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RE: [XP] Why XP works

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  • Morris, Chris
    ... I d say there are more prevalent reasons that requirements change. Problems are typically much more complex than people realize due to a plethora of
    Message 1 of 7 , Jul 5, 2001
      Looks good to me. Some comments:

      > The IT industry is very young. Most users do not have enough
      > experience of IT to understand exactly what they want, hence
      > requirements constantly change.

      I'd say there are more prevalent reasons that requirements change. Problems
      are typically much more complex than people realize due to a plethora of
      exception cases; people only tend to bring to mind common cases.

      > We also make sure that when we
      > Refactor, everything still works. We do this by using Automated
      > Testing for Unit, Integration, and System Testing.

      I think it's important to emphasize test-first here, not just testing.

      Chris
    • wecaputo@thoughtworks.com
      Hi Dave, I agree with your conclusions, but I am unsure about your premise as to why requirements change. I don t think it s because the industry is very young
      Message 2 of 7 , Jul 5, 2001
        Hi Dave,

        I agree with your conclusions, but I am unsure about your premise as to why
        requirements change. I don't think it's because the industry is very young
        (although it is very young), and I don't think it is because users lack of
        experience, I think it is much simpler:

        Change happens.

        It always happens, it always will happen. It isn't bad, and in fact, once
        we embrace it, it is an advantage.

        The key concept for making XP click in people's minds is to get them to
        recognize that change is the norm, and its our constant attempts to halt
        it, and predict it that are the unusual part.

        Traditional approach to change in requirements is: predict them and freeze
        them -- you are good if you predict well, and you can keep the users from
        demanding changes.

        The XP approach is: don't try to predict them, and never freeze them -- you
        are good if you can react very very quickly (agile like a cat), and you can
        keep the communication channel wide open to your users.

        IMHO XP works because change is the norm, and XP (and other agile meths)
        explicit recognize this.

        Best,
        Bill




        davechaplin@y
        ahoo.co.uk To: extremeprogramming@yahoogroups.com
        cc:
        07/05/2001 Subject: [XP] Why XP works
        11:07 AM
        Please
        respond to
        extremeprogra
        mming






        I was asked by someone to explain why I thought XP works....thought
        I'd run it past you all....let me know what you think.

        The IT industry is very young. Most users do not have enough
        experience of IT to understand exactly what they want, hence
        requirements constantly change. The capabilities of IT change
        rapidly, hence requirements constantly change. Since requirements
        constantly change, the design will need to change. There is no way to
        accurately predict what the final design should be, only that it
        should be a simple understandable one.

        XP: We make sure we build small parts of the system at a time, so we
        can get feedback to the users as soon as we can and find out what
        they really want. We can't do a lot of upfront design ? that would be
        pointless. So, we design on the fly (Refactor) and change our code
        accordingly to make it simple. We also make sure that when we
        Refactor, everything still works. We do this by using Automated
        Testing for Unit, Integration, and System Testing. If the tests do
        not pass, then the system is not released. Also, because we know
        requirements are going to change, we don't bother building anything
        that we don't need yet.

        XP works because it address the fact that we don't know from the
        outset what we are supposed to build. So, we strip away all the heavy
        processes that are based on the assumption that we think we do know.

        Dave Chaplin
        davechaplin@...



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      • Erik Hanson
        ... why ... It is easy to understand why people fear changing requirements. Five miles from my house is an overpass with no road attached. The requirements
        Message 3 of 7 , Jul 5, 2001
          <wecaputo@...> wrote:
          > I agree with your conclusions, but I am unsure about your premise as to
          why
          > requirements change. I don't think it's because the industry is very young
          > (although it is very young), and I don't think it is because users lack of
          > experience, I think it is much simpler:
          >
          > Change happens.
          >
          > It always happens, it always will happen. It isn't bad, and in fact, once
          > we embrace it, it is an advantage.

          It is easy to understand why people fear changing requirements. Five miles
          from my house is an overpass with no road attached. The requirements
          apparently changed after a very expensive construction project was already
          underway. Everyone who drives under that overpass (on their way to Silicon
          Valley, I might add) gets reminded that a successful project requires
          extensive requirements gathering, analysis and planning.

          Software developers need to understand that we're not civil engineers. We
          have a unique medium and we should exploit it.


