South East Training - Business Process Modelling Toolkit

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 More Sub-Processes

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Sub-processes are useful for numerous reasons. For example:

  • They allow you to model end-to-end process without having to illustrate the detail (which can make the model too large to handle).
  • The collapsed sub-process allows you to include in the end-to-end process those sub-processes that you have yet to model, without damaging the integrity of the overall structure.
  • They help define boundaries so that process ownership can be defined at different levels.


Two useful sub-process types, that we have not so far seen, include:

  • The Ad-Hoc Sub-Process - The expansion of the ad-hoc sub-process does not include sequence flow but instead a list of activities that could be performed.  The order of execution is not specified and it is not necessary to complete all the activities to complete the sub-process. 
    • The example illustrates what might happen when someone takes out a new gym membership.  Various members of staff may offer a variety of services including: ordering a new welcome pack; setting-up an induction; signing you up for classes; and introducing you to a personal trainer.  It doesn't matter in which order they are conducted.
  • The Transactional Sub-Process - Denoted by a double boarder, this is a special type of sub-process that illustrates a single business transaction. If the transaction sub-process does not execute successfully, the system must be returned to the state it was in before the transaction took place.
    • The example illustrates the buying of tickets for the 2012 Olympics. Following the ballot, tickets were allocated and the payment was taken some days or weeks later.  However,  if the credit card payment failed, as it did in some cases, the allocation had to be cancelled so the tickets could be offered for resale.  The transactional sub-process offers a convenient way of modelling this.

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