February 24, 2012

...Learn TDD with Codemanship

Agile Design - How A Bit Of Informal Visual Modeling Can Save A Heap Of Heartache

All my courses are, of course, fine holiday fine. But the Agile Design workshop's especially enjoyable, as it brings together a whole range of disciplines while challening participants to work effectively together in designing and implementing different features of the same simple system.

The group works in pairs (or threes, depending on the overall numbers). After a bit of a crash course in basic UML - use cases, class diagrams and sequence diagrams - each pair is given a user story for a community DVD library, and tasked with iteratively fleshing out an object oriented design to pass an acceptance test agreed with the customer (me).

In a break from the traditional approach, we turned the design process around - arguably the right way round - and spent day #1 telling the story using plain old objects, designing and implementing a functioning domain model that includes all the concepts and functions required to pass the tests.

On day #2, we look at how these cncepts and functions should be presented to the end users, designing a graphical user interface and retelling the story, this time through the GUI.

The impetus behind the course is to help teams avoid the design train wreck that can ensue when Agile teams pick up stories and go off into their silos to do the design for their part of the overall system. I've seen very experienced teams end up with duplicated classes, database tables, multiple architectures and disjoints in the same code base.

Using informal visual models in a collaborative design approach can aid us in externalising our thinking so that other people can see how what they're doing fits in what everyone else is doing.

Getting the team around the whiteboard to explore shared concepts like the domain model, the screenflow of the user interface or the patterns used in the technical architecture - especially in the earlier stages of development - can draw out misunderstandings and disjoints that might otherwise have only come to light in integration, when these issues can be much more costly to fix (and therefore often never get fixed).

Importantly, teams are soon testing their designs by implementing them in code (test-driven, of course), and important design decisions and changes to the shared vision that happen as a result of making the designs work for real can be visualised and communicated by sketching them out on flipchart paper or on whiteboards and keeping them around the team's work area for everyone to see.

On the course, teams discover just how much active collaboration's needed to coordinate design effectively, and to take the time to resolve design issues and conflicts at the whiteboard if they can. Pairs need to be going out of their way to find out what the other pairs are working on. In real life, we tend to put in a wholly inadequate amount of effort into collaborative design, and our ad hoc, inconsistent, and sometimes just plain wrong, designs can be the end result.

The more visible our work is, the easier it is to bring design issues out into the open early, and the sooner we're able to establish a shared language for meaningfully talking about our designs.

And we're not just talking about developers here, either. Testers and graphic designers can play an active and valuable role in this process, as well as the customer, of course. They should take an active interest in establishing the design of use cases, in designing UI storyboards and screenflows, and in designing good acceptance tests that will effectively constrain our designs to what will meet the customer's real needs.

That's why I love this workshop. You get a buzz and an energy in the room, and a real sense of "stuff happening" and of progress being made. And it incorporates disciplines like continuous integration, TDD and BDD (or, as I know it, "TDD with a B instead of a T"), making it a much closer fit to real-world Agile Software Development.

Posted 8 years, 8 months ago on February 24, 2012