          Erik
        • Bob Koss
          ... The extensiveness depends upon the pain involved in changing the implementation. ... Robert S. Koss, Ph.D. | Training and Mentoring Senior Consultant
          Message 4 of 7 , Jul 5, 2001
            >
            > It is easy to understand why people fear changing requirements. Five miles
            > from my house is an overpass with no road attached. The requirements
            > apparently changed after a very expensive construction project was already
            > underway. Everyone who drives under that overpass (on their way to Silicon
            > Valley, I might add) gets reminded that a successful project requires
            > extensive requirements gathering, analysis and planning.

            The extensiveness depends upon the pain involved in changing the
            implementation.

            ----
            Robert S. Koss, Ph.D. | Training and Mentoring
            Senior Consultant | Object Oriented Design
            Object Mentor, Inc. | C++, Java
            www.objectmentor.com | Extreme Programming
          • Dinwiddie, George
            The way software development is done in many organizations, changing requirements is still a big problem. The root of the difficulty is the lack of
            Message 5 of 7 , Jul 6, 2001
              The way software development is done in many organizations, changing
              requirements is still a big problem. The root of the difficulty is
              the lack of communication. It's hard to change anything because there's
              no way to communicate the changed requirements or the changed design
              to the team. It's also hard to change the culture that makes communication
              difficult.

              - George [still working on it]

              -----Original Message-----
              From: Erik Hanson [mailto:ehanson@...]
              Sent: Thursday, July 05, 2001 6:46 PM
              To: extremeprogramming@yahoogroups.com
              Subject: Re: [XP] Why XP works


              <wecaputo@...> wrote:
              >
              > Change happens.
              >
              > It always happens, it always will happen. It isn't bad, and in fact, once
              > we embrace it, it is an advantage.

              It is easy to understand why people fear changing requirements. Five miles
              from my house is an overpass with no road attached. The requirements
              apparently changed after a very expensive construction project was already
              underway. Everyone who drives under that overpass (on their way to Silicon
              Valley, I might add) gets reminded that a successful project requires
              extensive requirements gathering, analysis and planning.

              Software developers need to understand that we're not civil engineers. We
              have a unique medium and we should exploit it.


              Erik



              To Post a message, send it to: extremeprogramming@...

              To Unsubscribe, send a blank message to:
              extremeprogramming-unsubscribe@...

              Don't miss XP UNIVERSE, the first US conference on XP and Agile Methods.
              see www.xpuniverse.com for details and registration.

              Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            • stearnsr@daugherty.com
              I think the folks that started the overpass had, indeed, done extensive requirements gathering, analysis and planning. It still didn t help them. There are a
              Message 6 of 7 , Jul 6, 2001
                I think the folks that started the overpass had, indeed, done
                extensive requirements gathering, analysis and planning. It still
                didn't help them. There are a ton of overpasses to nowhere in
                Arizona, and driving under one now would remind me detailed up-front
                design didn't make the project a success.

                Randy


                --- In extremeprogramming@y..., "Erik Hanson" <ehanson@n...> wrote:
                > <wecaputo@t...> wrote:
                > > I agree with your conclusions, but I am unsure about your premise
                as to
                > why
                > > requirements change. I don't think it's because the industry is
                very young
                > > (although it is very young), and I don't think it is because
                users lack of
                > > experience, I think it is much simpler:
                > >
                > > Change happens.
                > >
                > > It always happens, it always will happen. It isn't bad, and in
                fact, once
                > > we embrace it, it is an advantage.
                >
                > It is easy to understand why people fear changing requirements.
                Five miles
                > from my house is an overpass with no road attached. The requirements
                > apparently changed after a very expensive construction project was
                already
                > underway. Everyone who drives under that overpass (on their way to
                Silicon
                > Valley, I might add) gets reminded that a successful project
                requires
                > extensive requirements gathering, analysis and planning.
                >
                > Software developers need to understand that we're not civil
                engineers. We
                > have a unique medium and we should exploit it.
                >
                >
                > Erik
              • azami@speakeasy.net
                ... already ... to Silicon ... requires ... I gotta say, IMHO that becomes an exceedingly successful project if it is recast as a work of public art. I love
                Message 7 of 7 , Jul 6, 2001
                  --- In extremeprogramming@y..., "Erik Hanson" <ehanson@n...> wrote:
                  > Five miles
                  > from my house is an overpass with no road attached. The requirements
                  > apparently changed after a very expensive construction project was
                  already
                  > underway. Everyone who drives under that overpass (on their way
                  to Silicon
                  > Valley, I might add) gets reminded that a successful project
                  requires
                  > extensive requirements gathering, analysis and planning.

                  I gotta say, IMHO that becomes an exceedingly successful project if it
                  is recast as a work of public art. I love it!

                  -Matthew
                  azami@...
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