Hi,

There are quite many things to cover in this answer..

Do you have an actual (real) case where a Server would change it’s certificate like this? In practice this has not been an expected scenario for like …15 years. Basically the world is waiting for a real GDS implementation and hopefully we are soon there.

Anyway, UaClient does cache the EndpointDescription, that can be reset by calling client.setEndpoint(null) (make sure it is not connected or it will throw). Though I should note that we have not tested it in a scenario like this.

Normally if AutoReconnect is true you should not do any disconnect/connect/reconnect operations manually except the first connect() call (or more, if the initial one fails). Though, if the server _really_ change it’s certificate that wont help.

The shutdown state doesn’t change anything i.e. it is connectable until the period ends. Once that happens the connections are closed. We could maybe improve this in the future..

The UaClient will try to re-use things as much as possible, but it would make a new Session if the older cannot be reactivated (and same goes for the SecureChannel as well).

The isConnected “doesn’t mean” do we have an active connection “exactly right now”, javadocs:
“Are we connected to the server?

isConnected is changed by calling connect() or disconnect().

When isConnected, getSession returns a valid session. In other words, isConnected=(getSession() != null)

When isConnected, also check getServerState() to check if the server is actuallyrunning. If communication fails, isConnected will still return true, but getServerState() will give ServerState.CommunicationFault.
Returns:true when we are connected to the server, false otherwise.”

However… that might not be so clear anymore as I too have mistaken it sometimes as the wording .. is not very optimal (we need to revisit that as well in the future…). I guess you could say it is a bit like: https://docs.oracle.com/javase/8/docs/api/java/net/Socket.html#isConnected– (though for UaClient if it is disconnected manually it would also mean the Session doesn’t exist anymore and isConnected would return then false). But normally after the initial connection the Session itself might still be valid on the server even if there is a temporary connection break and sometimes it is possible to re-ActivateSession it.

You mean ‘== Running’, I guess? 😉

And yes, it’s a bit complicated to use, but isConnected() is used also internally to detect if reconnections should happen, so therefore there is this diasctintion that if you have connected, you are connected until you disconnect. And everything else is just a temporary disruption.

But the certificate renewal can break this badly, if connect (or even reconnect) doesn’t work after that. It would be better to not cache the endpoint at all – or at least automatically refresh the cache if the connection fails.