Troubleshooting Client Server Connections

This page is in the very early stages. It helps to look at the section documenting how the rmi connection is established just to understand the difference between successfully connecting to the rmiregistry and connecting to the server.

The first thing to do is to look at any messages on the console. The most fundamental error that can arise is the following exception

SEVERE: java.rmi.ConnectException: Connection refused to host: localhost; nested exception is: 
	java.net.ConnectException: Connection refused
	at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:574)
	at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:185)
	at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:171)
	at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:306)
	at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
	at java.rmi.Naming.lookup(Naming.java:84)
	at edu.stanford.smi.protege.server.ServerPanel.connectToHost(ServerPanel.java:140)

Note that the exception happens when trying to call Naming.lookup. Usually the client will pop up a window that says Unable to Connect to Server. This means that the client could not connect to the rmiregistry. Possibly the rmiregistry is not running or there is a firewall or other network problem.