Keeping things together

I am asked this question at least once a week, and I’ve heard all kinds of arguments and disbeliefs in the theory of making every iteration “releasable”.  As one of the fundamental tenants of a good Agile practice and the antithesis of most Waterfall projects, the ability to keep the software in a customer-shippable format is a key measure into how “agile” a team really is.  It seems odd to me that it’s almost been a year since my last blog entry on this, and it’s still a nagging issue which we still struggle with from time to time.

So, what are the acceptance criteria for staying releasable?  Here’s a recent definition we have starting using on a daily and/or iteration basis:

• The software builds and can be installed in its current state.  (a daily requirement)
• No severity 1 or 2 defects exist.  If regression defects are found, they must be prioritized over new user stories in iteration planning.  (an iteration requirement)
• Shipping to a customer is 1 (2 max) hardening iterations away.  (an iteration requirement)

As mentioned previously, there are a variety of ways to address “the big feature at the core of code base”.  Beyond trying to break the feature down as much as possible, some methods include hiding the new functionality and using configuration to enable/disable the new functionality.  A more extreme way to solve this problem is to create a branch of the software that can be tested in some form or fashion.  This part of the software would be merged back into the main development path once it has proven its merit.  (While possible, this last approach is the least desired, due to the integration risk introduced later than normal.) 

Regardless, the actual implementation is often less important than the discussions related to mitigating the risk associated with destabilizing the existing functionality.  Having the releasability criteria often triggers conversations within the Agile teams on how to address trouble areas instead of dumping weeks of code into the product hoping for a miracle in the end.