Monday, February 25, 2008

Distributed Version Control Systems

A colleague of mine had a question for me about Distributed Versions Control Systems (or DVCS). There are a growing number of such systems these days: Mercurial, Bazaar, git, svk, BitKeeper, Gnu Arch, darcs, Monotone, Codeville, Arx, just to name a few. I referred them to a good essay by David Wheeler that talks about the fundamental differences between distributed vs centralized VCS (among other things).

I also Googled on the topic and came across some interesting links:
Anyone else have any links they recommend on the topic? (please, no spam/marketing)

Monday, February 18, 2008

BOOK: Lean Project Management

My review of Lean Project Management is in the February 2008 issue of the Agile Journal.
    Lean Project Management: Eight Principles for Success, is actually a second edition of the eBook Eight Secrets to Supercharge your Project with CCPM. It is available both in hardcopy and eBook formats. Lawrence Leach ( is perhaps best known as author of one of the most comprehensive texts on the subject of Critical Chain Project Management (CCPM). In this book, subtitled "Combining CCPM and Lean tools to accelerate project results," the author essentially integrates Lean Thinking into CCPM, along with elements from the Theory of Constraints (TOC) and PMBoK/PMI. Leach calls the result Lean Project Management or LPM.

    ... All in all, I found Lean Project Management to be a fairly quick read providing a good overview of some TOC and CCPM fundamentals and how they align with Lean thinking, as well as how Lean thinking can be applied to some of more traditional PMBoK methods. Someone looking for a more comprehensive reference on TOC thinking processes and CCPM would probably be better off reading Goldratt's books, the work of William H. Dettmer, and the 2nd edition of Leach's Critical Chain Project Management. But for those wanting the bird's eye overview with a brief "zoom in" on some of the details, along with how Lean thinking helps tie it all together with some of the more traditional project management methods, Lawrence Leach's Lean Project Management is a nice overview text describing some of the most powerful aspects of TOC and CCPM through "Lean eyes for the PM guy!"

Read the full review

Thursday, February 14, 2008

Software Architecture Quality Attributes

Following on to my previous blog-entry about Software Architecture Views and Perspectives, the book "Software Architecture in Practice" also describes a method called Attribute-Driven Design or ADD. This is not yet-another-design-method like BDD or TDD. ADD is concerned software architectural design (so it's at the "architecture-level" rather than what we might normally think of as the "design-level").

ADD is concerned with explicitly identifying the desired quality attributes of an architecture. Many of us know that simply implementing the (functional) requirements correctly is just the beginning of any good design, and possibly not even the most important attribute of the design. In addition to other attributes like security or availability, there are also attributes like modifiability of an architecture. And it is often these attributes that, if attained, are the true indication of whether or not we've done a good job.

Some of the more commonly desired quality attributes are:
  • Availability
  • Modifiability
  • Performance
  • Security
  • Testability
  • Usability
Many of us have also often had difficulty trying to explain to management the importance of things like "refactoring" and what that modifiability gives us in return. ADD makes such quality attributes an explicit goal of the architecture design process. One of the first things it asks us to do is the necessary homework (research and interviews) to analyze and identify what are the desired quality attributes for our architecture and its stakeholders. It also defines use-case-like entities called Quality Attribute Scenarios, which is a way of expressing such non-functional requirements as an explicit use-case (which can then have an associated business-value).

ADD also explicitly mentions the use of patterns and tactics as part of its methodology for achieving quality attributes and making design tradeoffs (quality attributes are often the "forces" for a pattern). For each of the common quality attributes above, it identifies a taxonomy of common tactics and patterns used to make good tradeoff decisions for particular aspects of the design.

Although it look s a bit heavyweight, ADD looks promising in its use of patterns and tactics and recursive/iterative nature. But what I like most about it is that fact that it makes explicit the kinds of quality attributes and their non-functional use-cases or "stories" which can then have business value/priority associated with it, and thereby justify the existence of activities that help realize those attributes of the system.

