Agile Software Development
Автор: Alistair Cockburn /
APPENDIX A: The Agile Software Development Manifesto Supporting the Values
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Часть 2
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The industry is littered with projects whose sponsors did not take the time to make sure they got what they needed. Frakes and Fox reported a study showing a strong correlation between links to users and project success or failure (Frakes 1995).
The best links are through on-site business expertise and daily discussions, which is what the statement calls for. The word "daily" refers to the sweet spot, where discussions are ongoing and on-demand. Daily discussions are not practical on most projects, which means that the project is not sitting at the sweet spot. The statement indicates that the longer the time to get information to and from the developers, the more damage to the project.
6. Build projects around motivated individuals.
Give them the environment and support they need, and trust them to get the job done.
We would rather see motivated, skilled people communicating well, and no process at all, than a well-defined process and unmotivated individuals. Dee Hock's story about the early VISA system gives an extreme example of this.
Individuals make projects work. Their motivation relates to the pride-in-work, amicability and community on the project.
I first encountered the above statement in a project interview with Dave A. Thomas, then Presdent of the very successful company, Object Technology International. He said, "We hire good people, give them the tools and training to get their work done, and get out of their way. " I keep finding evidence supporting his recommendation, . panteonbogov.ru
7. The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.
This falls directly out of Chapters 3 and 4 in this book. I won't repeat the discussion and caveats here. Review those chapters if you are just dipping into the book here.
8. The best architectures, requirements, and designs emerge from self-organizing teams.
We had some discussion around the choice of words in this principle. How self-organizing do we intend: completely self-organizing, or merely allowing good ideas to come from anyone on the project? Do we mean emerge mysteriously, emerge in small steps over time, or emerge as a logical consequence of the human-centric rules the team uses?
I prefer the middle of the three choices. Jim prefers the latter of the three. None of us intend the first of the three, which comes from a misunderstanding of the word emergent as "lucky. " Our common point is recognizing that the details of system design surprise even the most experienced designers.
We insist that the architecture be allowed to adjust over time, just as the requirements and process are. An architecture locked down too hard, too early, will not be able to adjust to the inevitable surprises that surface during implementation and with changing requirements. An architecture that grows in steps can follow the changing knowledge of the team and the changing wishes of the user community.
9. Continuous attention to technical excellence and good design enhances agility.
A tidy, well-encapsulated design is easier to change, and that means greater agility for the project. Therefore, to remain agile, the designer shave to produce good designs to begin with - and -also have to review and improve their design regularly, to deal with the better understanding of their design that comes with time and clean up from when they cut corners to meet a short-term goal. Managing Technical Debt
Ward Cunningham sometimes compares cleaning up the design with paying off debts. Going further, he discusses managing the technical debt on the project.
Making hasty additions to the system corresponds to borrowing against the future, taking on debt. Cleaning up the design corresponds to paying off the debt.
Sometimes, he points out, it is appropriate to take on deb and make hasty changes, in order to take advantage of an opportunity. Just as debt accumulates interest and grows over time, though, so does the cost to the project of not cleaning up those hasty design changes.
Cut corners in the design, he suggests, when you are willing to take on the debt, and clean up the design to pay off the debt before the interest grows too high.
Given the deep experience present in the room, I found it interesting to see this attention to design quality at the same time as the attention to short time scales, light documentation, and people.
The conflicting forces are resolved by designing as well as the knowledge at hand permits, but designing incrementally.
10. Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
There are two sides to this statement. One relates to social responsibility side, the other to project effectiveness. Not everyone at the meeting was interested in signing onto the social responsibility platform, but we all agreed on the effectiveness issue.
People tire as they put in long hours. Their rate of progress slows, not just during their overtime hours, but also during their regular hours. They introduce more errors into their work. Diminishing returns set in with extra hours. This is part of the non-linearity of the human component.
An alert and engaged staff is more agile than a tired, slogging staff, even leaving aside all of the social responsibility issues. Long hours are a sympton that something has gone wrong with the project layout.
11. Simplicity--the art of maximizing the amount of work not done--is essential.
Simplicity is essential. That much is easy to agree on. The notion of simplicity is so subjective, though, that it is difficult to say anything useful about it. We were therefore pleased to find we could all sign up for this statement.
In the design of development processes, simplicity has to do with accomplishing while not doing, maximizing the work not done while producing good software. Jon Kern reminds us of Pascal's remark: “This letter is longer than I wish, for I had not the time to make it shorter. ” That comment reveals the difficulty of making things simple. A cumbersome model is easy to produce. Producing a simple design that can handle change effectively is harder.
In terms of methodology and people, Jim Highsmith likes to cite Dee Hock:
“Simple, clear purpose and principles give rise to complex, intelligent behavior. Complex rules and regulations give rise to simple, stupid behavior. ”
12. At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.
It is fitting to end where we began. How light is right for any one project? Barely sufficient, and probably lighter than you expect.
How do we do this on our project? Bother to reflect on what you are doing. If your team will spend one hour together every other week reflecting on their working habits, you can evolve your methodology to be agile, effective and fitting. If you can't do that, well. .. you will stay where you are.
Reflecting on the Support Statements
Getting 17 people to agree on any set of words is difficult. The more detailed the advice, the more we different backgrounds and philosophies come into play.
We hope that the four leading value choices and the twelve supporting statements will give you enough information to build your own agile work habits.
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