parallel job logical transaction. A logical transaction provides a logical unit of work scope that spans all subjobs belonging to a parallel job. The ParallelJobManager starts a logical transaction before the subjobs are submitted and completes the logical transaction after all subjobs have completed.

Note: logical transactions provide a containment scope only - resource enlistment and coordination with resource manager JTA transactions is not provided.

Rollback is initiated in the following ways:

  1. When any SPI in the com.ibm.wsspi.batch.parallel family throws declared exception RollbackLogicalTXException.
  2. When any subjob completes in the Restartable or Failed state.

When rollback is triggered, the following actions are taken:

  1. In-flight subjobs are cancelled. This includes subjobs still executing on endpoints, as well as subjobs that may be awaiting dispatch.
  2. The rollBack method on this SPI is invoked. It is the responsibility of the rollBack method to undo any work done by subjobs that have successfully completed one or more checkpoints. Note this includes subjobs that have completed successfully - i.e. are in the "ended" state.

Implement the Synchronization SPI, by extending this class and implementing the begin, beforeCompletion, afterCompletion, and rollBack methods.

Configure this SPI with the following declaration in the xd.spi.properties file:

 spi.parallel.logicalTX.Synchronization=<fully-qualified implementation class name>
 

Notes:

  1. The xd.spi.properties file is located in:
  2.  <WAS install root>/properties.  E.g.
     
           /WebSphere/AppServer/properties
     
  3. The jar file containing the implementation of this SPI should be stored in:
  4.  <WAS install root>/lib/classes.  E.g.
     
           /WebSphere/AppServer/lib/classes
     

    You are responsible for creating the classes directory if it does not already exist.


    Nested Class Summary
    static class Synchronization.TXStatus
              Specifies status values for logical transaction outcome.
     
    Field Summary
    static boolean TX_NOT_RESTARTABLE
              Specifies that the logical transaction is not restartable.
    static boolean TX_RESTARTABLE
              Specifies that the logical transaction is restartable.
     
    Constructor Summary
    Synchronization()
               
     
    Method Summary
    abstract  void afterCompletion(java.lang.String logicalTXID, Synchronization.TXStatus status)
              Indicates the specified logical transaction has completed with the indicated status.
    abstract  void beforeCompletion(java.lang.String logicalTXID)
              Indicates all subjobs have ended and that the specified logical transaction is about to commit.
    abstract  void begin(java.lang.String logicalTXID)
              Indicates the specified logical transaction has begun.
     java.lang.String getName()
               
    abstract  RestartInstructions rollBack(java.lang.String logicalTXID, boolean restartable)
              Invoked to undo changes made by subjobs within the unit of work scope of the specified logical transaction.
     
    Methods inherited from class com.ibm.websphere.grid.spi.SPI
    compareTo, getInvocationOrder, setInvocationOrder, toString
     
    Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
     

    Field Detail

    TX_RESTARTABLE

    public static boolean TX_RESTARTABLE
    Specifies that the logical transaction is restartable.


    TX_NOT_RESTARTABLE

    public static boolean TX_NOT_RESTARTABLE
    Specifies that the logical transaction is not restartable.

    Constructor Detail

    Synchronization

    public Synchronization()
    Method Detail

    begin

    public abstract void begin(java.lang.String logicalTXID)
    Indicates the specified logical transaction has begun.

    Parameters:
    logicalTXID - specifies the unique identity of the logical transaction.

    beforeCompletion

    public abstract void beforeCompletion(java.lang.String logicalTXID)
                                   throws RollbackLogicalTXException
    Indicates all subjobs have ended and that the specified logical transaction is about to commit. This method may force logical transaction to rollback by throwing RollBackLogicalTXException.

    Parameters:
    logicalTXID - specifies the unique identity of the logical transaction.
    Throws:
    RollbackLogicalTXException

    afterCompletion

    public abstract void afterCompletion(java.lang.String logicalTXID,
                                         Synchronization.TXStatus status)
    Indicates the specified logical transaction has completed with the indicated status.

    Parameters:
    logicalTXID - specifies the unique identity of the logical transaction.
    status - specifies the outcome of the logical transaction - either COMMIT or ROLLBACK

    rollBack

    public abstract RestartInstructions rollBack(java.lang.String logicalTXID,
                                                 boolean restartable)
    Invoked to undo changes made by subjobs within the unit of work scope of the specified logical transaction.

    Parameters:
    logicalTXID - specifies the unique identity of the logical transaction.
    restartable - specifies whether or not this logical transaction is restartable as follows:
    • true
    • Indicates this logical transaction is restartable. A logical transaction is restartable if and only if none of its subjobs have completed in the failed state. This means the subjobs have completed in only the restartable and/or ended states. This also means the parallel job itself will complete in the restartable state.

    • false
    • Indicates this logical transaction is NOT restartable. A logical transaction is not restartable if at least one of its subjobs has completed in the failed state. In this case, the parallel job itself will complete in the failed state and is not restartable.

    Returns:
    RestartInstructions, which indicates which subjobs must restart when the parallel job instance associated with logicalTXID is restarted.

    getName

    public java.lang.String getName()
    Specified by:
    getName in class com.ibm.websphere.grid.spi.SPI