ATG (http://www.atg.com) is a frameowrk, a platform and a solution for content presentation and management, personalisation, e-commerce and customer relationship management.
Which free and open source frameworks or products would you recommend to replace the basic functionality it provides?
In the spirit of Stack Overflow, can you answer with one item in each answer and use the voting rather than duplicating someone else's answer.
I have started with some answers
Hibernate for database access Spring for integration GWT or good old JSP for presentation layer
Jboss is suitable for large applications requiring clustering and more sophisticated deployment. For simple web app Jetty or Tomcat are light and robust servers.
I propose to avoid EJB3, JMS etc, since once you start using them you can not get rid of them when they becoming obsolete, on the other hand POJOs are always up to date.
ATG modules: OSGI Nucleus: Spring or Guice Repository API: probably Hibernate Reposity Items / Dynamic beans: Groovy beans Search: Lucene / SOLR ACC: JBoss JMX console (?)
The real value of the ATG suite is in higher layers - Commerce, Content Administration, CSC and in the tools (ACC, BCC, Search admin). Even if you can find open source modules that provide similar featureset as one part of ATG stack, there is very long way to something practical.