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With proper mark-up/logic separation, a POJO data model, and a refreshing lack of XML, Apache Wicket makes developing web-apps simple and enjoyable again. Swap the boilerplate, complex debugging and brittle code for powerful, reusable components written with plain Java and HTML.
Wicket tutorials
You can generate a fully functioning Sakai app that uses Wicket via the Sakai Wicket Maven Archetype. One command and you are up and running. The Sakai AppBuilder now also has Wicket support . You can create a simple Hello World app or a full CRUD app using this plugin and check out the code createdbut it is rather dated. You can also use this quickstart to generate the Maven command to run to generate a sample Wicket application, for learning how to use the components without requiring it to be run up in Sakai first.
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Profile2 - http://confluence.sakaiproject.org/display/PROFILE/Profile2
SiteStats - http://confluence.sakaiproject.org/display/STAT/Home
Blog2 - https://source.sakaiproject.org/svn//blog/branches/post_2-5/
SCORM player - http://confluence.sakaiproject.org/display/SCORMPLAYER/SCORM+in+Sakai
News Feeds - https://confluence.sakaiproject.org/display/NFS/Home