HiveMQ, a robust and highly configurable MQTT broker, extends its functionality by offering an extensive array of metrics via Java Management Extensions (JMX): https://docs.hivemq.com/hivemq/4.20latest/user-guide/monitoring.html#jmx. This empowers users to engage in efficient monitoring through widely recognized JMX monitoring tools like JConsole.
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List all available metrics
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| title | JMXNamespacesJMXListAllMetrics.java |
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| import javax.management.*;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXServiceURL;
import java.util.Set;
/**
* This class demonstrates how to list JMX namespaces and MBeans on a remote JMX server.
*/
public class ListJMXNamespacesJMXListAllMetrics {
/**
* The main entry point of the program.
*
* @param args Command-line arguments (not used in this example).
*/
public static void main(String[] args) {
// Press Opt+Enter with your caret at the highlighted text to see how
// IntelliJ IDEA suggests fixing it.
System.out.printf("Hello and welcome!");
// Define the JMX server URL
String jmxUrl = "service:jmx:rmi:///jndi/rmi://localhost:9010/jmxrmi";
try {
// Create a JMX connector to connect to the remote JMX server
JMXServiceURL serviceURL = new JMXServiceURL(jmxUrl);
JMXConnector connector = JMXConnectorFactory.connect(serviceURL);
// Connect to the MBean server
MBeanServerConnection mbeanServerConnection = connector.getMBeanServerConnection();
// List all MBeans and their object names
System.out.println("Listing all MBeans and their namespaces:");
Set<ObjectName> mbeanNames = mbeanServerConnection.queryNames(null, null);
for (ObjectName mbeanName : mbeanNames) {
//System.out.println("MBean: " + mbeanName);
String namespace = mbeanName.getDomain(); // Extract the namespace
//System.out.println("Namespace: " + namespace);
System.out.println(namespace + " " + mbeanName);
}
// Close the JMX connector
connector.close();
} catch (Exception e) {
e.printStackTrace();
}
}
} |
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Compilation
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javac JMXListAllMetrics.java |
Execution
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java JMXListAllMetrics |
Scrape one metric periodically
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| title | JMXClientJMXOneMetric.java |
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| import javax.management.*;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXServiceURL;
/**
* This class represents a JMX client that connects to a remote JMX server to retrieve and print
* attribute values of a specified MBean (Managed Bean) object at regular intervals.
*/
public class JMXClientJMXOneMetric {
/**
* The main entry point of the JMX client application.
*
* @param args Command-line arguments. Expects two arguments: <ObjectName> and <DelayInMillis>.
* <ObjectName> specifies the target MBean's ObjectName, and <DelayInMillis> is
* the delay between metric checks in milliseconds.
* Example: java JMXClient metrics:name=com.hivemq.jvm.memory.heap.used 2000
* @throws Exception If there are errors in the JMX connection or attribute retrieval.
*/
public static void main(String[] args) throws Exception {
if (args.length != 2) {
System.err.println("Usage: java JMXClient <ObjectName> <DelayInMillis>");
System.err.println("Example: java JMXClient metrics:name=com.hivemq.jvm.memory.heap.used 2000");
System.exit(1);
}
// Parse command-line arguments
String objectNameStr = args[0];
long delayInMillis = Long.parseLong(args[1]);
// Define the JMX service URL for connecting to the remote JMX server
String jmxUrl = "service:jmx:rmi:///jndi/rmi://localhost:9010/jmxrmi";
JMXServiceURL serviceURL = new JMXServiceURL(jmxUrl);
JMXConnector connector = JMXConnectorFactory.connect(serviceURL);
MBeanServerConnection connection = connector.getMBeanServerConnection();
// Define the ObjectName based on the command-line argument
ObjectName mbeanName = new ObjectName(objectNameStr);
// Run indefinitely with the specified delay between checks
while (true) {
// Fetch and print the metric value
Object metricValue = connection.getAttribute(mbeanName, "Value");
System.out.println(objectNameStr + " " + metricValue);
// Sleep for the specified delay before the next check
Thread.sleep(delayInMillis);
}
}
} |
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Compilation
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javac JMXClientJMXOneMetric.java |
Execution
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java JMXClientJMXOneMetric <ObjectName> <DelayInMillis> |
Replace <ObjectName> with the desired metric's ObjectName and <DelayInMillis> with the desired delay between checks in milliseconds.
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