Class MLet

All Implemented Interfaces:
Closeable, Externalizable, Serializable, AutoCloseable, MLetMBean, MBeanRegistration
Direct Known Subclasses:

@Deprecated(since="20", forRemoval=true) public class MLet extends URLClassLoader implements MLetMBean, MBeanRegistration, Externalizable
Deprecated, for removal: This API element is subject to removal in a future version.
This API is part of Management Applets (m-lets), which is a legacy feature that allows loading of remote MBeans. This feature is not usable without a Security Manager, which is deprecated and subject to removal in a future release. Consequently, this API is also deprecated and subject to removal. There is no replacement.
Allows you to instantiate and register one or several MBeans in the MBean server coming from a remote URL. M-let is a shortcut for management applet. The m-let service does this by loading an m-let text file, which specifies information on the MBeans to be obtained. The information on each MBean is specified in a single instance of a tag, called the MLET tag. The location of the m-let text file is specified by a URL.

The MLET tag has the following syntax:

CODE = class | OBJECT = serfile
ARCHIVE = "archiveList"
[CODEBASE = codebaseURL]
[NAME = mbeanname]
[VERSION = version]


CODE = class
This attribute specifies the full Java class name, including package name, of the MBean to be obtained. The compiled .class file of the MBean must be contained in one of the .jar files specified by the ARCHIVE attribute. Either CODE or OBJECT must be present.
OBJECT = serfile
This attribute specifies the .ser file that contains a serialized representation of the MBean to be obtained. This file must be contained in one of the .jar files specified by the ARCHIVE attribute. If the .jar file contains a directory hierarchy, specify the path of the file within this hierarchy. Otherwise a match will not be found. Either CODE or OBJECT must be present.
ARCHIVE = "archiveList"
This mandatory attribute specifies one or more .jar files containing MBeans or other resources used by the MBean to be obtained. One of the .jar files must contain the file specified by the CODE or OBJECT attribute. If archivelist contains more than one file:
  • Each file must be separated from the one that follows it by a comma (,).
  • archivelist must be enclosed in double quote marks.
All .jar files in archivelist must be stored in the directory specified by the code base URL.
CODEBASE = codebaseURL
This optional attribute specifies the code base URL of the MBean to be obtained. It identifies the directory that contains the .jar files specified by the ARCHIVE attribute. Specify this attribute only if the .jar files are not in the same directory as the m-let text file. If this attribute is not specified, the base URL of the m-let text file is used.
NAME = mbeanname
This optional attribute specifies the object name to be assigned to the MBean instance when the m-let service registers it. If mbeanname starts with the colon character (:), the domain part of the object name is the default domain of the MBean server, as returned by MBeanServer.getDefaultDomain().
VERSION = version
This optional attribute specifies the version number of the MBean and associated .jar files to be obtained. This version number can be used to specify that the .jar files are loaded from the server to update those stored locally in the cache the next time the m-let text file is loaded. version must be a series of non-negative decimal integers each separated by a period from the one that precedes it.
This optional attribute specifies a list of one or more parameters for the MBean to be instantiated. This list describes the parameters to be passed the MBean's constructor. Use the following syntax to specify each item in arglist:
<ARG TYPE=argumentType VALUE=value>
  • argumentType is the type of the argument that will be passed as parameter to the MBean's constructor.

The arguments' type in the argument list should be a Java primitive type or a Java basic type (java.lang.Boolean, java.lang.Byte, java.lang.Short, java.lang.Long, java.lang.Integer, java.lang.Float, java.lang.Double, java.lang.String).

When an m-let text file is loaded, an instance of each MBean specified in the file is created and registered.

The m-let service extends the and can be used to load remote classes and jar files in the VM of the agent.

Note - The MLet class loader uses the MBeanServerFactory.getClassLoaderRepository( to load classes that could not be found in the loaded jar files.

See Also: