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+---
+title: Overview
+order: 1
+layout: page
+---
+
+[[intro.overview]]
+= Overview
+
+Vaadin Framework is a Java web application development framework that is
+designed to make creation and maintenance of high quality web-based user
+interfaces easy. Vaadin supports two different programming models: server-side
+and client-side. The server-driven programming model is the more powerful one.
+It lets you forget the web and program user interfaces much like you would
+program a desktop application with conventional Java toolkits such as AWT,
+Swing, or SWT. But easier.
+
+While traditional web programming is a fun way to spend your time learning new
+web technologies, you probably want to be productive and concentrate on the
+application logic. The server-side Vaadin framework takes care of managing the
+user interface in the browser and the __AJAX__ communications between the
+browser and the server. With the Vaadin approach, you do not need to learn and
+deal directly with browser technologies, such as HTML or JavaScript.
+
+[[figure.intro.architecture]]
+.Vaadin Application Architecture
+image::img/architecture-vaadin7-hi.png[]
+
+<<figure.intro.architecture>> illustrates the basic architectures of web
+applications made with Vaadin. The server-side application architecture consists
+of the __server-side framework__ and a __client-side engine__. The engine runs
+in the browser as JavaScript code, rendering the user interface, and delivering
+user interaction to the server. The UI logic of an application runs as a Java
+Servlet in a Java application server.
+
+As the client-side engine is executed as JavaScript in the browser, no browser
+plugins are needed for using applications made with Vaadin. This gives it an
+edge over frameworks based on Flash, Java Applets, or other plugins. Vaadin
+relies on the support of Google Web Toolkit for a wide range of browsers, so
+that the developer does not need to worry about browser support.
+
+Because HTML, JavaScript, and other browser technologies are essentially
+invisible to the application logic, you can think of the web browser as only a
+thin client platform. A thin client displays the user interface and communicates
+user events to the server at a low level. The control logic of the user
+interface runs on a Java-based web server, together with your business logic. By
+contrast, a normal client-server architecture with a dedicated client
+application would include a lot of application specific communications between
+the client and the server. Essentially removing the user interface tier from the
+application architecture makes our approach a very effective one.
+
+Behind the server-driven development model, Vaadin makes the best use of AJAX (
+__Asynchronous JavaScript and XML__, see
+<<dummy/../../../framework/architecture/architecture-technology#architecture.technology.ajax,"AJAX">>
+for a description) techniques that make it possible to create Rich Internet
+Applications (RIA) that are as responsive and interactive as desktop
+applications.
+
+In addition to the server-side Java application development, you can develop on
+the client-side by making new widgets in Java, and even pure client-side
+applications that run solely in the browser. The Vaadin client-side framework
+includes Google Web Toolkit (GWT), which provides a compiler from Java to the
+JavaScript that runs in the browser, as well a full-featured user interface
+framework. With this approach, Vaadin is pure Java on both sides. ((("Google Web
+Toolkit")))
+
+Vaadin uses a client-side engine for rendering the user interface of a
+server-side application in the browser. All the client-server communications are
+hidden well under the hood.
+((("JavaScript")))
+Vaadin is designed to be extensible, and you can indeed use any 3rd-party
+widgets easily, in addition to the component repertoire offered in Vaadin. In
+fact, you can find hundreds of add-ons in the Vaadin Directory.
+
+Vaadin allows flexible separation between the appearance, structure, and
+interaction logic of the user interface. You can design the layouts either
+programmatically or declaratively, at the level of your choosing. The final
+appearance is defined in __themes__ in CSS or Sass, as described in
+<<dummy/../../../framework/themes/themes-overview.asciidoc#themes.overview,"Themes">>.
+
+We hope that this is enough about the basic architecture and features of Vaadin
+for now. You can read more about it later in
+<<dummy/../../../framework/architecture/architecture-overview.asciidoc#architecture.overview,"Architecture">>,
+or jump straight to more practical things in
+<<dummy/../../../framework/application/application-overview.asciidoc#application.overview,"Writing
+a Server-Side Web Application">>.
+
+
+