I used to develop desktop applications based on Eclipse RCP. The development became much simpler after we switched to e4. The Eclipse RAP has this possibility too. You can write your application entirely in Java. If you are familiar with SWT/JFace/OSGi ecosystem from RCP that is the same for RAP with some additions. The visual editor for UI is free, and here are free add-ons too. Review collected by and hosted on G2.com.

There is not too much and detailed documentation about e4, and some are outdated too. You have to dig the Internet for information on e4. Uneasy to build the final product. (war) Review collected by and hosted on G2.com.