Class JMXConnectorServer

java.lang.Object
javax.management.NotificationBroadcasterSupport
javax.management.remote.JMXConnectorServer
All Implemented Interfaces:
MBeanRegistration, NotificationBroadcaster, NotificationEmitter, JMXAddressable, JMXConnectorServerMBean
Direct Known Subclasses:
RMIConnectorServer
public abstract class JMXConnectorServer extends NotificationBroadcasterSupport implements JMXConnectorServerMBean, MBeanRegistration, JMXAddressable

Superclass of every connector server. A connector server is attached to an MBean server. It listens for client connection requests and creates a connection for each one.

A connector server is associated with an MBean server either by registering it in that MBean server, or by passing the MBean server to its constructor.

A connector server is inactive when created. It only starts listening for client connections when the start method is called. A connector server stops listening for client connections when the stop method is called or when the connector server is unregistered from its MBean server.

Stopping a connector server does not unregister it from its MBean server. A connector server once stopped cannot be restarted.

Each time a client connection is made or broken, a notification of class JMXConnectionNotification is emitted.

Since:
1.5

Field Summary

Modifier and Type Field Description
static final String AUTHENTICATOR
Name of the attribute that specifies the authenticator for a connector server.

Constructor Summary

Constructor Description
JMXConnectorServer()
Constructs a connector server that will be registered as an MBean in the MBean server it is attached to.
JMXConnectorServer(MBeanServer mbeanServer)
Constructs a connector server that is attached to the given MBean server.

Method Summary

Modifier and Type Method Description
protected void connectionClosed(String connectionId, String message, Object userData)
Called by a subclass when a client connection is closed normally.
protected void connectionFailed(String connectionId, String message, Object userData)
Called by a subclass when a client connection fails.
protected void connectionOpened(String connectionId, String message, Object userData)
Called by a subclass when a new client connection is opened.
String[] getConnectionIds()
The list of IDs for currently-open connections to this connector server.
MBeanServer getMBeanServer()
Returns the MBean server that this connector server is attached to.
MBeanNotificationInfo[] getNotificationInfo()
Returns an array indicating the notifications that this MBean sends.
void postDeregister()
Allows the MBean to perform any operations needed after having been unregistered in the MBean server.
void postRegister(Boolean registrationDone)
Allows the MBean to perform any operations needed after having been registered in the MBean server or after the registration has failed.
void preDeregister()
Called by an MBean server when this connector server is unregistered from that MBean server.
ObjectName preRegister(MBeanServer mbs, ObjectName name)
Called by an MBean server when this connector server is registered in that MBean server.
void setMBeanServerForwarder(MBeanServerForwarder mbsf)
Inserts an object that intercepts requests for the MBean server that arrive through this connector server.
JMXConnector toJMXConnector(Map<String,?> env)
Returns a client stub for this connector server.

Methods declared in class javax.management.NotificationBroadcasterSupport

addNotificationListener, handleNotification, removeNotificationListener, removeNotificationListener, sendNotification

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods declared in interface javax.management.remote.JMXAddressable

getAddress

Methods declared in interface javax.management.remote.JMXConnectorServerMBean

getAddress, getAttributes, isActive, start, stop

Field Details

AUTHENTICATOR

public static final String AUTHENTICATOR

Name of the attribute that specifies the authenticator for a connector server. The value associated with this attribute, if any, must be an object that implements the interface JMXAuthenticator.

See Also:

Constructor Details

JMXConnectorServer

public JMXConnectorServer()

Constructs a connector server that will be registered as an MBean in the MBean server it is attached to. This constructor is typically called by one of the createMBean methods when creating, within an MBean server, a connector server that makes it available remotely.

JMXConnectorServer

public JMXConnectorServer(MBeanServer mbeanServer)

Constructs a connector server that is attached to the given MBean server. A connector server that is created in this way can be registered in a different MBean server, or not registered in any MBean server.

