Archive of Requirements Models Articles

In our agile project case study we defined corporate goals and user personas, and from our understanding created a list of use case names. We refined those use cases into use case briefs, filtering out some of the use cases (for the first revision) narrowing the list to six use cases. In this article, we propose a prioritization of those use cases and ask you to vote to share your thoughts.

Each of the use cases defined as part of our use case names post is described at a high level of detail here. The goal is to get a broad view of the domain for our project so that we can focus on the most important elements. This is a key step in using use cases in an agile project. We need to understand enough of the big picture in order to determine what is actually the most important. Then we will work on the more important use cases.

In our agile programming case study, we have two corporate goals, but one of them (learn Ruby on Rails) only drives constraints, not requirements. The other goal is to make it easier for people to find and read great content in our niche. This makes the documentation of goal-driven use cases pretty straightforward. All of the use cases support this single goal.

With an understanding of the goals, the next step is to define the use case names.

People who are new to software, requirements, or testing often ask “What’s the difference between a use case and a test case?” This article answers that question, by building on earlier articles about use cases and use case scenarios. At the soundbite level, each use case has one or more scenarios, and each use case scenario would lead to the creation of one or more test cases.

It is easy to mix up the definitions of use case and use case scenario. A use case represents the actions that are required to enable or abandon a goal. A use case has multiple “paths” that can be taken by any user at any one time. A use case scenario is a single path through the use case. This article provides an example use case and some diagrams to help visualize the concept.

Here’s an example of a use case that has some system complexity. The user interacts with the main system that we are describing. The system also interacts with two external systems. This use case example shows how to describe the steps that demonstrate all interactions with the system.

We proposed a strategy for developing use cases as part of an agile development methodology last week. In this article, we will look in more detail at that proposal, and also look at a specific way to apply agile techniques to the development of the use cases. What we propose is essentially incremental development of use cases, and starting what comes next as soon as you can.

UML Statecharts can be very effective modeling tools for describing systems and software requirements. They provide a clear framework for identifying business rules. The same business rules often apply to multiple states - defining a commonality for those states. There is an element called a substate in UML statecharts that can be used to make it more obvious that a particular business rule applies to multiple states.

One of the goals of agile software development is to deliver value quickly and iteratively. One of the most effective ways to begin the software development process is with use cases. To deliver with agility, you start with the most valuable use case, bang it out, and then move on to the next most valuable use case. How do you know which use case is the most valuable if you haven’t defined all the use cases first?

In yesterday’s article we compared use cases and UML statecharts as tools for discovering business rules. James Taylor asked a question about how we would document those rules, and then followed up my comment response with an article about business rules and RUP. In this article we move the conversation slightly forward - recognizing that we’re slowly entering the ocean of business process management.