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Scott Ambler
Glen Little
Mark Lines
Valentin Mocanu
Daniel Gagnon
Michael Richardson
Joshua Barnes
Kashmir Birk

Recent Posts

What Does it Mean to Be Awesome?

Failure Bow: Choosing Between Life Cycles Flowchart Update

Evolving Disciplined Agile: Guidelines of the DA Mindset

Evolving Disciplined Agile: Promises of the DA Mindset

Evolving Disciplined Agile: Principles of the DA Mindset

Successful Agile Software Development Requires a Hybrid Approach

Hybrid

Disciplined Agile Delivery (DAD) is a hybrid framework that builds upon the solid foundation of other methods and software process frameworks.  The DA toolkit adopts practices and strategies from existing sources and provides advice for when and how to apply them together.  In one sense methods such as Scrum, Extreme Programming (XP), Kanban, and Agile Modeling (AM) provide the process bricks and DAD the mortar to fit the bricks together effectively.

The DA toolkit adopts strategies from the following sources:

  • Scrum.  The Scrum method focuses on team leadership and requirements change management during the construction portion of the delivery lifecycle.  Scrum captures some really great ideas that have become commonly adopted by agile teams.
  • Extreme Programming (XP). XP is an agile method that focuses primarily on construction-oriented practices such as continuous integration (CI), test-driven development (TDD), pair programming, sustainable pace, small releases, simple design, and many others.  Although XP’s practices appear straightforward on the surface, many of them require significant technical skill and discipline on the part of practitioners.
  • Lean software development.  Practitioners of agile development are increasing looking to adapt ideas from lean thinking.  Lean software development is based on seven principles: Eliminate waste, amplify learning, decide as late as possible, deliver as fast as possible, empower the team, build integrity in, and see the whole.
  • Kanban.  Kanban is a method for managing knowledge work with an emphasis on just-in-time delivery while not overloading the team members. In this approach, the process, from definition of a task to its delivery to the customer, is visualized and team members pull work from a queue or work item pool.
  • Unified Process (UP).  The UP is an iterative and incremental process framework for software development.  Although often instantiated as a heavy-weight approach, it has in fact been instantiated in a very light weight and agile manner, particularly in the form of Agile Unified Process (AUP) or OpenUP.  The DA toolkit adopts and enhances several critical governance strategies from the UP.
  • Agile Modeling (AM).  AM is a practice-based methodology for effective modeling and documentation of software-based system. AM was purposely architected to be a source of strategies which can be tailored into other base processes, something DAD takes explicit advantage of.   AM strategies adopted by DAD include initial requirements and architecture envisioning, just in time (JIT) model storming, continuous documentation, and several others.
  • Agile Data.  The Agile Data (AD) method defines a collection of strategies that IT professionals can apply in a wide variety of situations to work together effectively on the data aspects of software systems. Practices for evolutionary/agile database development include database refactoring, database regression testing, agile data modeling, and continuous database integration.
  • Enterprise methods. DAD is starting to adopt strategies from enterprise IT methods such as Scaled Agile Framework (SAFe) and Enterprise Unified Process (EUP).  These strategies address enterprise architecture, product management, portfolio management, operations and support, release management and other important IT disciplines. These strategies reflect the DAD philosophy of enterprise awareness.
  • Other methods.  DAD adopts techniques and practices from other methods such as Dynamic System Development Method (DSDM), Feature Driven Development (FDD), Evo, Outside-In Development (OID), and Crystal Clear.
  • Agile development practices.  There are many practices that are not specific to agile methods that have been developed within the agile community, and DAD leverages many of them.

One of the great advantages of agile and lean software development is the wealth of practices, techniques, and strategies available to you.  This is also one of its greatest challenges because without something like DAD it’s difficult to know what to choose and how to fit them together.

Posted by Scott Ambler on: February 05, 2014 02:43 PM | Permalink | Comments (0)

Whitepaper: Going Beyond Scrum

Going Beyond Scrum

This paper describes, step-by-step, how to evolve from today’s Scrum vision of agile software development to a disciplined agile solution delivery.  It begins with a brief overview of the agile software development movement and its implications.  We then overview the Scrum method with its associated benefits and drawbacks, and then how to move beyond Scrum to a full delivery process framework called Disciplined Agile Delivery (DAD).  DAD is a governed, hybrid approach that provides a solid foundation from which to scale agile solution delivery within enterprise-class organizations.    The steps to do this are:

  1. Focus on consumable solutions, not just potentially shippable software
  2. Extend Scrum’s construction lifecycle to address the full delivery lifecycle
  3. Move beyond method branding
  4. Adopt explicit governance strategies
  5. Take a goal-based approach to enable tailoring and scaling

You can download the paper here.

