We can improve the overall structure of our application by creating
a separate configuration file for each tier. So far, we have
world-servlet.xml but, as the name suggests, this should only provide
configuration details for the presentation layer.
Business Logic Configuration
A second file called applicationContext.xml is created in the WEB-INF directory,
with the following contents:
ContextLoaderListener loads the configuration file(s) specified
in the contextConfigLocation context parameter into Spring's root context.
DispatcherServlet then loads the servlet configuration into a
separate context, with the root context as its parent. This means that the settings in
the servlet context can refer to, and even override, the settings in the root context.