We all learned in junior high school math class about sets and Venn diagrams. Which elements of set A are also members of set B? This concept comes up in decision logic as well, and you would expect DMN to be able handle it. It can, but it's a little complicated, because technically DMN does [...]
One of the great things about the DMN standard is it is continually being updated with new features that make it more powerful and easier to use. As soon as the DMN Revision Task Force (RTF) submits a new version for OMG approval, it immediately begins on the next revision. That approval process, for some [...]
When we create a decision model, we imagine we can design the input data in a way that is most convenient for our logic. But that is not always the case. It could be that the input to our model is required to be XML in some industry-defined format, and we need to convert that [...]
In a post last summer, I began to question the value of assigning constraints like a range of allowed values to datatypes in DMN, in favor of performing data validation using a decision table inside the decision model. There were a few reasons for this: Data values violating the constraint behaved differently in decision tables [...]
DMN's most widely used boxed expression type is the decision table. It's popular because its meaning is intuitive and generally understood without training. The DMN spec imposes certain constraints on the format - what expressions are allowed in a condition cell, for instance. Even when these are ignored by legacy rule engine vendors, the intent [...]
In my BPMN Method and Style training, I show the following BPMN and ask students, "What does this diagram say?" You really cannot tell. It says something happens and then either the process ends or something else happens. Not very informative. But if you run Validation against the rules of the BPMN spec... no errors! [...]
A primary design goal of the DMN standard was accessibility to subject matter experts and other "business users", i.e. non-programmers. DMN promises executable decision logic without programming, and it achieves that through a combination of standard diagrams (DRDs), standard tabular formats (boxed expressions), and a business-friendly expression language (FEEL). Nevertheless, you constantly hear that it's [...]
In my BPMN Method and Style training, we use examples like the one below to illustrate the difference between interrupting and non-interrupting boundary events: Here an Order process with four subprocesses could possibly be cancelled by the Customer at any time. As you can see, a single physical Cancellation message from Customer is modeled as [...]
I have made the point on multiple occasions (for example, here) that DMN is both more business-friendly and more powerful than better-known Low-Code languages such as Microsoft's Power FX. One reason for that is DMN's context boxed expression, which breaks down a complex bit of business logic (or decision logic, if you prefer) into multiple [...]
[This post is my presentation at Decision Camp 2022, delivered September 27, 2022.] As a longtime DMN practitioner and from the beginning one of its biggest boosters, I am what you call a true believer. But while DMN continues to gain traction, even I would have to admit it has so far underperformed in the [...]