Client Side Enhancement

Obviously, it is not a favorable job to directly compose XML workflow file. Users may spend more time on XML formatting (start tags, end tags ...) than on business logic. So it is good news to provide auxiliary tools to ease composition of workflows. Visual widgets which support drag and drop can be used. In web2.0, there are several mainstream technologies including Ajax, Flash, Flex, Silverlight and OpenLaszlo, etc. I think Ajax is preferred because it can be run on almost all platforms. Support for Ajax is almost built in every prevailing browsers.
If we decide to use Ajax, it is time consuming to build our application from the scratch, considering there are so many mature Ajax frameworks. I can list some frameworks here: dojo, qooxdoo, jquery, prototype, mootools, GWT, YUI, Ext ... I have surveyed these frameworks.
GWT is developed by Google and YUI is developed by Yahoo. GWT provides conversion from Java to Javascript so that programmers can use Java to build web application. However, the customization of the webpage (layout, style ...) is not convenient.
Frameworks Prototype, Dojo, Qooxdoo, Jquery and mootools are all open-source and they have their own good and bad. However, the difference is kind of subtle. I used Qooxdoo in previous project and I don't recommend us to use it. All other frameworks seem good and further investigation is necessary to pick up the most appropriate one for us.