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Struts
Struts
is a open source framework which make building
of the web applications easier based on the
java Servlet and JavaServer pages technologies.
Struts framework was created by Craig R. McClanahan
and donated to the Apache Software Foundation
in 2000. The Project now has several committers,
and many developers are contributing to overall
to the framework.
Developing web application using struts frame
work is fairly complex, but it eases things
after it is setup. It encourages software development
following the MVC design pattern. Many web applications
are JSP-only or Servlets-only. With JSP and
Servlets, Java code is embedded in the HTML
code and the Java code calls println methods
to generate the HTML code respectively. Both
approaches have their advantages and drawbacks;
Struts gathers their strengths to get the best
of their association.
Struts
is based on Model-View-Controller (MVC) design
paradigm, it is an implementation of JSP Model
2 Architecture. For more of Model-View-Controller
(MVC) click here.
Consists of 8 Top-Level Packagesand approx 250
Classes and Interfaces.
Struts is a set of cooperating classes, servlets,
and JSP tags that make up a reusable MVC 2 design.
This definition
implies that Struts is a framework, rather than
a library, but Struts also contains an extensive
tag library and utility classes that work independently
of the framework.
The overview of struts
Client
browser
An HTTP request from the client browser creates
an event. The Web container will respond with
an HTTP response.
Controller
The controller is responsible for intercepting
and translating user input into actions to
be performed by the model. The controller is
responsible for selecting the next view based
on user input and the outcome of model operations.The
Controller receives the request from the browser,
and makes the decision where to send the request.
With Struts, the Controller is a command design
pattern implemented as a servlet. The struts-config.xml
file configures the Controller.
Business
logic
The business logic updates the state of the model
and helps control the flow of the application.
With Struts this is done with an Action class
as a thin wrapper to the actual business logic.
Model
A model represents an application’s data and contains
the logic for accessing and manipulating that
data. Any data that is part of the persistent
state of the application should reside in the
model objects. The business objects update the
application state. ActionForm bean represents
the Model state at a session or request level,
and not at a persistent level. Model services
are accessed by the controller for either querying
or effecting a change in the model state. The
model notifies the view when a state change occurs
in the model.The JSP file reads information from
the ActionForm bean using JSP tags.
View
The view is responsible for rendering the state
of the model. The presentation semantics are encapsulated
within the view, therefore model data can be adapted
for several different kinds of clients.The view
modifies itself when a change in the model is
communicated to the view. A view forwards user
input to the controller.The view is simply a JSP
file. There is no flow logic, no business logic,
and no model information -- just tags. Tags are
one of the things that make Struts unique compared
to other frameworks like Velocity. |
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