Tag Archives: BDD

Software Development

Monsters, Names, Pot-Roast & The Waterfall Model

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“Antony” (without the ‘H’) is the anglicised version of Antonius. In victorian times (there or thereabouts I’m guessing), among those wishing to appear oh so intelligent, gossip spread that the spelling of “Antony” was wrong… For, so they would say, it is born of the greek word “anthos” (meaning “flower”) – oh dear… so many poor children with misspelt names… 

Despite being completely wrong, the world forgot of my name’s etruscan origin and spelt it with an ‘H’… This misinformation established itself through the eras so much so that, today, the de-facto spelling is “Anthony”. It has even found it’s way into the American pronunciation of the name as: “An-thon-ee”.

Waterfall development has something in common with this story… somehow, through misinformation, what it once was has been warped, into something else.

The key difference is that Waterfall is now increasingly represented as was originally intended. Unfortunately for me, my name is not…

 

Monsters & Legends

Some might think that the Waterfall Model is an approach to software development, first explained (but not named) in Winston Royce’s 1970 Paper “Managing the Development of Large Software Systems” (PDF), but they could be wrong…

Somehow, it seems to have become something else… it became the way (many) people thought software should be developed… the norm for software ‘professionals’. Years of anecdotal failure followed and Waterfall became a legend – told time and again much like a scary camp-fire story… The enemy of effective software development… A monster that will consume all the resources it can, spewing out nothing but documentation, rarely concluding in working software – at best 20% of the time.

This negative view, to what was once the de-facto approach to software development, is actually far closer to Royce’s original words on Waterfall than many seem to know…

 

The Truth & Technology

In Royce’s original paper, he shows a progression of activities, that came to be known as the waterfall model.

What we rarely hear of is Royce’s original words on the subject:

“…the implementation described above is risky and invites failure.”

Further to this, Royce goes on to explain that the reason that this cannot work is because there are too many things we cannot analyse up-front:

“The testing phase which occurs at the end of the development cycle is the first event for which timing, storage, input/output transfers, etc., are experienced as distinguished from analyzed. These phenomena are not precisely analyzable. They are not the solutions to the standard partial differential equations of mathematical physics for instance.”

He explains that we need feedback loops. He goes on to warn of (a conservative) 100% overrun in schedule and costs:

“…invariably a major redesign is required. A simple octal patch or redo of some isolated code will not fix these kinds of difficulties. The required design changes are likely to be so disruptive that the software requirements upon which the design is based and which provides the rationale for everything are violated. Either the requirements must be modified, or a substantial change in the design is required. In effect the development process has returned to the origin and one can expect up to a 100-percent overrun in schedule and/or costs.”

Some of Royce’s strategies, like “Involve the customer” and obtaining early feedback, have lived on in modern (Agile) methodologies. Beyond that, we should remember that his specific recommendations on how to solve the problems of a waterfall model were all based on the technology of the time.

 

Pot-Roast & The Cost of Change

In 1970, computing was much more expensive than it is today. In those days, changing software was far more expensive than changing pictures and words on paper. It was also much harder to express your design in a human-friendly way in the programming languages of that time. As a result of these and other factors, documentation was a major part of how Royce tried to solve the inherent problems of the Waterfall model.

 

Technology, tools & thinking have moved on and our documentation no longer needs to be static. It lives. It can breath. The specification can automatically verify that the implementation does what we said it should do (e.g. as in BDD Specs or ATDD/TDD Tests). Modern programming languages allow us to express the design and our understanding of the domain far more clearly, negating the need to first detail our thoughts on paper in natural language. We simply don’t have to cut the ends off that pot-roast anymore.

 

Only now, at the end…

Waterfall, thanks to the popularity of Agile, has gone from something I was shown at school as “how software is developed” to being seen in the light that it was originally presented – how software should not be implemented.

This is despite those who still profess the legitimacy of Waterfall and those still shocked and surprised when they hear of Royce’s own words against the monster he unintentionally created.

As for my name, I hold out little hope for change. I doubt that the world will use my name as it was originally intended and so I have resigned myself to needing two domain names… one with an ‘H’ in it, and the correct one without – I wonder which one brought you here.

Agile, BDD/ATDD, Business Analysis, Project Management

Taking repetition to task

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This originally appeared on my old blog in March 2010.

Others have talked about the virtues of stories as vertical slices of a problem (end-to-end capabilities) rather than horizontal slices (system layers or components). So, if we slice the problem with user stories, how do we slice the user-stories themselves?

If, as I sometimes say, acceptance tests (a.k.a. examples/scenarios/acceptance-criteria) are the knife with which we slice a story into even thinner vertical slices, then I would say my observation of ‘tasks’ is that they are used as the knife used to cut a story into horizontal slices. This feels wrong…

Sometimes I also wonder, hasn’t anyone else noticed that the idea of counting the effort of completed tasks on burn-down/up charts is counter to the value that we measure progress only with working software? Surely it makes more sense to measure progress with passing tests (or “checks” – whichever you prefer).

These are two of the reasons I’ve never felt very comfortable with tasks, because:

  • they’re often applied in such a way that the story is sliced horizontally
  • they encourage measuring progress in a less meaningful way than working software

Tasks are, however, very useful for teams at first. Just like anything else we learn how to do, learning how to do it on paper can often help us then discard the paper and do the workings in our heads. However, what I’ve noticed is that most teams I’ve worked with continue to write and estimate tasks long after the practice is useful or relevant to them.

For example, there comes a time for many teams where tasks become repetitive. “Add x to the Model”, “Change View”… and so on. Is this adding value to the process or are you just doing it because the process says you should do it?

Simply finding that your tasks are repetitive doesn’t mean the team is ready to stop using them. There is another important ingredient, meaningful acceptance criteria (scenarios / acceptance-tests / examples).

I often see stories with acceptance criteria such as:

  • Must have a link to save the profile
  • Must have a drop down to select business sector
  • Business sector must be mandatory
  • …

Although these are “acceptance criteria” they aren’t what we mean by acceptance criteria in the context of user stories. Firstly, they are talking about how the user interacts rather than what they need to achieve (I’ve talked about this before). Secondly, they aren’t examples. What we want are the variations that alter the behaviour or response of the product:

  • Should create a new profile
  • Profile cannot be saved with blank “business sector”

As our product fulfils each of these criteria, we are making progress. Jason Gorman illustrates one way of approaching this.

So, if you are using tasks, consider an alternative approach. First, look at your acceptance criteria, make sure they are more like examples and less like instructions. Once that’s achieved, consider slicing each criterion (or scenario) horizontally with the tasks rather than the story. Pretty soon, you’ll find that you don’t need tasks anymore and you can simply measure progress in terms of the new capabilities you add to your product.

Updated 30-02-2010: I’ve inserted a new paragraph as the opening paragraph referencing an article on slicing user-stories to add some background to the vertical slicing metaphor. I’ve provided a link but I’m not sure who first came up with the metaphor.