I’m at the 13th International Conference on Agile Software Development in Malmö Sweden. As usual when I listen to presentations these tend to trigger new liner of thoughts instead of pondering the details of what was said. I guess this is a flaw in how I internalise knowledge from others.
Not surprising, nobody here mentioned the V-model. Too bad,since I think it is one of the most important metaphors regarding software (and system) development there is. But it is also on of the metaphors that have been used in ways which are completely inappropriate.
My “condensed understanding” of the strengths of the V-model is this:
It defines a set of activities on the left side of the V with associated artefacts aimed at exploring the problem and detailing the solution down to the actual product (the code!). The important part is that these design activities have corresponding activities of verification & validation on the right hand side of the V, in a one-to-one relationship between the design and V&V activity. The number of levels is individual, but usually about 3-5, including code is reasonable.
Where it goes wrong is when the V is laid out in time as a template for progress of a project. This may make sense if you are designing for manufacturing-heavy products, but is useless for software, the time between understanding the problem (top-left part of the V) and where you verify that your understanding is correct is just way too long to be competitive. This is definitely not news for software developers, and is a key point in agile software development (but probably phrased differently).
But it seems to me that in order to optimise the efficiency and speed there is a tendency to downplay the activities above the point of the V ( the working code). Big-upfront-design is seen as such a bad thing that it ends up in no design at all, there is a direct jump between formulating the problem (e.g. user stories) and start coding.
I believe that in an agile project all activities in a V must be executed in each sprint in order to claim to be “truly agile”. Each sprint means a better understanding the problem, a better design to solve it, and a better implementation in the code. Of course all of these are verified and validated. That does not say that these activates are equally large, or the size of the V is the same in alls sprints, but if you leave out the conscious architecture in the sprints you don’t learn to do better in the next sprints.
You should design the activities in the V to provide the maximum added value with respect to the spent effort, which obviously depends on thousands of context-specific factors), but saying they are irrelevant is only reasonable for the simplest of systems, where you have a definition of the problem and code.
Personally I rather define the result of the activities, i.e.the artefacts, and let the teams decide themselves on how to populate them. I know blog readers may cry about excessive documentation, but what I am talking about is the necessity to externalise information necessary to share between developers, and teams, and to preserve this information over time, something which code never can do.
Long rant, and I’m not even close the exhausting my thoughts on the subject….
Showing posts with label Project Management. Show all posts
Showing posts with label Project Management. Show all posts
When to decide?
Tuesday, September 20, 2011 at 1:17 AM
I have recently experienced several occasions where people want to decide things as early as possible in a project. This seems to be based on previous experiences that this was difficult in the last project and we want to eliminate things to worry about late in the project since there will be new things to worry about then anyway. So why not solve the major problems you are aware about anyway?
I think this kind of thinking is detrimental for the success of the project, especially if the decision influences the architecture (Grady Booch said something like "the architectural decisions are those costly to change").
If one looks at the reason the problems came up in the first place it is usually things like the implications (especially technical) of the decisions was not fully understood, the requirements were not suitable, or my personal nightmare that my team will not suffer any consequences whatever the outcome so why not decide this now...
If one has superficial understanding of the consequences or if the requirements are unstable it is a better strategy to postpone the decision as late as possible, and also delegate it to those who are most affected/concerned. But this means you and your organisation is comfortable with living with uncertainty. Which may be very difficult depending on the culture or the organisation. For example if all of your project revolves around a stage-gate process (very common in the automotive industry) it really does not fly well to say "let's postpone this decision for another 6 months and make progress with what we can".
It may sound I ampreaching the agility gospel, but that is not the case. I have full understanding that once you have made an architectural decision you don't want to change it. I just want to argue for the heuristic that you should not decide something because you can, postpone it to when you have make it.
And as a consequence I really dislike when you have to decide things just to feed the process, especially if the process is very slow to change.
I think this kind of thinking is detrimental for the success of the project, especially if the decision influences the architecture (Grady Booch said something like "the architectural decisions are those costly to change").
If one looks at the reason the problems came up in the first place it is usually things like the implications (especially technical) of the decisions was not fully understood, the requirements were not suitable, or my personal nightmare that my team will not suffer any consequences whatever the outcome so why not decide this now...
If one has superficial understanding of the consequences or if the requirements are unstable it is a better strategy to postpone the decision as late as possible, and also delegate it to those who are most affected/concerned. But this means you and your organisation is comfortable with living with uncertainty. Which may be very difficult depending on the culture or the organisation. For example if all of your project revolves around a stage-gate process (very common in the automotive industry) it really does not fly well to say "let's postpone this decision for another 6 months and make progress with what we can".
It may sound I ampreaching the agility gospel, but that is not the case. I have full understanding that once you have made an architectural decision you don't want to change it. I just want to argue for the heuristic that you should not decide something because you can, postpone it to when you have make it.
And as a consequence I really dislike when you have to decide things just to feed the process, especially if the process is very slow to change.
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