An Introduction to Requirements Modeling Language

What is Requirements Modeling Language?

Requirements Modeling Language (RML®) is a toolbox of visual models created to support the requirements elicitation, analysis, and documentation process. It is a language designed specifically for easy consumption by executive, business, and technical stakeholders. We’ve used and refined these over literally hundreds of projects.

RML® Models Defined

Requirements models are diagrams that organize information to help you find missing, redundant, and conflicting pieces of information and bring context to a set of text. Models are things like Process Flows, Ecosystem Maps, and State Diagrams, but there are many more.

RML® Model Categories

RML® models are grouped into four complementary areas designed to analyze the solution from different perspectives: Objectives (describe the business value of the system), People (describe who uses the system and how), Systems (detail the interaction between systems), and Data (define the information in the system and how it is modified). It is rarely the case that all RML models need to be employed to derive complete requirements. With these visual models, business analysts are better equipped to organize the requirements in a way that makes it easy to see when requirements are missing, extraneous, or incorrect.

requirements modeling language - data flow diagram

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requirements modeling language - text requirements vs RML visuals

Why Text-Based Requirements Aren't Enough

Analysts who only use traditional text-based techniques to document software requirements experience common problems during analysis, organization, and consumption of the requirements. These traditional practices use long lists of text requirements in the form of shall statements, use cases, or, more recently, user stories and product backlogs. It is extraordinarily difficult to ensure completeness when you are given a long list of “system shall“ statements but adding structure to the requirements takes advantage of their relationship and greatly simplifies the task by allowing you to analyze smaller groups of information at one time. The key to finding missing requirements is to take advantage of the fact that each requirement is related to other requirements in some way.

RML® helps address a unique fact about human cognition – popularized by the American Psychologist George Miller. Miller uncovered the fact that humans have a limited capacity to retain multiple concepts in their working memory:  7(+/-) 2 also known as “Miller’s Magic Number”. RML’s visual approach helps circumvent this phenomenon by taking the age-old adage, “a picture is worth a thousand words” to heart. Models are visual representations (pictures) of information related to the processes, data, and interactions within and surrounding the solution being developed. These RML® models provide visual groupings that enable you to quickly analyze large amounts of disparate information while not exceeding human beings limited short-term memory.

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Requirements Models Are a Path to Better Communication

It is important to remember that requirements are not stand-alone statements – requirements are deeply intertwined with each other. RML® models are designed to be understood by all parties involved in the requirements gathering process – executive, business, and technical stakeholders. George Bernard Shaw said, “the biggest problem in communication, is the illusion it has taken place”, RML® models help break apart this illusion by embracing a deeply rooted fact of human nature – pictures are easier to comprehend than words.

Source

This page is adapted from Visual Models for Software Requirements (Microsoft Press 2012) by Joy Beatty and Anthony Chen of ArgonDigital.

RML - business objective model