The AppLife Update Blog

  • Functional Requirements Completeness vs. Scope Creep

    When discussing software requirements documentation, a very common question asked is "When is a software specification complete?"  This is a very subjective question, and answers are often as far apart as discussions comparing waterfall to agile software development methodologies.  I like to break the discussion into two parts.

    1. When is requirements elicitation complete?
    2. When is requirements elaboration complete?

    If you split the question and look at the issue in this way, you can at least get to a non-subjective half answer.  I know... what a terrible result.  But the truth is sometimes like that.  The answer to question 1 is still subjective, but at least we have succeeded in identifying a more specific point to discuss.  completeness The answer to question 2 is far less subjective.  In fact, removing arguments based on the quality of the elaboration work product, one could argue that answering question 2 is absolutely non-subjective.  Requirements elaboration completeness is identified when all elicited requirements are described sufficiently to transfer understanding of the requirement to the software documentation reader.  In other words, when each requirement is checked as complete by the software documentation author, and agreed as complete by stakeholder reviewers.

    The Requirements Elicitation Completeness Conundrum

    Question 1 is much harder to identify. The inability to identify the answer to this question, and the frustrations of teams that have tried, is a huge contributor to the industry-wide recognition of agile methodologies as a potential better way to work software projects.  Any attempt at identifying completeness can only take into account known issues. You simply don't know what you haven't yet discovered, and the best advice in assessing requirements completeness is to acknowledge this simple truth.  Don't get hung up on it.  Diligently attempt to elicit the known requirements, and plan to iterate early and often in order to catch the unknown requirements. 

    It can become very costly when we try to completely identify all requirements of a software project up front.  This cost is not just in the analysis time we spend chasing perfection, but also in all the requirements that are identified in our quest, but are not really requirements. These requirements turn into software features that are developed, but never used.

    Software teams should expend reasonable resources in identifying known requirements up front, elaborate those requirements to completeness, then recognize and embrace requirements change that comes from iterative understanding of the problem domain and iteratively incorporate changes as the unknowns become known.  This is scope creep, but it is not bad, and should be planned for.  Your team will fair far better technically and financially when necessary scope creep is expected, planned for, and then analyzed and documented as part of your iterative development process.

    Posted at 26 January, 2010 | By :Brian Haas | Categories : Functional Specs | Requirements Management |
  • The Past, Present and Future of Requirements Documentation

    Do you remember the days before Agile changed the software development discussion? Back before waterfall wasn't the term coined for all things bad about software development.  You should. It wasn't really that long ago.  Back in those days, believe it or not, there... gasp.... were successful software projects.  But how could that be!  Any time spent in today's software blogosphere would have you asking that question for sure. Successful projects have always been worked through some level of iteration. There just hasn't always been a recognizable methodology name for it.


    Back in those long lost days of yesteryear it would have been unthinkable to initiate a software project without any documentation.  Today, it seems almost unthinkable to document anything. Tomorrow, we think that today's experiences will bring about a resurgence of the importance of software requirements documentation.  These documents will not be created and managed like they were yesterday though. Iteratively creating and maintaining requirements documentation will be the way it's done.

    But what does it mean to iteratively create documentation?  Isn't all documents inherently created iteratively?  Iterations in requirements documentation are as much a mindset as it is an action. Its accepting the notion that documents are never finished, and that acceptance does not have to mean finalized.  Yesterday, a requirements document was written with the expectation of completion.  The document was completed when it passed a thorough stakeholder review.  Upon completion, strict change control was set in place, requiring the organizational equivalent of an act of congress to modify.  This type of requirements documentation is probably familiar to you, and it is not an iterative requirements doc. Authors of requirements docs that cannot be easily changed have an overwhelming burden to continue analyzing beyond the point of effective prudence.  These documents take a long time to "complete" and once completed, they are not maintained due to the organizational resistance to change.  These documents are often very expensive to create and filled with inaccuracies and bad assumptions. Instead of providing clear guidance, accurate estimates, and minimizing scope creep, they creating more harm than good.   This is precisely what has lead to the agile wave and a constant search for a better way.

    The "better way" is not to abandon documentation all together, as desirable as that may be to some.  Requirements communications always live longer than the verbal discussion they are born in.  If they are not captured somehow, problems later in the software development cycle will surely ensue.  If requirements documentation can be viewed as an iterative communications medium, a capture of conversation, and not a stone tablet, your documentation efforts will be worthwhile and lead to less scope creep, rework, and higher quality software.  Welcome to the future.

    Posted at 6 January, 2010 | By :Brian Haas | Categories : Functional Specs | Requirements Management |