Posted by Scott Ambler on: October 24, 2013 08:00 AM | Permalink | Comments (0)

Strategies for Implementing Non-Functional Requirements

Non-functional requirements, also known as quality of service (QoS) or technical requirements, are typically system-wide thus they apply to many, and sometimes all of your functional requirements.  Part of ensuring that your solution is potentially consumable each iteration is ensuring that it fulfill its overall quality goals, including applicable NFRs.  This is particularly true with life-critical and mission-critical solutions.  Good sources for NFRs include your enterprise architects and operations staff, although any stakeholder is a potential source for NFRs.

As your stakeholders tell you about functional requirements they will also describe non-functional requirements (NFRs).  These NFRs may describe security access rights, availability requirements, performance concerns, or a host of other issues as saw in my blog regarding initial architecture envisioning.  There are three basic strategies, which can be combined, for capturing NFRs: technical stories; acceptance criteria for individual functional requirement (such as stories); and an explicit list.

 

So what are the implications for implementing NFRs given the three previous capture strategies?    Although in the DAD book we make this sort of comparison via a table to improve consumability, in this blog posting I will use prose due to width constraints.  Let’s consider each one:

  1. Technical stories.  The advantages of this approach are that it is a simple strategy for capturing NFRs and that it works well for solutions with a few NFRs or simple NFRs.  But, the vast majority of NFRs are cross-cutting aspects to several functional stories and as a result cannot be implemented within a single iteration.  This strategy also runs the risk of teams leaving NFRs to the end of the construction phase, thereby pushing technical risk to the end of the lifecycle where it is most difficult and expensive to address.
  2. Acceptance criteria. This is a quality focused approach which makes the complexity of an individual functional requirement apparent, working well with test driven approaches to development.  NFR details are typically identified on a just in time (JIT) basis during construction, fitting in well with a disciplined agile approach.  But, because many NFRs are cross cutting the same NFR will be captured for many functional requirements.  It requires the team to remember and consider all potential NFR issues (see Figure in my previous posting) for each functional requirement.  You will still need to consider NFRs as part of your initial architecture efforts otherwise you risk a major rework effort during the Construction phase because you missed a critical cross-cutting concern).
  3. Explicit list.  This strategy enables you to explore NFRs early in the lifecycle and then address them in your architecture.  The list can be used to drive identification of acceptance criteria on a JIT basis.  But, NFR documents can become long for complex systems (due to the large number of NFRs).  This can be particularly problematic when you have a lot of NFRs that are specific to a small number of functional requirements.  Teams lacking in discipline may not write down the non-functional requirements and trust that they will remember to address them when they’re identifying acceptance criteria for individual stories.

In most situations you should maintain an explicit list and then use that to drive identification of acceptance criteria as we’ve found that it’s more efficient and lower risk in the long run.  Of course capturing NFRs is only one part of the overall process of addressing them.  You will also need to implement and validate them during construction, as well as address them in your architecture.

An important issue which goes to NFRs such as consumability, supportability, and operability, is that of deliverable documentation.  At the start of the project is the best time to identify the required documentation that must be created as part of the overall solution.  This potentially includes operations manuals, support manuals, training materials, system overview materials (such as an architecture handbook), and help manuals to name a few.  These deliverable documents will be developed and kept up to date via the continuous documentation practice.

 

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Posted by Scott Ambler on: October 14, 2012 10:39 AM | Permalink | Comments (0)

Disciplined Agile Architecture: Initial Architecture Envisioning

An important aspect of Disciplined Agile Delivery (DAD) is its explicit inclusion of an Inception phase where project initiation activities occur.  Although phase tends to be a swear word within the agile community, the reality is that the vast majority of teams do some up front work at the beginning of a project.  Some people will mistakenly refer to this effort this Sprint/Iteration 0 it is easy to observe that on average this effort takes longer than a single iteration (the 2009 Agile Project Initiation survey  found the average agile team spends 3.9 weeks in Inception and the November 2010 Agile State of the Art survey found that agile teams have Construction iterations of a bit more than 2 weeks in length).

