基于Ajax技術的Web UI開發框架，Vaadin 7.0.0.beta5 發布

Vaadin 是一個基于Ajax技術的UI Web 開發框架。與 JavaScript 庫或者是基于瀏覽器插件的解決方案不同，Vaadin 包含一個服務器端的結構，主要的應用邏輯都在服務器端運行，瀏覽器通過 Ajax 技術跟服務器端進行交互。Vaadin 提供多種各樣的UI組建，例如按鈕、表格、樹形列表等等，每個組件都具有事件、偵聽器、數據綁定和業務邏輯等功能。

7.0.0.beta5是即將推出7.0版本的一個beta版本發布。它介紹了一些細微的變化，小新的功能和修正。

主要變化如下：

• GWT現在集成至Vaadin框架
  • New SuperDevMode allows debugging client-side Java code in the browser without any plugins
• API視圖導航
  • View navigation with bookmarking/linking with URI fragments and browser history support
  • Access control for views, view change confirmation
• 組件和用戶界面擴展
• 資源加載（JS / CSS）的框架
• 客戶端 - 服務器通信架構的完整的檢修
  • 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.