For some more information on ADD, see the following:
Now I want to ask the question of applying this same idea to software processes and software process architecture: Seems to me that in Agile development, we're really not anti-process, but there are some really important things (quality attributes of a process?) that we feel are often left out to pasture by a lot of the very formal, CMMI-based processes we witness. Perhaps they're ignoring these important process-design quality attributes? (as embodied in the Agile Manifesto?)

Sunday, February 10, 2008

Software Architecture Views and Perspectives

I'm fairly interested in the literature on Software Architecture Views and Perspectives. Folks here may remember my work on Dimensions and Views of SCM Architecture as one of the reasons why ...

The text of the entire 2nd edition of the "Software Architecture in Practice" textbook is available online as one source fo information on the subject (among others). I found another good link (& book reference) at

It's the website for the book "Software Systems Architecture: Working With Stakeholders Using Viewpoints and Perspectives" by Nick Rozanski and Eoin Woods. They classify/use "Viewpoints" and "Perspectives" as follows:

  • Functional
  • Information
  • Concurrency
  • Development
  • Deployment
  • Operational
  • Security
  • Performance and Scalability
  • Availability and Resilience
  • Evolution
  • Accessibility
  • Development Resource
  • Internationalization
  • Location
  • Regulation
  • Usability
Found a few other links too:

Monday, February 04, 2008

KanBan is NOT Iteration-Free!

Regarding my previous posting about Software KanBan, much as I really do like it and have nothing but the utmost respect for the likes of Corey Ladas and David Anderson, there is one major quibble I have with some of the stuff being said ...

I think all the stuff saying it is Iteration-less and Iteration-free is a bunch of hooey! I don't agree at all and I think it is extremely misleading to say that Software KanBan doesn't use or need iterative development.

Don't get me wrong - I think I understand where they are coming from. There is often a great deal of recurring and heated discussion on numerous Agile forums about "Ideal" iteration length. I understand how folks can be sick and tired of that (to be honest, I myself never really paid too much attention to those particular discussion threads about ideal iteration-size).

The idea that is new or revolutionary for some is that release/feature content is decoupled from development! One or more features/requests are being worked in parallel, and every two weeks (or however long) some combination of newly developed functionality from those that are ready is selected to be released (rather than before development is underway).

But it seems to me that this is just an application of Agile-style development iterations applied to multi-project management. It is Releases that are decoupled from iterations (and hence iteration-free). But as I see it, the iterations are still present: they are where the development is, on the various feature "projects" that are being developed in an incremental and iterative manner, each at their own rhythm (some might be every two weeks, others might be less frequent, but they all find their pace).

I don't believe for one second that each of those features/requests are specifying and elaborating 100% of their requirements before they start coding anything. Looks to me like, for all but the smallest of requests, they may flesh out a certain amount of requirements up-front (be it lightweight use-cases, or even something a bit more formal), but only to a high-level or medium-level of detail. And from that point on through, the detailed requirements, implementation, and feature-level testing and integration-testing they are proceeding in a VERY MUCH iterative fashion.

It may not be a strict fixed length, in that the rhythm may fluctuate and readjust from time-to-time, but it definitely does have a regular rhythm! The length of any given "iteration" is fixed to the cadence of the feature-team (even if it is a team of 1 or 2). Not all iterations may be the same length, but any given iteration is working to a fixed due-date rather than letting that cycle stretch out until the "scope" is complete.

So don't let anyone tell you that Agile development need not require working in an iterative manner. It most definitely does (and at multiple levels of scale). Just don't assume it means that iterations must always be a property of a "release" as opposed to some other related chunk of work (possibly multiple ones proceeding in parallel).

It is not the releasing that needs to be iterative, it is the development. And if the releases are decoupled form development (which I think is a GREAT idea), then the development of any non-trivial sized feature or request still will need to proceed in an iterative manner according to some regular cadence that gets established.