During a lunchtime conversation with a colleague, we chatted about project management and gained some insights into the Waterfall and Agile project management techniques.
Our first insight was that an organization cannot split its project management methods. It cannot run some projects with a Waterfall process and other projects with Agile processes. (At least not if the projects must coordinate deliverables.) A company that uses Waterfall processes may be tempted to run a pilot project with Agile processes -- but if that pilot project "plugs in" to other projects, the result will be failure.
The problem is that Waterfall and Agile make two different promises. Waterfall promises a specific set of functionality, with a specific level of quality, delivered on a specific date. Agile makes no such promise; it promises to add functionality and have a product that is always ready to ship (that is a high level of quality), albeit with an unknown set of functionality. The Agile process adds small bits of functionality and waits to get them correct before adding others -- thus ensuring that everything that has been added is working as expected, but not promising to delivery everything desired by a specific date. (I am simplifying things here. Agile enthusiasts will point out that there is quite a bit more to Agile processes.)
Waterfall processes make promises that are very specific in terms of feature set, quality, and delivery time -- but are not that good at keeping them. Hence, we have a large number of projects that are late or have low quality. Agile makes promises that are specific in terms of quality, and are good at keeping them. But the promises of the Agile processes are limited to quality; they do not propose the specifics that are promised by Waterfall.
With two different promises, it is no surprise that waterfall and agile processes don't co-exist. (There are other reasons that the two methods fail to cooperate, including the "design up front" of Waterfall and the "design as you go" of Agile.)
Our second insight was that transitioning an IT shop from Waterfall to Agile methods should not be accomplished by pilot projects.
Pilot projects are suitable to introduce people to the methods -- but those pilot projects must exist in isolation from the "regular" projects. Such projects were easy to establish in the earlier age of separate systems -- "islands of automation" -- that gave each system a measure of independence. Today, it is rare to see an IT system that exists in isolation.
Rather that use pilot projects, we like the idea of introducing ideas from Agile into the standard process used within the company. Our first choice is automated testing, the unit-level automated testing that can be performed by developers. Giving each developer the ability to run automated tests introduces them to a core practice of Agile, without creating an impedance mismatch.
After automated testing, we like the idea of allowing refactoring. Often omitted from plans for Waterfall projects, refactoring is another key practice of Agile development. Once unit tests are in place, developers can refactor with confidence.
Our third insight relates to project methods and project size. We think (and this is speculation) that Agile is better suited to small projects (and small systems) and Waterfall may be better suited to large systems. Thus, if you have large, complex systems, you may want to stay with Waterfall; if you have small systems (or even small applications) then you may want to use Agile.
We think that this relationship is correlation, not causal. That is, you can pick one side of the equation and drive the other. If you have large systems, you will end up with Waterfall. But the equation works in both directions, and you don't have to start with the size of your systems. If you use Agile methods, you will end up with smaller, collaborating systems.
Now, we realize that a lot of companies have large systems. We don't believe that by switching overnight to Agile methods will lead to smaller systems overnight. A base of large systems contains a certain amount of inertia, and requires a certain effect to redesign into smaller systems.
What we do believe is that you have a choice, that you can choose to use Agile (or Waterfall) methods (carefully, avoiding impedance mismatches), and that you can change the size of your systems. You can manage the size and complexity of your systems by selecting your processes.
These are choices that managers should accept and make carefully. They should not assume that "the system is the system" and "things are big and complicated and will always be so".
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