Hello,
I updated support for XDI link contracts in XDI4j according to the pattern at
http://wiki.oasis-open.org/xdi/XdiOneIssues/LinkContractPattern.
There is no separate demo application for this, because link contracts are really a part of XDI messaging. The best way to experiment with them is the XDI Local Messenger. This is an application that applies the XDI message in the right text area to the XDI graph in the left text area:
http://graceland.parityinc.net/xdi-localmessenger/XDILocalMessengerIf you simply click "Go", you will see that everything works. But if you enable link contracts, you will get an error, because the message is not allowed under the existing link contracts. As an exercise, you can try to modify the link contract in the left text area, so that the message succeeds again :)
Markus