Initialized webserver8081
Exception in thread "main" java.rmi.server.ExportException: remote object implements illegal remote interface; nested exception is: 
	java.lang.IllegalArgumentException: illegal remote method encountered: public abstract void dk.thomasdamgaard.diku.distsys.interfaces.ICallback.invalidate(java.lang.String)
	at sun.rmi.server.UnicastServerRef.exportObject(Unknown Source)
	at java.rmi.server.UnicastRemoteObject.exportObject(Unknown Source)
	at java.rmi.server.UnicastRemoteObject.exportObject(Unknown Source)
	at java.rmi.server.UnicastRemoteObject.<init>(Unknown Source)
	at java.rmi.server.UnicastRemoteObject.<init>(Unknown Source)
	at dk.thomasdamgaard.diku.distsys.webserver.Callback.<init>(Callback.java:23)
	at dk.thomasdamgaard.diku.distsys.webserver.WebServer.run(WebServer.java:97)
	at dk.thomasdamgaard.diku.distsys.webserver.WebServer.main(WebServer.java:68)
Caused by: java.lang.IllegalArgumentException: illegal remote method encountered: public abstract void dk.thomasdamgaard.diku.distsys.interfaces.ICallback.invalidate(java.lang.String)
	at sun.rmi.server.Util.checkMethod(Unknown Source)
	at sun.rmi.server.Util.getRemoteInterfaces(Unknown Source)
	at sun.rmi.server.Util.getRemoteInterfaces(Unknown Source)
	at sun.rmi.server.Util.createProxy(Unknown Source)
	... 8 more