Contrary to popular belief, agile development teams do in fact model and yes, they even do some up front requirements and architecture modeling. Two of the best practices of Agile Modeling are Requirements Envisioning
and Architecture Envisioning
where you spend a bit of time at the beginning of the project doing enough initial modeling to get you going in the right direction. The strategy is to take advantage of modeling, which is to communicate and think things through without taking on the risks associated with detailed specifications written early in the lifecycle
. In this blog posting I will focus on requirements envisioning, in a future posting I'll cover architecture envisioning.
The goal of initial requirements envisioning is to identify the scope of your effort. You need to do just enough modeling early in the project to come to stakeholder concurrence and answer questions such as what you're going to build, roughly how long it's going to take (give a range), and roughly how much it's likely to cost (once again, give a range). If you can get the right people together in the room, which can sometimes be a logistics challenge but not one that you couldn't choose to overcome, there are very few systems (I suspect less than 5%) that you couldn't initially scope out in a few days or a week. I also suspect that most of the remaining systems could be scoped out with less than 2 weeks of modeling, and if not then I'd take that as an indication that you're taking on too large of a project. I'm not saying that you'll be able to create big detailed specifications during this period, and quite frankly given the problems associated with "Big Requirements Up Front (BRUF)
" you really don't want to, but I am saying that you could gain a pretty good understanding of what you need to do. The details, which you'll eventually need, can be elicited throughout the lifecycle when you actually need the information. A common saying in the agile community is that requirements analysis is so important for us that we do it every single day, not just during an initial phase. I'll discuss just in time (JIT) approaches to requirements modeling in a future posting.
To envision the requirements for a business application, you might want to consider creating the following models:
- High-level use cases (or user stories). The most detail that I would capture right now would be point form notes for some of the more complex use cases, but the majority just might have a name. The details are best captured on a just-in-time (JIT) basis during construction.
- User interface flow diagram. This provides an overview of screens and reports and how they're inter-related. You just need the major screens and reports for now.
- User interface sketches. You'll likely want to sketch out a few of the critical screens and reports to give your stakeholders a good gut feeling that you understand what they need. Sketches, not detailed screen specifications, are what's needed at this point in time.
- Domain model. A high-level domain model, perhaps using UML or a data modeling notation, which shows major business entities and the relationships between them, can also be incredibly valuable. Listing responsibilities, both data attributes and behaviors, can be left until later iterations.
- Process diagrams. A high-level process diagram, plus a few diagrams overviewing some of the critical processes, are likely needed to understand the business flow.
- Use-case diagram. Instead of a high-level process diagram you might want to do a high-level use case diagram instead. This is a matter of preference, I likely wouldn't do both.
- Glossary definitions. You might want to start identify key business terms now, although I wouldn't put much effort into settling on exact definitions. I've seen too many teams run aground on "analysis paralysis" because they try to define exact terminology before moving forward. Don't fall into this trap.
For small teams simple tools such as whiteboards and paper are usually sufficient for requirements envisioning. But what happens at scale? What if you're working on a large agile team, say of 50 people, 200 people (IBM has delivered software into the marketplace with agile teams of this size), or even 500 people (IBM currently has teams of this size applying agile techniques)? What if your team is distributed? Even if you have people working on different floors of the same building, let alone working from home or working in different cities or countries, then you're distributed (see my postings about distributed agile development
). Suddenly whiteboards and paper-based tools (index cards, sticky notes, ...) aren't sufficient. You're still likely to use these sorts of tools in modeling sessions with stakeholders, but because of one or more scaling factors you need to capture your requirements models electronically.
In January Theresa Kratschmer and I gave a webcast entitled Agile Requirements: Collaborative, Contextual, and Correct
which overviewed agile approaches to requirements elicitation and management, including requirements envisioning. We also showed how Rational Requirements Composer (RRC)
can be used to electronically capture critical requirements information, enabling you to address the needs of large and/or distributed agile teams, while still remaining lightweight and flexible. I suspect that you'll find the webcast to be very illuminating and RRC something that you want to take a look at (the link leads to a trial version). Of course RRC can be used in other situations as well, but that's not what I'm focused on right now.
Teams which find themselves in regulatory environments will likely need to do more than just use RRC, as might very large teams. Regulatory compliance often requires more complex requirements documentation, which in turn requires more sophisticated tools such as DOORS or Requisite Pro, and I would consider using those tools in the types of situations that warrant it. One of the things that people often struggle to understand about agile approaches is that you need to tailor your strategy to reflect the situation at handle. One process size does not fit all, so you will end up using different tools and creating different artifacts to different extents in different situations. Repeatable results, not repeatable processes
, is the rule of the day. Further reading: