THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
WebWork: Strutting the OpenSymphony way - Mike Cannon-Brookes
Home is a pull-based MVC framework focused on componentization and code reuse. It is currently in beta, but is being used by several opensource projects and a few commercial projects in development. This is the second generation of WebWork, which was originally developed by Rickard Oberg, and in this release, what was WebWork has been broken into two projects, XWork and Home.
XWork is a generic command pattern implementation with absolutely NO ties to the web. XWork provides many core services, including interceptors, meta-data based validation, type conversion, a very powerful expression language (OGNL - the Object Graph Notation Language) and an Inversion of Control (IoC) container implementation.
WebWork provides a layer on top of XWork to do HTTP request / response handling. It includes a ServletDispatcher to turn HTTP requests into calls to an Action, session and application scope mapping, request parameter mapping, view integration with various web view technologies (JSP, Velocity, FreeMarker, JasperReports), and user interface components in the form of JSP tags and Velocity macros wrapped around reusable UI components.
An Action is the basic unit of work in WebWork. It is a simple command object that implements the Action Interface, which has only one method: execute(). Action implementers can extend the ActionSupport class, which provides i18n localization of messages (with one ResourceBundle per Action class and searching up the inheritance tree) and error message handling including class level and field level messages.
Actions can be developed in one of two styles: Model driven or field driven. Model driven Actions expose a model class via a get method, and the form fields refer directly to the model properties using expressions like "pet.name". XWork uses Ognl (the Object Graph Notation Language) as its expression language, and when rendering the page, this expression will translate to
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getPet().getName().
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When
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setting
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properties,
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this
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will
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translate
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to
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getPet().setName().
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This
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style
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of
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development
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allows
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for
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a
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great
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deal
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of
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model
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reuse
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and
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can
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allow
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you
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to
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directly
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edit
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your
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domain
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objects
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in
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your
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web
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pages,
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rather
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than
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needing
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a
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translation
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layer
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to
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form
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beans.
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Field
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driven
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Actions
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have
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their
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own
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properties
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which
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are
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used
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in
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the
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view.
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The
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action's
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execute()
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method
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collates
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the
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properties
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and
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interacts
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with
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the
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model.
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This
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can
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be
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very
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useful
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when
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your
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form
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and
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model
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are
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not
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parallel.
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Even
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in
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this
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case,
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the
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powerful
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expression
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language
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in
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WebWork
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can
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allow
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you
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to
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compose
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your
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form
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fields
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into
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aggregate
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beans,
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such
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as
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an
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address
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bean,
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which
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you
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can
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reuse
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to
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simplify
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your
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action
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classes.
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WebWork
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allows
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you
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to
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build
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your
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own
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reusable
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UI
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components
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by
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simply
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defining
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a
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Velocity
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template.
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This
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is
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how
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the
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pre-built
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components
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of
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WebWork
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are
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built
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for
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common
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components
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such
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as
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text
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fields,
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buttons,
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forms,
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etc.
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and
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made
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available
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from
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any
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view
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type
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(either
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JSP
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or
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Velocity
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at
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the
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moment).
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These
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components
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are
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skinnable
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by
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defining
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multiple
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templates
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for
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the
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same
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component
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in
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different
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paths.
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If
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your
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components
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include
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the
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default
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header
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and
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footer
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templates
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that
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are
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used
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in
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the
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pre-built
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templates,
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then
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they
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will
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inherit
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the
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ability
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to
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automatically
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handle
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displaying
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error
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messages
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beside
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the
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problem
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form
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field.
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These
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custom
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UI
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components
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are
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especially
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handy
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for
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reusing
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templates
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which
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handle
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your
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custom
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model
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types
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or
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for
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things
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like
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date
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pickers,
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which
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Mike
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showed
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as
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an
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example.
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Interceptors
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in
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XWork
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allow
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common
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code
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to
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be
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applied
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around
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(before
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and/or
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after)
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action
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execution.
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This
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is
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what
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Mike
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calls
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"Practical
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AOP".
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Interceptors
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help
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to
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decouple
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and
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componentized
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your
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code.
