I would like to build an integrated portal using the J2EE technology. The portal will include news, forum, blogs, search engine, gallery and other modules. The portal must support single sign-on for all modules, be manageable, use role-based security. All modules should have consistent look as proposed by our designers.
My question is: how would you recommend me to build it? I mean should I write if from scratch or use some portal engine that market has to offer? If I use a portal engine, which one would you recommend, and where can I find additional modules for it (like forum, blogs, news etc.)?