基于Ajax技术的Web UI开发框架，Vaadin 7.0.0.beta5 发布

Vaadin 是一个基于Ajax技术的UI Web 开发框架。与 JavaScript 库或者是基于浏览器插件的解决方案不同，Vaadin 包含一个服务器端的结构，主要的应用逻辑都在服务器端运行，浏览器通过 Ajax 技术跟服务器端进行交互。Vaadin 提供多种各样的UI组建，例如按钮、表格、树形列表等等，每个组件都具有事件、侦听器、数据绑定和业务逻辑等功能。

7.0.0.beta5是即将推出7.0版本的一个beta版本发布。它介绍了一些细微的变化，小新的功能和修正。

主要变化如下：

• GWT现在集成至Vaadin框架
  • New SuperDevMode allows debugging client-side Java code in the browser without any plugins
• API视图导航
  • View navigation with bookmarking/linking with URI fragments and browser history support
  • Access control for views, view change confirmation
• 组件和用户界面扩展
• 资源加载（JS / CSS）的框架
• 客户端 - 服务器通信架构的完整的检修
  • All add-on components that have widgets need to be ported to Vaadin 7
  • Integration of a GWT widget is done in a connector class
  • Component-to-widget mapping now defined on the client-side, in the connector
  • No more Paintable or VariableOwner
  • Server-side component and client-side widget can have a shared state object which is automatically synchronized
  • Both client-side and server-side can make RPC calls to the other side
    • Communicated in the next request/response
    • No return values
    • Typically for communicating events
  • Support for JavaScript components - GWT integration code not required
  • Handle JavaScript callbacks on the server-side
  • UIDL is deprecated
  • Compatibility layer for Vaadin 6 included for easy migration
• Form is deprecated and form hand is replaced with the FieldGroup
• Get computed style of a component from the browser
• Support for border, padding, and margin in core layout components
• Applications are now written by extending the UI class
  • UIs use heartbeat to detect closing
• The Application class is removed altogether
  • ApplicationServlet is replaced with VaadinServlet
  • ApplicationResource is replaced with ConnectorResource
• Themeing with SASS in addition to CSS
  • SASS themes need to (and CSS themes can) be compiled to a single CSS stylesheet with the vaadin-theme-compiler
• Add-ons can modify the startup page
• All addListener() methods have changed to listener-specific methods, such as addClickListener(), addValueChangeListener(), etc.
• Packaging has changed, now in a ZIP package (see Package Contents above)

There are many other enhancements. Most of them are described in more detail in the mini-tutorials in the Vaadin Wiki.

Please see the release notes for alpha1, alpha2, alpha3, and beta1 for the lists of where the major enhancements were introduced.