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Interceptors
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can
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be
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organized
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into
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stacks,
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which
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are
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lists
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of
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interceptors
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to
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be
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applied
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in
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sequence,
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and
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can
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be
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applied
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to
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actions
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or
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whole
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packages.
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Much
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of
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the
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core
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functionality
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of
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XWork
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and
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WebWork
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is
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implemented
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as
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Interceptors.
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The
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common
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basic
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examples
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of
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Interceptors
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are
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timing
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and
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logging,
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and
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these
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are
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built
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in
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with
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XWork.
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Mike
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went
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through
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an
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example
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of
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an
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interceptor
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to
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identify
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users
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of
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events
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via
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email.
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This
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interceptor
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has
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its
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own
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external
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configuration
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file
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which
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specifies
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which
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users
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are
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interested
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in
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which
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events,
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and
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it
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compares
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this
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configuration
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with
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the
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action
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invocations
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passing
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through
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it
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to
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determine
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if
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any
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messages
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should
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be
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sent.
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XWork's
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validation
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framework
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allows
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for
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decoupled
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validation
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of
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action
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properties.
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It
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is
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implemented
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as
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an
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Interceptor
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and
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reads
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external
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XML
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files
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which
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define
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the
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validations
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to
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be
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applied
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to
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the
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Action.
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Error
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messages
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are
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loaded
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from
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the
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Action's
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localized
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messages
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and
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flow
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through
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to
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the
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UI.
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Validator
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classes
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can
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be
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plugged
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in
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to
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add
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to
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the
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set
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of
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bundled
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validators.
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The
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bundled
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validators
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include
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required
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field
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and
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required
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String
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validators,
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range
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validators
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for
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Dates
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and
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numbers,
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and
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and
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URL
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validators.
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XWork
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also
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includes
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expression
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validators
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at
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both
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the
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Action
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and
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field
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level
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which
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allow
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you
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to
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use
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any
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Ognl
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expression
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as
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the
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validation.
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Inversion
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of
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Control
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(IoC)
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removes
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the
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burden
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of
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managing
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components
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from
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your
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code
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and
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puts
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it
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on
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the
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container.
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The
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container
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takes
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care
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of
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managing
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component
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lifecycle
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and
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dependencies.
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EJB
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is
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an
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example
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of
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IoC,
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but
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with
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limited
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services.
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IoC
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promotes
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simplicity
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and
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decoupling
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of
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your
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components
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and
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encourages
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your
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classes
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to
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be
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smaller
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and
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more
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focused.
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Unit
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testing
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is
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also
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simplified,
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as
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you
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can
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just
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supply
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MockObject
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instances
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of
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the
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services
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your
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code
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depends
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upon
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during
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testing.
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XWork
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and
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WebWork
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provide
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a
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web-native
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IoC
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container
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which
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manages
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component
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dependencies.
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In
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WebWork
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IoC
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is
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implemented
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as
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lifecycle
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managers
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(SessionLifecycleListener,
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etc)
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and
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an
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Interceptor.
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There
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are
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4
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component
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scopes
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in
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WebWork
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IoC:
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Application,
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HTTP
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Session,
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HTTP
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Request,
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and
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Action
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invocation.
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IoC
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in
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XWork
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/
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WebWork
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is
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purely
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optional,
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so
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you
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can
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use
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it
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if
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you
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want
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it.
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XWork
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/
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WebWork
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allows
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for
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sets
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of
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Actions
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and
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their
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views
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to
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be
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bundled
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as
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a
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jar
...
file
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and
...
reused.
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Your
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main
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xwork.xml
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file
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can
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include
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the
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xml
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configuration
...
file
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of
...
the
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jar
...
file
...
because
...
they
...
are
...
included
...
from
...
the
...
classpath.
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Similarly,
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if
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your
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views
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are
...
I have to admit, when Mike mentioned this feature, I thought he was crazy. I didn't say anything at the session, but asked him about it later, and he said "didn't you write the package include stuff?" I'll take it as a good sign that things can be used in a different way than was imagined. 
Mike finished up with a comparison of WebWork vs.
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