index-group=Unrevised type=page status=published title=dynamic-proxy-to-access-mbean
*Help us document this example! Click the blue pencil icon in the upper right to edit this page.* ## Example Acessing MBean is something simple through the JMX API but it is often technical and not very interesting. This example simplify this work simply doing it generically in a proxy. So from an user side you simple declare an interface to access your MBeans. Note: the example implementation uses a local MBeanServer but enhancing the example API it is easy to imagine a remote connection with user/password if needed. ## ObjectName API (annotation) Simply an annotation to get the object package org.superbiz.dynamic.mbean; import java.lang.annotation.Retention; import java.lang.annotation.Target; import static java.lang.annotation.ElementType.TYPE; import static java.lang.annotation.ElementType.METHOD; import static java.lang.annotation.RetentionPolicy.RUNTIME; @Target({TYPE, METHOD}) @Retention(RUNTIME) public @interface ObjectName { String value(); // for remote usage only String url() default ""; String user() default ""; String password() default ""; } ## DynamicMBeanHandler (thr proxy implementation) package org.superbiz.dynamic.mbean; import javax.annotation.PreDestroy; import javax.management.Attribute; import javax.management.MBeanAttributeInfo; import javax.management.MBeanInfo; import javax.management.MBeanServer; import javax.management.MBeanServerConnection; import javax.management.ObjectName; import javax.management.remote.JMXConnector; import javax.management.remote.JMXConnectorFactory; import javax.management.remote.JMXServiceURL; import java.io.IOException; import java.lang.management.ManagementFactory; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.util.HashMap; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; /** * Need a @PreDestroy method to disconnect the remote host when used in remote mode. */ public class DynamicMBeanHandler implements InvocationHandler { private final Map<Method, ConnectionInfo> infos = new ConcurrentHashMap<Method, ConnectionInfo>(); @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { final String methodName = method.getName(); if (method.getDeclaringClass().equals(Object.class) && "toString".equals(methodName)) { return getClass().getSimpleName() + " Proxy"; } if (method.getAnnotation(PreDestroy.class) != null) { return destroy(); } final ConnectionInfo info = getConnectionInfo(method); final MBeanInfo infos = info.getMBeanInfo(); if (methodName.startsWith("set") && methodName.length() > 3 && args != null && args.length == 1 && (Void.TYPE.equals(method.getReturnType()) || Void.class.equals(method.getReturnType()))) { final String attributeName = attributeName(infos, methodName, method.getParameterTypes()[0]); info.setAttribute(new Attribute(attributeName, args[0])); return null; } else if (methodName.startsWith("get") && (args == null || args.length == 0) && methodName.length() > 3) { final String attributeName = attributeName(infos, methodName, method.getReturnType()); return info.getAttribute(attributeName); } // operation return info.invoke(methodName, args, getSignature(method)); } public Object destroy() { for (ConnectionInfo info : infos.values()) { info.clean(); } infos.clear(); return null; } private String[] getSignature(Method method) { String[] args = new String[method.getParameterTypes().length]; for (int i = 0; i < method.getParameterTypes().length; i++) { args[i] = method.getParameterTypes()[i].getName(); } return args; // note: null should often work... } private String attributeName(MBeanInfo infos, String methodName, Class<?