Read: http://static.springsource.org/spring/docs/3.0.x/reference/mvc.html

- Controller classes marked with @Controller, request handling methods
  with @RequestMapping.

- lots of parameters are accepted for handling methods; see
  http://static.springsource.org/spring/docs/3.0.x/reference/mvc.html#mvc-ann-requestmapping-arguments

  - .....

  - request parameters can be automatically captured in "command/form
    objects", which are accepted as handling method parameters. This
    process ("binding") can be customized by writing an @InitBinder
    method that takes a WebDataBinder. Command/form objects may be any
    objects conforming to the JavaBean conventions

- Model / ModelAndView objects for transferring data between
  controller and view

  - Model / ModelAndView object may be explicitly created and
    returned, or it may be declared as a handler method parameter, or
    not be declared/used at all -- in which case one is automatically
    created by the framework. Some attributes are automatically added
    to the model: command/form objects and the results of
    @ModelAttribute annotated reference data accessor methods

- in the form tag, the 'modelAttribute' attribute specifies which
  object from the model (specified by the model attribute) to use as
  the backing object of the form. That object will also be used as the
  target of the binder (@InitBinder method)

- if you find out in a createForm handler for an entity type that an
  instance of the type can't currently be created because some
  dependent entities are missing, you can add to the model an entry
  with "dependencies" as the key and a list of the missing property
  names of the to-be-created entity as the value. In the view, the
  Spring form tag and related tags will recognize this and show a
  corresponding error display instead of the regular entry form.