Regardless of terminology, agile teams are doing some up front work.  Part of that initial work is identifying an initial technical architecture, typically via some initial architecture envisioning http://www.agilemodeling.com/essays/initialArchitectureModeling.htm.  Because your architecture should be based on actual requirements, otherwise you’re “hacking in the large”, your team will also be doing some initial requirements envisioning  http://www.agilemodeling.com/essays/initialRequirementsModeling.htm in parallel.  Your architecture will be driven in part by functional requirements but more often the non-functional requirements, also called quality of service (QoS) or simply quality requirements.  Some potential quality requirements are depicted in the figure below (this figure is taken from the Disciplined Agile Delivery book but was first published in Agile Architecture Strategies ).

Architectural views and concerns

Some architects mistakenly believe that you need to do detailed up front modeling to capture these quality requirements and then act upon them.  This not only isn’t true it also proves to be quite risky in practice, see my discussion about Big Modeling Up Front (BMUF)  for more details.  Disciplined agilists instead will do just enough initial modeling up front and then address the details on a just-in-time (JIT) basis throughout construction.  Of course it’s important to recognize that just enough will vary depending on the context of the situation, teams finding themselves at scale will need to do a bit more modeling than those who don’t.  It’s also important to recognize that to address non-functional requirements throughout construction that you need to have more than just architectural modeling skills.  This topic will be the focus of my next blog posting in this series.

Posted by Scott Ambler on: October 09, 2012 08:41 AM | Permalink | Comments (0)

Potential Misconceptions about Agile Architecture

Recently at the Scott W. Ambler + Associates site we received a series of questions from someone who wanted to better understand how architecture issues are addressed on agile project teams.  It seemed to me that the questions were sufficiently generic to warrant a public response instead of a private one.  So, over the next few days I’m going to write several blog postings here to address the issues that were brought up in the questions.  It’s important to note that I will be answering from the point of view of Disciplined Agile Delivery (DAD), and not agile in general.  Other agile methods may provide different advice than DAD does on this subject, or no advice at all in some cases.

The goal of the first blog posting in this series is to address several potential misconceptions that appeared in the email.  I want to start here so as to lay a sensible foundation for the follow-on postings.

Partial Misconception #1: Agile can be prefixed in iteration 0 by architectural design

I’ve named this a “partial misconception” for a few reasons:

  1. Disciplined agile teams do some up-front work.  This is called the Inception Phase in DAD, although other methods may refer to it as iteration/sprint 0, warm up, initiation, or other names.  Up-front work is an explicit part of DAD.
  2. Iteration 0 isn’t an accurate term.  Although I have used this term in the past when discussing project initiation, the reality is that the average agile team spends about a month doing project initiation activities whereas the average iteration length is two weeks.  So, Inception really isn’t a proper iteration.
  3. Inception is more than just architecture.  Several activities typically occur at this point in time, particularly initial architecture envisioning, initial requirements envisioning, initial release planning, and putting the team together to name a few things.

Chapters 6 through 12 in Disciplined Agile Delivery describe these project initiation activities in detail.  Also, I recently wrote that it requires discipline to keep Inception short.

Partial Misconception #2: On principle, Agile is against “big” anything

This is also a “partial misconception” for several reasons:

  1. There is in fact a lot of agile rhetoric against big artifacts.  It’s very easy to find agile writings about the challenges with big requirements up front (BRUF), big modeling up front (BMUF) in general, and detailed up front planning for instance.
  2. Disciplined agile is against needless waste, not “big” things.  Many traditional modeling and planning practices prove to be quite wasteful in practice.  A serious cultural challenge that the traditional community has is that they are afraid to throw out the bathwater because they assume that the baby will go with it.  I believe that Disciplined Agile Delivery (DAD), and Agile Modeling before it, make it quite clear that it’s possible to gain the benefit of thinking before doing without taking on the very serious problems around doing too much thinking before doing.  So, have the discipline to keep the thinking “baby” yet discard any needless documentation “bathwater”.
  3. In rare situations it’s appropriate to create “big” artifacts.  Disciplined agilists aim for sufficient artifacts, the size of which will depend on the context of the situation that your team finds itself in.  In a recent article for Dr. Dobb’s Journal, Disciplined Agile Architecture, I explicitly explored how initial architecture envisioning on an agile project may result in “big” artifacts in some situations.  These situations are very rare mind you, ignoring cultural imperatives to create big artifacts because some people still haven’t made the jump to a disciplined agile approach, but they do happen.  One of the strengths of the DA toolkit is that it is goal driven, not prescriptive, and explicitly explores the tradeoffs surrounding the amount of detail to capture and when to do so.