Parameters:
mbeanServer - the MBean server that this connector server is attached to. Null if this connector server will be attached to an MBean server by being registered in it.

Method Details

getMBeanServer

public MBeanServer getMBeanServer()

Returns the MBean server that this connector server is attached to.

Returns:
the MBean server that this connector server is attached to, or null if it is not yet attached to an MBean server.

setMBeanServerForwarder

public void setMBeanServerForwarder(MBeanServerForwarder mbsf)
Description copied from interface: JMXConnectorServerMBean

Inserts an object that intercepts requests for the MBean server that arrive through this connector server. This object will be supplied as the MBeanServer for any new connection created by this connector server. Existing connections are unaffected.

This method can be called more than once with different MBeanServerForwarder objects. The result is a chain of forwarders. The last forwarder added is the first in the chain. In more detail:

  • If this connector server is already associated with an MBeanServer object, then that object is given to mbsf.setMBeanServer. If doing so produces an exception, this method throws the same exception without any other effect.

  • If this connector is not already associated with an MBeanServer object, or if the mbsf.setMBeanServer call just mentioned succeeds, then mbsf becomes this connector server's MBeanServer.

Specified by:
setMBeanServerForwarder in interface JMXConnectorServerMBean
Parameters:
mbsf - the new MBeanServerForwarder.

getConnectionIds

public String[] getConnectionIds()
Description copied from interface: JMXConnectorServerMBean

The list of IDs for currently-open connections to this connector server.

Specified by:
getConnectionIds in interface JMXConnectorServerMBean
Returns:
a new string array containing the list of IDs. If there are no currently-open connections, this array will be empty.

toJMXConnector

public JMXConnector toJMXConnector(Map<String,?> env) throws IOException

Returns a client stub for this connector server. A client stub is a serializable object whose connect method can be used to make one new connection to this connector server.

A given connector need not support the generation of client stubs. However, the connectors specified by the JMX Remote API do (JMXMP Connector and RMI Connector).

The default implementation of this method uses JMXConnectorServerMBean.getAddress() and JMXConnectorFactory to generate the stub, with code equivalent to the following:

 JMXServiceURL addr = getAddress();
 return JMXConnectorFactory.newJMXConnector(addr, env);

A connector server for which this is inappropriate must override this method so that it either implements the appropriate logic or throws UnsupportedOperationException.

Specified by:
toJMXConnector in interface JMXConnectorServerMBean
Parameters:
env - client connection parameters of the same sort that could be provided to JMXConnector.connect(Map). Can be null, which is equivalent to an empty map.
Returns:
a client stub that can be used to make a new connection to this connector server.
Throws:
UnsupportedOperationException - if this connector server does not support the generation of client stubs.
IllegalStateException - if the JMXConnectorServer is not started (see JMXConnectorServerMBean.isActive()).
IOException - if a communications problem means that a stub cannot be created.

getNotificationInfo

public MBeanNotificationInfo[] getNotificationInfo()

Returns an array indicating the notifications that this MBean sends. The implementation in JMXConnectorServer returns an array with one element, indicating that it can emit notifications of class JMXConnectionNotification with the types defined in that class. A subclass that can emit other notifications should return an array that contains this element plus descriptions of the other notifications.

Specified by:
getNotificationInfo in interface NotificationBroadcaster
Returns:
the array of possible notifications.

connectionOpened

protected void connectionOpened(String connectionId, String message, Object userData)

Called by a subclass when a new client connection is opened. Adds connectionId to the list returned by getConnectionIds(), then emits a JMXConnectionNotification with type JMXConnectionNotification.OPENED.

Parameters:
connectionId - the ID of the new connection. This must be different from the ID of any connection previously opened by this connector server.
message - the message for the emitted JMXConnectionNotification. Can be null. See Notification.getMessage().
userData - the userData for the emitted JMXConnectionNotification. Can be null. See Notification.getUserData().
Throws:
NullPointerException - if connectionId is null.

connectionClosed

protected void connectionClosed(String connectionId, String message, Object userData)

Called by a subclass when a client connection is closed normally. Removes connectionId from the list returned by getConnectionIds(), then emits a JMXConnectionNotification with type JMXConnectionNotification.CLOSED.

