Develop an Ajax-Based File Upload Portlet Using DWR
http://www.ibm.com/developerworks/xml/library/wa-aj-dwr/index.html?S_TACT=105AGX06&S_CMP=EDU

Yang, Xiabo and Robert Allan
IBM
2007

Abstract:

File upload is a basic function of today's Web portals. In this article, authors Xiaobo Yang and Rob Allan describe how to develop an Ajax-based file upload JSR 168-compliant portlet using DWR (Direct Web Remoting). DWR is an ideal Ajax framework for Java developers that dynamically generates JavaScript based on server-side deployed Java classes. You will learn how you can use DWR to retrieve file upload progress from the portal server.