Partial Misconception #3: Refactoring system architecture beyond mid-implementation is much more expensive than refactoring components

Once again, this is a partial misconception.  I suspect part of the problem is a lack of understanding of what refactoring is really all about, a recurring problem with experienced traditionalists, and part because of a lack of understanding of how architecture is address by disciplined agile teams.  Some thoughts:

  1. Refactorings are simple, not difficult.  The goal of refactoring is to make SMALL changes to your design that improve the quality without changing the semantics of the design in a practical manner.  This is true of code refactorings, database refactorings, user interface refactorings, and other types of refactorings.  Small changes are inexpensive to make given the appropriate skills, tools, and organizational environment.
  2. Architectural rework (not refactoring) is often difficult.  Rework, or rewrites, are very large changes the goal of which is typically to replace large portions of your solution.  Yes, the later in the lifecycle such rework occurs very likely the more expensive it will be because you’ve built more based on that architecture that is now being reworked.  This is a general issue, not just an agile one.
  3. Disciplined agile teams get going in the right direction to begin with. The practice of initial architecture envisioning, which we describe in detail in Chapter 9 of Disciplined Agile Delivery, aims to think through the architectural strategy before getting into construction.
  4. Disciplined agile teams prove their architecture works early. The first construction milestone, prove the architecture, reduces the risk of architectural rework.  The goal is to prove that the architecture works by building a working end-to-end skeleton of the solution which implements critical/difficult technical requirements.  This is an agile “fail fast” strategy, or as we say in DAD a “succeed early” strategy, that reduces technical risk on your project.   As an aside, including explicit light-weight milestones such as this is one of many agile governance aspects built right into DAD.
  5. Disciplined agile teams have an architectural role.  This role is called Architecture Owner and one of the responsibilities of the person in this role is to guide the team in architectural issues throughout the entire DAD lifecycle.
  6. There are no guarantees.   No matter how smart your approach, there’s still a chance that rework can happen.  For instance, you can be mid-way through a project and the vendor of a major architectural component of your solution decides to withdraw it from the market.  Or the vendor goes out of business.  Or perhaps your firm is taken over by another firm and the new owners decide to inflict, oops I mean bless you with, their architectural strategy.  Stuff happens.  Once again, this is a general issue, not specifically an agile one.
  7. Quality decreases the cost of rework.  Disciplined agilists will write high-quality code, with a full regression test suite in place, at all times during Construction.  It’s easier to rework high quality artifacts compared with low quality artifacts, so if you get stuck having to perform rework at least the pain is minimized.  My article Agile Testing and Quality Strategies overviews many techniques.

In short, disciplined agile teams do what they can to avoid architectural rework to begin with by having an explicit architecture owner role who focuses on architectural issues throughout the entire lifecycle, by identifying a viable architectural strategy early in the project, proving that architectural strategy works early in Construction, and producing high-quality artifacts throughout the lifecycle that are easier to rework if needed.   With continuous documentation practices and a focus on producing artifacts which are just sufficient enough for the situation at hand, this proves to be far more effective than traditional strategies that assume you require large up-front investments in “big” artifacts, that rely on validation techniques such as architecture reviews instead of the far more concrete feedback of working code, and that often leave quality strategies to the end of the lifecycle (thereby increasing the cost of any rework).

I plan two follow-on blog postings in this series, one exploring how initial architecture envisioning works and one about how to address initial quality requirements (also called non-functional requirements or quality of service requirements) on disciplined agile projects.  Stay tuned!

At Scott W. Ambler + Associates we offer a one-day workshop entitled Agile Architecture: A Disciplined Approach that you should consider if you’re interested in this topic.  We also offer coaching and mentoring services around agile architecture.

Posted by Scott Ambler on: October 01, 2012 09:31 AM | Permalink | Comments (0)
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