基于JAVA的web架構 GWT SmartGWT ExtGWT Vaadin

<a href="http://code.google.com/p/gwt-ext/">http://code.google.com/p/gwt-ext/</a>

<a href="http://www.smartclient.com/smartgwt/showcase/">http://www.smartclient.com/smartgwt/showcase/</a>

<a href="http://www.smartclient.com/smartgwtee/showcase">http://www.smartclient.com/smartgwtee/showcase</a>

Smart GWT

When development of GWT-Ext came to an end, Sanjiv Jeevan started a new project named

Smart GWT: http://www.smartclient.com/smartgwt/. This is a LGPL framework that

wraps the Smart Client JavaScript library in a similar way that GWT-Ext wraps Ext JS. Smart

GWT has the advantage that it is still being actively developed. Being LGPL-licensed, it also

can be used commercially without the need to pay the license fee that is required for Ext

GWT. Smart GWT still has the debugging problems of GWT-Ext and the components are often

regarded not as visually pleasing as Ext GWT. This could be down to personal taste of course.

Sencha GXT 3其實就是原來的 Ext GWT,Ext GWT 是基于 Google Web Toolkit（GWT） 和 ExtJs 的功能強大的網頁開發控件庫。它擴充了 GWT，在 ExtJs 的基礎上實作了有排序功能的表格（Grid）、分頁、過濾，支援有拖拽功能的樹，高度可定制的組合下拉框（Combobox）、目錄、對話框、表單 （Form）以及功能豐富、強大且易用的 API。

<a href="http://extjs.org.cn/taxonomy/term/179">http://extjs.org.cn/taxonomy/term/179</a>

<a href="http://www.sencha.com/products/gxt/examples/">http://www.sencha.com/products/gxt/examples/</a>

<a href="http://www.sencha.com/examples-dev/#ExamplePlace:overview">http://www.sencha.com/examples-dev/#ExamplePlace:overview</a>

The first license is an open source license compatible with the GNU GPL license v3. If you

wish to use this license, you do not have to pay a fee for using Ext GWT, but in return you

have to make your source code available under an open source license. This means you have

to contribute all the source code of your project to the open source community and give

everyone the right to modify or redistribute it.

If you cannot meet the obligations of the open source license, for example, you are

producing a commercial product or simply do not want to share your source code, 

you have to purchase a commercial license for Ext GWT.

Vaadin, http://vaadin.com, is a third alternative to Ext GWT.  Vaadin  is a server-side

framework that uses a set of precompiled GWT components. Although you can write your

own components if required, Vaadin is really designed so that you can build applications by

combining the ready-made components.

In Vaadin the browser client is just a dumb view of the server components and any user

interaction is sent to the server for processing much like traditional Java web frameworks.

This can be slow depending on the speed of the connection between the client and  

the server.

The main disadvantage of Vaadin is the dependency on the server. GWT or Ext GWT's

JavaScript can run in a browser without needing to communicate with a server. This is 

not possible in Vaadin.