Have you ever heard about RWT standalone? RWT standalone applications use the widget toolkit of RAP called RWT for their user interface. These applications can be standard Java applications with no need to create an OSGi based application.
For Java applications it can be quite challenging to find the required dependencies but Maven can help here. And, to make the life easier for RWT standalone developers, we contributed the RAP bundles and the dependencies needed for a RWT standalone application to the Maven Central Repository. To find the RAP bundles in the Maven Central Repository just search for “org.eclpse.rap”.
To try it yourself, I recommend that you download the latest Eclipse for RCP and RAP Developers package from here. Then you can install the Eclipse Maven Integration into your IDE from here. After that you can import the example project into your IDE. The example project contains a launch configuration which you can start with the RWT-Launcher included in the RCP and RAP Developers package.