> type) { String found = null; String foundBackUp = null; // without checking the type final String attributeName = methodName.substring(3, methodName.length()); final String lowerName = Character.toLowerCase(methodName.charAt(3)) + methodName.substring(4, methodName.length()); for (MBeanAttributeInfo attribute : infos.getAttributes()) { final String name = attribute.getName(); if (attributeName.equals(name)) { foundBackUp = attributeName; if (attribute.getType().equals(type.getName())) { found = name; } } else if (found == null && ((lowerName.equals(name) && !attributeName.equals(name)) || lowerName.equalsIgnoreCase(name))) { foundBackUp = name; if (attribute.getType().equals(type.getName())) { found = name; } } } if (found == null && foundBackUp == null) { throw new UnsupportedOperationException("cannot find attribute " + attributeName); } if (found != null) { return found; } return foundBackUp; } private synchronized ConnectionInfo getConnectionInfo(Method method) throws Exception { if (!infos.containsKey(method)) { synchronized (infos) { if (!infos.containsKey(method)) { // double check for synchro org.superbiz.dynamic.mbean.ObjectName on = method.getAnnotation(org.superbiz.dynamic.mbean.ObjectName.class); if (on == null) { Class<?> current = method.getDeclaringClass(); do { on = method.getDeclaringClass().getAnnotation(org.superbiz.dynamic.mbean.ObjectName.class); current = current.getSuperclass(); } while (on == null && current != null); if (on == null) { throw new UnsupportedOperationException("class or method should define the objectName to use for invocation: " + method.toGenericString()); } } final ConnectionInfo info; if (on.url().isEmpty()) { info = new LocalConnectionInfo(); ((LocalConnectionInfo) info).server = ManagementFactory.getPlatformMBeanServer(); // could use an id... } else { info = new RemoteConnectionInfo(); final Map<String, String[]> environment = new HashMap<String, String[]>(); if (!on.user().isEmpty()) { environment.put(JMXConnector.CREDENTIALS, new String[]{ on.user(), on.password() }); } // ((RemoteConnectionInfo) info).connector = JMXConnectorFactory.newJMXConnector(new JMXServiceURL(on.url()), environment); ((RemoteConnectionInfo) info).connector = JMXConnectorFactory.connect(new JMXServiceURL(on.url()), environment); } info.objectName = new ObjectName(on.value()); infos.put(method, info); } } } return infos.get(method); } private abstract static class ConnectionInfo { protected ObjectName objectName; public abstract void setAttribute(Attribute attribute) throws Exception; public abstract Object getAttribute(String attribute) throws Exception; public abstract Object invoke(String operationName, Object params[], String signature[]) throws Exception; public abstract MBeanInfo getMBeanInfo() throws Exception; public abstract void clean(); } private static class LocalConnectionInfo extends ConnectionInfo { private MBeanServer server; @Override public void setAttribute(Attribute attribute) throws Exception { server.setAttribute(objectName, attribute); } @Override public Object getAttribute(String attribute) throws Exception { return server.getAttribute(objectName, attribute); } @Override public Object invoke(String operationName, Object[] params, String[] signature) throws Exception { return server.invoke(objectName, operationName, params, signature); } @Override public MBeanInfo getMBeanInfo() throws Exception { return server.getMBeanInfo(objectName); } @Override public void clean() { // no-op } } private static class RemoteConnectionInfo extends ConnectionInfo { private JMXConnector connector; private MBeanServerConnection connection; private void before() throws IOException { connection = connector.getMBeanServerConnection(); } private void after() throws IOException { // no-op } @Override public void setAttribute(Attribute attribute) throws Exception { before(); connection.setAttribute(objectName, attribute); after(); } @Override public Object getAttribute(String attribute) throws Exception { before(); try { return connection.getAttribute(objectName, attribute); } finally { after(); } } @Override public Object invoke(String operationName, Object[] params, String[] signature) throws Exception { before(); try { return connection.invoke(objectName, operationName, params, signature); } finally { after(); } } @Override public MBeanInfo getMBeanInfo() throws Exception { before(); try { return connection.getMBeanInfo(objectName); } finally { after(); } } @Override public void clean() { try { connector.close(); } catch (IOException e) { // no-op } } } } ## Dynamic Proxies ### DynamicMBeanClient (the dynamic JMX client) package