The Disciplined Agile (DA) toolkit references hundreds of agile, lean, and in some cases “traditional” techniques, putting them into context. One such technique is database refactoring, adopted from the Agile Data (AD) method, which is critical for the Improve Quality process goal. Where a code refactoring is a simple change that improves the quality of code, a database refactoring is a simple change to your database that improves the quality of its design without changing the semantics in a practical manner. Database refactoring is a sophisticated practice, in fact I co-wrote a 400+ page book about it, Refactoring Databases: Evolutionary Database Design, with Pramod Sadalage in 2006. The book, which won a Jolt Productivity Award, provides a detailed description of the practice. But what if you’d like to start with something simpler before jumping into the details? This is where Essence comes in.
A few months ago a group of us – Roly Stimson of IJI, Nebojsa Trninic, Vladimir Savic, Ervin Varga, and myself – decided to experiment with the idea of essentializing DA. To focus our work we decided to start with a simpler problem, that of essentializing a subset of the techniques referenced by DA, in this case those of Agile Data. We then focused further on a minimal viable product (MVP), in this case the single practice of database refactoring.
We captured the practice using Essence Enterprise 365 from IJI, a screen shot from which is shown below. Essence is a language for describing software engineering methods and practices from Ivar Jacobson International (IJI). Essence was created as a part of Software Engineering Method and Theory (SEMAT) and approved by The Object Management Group as a standard in 2014. I’ve been working with SEMAT from its beginnings in 2009 and have known (and admired) Ivar since the late 1990s.
As you see in the screen shot we summarized database refactoring using the tool, describing the practice as a collection of cards. The tool can be used to develop process material, as we’ve done, and more importantly it can be used by teams to tailor and evolve their own process. Within the tool are dozens of practices, including ones from Scrum and XP, that a team can configure to reflect their own way of working (WoW).
In the following picture you see that these cards can also be printed out and used in a physical manner, often for process tailoring or training. In November I experimented using the cards to train a small group of people. We played a game where the group worked through how they would go about refactoring an existing database. They discussed each card, moving them around on the table until they had something that looked like the picture below. The cards provided a tactile way for them to explore database refactoring by thinking through how they would apply it in practice. IJI has identified a collection of teaching and process tailoring games using cards such as this.
An interesting result of this teaching experiment is that we discovered that we wanted more cards. The group wanted cards to explore automated database regression testing, agile data modelling, and continuous database integration in detail, and of course how all of these things fit together. So it looks like we have our work cut out for us.
We’d love to hear what you think about this effort. This blog has been a brief description of our work to essentialize the practice of database refactoring, but we have a lot more work ahead of us. A more detailed description will be presented in a forthcoming research paper that the team is working on. We also intend to continue with this essentialization effort to share some of the key DA techniques within Essence. Stay tuned!