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18496Re: Architecture for XP and scalable web sites

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  • Chad Fowler
    Jan 1, 2001
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      --- In extremeprogramming@egroups.com, "Keith Richardson"
      <keith@s...> wrote:
      > Hello,
      > This forum has included several messages describing problems using
      XP
      > with EJB, describing EJB as non-OO and other difficulties with the
      > EJB architecture. A highly scalable web site must be able to
      automate
      > persistance of session and environment data, allow deployment to be
      > easily adjusted and many other features that EJBs (and more
      > completely J2EE) provides. Are there other environments that have
      > proven to be better for developing highly scalable solutions with
      XP
      > or should I interpret these messages as saying that XP is not
      > applicable for these needs? Any XP success stories in this area to
      be
      > shared?
      > Keith Richardson

      I think the point of a lot of these messages is that EJB is not, at
      least at the beginning of a project, (in most cases) the simplest
      thing that could possibly work. A well factored servlet application
      provides session persistence (not sure what you mean by "environment"
      in this context) and (being well factored) would also give
      flexibility for deployment options (things are logically decoupled,
      so they can be physically separated down the road).

      In the past, our developers were assuming that scalable-web-
      application == J2EE-all-the-way and just going with EJB from the
      start. This instroduced complexity in the code, the
      development/build process, and the application server deployment.
      This complexity invariably lead to various problems (more points of
      potential failure).

      The approach we've taken semi-recently with our developers is to
      say, "You are free to use EJB (and the rest of the J2EE baggage) if
      you can explain why you need it." What we've found so far is that no
      one has ever needed it, and we haven't had any related problems.
      (And, our applications are *so* much easier to deploy and maintain
      now!) In the mean time, we've been trying to keep things well
      factored, so they could be easily moved to the more complex solution
      should we ever hit the scalability barriers of this approach. My
      guess is that we won't ever get there.

      Of course, we're no amazon.com, but we get some pretty heavy traffic.

      Just as an addendum, here's my XP zealot answer:
      "must be able to automate persistance of session and environment
      data, allow deployment to be easily adjusted and many other features
      that EJBs (and more completely J2EE) provides" wasn't in my user
      stories. :)

      Chad
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