org.superbiz.dynamic.mbean; import org.apache.openejb.api.Proxy; import org.superbiz.dynamic.mbean.DynamicMBeanHandler; import org.superbiz.dynamic.mbean.ObjectName; import javax.ejb.Singleton; /** * @author rmannibucau */ @Singleton @Proxy(DynamicMBeanHandler.class) @ObjectName(DynamicMBeanClient.OBJECT_NAME) public interface DynamicMBeanClient { static final String OBJECT_NAME = "test:group=DynamicMBeanClientTest"; int getCounter(); void setCounter(int i); int length(String aString); } ### DynamicMBeanClient (the dynamic JMX client) package org.superbiz.dynamic.mbean; import org.apache.openejb.api.Proxy; import javax.annotation.PreDestroy; import javax.ejb.Singleton; @Singleton @Proxy(DynamicMBeanHandler.class) @ObjectName(value = DynamicRemoteMBeanClient.OBJECT_NAME, url = "service:jmx:rmi:///jndi/rmi://localhost:8243/jmxrmi") public interface DynamicRemoteMBeanClient { static final String OBJECT_NAME = "test:group=DynamicMBeanClientTest"; int getCounter(); void setCounter(int i); int length(String aString); @PreDestroy void clean(); } ## The MBean used for the test ### SimpleMBean package org.superbiz.dynamic.mbean.simple; public interface SimpleMBean { int length(String s); int getCounter(); void setCounter(int c); } ## Simple package org.superbiz.dynamic.mbean.simple; public class Simple implements SimpleMBean { private int counter = 0; @Override public int length(String s) { if (s == null) { return 0; } return s.length(); } @Override public int getCounter() { return counter; } @Override public void setCounter(int c) { counter = c; } } ## DynamicMBeanClientTest (The test) package org.superbiz.dynamic.mbean; import org.junit.After; import org.junit.AfterClass; import org.junit.Before; import org.junit.BeforeClass; import org.junit.Test; import org.superbiz.dynamic.mbean.simple.Simple; import javax.ejb.EJB; import javax.ejb.embeddable.EJBContainer; import javax.management.Attribute; import javax.management.ObjectName; import java.lang.management.ManagementFactory; import static junit.framework.Assert.assertEquals; public class DynamicMBeanClientTest { private static ObjectName objectName; private static EJBContainer container; @EJB private DynamicMBeanClient localClient; @EJB private DynamicRemoteMBeanClient remoteClient; @BeforeClass public static void start() { container = EJBContainer.createEJBContainer(); } @Before public void injectAndRegisterMBean() throws Exception { container.getContext().bind("inject", this); objectName = new ObjectName(DynamicMBeanClient.OBJECT_NAME); ManagementFactory.getPlatformMBeanServer().registerMBean(new Simple(), objectName); } @After public void unregisterMBean() throws Exception { if (objectName != null) { ManagementFactory.getPlatformMBeanServer().unregisterMBean(objectName); } } @Test public void localGet() throws Exception { assertEquals(0, localClient.getCounter()); ManagementFactory.getPlatformMBeanServer().setAttribute(objectName, new Attribute("Counter", 5)); assertEquals(5, localClient.getCounter()); } @Test public void localSet() throws Exception { assertEquals(0, ((Integer) ManagementFactory.getPlatformMBeanServer().getAttribute(objectName, "Counter")).intValue()); localClient.setCounter(8); assertEquals(8, ((Integer) ManagementFactory.getPlatformMBeanServer().getAttribute(objectName, "Counter")).intValue()); } @Test public void localOperation() { assertEquals(7, localClient.length("openejb")); } @Test public void remoteGet() throws Exception { assertEquals(0, remoteClient.getCounter()); ManagementFactory.getPlatformMBeanServer().setAttribute(objectName, new Attribute("Counter", 5)); assertEquals(5, remoteClient.getCounter()); } @Test public void remoteSet() throws Exception { assertEquals(0, ((Integer) ManagementFactory.getPlatformMBeanServer().getAttribute(objectName, "Counter")).intValue()); remoteClient.setCounter(8); assertEquals(8, ((Integer) ManagementFactory.getPlatformMBeanServer().getAttribute(objectName, "Counter")).intValue()); } @Test public void remoteOperation() { assertEquals(7, remoteClient.length("openejb")); } @AfterClass public static void close() { if (container != null) { container.close(); } } }