A traveling analogy of goals, requirements, and specifications
Here's a thought experiment to help you to visualize the relationship between goals, requirements, and specifications. Imagine, for a moment, that you're a visitor to the great city of Cardiff in Wales, United Kingdom, and you want to sample some of the famous Welsh cakes you have heard so much about – mainly from me! So, you take out your cell phone map app and you search for the nearest Welsh cake bakery. You then ask the app for directions to the bakery. The app gives you a choice of routes dependent on your mode of transportation, the time of the day and the local traffic conditions. You then choose a route and follow it, hoping to sample some local delicacies. Let's relate this to requirements management:
- Your goal is to eat some Welsh cakes.
- Getting to the bakery is your requirement.
- The route you choose to follow is your specification.
It's clear that unless you have the specification (route to bakery), you will never be able to realize your requirement (get to the bakery), and achieve your goal (eat some yummy Welsh cakes!). In much the same way, unless we have a specification, we will never be able to build a system that will help our stakeholders reach their goals.
