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130RE: [scrumdevelopment] Re: book, "Agile Software Development with Scrum"

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  • Ken Schwaber
    Nov 29 7:57 AM
      Many methodologies initiate a project with a phase that defines the business
      architecture and the technical architecture of the system, in full. Based on
      the user fully stated requirements, the team defines a model of the overall
      business processes and how they interact, as well as all of the technology
      that underlies the business processes and allows them to interact and
      operate with the reliability, scalability, and performance required. The
      problem with this approach is that the requirements have to be fully known
      to do so, and the implication is that the system will be delivered as
      modeled (either iteratively or with a big bang).

      Emergent architecture (business and technical) says that the team thinks
      through, designs, and builds only that architecture needed to support the
      business value (sprint goal) needed to deliver the functionality for that
      iteration (sprint). Anything beyond that architecture is speculative (since
      requirements emerge), unnecessary for supporting that sprint's
      functionality, and extra cost - both in development, debugging, and

      Although the team may "whiteboard" an overall model of the the system prior
      to starting, so they have a context, the model only provides a context. The
      details emerge with each sprint.


      -----Original Message-----
      From: Peter McGowan [mailto:peter@...]
      Sent: Thursday, November 29, 2001 10:28 AM
      To: Ken Schwaber
      Subject: Re: [scrumdevelopment] Re: book, "Agile Software Development
      with Scrum"

      Hi Ken,

      What's "Emerging Architecture"?


      ----- Original Message -----
      From: "Ken Schwaber" <ken.schwaber@...>
      To: <scrumdevelopment@yahoogroups.com>
      Sent: Wednesday, November 28, 2001 7:34 PM
      Subject: RE: [scrumdevelopment] Re: book, "Agile Software Development with

      > I don't understand the theoretical underpinnings of why emerging
      > architecture and design work either. A number of us that develop and
      > practice agile were talking about this the other day, and we agreed that:
      > 1. We don't know why it works.
      > 2. Preparing a detailed architecture and design at the beginning of a
      > project is wasteful. It presupposes the requirements, often leads to
      > developing technical capabilities that aren't needed (and require
      > and maintenance), doesn't fit with the desire to simplify, and imposes
      > of the customer that they haven't agree to.
      > 3. In every case that we've relied on a stable architecture and design
      > emerging, they did. Part of the reason is refactoring, but I suspect that
      > the other reason has to do with team experience and the chaos theory
      > "strange attractor."
      > So, this is another of my research areas.
      > Ken
      > -----Original Message-----
      > From: jonas.b@... [mailto:jonas.b@...]
      > Sent: Wednesday, November 28, 2001 6:03 PM
      > To: scrumdevelopment@yahoogroups.com
      > Subject: [scrumdevelopment] Re: book, "Agile Software Development with
      > Scrum"
      > Hi,
      > Emerging requirements and self-organization I can understand and
      > agree to. But I have harder understanding emerging architecture. Self-
      > organizing teams are just human nature, whereas architecture is a
      > complex composition which is hard to change. I don't imply that
      > emerging architecture is nonsense but I can't understand how it's
      > possible.
      > Thanks for the articles on InformIT Ken, they were great!
      > Regards,
      > Jonas
      > --- In scrumdevelopment@y..., "Ken Schwaber" <ken.schwaber@v...>
      > wrote:
      > > <Won't it be hard to create a stable architecture if you don't have
      > > the end goal in sight? Or it is sufficient to use the information in
      > > the backlog as a foundation?>
      > >
      > > Emergence of requirements and architecture, and self-organization
      > are
      > > research topics. Experientially, we know they work and are
      > applicable to
      > > software development, but the theoretical basis and its connection
      > to
      > > software development hasn't been made. See two articles that
      > Prentice Hall
      > > put up on www.informit.com under agile development that I wrote.
      > >
      > > <But doesn't it cause problems if highly skilled and
      > > experienced engineers recieve the same salary as newly examined
      > > nitwits? Are the Scrum team persistent? Do they remain the same in
      > several
      > > projects if they are well-fuinctioning?>
      > >
      > > In the overall performance review, evaluate the team and the
      > individual's
      > > contributions. Unless disfunction occurs, it's in the team and the
      > > organization's benefit to keep teams working together, owning
      > products and
      > > systems.
      > >
      > > <Quite incompatible with the collective ownership rule of XP :-)>
      > >
      > > The product wasn't using XP, so we felt free to use this rule.
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