Fowler: Agile Vs. Lean Misses the Point
In a recent blog post, Martin Fowler explains how the question "Should I use Lean software development instead of Agile?" is based on a false premise. Agile and lean are so deeply interwoven that if you are doing agile you are doing lean, and vice-versa. Those considering process change will likely find the description of the interrelatedness interesting and enlightening.
Fowler starts off explaining a bit of the history of lean, which traces its roots to lean manufacturing and the Toyota Production System developed in the 1950's. This system, and the thinking behind it, is widely credited with giving Japanese manufacturing, and Toyota in particular, a significant edge.
Lean has come to be used as an umbrella term for any approach to work based on lean manufacturing and the Toyota Production System. This includes lean construction, lean laboratory, as well as lean software development.
Agile is the umbrella term for a family of software development methodologies, including Scrum and XP, all of which share some core principals. When someone says they are doing agile software development, they might mean that they are using any one of these methodologies, a hybrid of several, or simply working in a way that embodies the core agile principals.
Many of the people who developed the current crop of agile methodologies were strongly influenced by lean manufacturing and the ideas behind it. This can be seen in the many commonalities between lean and agile, including:
- People centric approach
- Empowered teams
- Adaptive planning
- Continuous improvement
Based on the work of Mary and Tom Poppendieck, Alan Shalloway, and others, a lean software development community has come into existence. This community is distinct from other communities, such as Scrum, XP, DSDM, and FDD. Yet all of these communities exist under the umbrella of agile. Agile, in turn, is highly influenced by the original lean manufacturing ideas.
It is true that 'lean software development' is agile. It is also true that 'agile software development' is lean. Thus, it makes no more sense to ask "Should I adopt agile software development or lean software development?" than it does to ask "Should I adopt Scrum or agile?"
It's all true!
There was also some solid talk about creating a model around Agile at Agile2008. Expect to hear more about this soon, and check at the agile-model-evolution group at Yahoo Groups (tech.groups.yahoo.com/group/agile-model-evolution/)
True, but sad he had to say it
There is no versus
No, they are different
The 4 principles of Lean Development are:
-Add Nothing But Value (Eliminate Waste)
-Center On The People Who Add Value
-Flow Value From Demand
-Optimize Across Organizations
The Agile Manifesto says:
-Individuals and interactions over processes and tools
-Working software over comprehensive documentation
-Customer collaboration over contract negotiation
-Responding to change over following a plan
The Agile Manifesto satisfies the middle two Lean principles and a bit of the first. Lean is all about waste elimination and (multi-)organizational optimization. At best, Agile is a subset of Lean. It's false to say that if one is doing agile, one is doing lean. It may be true to say that if one is doing lean, one is doing agile, however.
XP actually violates the first principle of the Agile Manifesto. XP is an extremely prescriptive and disciplined process requiring complex and sophisticated tools (for re-factoring). There are many practitioners who insist that if all of the practices aren't being followed, XP isn't being practiced. That's process and tools over people. Lean also requires that if a process is not needed or isn't working, get rid of it. That's how Lean can break XP.
Lean is also designed to scale and scale well. Agilistas are still wringing their hands over this one. Go back and read what Shewart, Fruth, Deming and Taylor wrote. The similarites and differences between Lean, Agile and XP will become very apparent.