In manufacturing, any piece of work that is ready for the next step might be considered inventory: finished goods, works in progress, and even raw material.
For a software delivery team, it’s hard to measure inventory. For some teams, they are done with a feature when it is checked into source control. For others, they are done when they have delivered build artifacts. A team’s definition of done comes into play here. A definition of done can be thought of as a list of characteristics of completed work. One common example is that all new functionality is covered by unit tests. If Team Bravo tells me a feature is done, then I can assume that if I ask to see unit tests that exercise the new feature, Team Bravo can point me to them.
Whether the finished product is code or binaries, until that deliverable is in the hands of customers (internal or external), the producer earns nothing from producing it and thus that code has a potential to be waste. Firms don’t pay teams to produce code, they need their customers to pay for the features that are realized by that running code. And I’ve been on teams producing a feature that was cancelled or shelved before delivery.
Before the advent of distributed version control systems like Git and Mercurial, source control systems used to store a full copy of each file being monitored. In systems like those, branching was expensive in terms of time and disk space. Keeping dorment branches beyond their usefulness was a form of waste. Even using Git, I recommend that teams utilize tags and remove inactive branches, because branches are easy to recreate.
Still, having seen the contents of many of my colleague’s “temp” folders, teams need to be disciplined about cleaning build and work artifacts — for example, sample production data used to diagnose an issue solved months ago. Often these files can be huge, which makes them poor candidates for a version control system. Teams should take the time to set up a shared file system for such files, so that a hard drive failure on Keith’s machine won’t start a panic. Free options like Box, Dropbox and SugarSync might suffice for small shops, enterprise solutions like Amazon S3 also exist.
Developers also experiment on their machines, and it’s easy for those machines to become tainted by unusual software installations as well as experimental and debug versions of code libraries. Having a continuous integration system can help protect against unwitting building a environmental dependency into your software. I say from experience that you don’t want to be a position where you need to keep a departed developer’s machine up and running on the network because it’s the only place a piece of production code will compile.
For every group that produces an output (code library, software package, what have you), they require a set of inputs. Software is built from raw materials, but instead of physical items programs are built from ideas. Backlog grooming is analogous to a crude oil refinery, substituting ideas for crude oil and requirements for gasoline.
If a team does not have good discipline around its backlog, much like those “temp” folders above, there will be items in the backlog that won’t see the light of day in the near future. Ideas that are no longer relevant, or as some say have been “overtaken by events”. Ones that aren’t commercially viable. Defects that don’t apply anymore. If the backlog gets months long, you may find that people create new stories and features that duplicate ones already in the backlog.
Whether it’s the team that decides what to do next or a product owner, each of those items needs to be reevaluated. This accumulated time reviewing stale features is wasteful. Teams should strive to keep their backlogs trim. Really, as long as there is always one single thing more to do, the team can continue working, so teams should keep their backlogs as small as possible without running dry. A kanban board can be of immense help in planning workflows like this.
Next installment is wasted motion and transportation.