WaitOne while I introduce multithreading

For some time I've been meaning to do some multi threading in the Dynamics SOP Fulfilment software I wrote. I have always thought that I could make things run a little more slickly. At fulfilment the following processes occur;

  • Credit/debit card debited if one is attached to the order
  • Order lines are fulfilled by quantities on the pick list being fulfilled
  • receipt printed (optional depending on carriage option- customer collect etc)
  • despatch note printed (optional)
  • invoice printed (optional)
  • thermal parcel label(s) printed one for each parcel entered
  • consignment details are exported via XML to UPS / Business Post / TNT depending on carriage routing algorithm
  • UI is constantly updated with progress bar and messages about progress

Spinning the fulfilment thread off on to its own thread using a background worker control was straight forward and is something I did when VS2005 was released. However some of the above processes take quite a few seconds to run, the fulfilment computers are quite recent hardware and thus should be able to perform better.
Thanks to good object orientated design, it turned out to be fairly trivial to get each of these processes to run on their own thread and synchronise them using wait handles. I had to use wait handles as some tasks depend on the successful completion of others. More...