How Do You Choose Between Software Lifecycles?

Confused

As you know the Disciplined Agile framework supports several delivery lifecycles – Agile, Lean, Continuous Delivery: Agile, Continuous Delivery: Lean, Exploratory.  We do this because solution delivery teams face different situations, so one lifecycle will not fit all.  This begs the question of when would a team adopt each lifecycle?  That is the focus of this blog.

This blog explores the following topics:

  1. What lifecycles does DAD support?
  2. What criteria should you consider when choosing a lifecycle?
  3. Who chooses?

What Lifecycles Does DAD Support?

The delivery lifecycles we will explore are:

  1. Agile/Basic. DAD’s Agile/Basic lifecycle which extends Scrum’s construction lifecycle. We call this the basic/agile lifecycle because it’s likely where you’re going to start. Common scenarios for adopting this version of the lifecycle include situations where you’re extending Scrum to be sufficient for your needs or you’re transitioning from RUP to a disciplined agile approach.
  2. Lean/Advanced. The Advanced/Lean lifecycle encompasses lean strategies such as minimizing work in process, maximizing flow, a continuous stream of work (instead of fixed iterations), and reducing bottlenecks. New work is pulled from the work item pool when the team has capacity.
  3. Continuous Delivery: Agile.  The Continuous Delivery: Agile lifecycle  is a natural progression from the Agile/Basic lifecycle. Teams typically evolve to this lifecycle from the Agile/Basic lifecycle, often adopting iteration lengths of one-week or less. The key difference between this and the Agile lifecycle is that the continuous delivery lifecycle results in a release of new functionality at the end of each iteration rather than after a set of iterations.
  4. Continuous Delivery: Lean. DAD’s Continuous Delivery: Lean lifecycle is basically a leaner version of the Continuous Delivery: Agile lifecycle where the product is shipped into production or the marketplace on a very regular basis. This could be often as daily, although weekly or monthly is quite common too.
  5. Exploratory/Lean Startup.  DAD’s Exploratory lifecycle is followed by agile or lean teams that find themselves in startup or research situations where their stakeholders have an idea for a new product but they do yet understand what is actually needed by their user base.
  6. Waterfall/Serial.  Although this is not supported by Disciplined Agile, we do recognize that some teams will still follow this more traditional way of working.  For more thoughts on this subject, please see the blog posting When Does Traditional Software Development Make Sense?

 

What Criteria Should You Consider When Choosing a Lifecycle?

The following table compares the lifecycles, suggesting when you would choose to follow each one.

Lifecycle Team Type Time to Market Advantages Disadvantages When to Use
Agile/Basic Project Medium
  • Straightforward lifecycle based on Scrum that is easy to learn due to its prescription
  • Iterations (sprints) motivate teams to build functionality in multi-week batches
  • Releases into production typically months apart
  • Tends to fall apart when requirements change often
Teams new to agile
Lean/Advanced Project Fast
  • Functionality is released into production when it`s ready to go
  • Work can be prioritized via a variety of criteria
  • Small batches of work lead to quick flow
  • Requires greater skill and discipline compared to the Agile lifecycle
Disciplined teams with quickly evolving requirements
Continuous Delivery: Agile Product (long lived) Fast
  • Functionality is released into production regularly at a steady flow (typically weekly)
  • Requires significant skill and discipline
  • Requires automated testing, integration, and deployment
Long-running teams
Continuous Delivery: Lean Product (long lived) Very Fast
  • Functionality is released into production continuously, typically one or more times a day
  • Requires significant skill and discipline
  • Requires automated testing, integration, and deployment
Long-running, disciplined teams
Exploratory/Lean Startup Experimental Fast
  • Quick and inexpensive way to run business experiments
  • Low-risk approach to validating potential new business strategies
  • Requires a way to target a subset of your (potential) customer base
  • Often not applicable in regulatory compliance situations
  • Often perceived as a strategy for startup companies only
Identification of a new product or service offering for the marketplace where there is a high risk of misunderstanding the needs of potential end users
Waterfall/Serial Project Slow
  • Comfortable approach for experienced IT professionals who have not yet transitioned to an agile or lean way of working
  • Tends to be very high-risk in practice due to long feedback cycles and delivery of a solution only at the end of the lifecycle
  • Associated risks are often overlooked by management due to façade of predictability and control provided by the paperwork produced
Low-risk situations where the requirements are stable and the problem has a well-known solution.  For example, upgrading the workstations of a large number of users or migrating an existing system to a new platform

 

Who Should Choose the Lifecycle?

The team.

They will often do this with the guidance of an experienced Disciplined Agile coach, particularly when they are new to DA.  It’s tempting to have your portfolio management team to make this choice, and they may often make a (hopefully solid) suggestion when the first initiated an endeavour, but in the end it needs to be the choice of the team.  As you see in the table above there are common considerations for when to use each lifecycle, but the primary considerations are always the skill and preferences of the team itself.

 

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4 thoughts on “How Do You Choose Between Software Lifecycles?

  1. Paul Oldfield

    Exploratory / Lean Startup – most of the other lifecycles depend to some large degree on somebody being able to say what would be “valuable”. Where you don’t yet know what is valuable, “Lean Startup” can be very helpful. You might swap later to a different lifecycle… later there might be a reasonable alternative!

    Reply
  2. Thomas Owens

    “As you know the Disciplined Agile framework supports several delivery lifecycles – Agile, Lean, Continuous Delivery: Agile, Continuous Delivery: Lean, Exploratory. ”

    Something that I still haven’t quite figured out,

    These are the lifecycles that are often discussed in the context of DA. Are these the ones that have been discovered, documented, and vetted against the framework or is it possible to take the framework and define a new lifecycle that is not one of these? Or are these generic enough that it encompasses the breadth of tailoring within these variations?

    Reply
  3. Scott Ambler Post author

    Owen, yes these are the ones that have been “discovered” or perhaps observed is a better word. We’ve also observed mixes as well. For example, it’s quite common for a team to evolve from the Agile lifecycle to the CD: Agile or CD: Lean lifecycles. There can be several months of transition period as they work their way into the new lifecycle. See http://www.disciplinedagiledelivery.com/lifecycle/#ContinuousImprovement for some thoughts on that.

    Reply

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