You can monitor the network-operations of db4o in client-server mode.
First you need to add the monitoring support to the db4o configuration. The network monitoring support is in two separate configuration-items. The NetworkingMonitoringSupport can be used on the server and client to monitor the network statistics.
configuration.common().add(new NetworkingMonitoringSupport());
The ClientConnectionsMonitoringSupport can be added to the db4o server to monitor the connected clients.
configuration.addConfigurationItem(new ClientConnectionsMonitoringSupport());
BytesReceivedPerSecond: Tells you how many bytes this client or server has receives per second.
BytesSentPerSecond: Tells you how many bytes this client or server sends per second.
MessagesSentPerSecond: Tells you how many messages this client or server sends per second.
ConnectedClientCount: Tells you how many clients are connected to this server.