Multiple phases commit

psedocode
client invokes System A
  System A performs process
  if success
    System A commits
    System A invokes System B
    System B performs process
    if success
      System B commits
      System B invokes System N..
      System N.. performs process
      if success
        System N.. commits
      else
        System N.. rollback
        System N.. return false
    else
      System B rollback
      System B return false
  else
    System A rollback
    System A returns fail


to simplified the above logic,
1.    process and commit own transaction.
2.    invoke external system/process
3.1 if success, return true
3.2 if failed, return false, manual rollback the transaction.


Done!!