How to detect an invalid proxy?

[ssergei]

My question is, is there a way to detect if a proxy is bad, i.e. the server exited uncleanly, simply crashed? If a client tries to use proxy when server crashed the remote calls will never return. At least if you use an indirect proxy. I tried ice_ping() - it didn't return too.

Thanks,
Sergei.

[marc]

If the server process crashes, then ice_ping() should return with an exception (usually ConnectFailedException or ConnectionLostExcpetion). I do not know why it doesn't return such an exception in your case. The only case I can think of is if the server host (not just the server process) crashes. In this case, it might either take a very long time until the TCP stack detects that the server is not reachable, or it might not detect it at all. Setting a timeout on the calling proxy is the best option to avoid this problem.

In any case, you should be able to get more information about what's going on by analyzing the network tracing output of the client (with Ice.Trace.Network=2).

[ssergei]

Thanks, Marc. No the server's host is ok. I think, it has something to do with an indirect proxy I use. The server registers an object with the registry and when server crashes, the object doesn't exist anymore but is still registered. When I remove the object from the registry manually, then ice_ping throws the "ObjectNotRegistered" exception.

Sergei.

[marc]

You should still get an exception when your client tries to connect to the server that is not running (after the client received the endpoint information for the server from IcePack). What is the tracing output of the client with Ice.Trace.Network=2?

[ssergei]

Here is the trace output: "trying to establish tcp connection to <server's IP address:4471>. And this message repeats endlessly. And it stops and throws NotRegistered exception after I removed the object manually.

Sergei.

[marc]

Hmm... perhaps there is a bug with retry and indirect proxies. Can you run with Ice.Trace.Retry=2 and post the output here?

[ssergei]

The output with trace.retry and trace.network:
----------------
Network: trying to establish tcp connection to <server's IP number>:1783
Retry: connection to endpoint failed, trying next endpoint
.\Network.cpp:536: Ice::ConnectionRefusedException:
connection refused: WSAECONNREFUSED ]
Retry: connection to cached endpoints failed
removing endpoints from cache and trying one more time
----------------
And again, this repeats endlessly.

[marc]

OK, looks as if there is a bug

Thanks for the report, we will investigate this.

[benoit]

I was able to reproduce the problem. I believe this occurs only for indirect proxies containing only the identity of the object (let me know if that's not your case however). To work-around the problem for now, you could specify the adapter id in your proxy, i.e.: use 'identity@AdapterId' instead of just 'identity'.

We'll fix this bug ASAP and thanks again for the report!

Benoit.

[benoit]

I've posted a patch here that should fix this bug. Thanks again for reporting this!

Benoit.

[ssergei]

Thanks, Benoit. The program is working now. But C# part doesn't work. I guess, there is the same bug in C# (icecs library) code. Could you provide C# patch?

Thanks again,
Sergei.

[benoit]

I've added the patch for C# here.

Benoit.