UPN LO3-7: Best practice 3 – Decisions and logic
Diamonds are intrinsically worthless, except for the deep psychological need they fill.
– Nicky Oppenheimer
If you’re used to flowcharting, or are familiar with the richness of BPMN, one of the things you’ll notice is that… we don’t have anything but a rectangle symbol. One of the symbols that aren’t there is the decision symbol or diamond shape. It represents a decision point in a process flow. The question, therefore, is: How do I represent this, using UPN?
Well, a decision is nothing more than an activity. So in the example we “Lookup customer details”. As we do this, we already know whether we’re dealing with an existing or non-existing customer. Basically, we can use the text in the diamond as an outcome of the previous activity.
EXPERT
There are situations where you want to follow a detailed decision tree (using many diamonds). Mostly on a very detailed level.
Using logic gates
Another challenge can be how to represent logic gates. The simplest logic gates are AND and OR. So, after executing activity A you would get 2 flowlines that trigger both activities B AND C. Or: after executing activity A you would get 2 flowlines that trigger either activity B OR C. Whilst this tends to be already pretty technical, you could represent this on business level by joined lines (AND), or separated lines (OR).
The opposite is also true: Both activities A AND B need to be executed in order to trigger activity C. Or: Either activity A OR B needs to be executed to trigger activity C.
Remember that UPN is a contextual business language; so when you want to go all the way (see BPMN or EPC), don’t use UPN for this as you’re already acting on technical expert level. So, rather than do this using UPN, you could create that in another tool (e.g. Visio, Lucidchart) and add that as an attachment in the right business context.