Friday, October 30, 2009


I have spent the past month digging deeper into lean (or agile) software development principles and practices. I have led many successful software projects and programs that have yielded high-quality, well-received software. For various reasons during the past four years, I have led software projects using agile development. Originally, I was trained in the classic waterfall model for software development engineering and management. I have also worked with many successful senior architects who are deeply entrenched by their successes in waterfall practices.

Distinctions help me learn by having opposing views in front of me and asking why people favor one idea over the other. For this investigation, I mentally placed a miniature version of a waterfall architect on one of my shoulders and a miniature version of a lean software development proponent on the other in a similar fashion as one might imagine conscience as an angel and a devil on each shoulder. I won't assign good or evil to either because such assignments make no sense and because I have been a witness to techno-religious wars that are never resolved, for example, the still on-going emacs versus vi war. I would rather master both methods and apply the best for the job at hand.

In my mind, the waterfall architect tells me that long, deep research cycles, in-depth, insightful discussions with multiple customers, careful, precise crafting of specifications, thorough hiring of skilled and capable engineers, well-engineered components, well-planned integration cycles, construction of comprehensive testing and release engineering functions, beta testing for customer feedback and verification, and production release of the final product are needed for successful projects. I appreciate his reasoning behind this statement because of our many successes with waterfall. His challenge is: fundamentally, why does a lean, iterative, agile development process produce as good or better results compared to what we know works?

Metaphorically, I turn to the lean software proponent and raise my eye brows looking for the response. She responds to my silent inquiry with we don't know what we don't know. The architect smiles. I know that he's thinking that's why we spend time carefully thinking through every step before proceeding to the next one. She continues, therefore we need to factor that reality into a different approach by eliminating waste, amplifying learning, deciding as late as possible, delivering as fast as possible, empowering the decision makers, and building in integrity. That sounds intriguing to me. I respond, please continue.

Waste in software development takes many forms such as waiting for approvals and resources to become available, working on features that will never be used by customers, and developer context switching. Learning can be amplified by multiple iterations (think practice makes perfect), feedback, and transparency (anyone can inspect project status at anytime). Deciding as late as possible sounds counter to making decisions but it isn't. Decide on those items that must be decided on first. For those items that you don't need to initially decide upon, allow those decisions to go unmade until you have learned more. Work on items in a depth-first approach to create more information to make better decisions as you go. Delivering as fast as possible to create working versions that customers and sponsors can verify is (or isn't) meeting the need. Empower the rank and file decision makers to make the hundreds of decisions daily to be consistent with the current plan and customer feedback. Allow them to organize the work to deliver potentially shippable units of work with each iteration. Finally, build both conceptual and perceived integrity into the project such that the incremental changes and re-factoring can be done while maintaining a consistent customer experience. This can be achieved by frequent inspections and test driven design with automated test development done either prior to or concurrent with implementation. While these techniques are promising, they are relatively new, not yet applied in a consistent, repeatable fashion, and are usually engineering centric instead of being embraced by the whole organization.

I turn to the architect and ask if these seem incongruent with his perspective. His response is that in theory, there are big differences, however, in practice, many of these techniques are used in pragmatic, successful applications of waterfall. For example, waterfall development projects are often slowed down by waiting for permission and approval, so he often takes risks by proceeding on work before approval or permission is granted. His motto is, "It's better to ask for forgiveness than to ask for permission". He is often frustrated by the lack of clarity of early customer requirements, even those formally specified in contracts. He's equally frustrated by changes in requirements as the project is under development and initiates a formal change request approval process. He keeps track of all of the changes to justify the additional time needed to redesign or re-implement previously completed work. He plans on multiple implementation and integration cycles to resolve dependencies among components and enable testers' early access to functionality. He finds ways to unlink dependencies so groups can work independently. He is frustrated by the constant requests for project status and lack of insight into what's being done by the various groups. He is particularly frustrated by the 'schedule chicken' that occurs between groups. Critical bugs found during testing are problematic, especially, those that uncover issues with the specifications. In response, he asks for design and code reviews to inspect work before it is integrated. He meets with testing organizations to develop test plans in advance so he knows what they will be doing and ensures the implementations can holdup during testing. He encourages testing to make automated test environments available early so engineers can run them locally prior to putting back changes.

I, too, have used these techniques to deliver waterfall projects on time. On the other hand (or, er, shoulder) these techniques are inherent in lean software development. My next question to the architect is so why don't we just use lean software development techniques directly instead of remaining entrenched with waterfall and applying techniques to address its short comings?

He nods and smiles.

At least, he didn't glare at me like he does when someone tells him that emacs is better than his beloved vi.

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