Another TomP2P 5 Alpha has been released. Stubs for disk-based storage were added and several smaller bugfixes. Check out the latest alpha version.
If you want to switch from TomP2P 4 to TomP2P 5, just change your pom.xml to:
<dependency>
<groupId>net.tomp2p</groupId>
<artifactId>tomp2p-core</artifactId>
<version>5.0-Alpha6</version>
<scope>compile</scope>
</dependency>
Some methods changed from get*() to *() -> getPeerMap() to peerMap() and more methods will be renamed for the beta release of TomP2P 5. Another big change is that FutureDHT is now split into FutureGet, FuturePut, etc.