Requirements Analysis Using Event/Response and Use Cases – Functional Requirements

Planning

In my previous post on the topic of Requirements Analysis, I showed you how to derive your Use Cases from the Event List. I also presented a list of recommended elements to be included in each Use Case. The primary element is the list of steps taken by the Actors and the System they interact with. Within these steps are the Functional Requirements.

In my initial post in this series, I mentioned that starting and ending requirements gathering with functional requirements was not very effective. Why? Because functional requirements are at too low of a level and places the burden on the memories of SME’s (Subject Matter Experts) instead of the analytical questions of the Business Analyst, where the burden really belongs. For large systems, if you start and end with functional requirements you will almost assuredly have an incomplete set of requirements.

Using the Event/Response methodology, we started with Event Discovery, using a wide variety of techniques to generate the questions the Business Analyst needs to ask. We fleshed out the Events, which led to discovery of the business processes in scope. We validated the model to make sure we had the complete list of Events and processes. We used the processes to create our Use Cases. We will now examine the Use Cases to derive the functional requirements. This is an organized, top down approach to requirements that will output as complete a set of requirements as is possible.

Within the steps of the Use Cases are things like “Insert Debit Card”, “Read Card”, “Select Action”, “Browse by Last Name”, etc. These are all functional requirements that must be satisfied by the solution. The system design must address all of these requirements. However, these are low-level capabilities and are not a good source for overall system design. By using the Event Model, the system designer can see the big picture and design a friendlier, more efficient system than is possible using just the functional requirements.

In the next post I will address the advantages of the Event Model when designing and executing tests.

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