A critical piece of what makes DMN accessible to business users is its expression language FEEL. FEEL variable names are business-friendly. Because they are simply the labels of the shapes in the Decision Requirements Diagram (DRD), FEEL names may contain spaces and other punctuation not allowed by other expression languages. OK, you already know this. [...]
They used to say Seinfeld was a show about Nothing. But given its enduring influence on popular culture, Nothing is clearly not nothing. Attention must be paid. In DMN, as well, Nothing demands attention. In simple models like the ones we study in my DMN Method and Style Basics and Advanced training, it doesn't come [...]
One of the basic principles of DMN is that decision services are stateless, meaning that given the same set of input data values, the service output will always be the same. But sometimes it is convenient to break that rule with tool-specific extensions. For example, in Trisotech Decision Modeler the FEEL built-in functions Today and [...]
As I write this, everyone is freaking out over COVID-19. We know it is a highly contagious and dangerous disease, with particular risk to groups in a confined space such as an airplane or cruise ship. Researchers are scrambling to model the contagion risk, but detailed data is almost nonexistent. With a good model, you [...]
In recent posts I reviewed the use and benefits of BKMs and contexts for DMN modelers and stakeholders. This time we'll continue that theme with an explanation of another of DMN's woefully underutilized features, decision services. The introduction of decision service as a formal element in DMN came about in a surprising way. The spec's [...]
Last time I showed the value of Business Knowledge Models (BKMs), those misunderstood and often-maligned elements in DMN diagrams. In this post I'm going to try to do the same for contexts, another DMN feature that is similarly underappreciated and frequently disparaged by tool vendors that don't support them. Unlike BKMs, contexts are not DRG [...]
In a recent post, I showed how DMN could be used to model and execute decision logic on complex XML input data such as loan application information in MISMO format. The MISMO schema was envisioned as an enterprise data dictionary for the mortgage industry, standardizing the names of various information elements for use across any [...]
Newcomers to DMN may wonder, What is the point of Business Knowledge Models (BKMs), those funny-looking boxes with clipped corners in the DRD? When I was first introduced to DMN, struggling to understand the DMN 1.0 spec, I wondered the same thing. The spec was (and remains) largely impenetrable to decision modelers, except for the [...]
Fannie Mae is one of two major Government Sponsored Entities (GSEs) underpinning the residential mortgage market in the USA. They supply liquidity to the system by purchasing mortgages from lenders and repackaging them as interest-paying securities sold to investors. Without them, we wouldn't have the low-rate long-term fixed rate loans that so many home buyers [...]
While DMN adoption continues to accelerate, we can only admire the current frenzied interest in machine learning. Both technologies are trying to do similar things - make decisions - but they go about it in very different ways. DMN, which evolved from business rules and, before that, expert systems, is based on intuitive understanding of [...]