I now few books about portal system in general , most of books are vendor specefic , for example you can find books about IBM portal in www.redbooks.ibm.com or about BEA portal system or Sun MicroSystem in thier site.
but some books about Portlet API
Professional Portal Development with Open Source Tools: JavaTM Portlet API, Lucene, James, Slide
Building Portals with the Java Portlet API (Expert's Voice)
keep in mind that IBM portals are proprietary, and are not based on JSR-168. Just something to be aware of when book hunting.
Joined: Nov 22, 2002
Do tell me which book is good if we go for vendor specific portal development. Which is most famous wheather ibm portal or weblogic portal. Also want to are there any opensource software for developing portal.