What is “Agile”? And what is “Scrum”? And “XP”? Oh.. And Lean? What is that? Can you “work with” Agile? Or what exactly is it that you do? Are all just different and c00l buzzwords meaning the same thing?
Oh, the confusion… =)
Well, I think of Agile as a “value package”. The word “Agile” is simply the name of a set of core values and principles about how “development projects” is viewed. So, you can’t really “work with Agile”, but you can have processes and project methodologies that are Agile – they fit the Agile core values. Here’s what’s written on Wikipedia about Agile Software Development: “Agile methodologies generally promote: A project management process that encourages frequent inspection and adaptation; a leadership philosophy that encourages team work, self-organization and accountability; a set of engineering best practices that allow for rapid delivery of high-quality software; and a business approach that aligns development with customer needs and company goals.”. There’s a manifesto that covers the core values, which you can find here: http://agilemanifesto.org/.
So, “Scrum” then, what is that? Is that a process? Or a is it also just a “value package”? No, to both questions. Scrum is an agile "process framework". It is not a process, it is a framework for processes to exist (be formed) within. Scrum is an interpretation of Agile Development. Right or wrong, I view Scrum as an “instance” of an Agile development approach. Scrum sets the boundaries and the general direction for the processes but it doesn’t state exactly what those processes should be or what steps and methods they need to hold. That is why it is said that if you “implement scrum” you have to find your own way: you have to create your own set of processes and practices that fits your organization and the Scrum framework. It is quite correct to say that you “do Scrum”: it means that you have identified and enforced a set of practices that cover all the aspects of Scrum. You can read more about Scrum on (lots of places) for example http://www.scrumalliance.com/ and on Wikipedia.
Ok, and “XP” (eXtreme Programming)? Just like Scrum, XP is an “instance” of an Agile development approach. So XP too needs interpretation and adaptation to be implemented in your organization; it is not an out-of-the-box ready set of processes. The difference between Scrum and XP is that Scrum is more focused on project management and team aspects of software development, while XP focuses almost entirely on the hands-on development practices. Scrum for example talks about how to plan your iterations, using Sprint Planning meetings and Sprint Reviews. It doesn’t say much about how to actually write code. XP on the other hand doesn’t say as much about managing your project (although there is some overlap) but focuses much more on how the developers need to sit together and work in pairs, or that you need to have continuous integration, automatic testing, Test Driven Development (TDD), and so on. Scrum and XP fits really nicely together, and together they form a great and whole-covering framework for a really agile development approach. In our organization we have yet to adopt XP to any extent. But we’re getting there.
You can read more about XP on (lots of places) for example Wikipedia.
And finally, what is “Lean” in all of this? Well, it too is a way of observing the world - the world of manufacturing to be precise. According to Wikipedia, Lean is “the practice of a theory of production that considers the expenditure of resources for any means other than the creation of value for the presumed customer to be wasteful, and thus a target for elimination.”. It originates from the automotive industry (e.g. Toyota in the 1950s) and was later adapted to software development (Lean Software Development) by Mary and Tom Poppendieck. Just like Agile it covers a set of core values, and sets a direction for how to go about “manufacturing”, in our case Software Development. Lean is all about spotting and removing sources of “waste”, decreasing cycle time, continuous improvement, respect for and personal growth of individuals, etc. Lean and Agile fits very nicely together.
Confused? Yeah, me too ;-)
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