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18517Re: [XP] Re: Architecture for XP and scalable web sites

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  • Dossy
    Jan 1, 2001
      On 2001.01.02, Keith Richardson <keith@...> wrote:
      > I think I am faced with having to take a copout of some form. We will
      > be creating solutions that are installed by our clients and used by
      > their customers. Some clients are large with jobs running through
      > hundreds of plants that are accessed though a single Web site. I have
      > absolutely no idea how often their customers will be accessing the
      > site - the clients don't know either. Trying to put a number of this
      > would be a wild guess at best.

      This does sound like a big cop-out. Can we not apply Yesterday's
      Weather to this problem?

      Do you have ANY customers? Or are you still in the "haven't sold
      product" stage and we're just doing a lot of what-if? (If your
      answers are "no" and "yes", then I'm tempted to say YAGNI. ;-) )

      If you already have a customer, can you not use them as a "model"
      for other customers in their size/scale/class, at least to create
      estimates that are even slightly better than WAGs?

      Can you not use measurements from smaller customers to approximate
      what measurements might look like for larger customers? Can you
      not create a spike to at least verify that these approximations
      are "close enough"? (Complexologists would suggest building
      simulations - I tend to agree.)

      It might be very costly to build a worthwhile simulation of a
      theoretical "huge" customer, but with the kind of dollars on
      the line for that kind of customer, wouldn't it be worth it?
      What would be more costly, the simulation or the loss of the
      customer because you didn't fully understand your own product
      that you're selling?

      > The worst that can happen if the most
      > scalable technology is selected is the project takes longer to
      > implement and the deployment costs are slightly higher. The worst
      > that can happen if we go for lightweight solutions is that we find
      > the system is unusable when it eventually gets deployed. That would
      > be bad!

      If you're really doing XP, the cost of change curve should be
      "flat enough" such that moving from a lightweight solution to a
      "scalable technology" shouldn't have an oppressive cost.

      If you implement the lightweight solution poorly, sure, it'll
      be that much tougher to enhance the system to meet scalability
      needs later on. But that's not a technology selection problem...

      Make the system usable when it's deployed, and make it deployable
      ASAP for the customers you DO know about. When a big fat customer
      comes along, the money they should pay should justify any serious
      enhancements to the system, and as long as you've kept the system
      as simple as possible, enhancing where it's necessary (and only
      where it's necessary) shouldn't be too hard.


      - Dossy

      --
      Dossy Shiobara mail: dossy@...
      Panoptic Computer Network web: http://www.panoptic.com/
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