Parameters:
connectionId - the ID of the closed connection.
message - the message for the emitted JMXConnectionNotification. Can be null. See Notification.getMessage().
userData - the userData for the emitted JMXConnectionNotification. Can be null. See Notification.getUserData().
Throws:
NullPointerException - if connectionId is null.

connectionFailed

protected void connectionFailed(String connectionId, String message, Object userData)

Called by a subclass when a client connection fails. Removes connectionId from the list returned by getConnectionIds(), then emits a JMXConnectionNotification with type JMXConnectionNotification.FAILED.

Parameters:
connectionId - the ID of the failed connection.
message - the message for the emitted JMXConnectionNotification. Can be null. See Notification.getMessage().
userData - the userData for the emitted JMXConnectionNotification. Can be null. See Notification.getUserData().
Throws:
NullPointerException - if connectionId is null.

preRegister

public ObjectName preRegister(MBeanServer mbs, ObjectName name)

Called by an MBean server when this connector server is registered in that MBean server. This connector server becomes attached to the MBean server and its getMBeanServer() method will return mbs.

If this connector server is already attached to an MBean server, this method has no effect. The MBean server it is attached to is not necessarily the one it is being registered in.

Specified by:
preRegister in interface MBeanRegistration
Parameters:
mbs - the MBean server in which this connection server is being registered.
name - The object name of the MBean.
Returns:
The name under which the MBean is to be registered.
Throws:
NullPointerException - if mbs or name is null.

postRegister

public void postRegister(Boolean registrationDone)
Description copied from interface: MBeanRegistration
Allows the MBean to perform any operations needed after having been registered in the MBean server or after the registration has failed.

If the implementation of this method throws a RuntimeException or an Error, the MBean Server will rethrow those inside a RuntimeMBeanException or RuntimeErrorException, respectively. However, throwing an exception in postRegister will not change the state of the MBean: if the MBean was already registered (registrationDone is true), the MBean will remain registered.

This might be confusing for the code calling createMBean() or registerMBean(), as such code might assume that MBean registration has failed when such an exception is raised. Therefore it is recommended that implementations of postRegister do not throw Runtime Exceptions or Errors if it can be avoided.

Specified by:
postRegister in interface MBeanRegistration
Parameters:
registrationDone - Indicates whether or not the MBean has been successfully registered in the MBean server. The value false means that the registration phase has failed.

preDeregister

public void preDeregister() throws Exception

Called by an MBean server when this connector server is unregistered from that MBean server. If this connector server was attached to that MBean server by being registered in it, and if the connector server is still active, then unregistering it will call the stop method. If the stop method throws an exception, the unregistration attempt will fail. It is recommended to call the stop method explicitly before unregistering the MBean.

Specified by:
preDeregister in interface MBeanRegistration
Throws:
IOException - if thrown by the stop method.
Exception - This exception will be caught by the MBean server and re-thrown as an MBeanRegistrationException.

postDeregister

public void postDeregister()
Description copied from interface: MBeanRegistration
Allows the MBean to perform any operations needed after having been unregistered in the MBean server.

If the implementation of this method throws a RuntimeException or an Error, the MBean Server will rethrow those inside a RuntimeMBeanException or RuntimeErrorException, respectively. However, throwing an exception in postDeregister will not change the state of the MBean: the MBean was already successfully deregistered and will remain so.

This might be confusing for the code calling unregisterMBean(), as it might assume that MBean deregistration has failed. Therefore it is recommended that implementations of postDeregister do not throw Runtime Exceptions or Errors if it can be avoided.

Specified by:
postDeregister in interface MBeanRegistration

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https://docs.oracle.com/en/java/javase/17/docs/api/java.management/javax/management/remote/JMXConnectorServer.html