Cannot connect to an application

Possible solutions if the application you want to monitor does not appear in the connection dialog list.

Before any application can be monitored, the Java™ Virtual Machine (JVM) it is running on must have a Health Center agent installed. See the agent installation instructions.

Is the Health Center agent installed correctly?

Check the Health Center agent installation. See Installing the Health Center agent for more information.

Has the application been enabled for monitoring?

Check that the application has been enabled for monitoring. See Starting a Java application with the Health Center agent enabled for more information.

Check that the agent and application are running

Check the application to see if it has been started. Check that the agent is running on the application. If the agent has started successfully, you normally see a message like INFO: Health Center agent started on port 1972 in the application console. The port number is also written to the healthcenter.<pid>.log file in the users temporary directory. The <pid> is the process ID for the agent that is listening on that port.

Check that the application is still running. Sometimes applications end unexpectedly early.

Connection problems are also possible if the monitored Virtual Machine (VM) is running, but there are no more live application threads.

Check for suspended applications

If the monitored VM has been suspended, the connection dialog cannot connect to the monitored VM and might timeout.

Check firewalls

When the monitored application is not on the same workstation as the client, the client must be able to access the monitored application remotely. If the remote workstation is protected by a firewall, a port must be opened in the firewall to enable the Health Center agent to listen for connections. Firewalls can also cause timeouts when scanning for Health Center agents on a remote machine. In these cases, specify the exact Health Center port, and clear the Scan next ports for available ports option.

Check network interfaces

If the system running the monitored application has multiple network interfaces, the agent might listen on a different interface to the one the client uses. To set the interface that the agent listens on, use system properties. To use a specific network interface, run the server with the follow property:
-Djava.rmi.server.hostname=<preferred_ip_address>
The <preferred_ip_address> determines the interface used by the agent.

Check authentication

If authentication is enabled on the monitored application, ensure that security credentials have been entered on the first page of the connection wizard. Without these credentials, the monitored application might not appear in the application list on the second page of the connection wizard.

Check that application threads are running

The Health Center agent shuts down when it detects that all application threads have terminated. In some cases, you do not want the Health Center to shut down. For example, an application which exports objects to an external RMI registry stays alive to allow RMI connections, but there are no active application threads. The Health Center agent cannot find application threads, so it terminates. To ensure that the Health Center agent keeps running, add the keepAlive option to the Health Center launch parameters:
-agentlib:healthcenter=keepAlive
Note: A side-effect of the keepAlive option is that the monitored JVM does not terminate.


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