javax.management.loading
Class MLet

java.lang.Object
  |
  +--java.lang.ClassLoader
        |
        +--java.security.SecureClassLoader
              |
              +--java.net.URLClassLoader
                    |
                    +--javax.management.loading.MLet

All Implemented Interfaces:

MBeanRegistration, MLetMBean

public class MLet

extends java.net.URLClassLoader

implements MLetMBean, MBeanRegistration

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: [arglist] where: 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 domain of the agent. The m-let service invokes the getDomain() method of the Framework class to obtain this information. 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. arglist 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: where: 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 java.net.URLClassLoader 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(javax.management.MBeanServer) to load classes that could not be found in the loaded jar files.

Author:

Young Yang

Field Summary

protected PrimitiveClassLoader	paramLoader
protected MBeanServer	server

Constructor Summary

MLet()

MLet(java.net.URL[] urls)

MLet(java.net.URL[] urls, java.lang.ClassLoader parent)

MLet(java.net.URL[] urls, java.lang.ClassLoader parent, java.net.URLStreamHandlerFactory factory)

Method Summary

void	addURL(java.lang.String url) Appends the specified URL to the list of URLs to search for classes and resources.
void	addURL(java.net.URL url) Appends the specified URL to the list of URLs to search for classes and resources.
protected ObjectInstance	createMBean(MLetObject mlet) doCreate a MBean by the offered mlet
java.lang.String	getLibraryDirectory() Gets the current directory used by the library loader for storing native libraries before they are loaded into memory.
java.util.Set	getMBeansFromURL(java.lang.String url) Loads a text file containing MLET tags that define the MBeans to be added to the agent.
java.util.Set	getMBeansFromURL(java.net.URL url) Loads a text file containing MLET tags that define the MBeans to be added to the agent.
protected java.net.URL[]	getMLetURLs(MLetObject mlet, java.lang.String defaultCodeBase) get the jar urls, so can add it the the classloader path
java.lang.Class	loadClass(java.lang.String name)
static void	main(java.lang.String[] args)
void	postDeregister() Allows the MBean to perform any operations needed after having been de-registered in the MBean server.
void	postRegister(java.lang.Boolean success) Allows the MBean to perform any operations needed after having been registered in the MBean server or after the registration has failed.
void	preDeregister() Allows the MBean to perform any operations it needs before being de-registered by the MBean server.
ObjectName	preRegister(MBeanServer server, ObjectName objName) get server & objectName & classLoaderRepository
void	setLibraryDirectory(java.lang.String ld) Sets the directory used by the library loader for storing native libraries before they are loaded into memory.

Methods inherited from class java.net.URLClassLoader

definePackage, findClass, findResource, findResources, getPermissions, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass

Methods inherited from class java.lang.ClassLoader

defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getPackage, getPackages, getParent, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, resolveClass, setSigners

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.management.loading.MLetMBean

getResource, getResourceAsStream, getResources, getURLs

Field Detail

server

protected MBeanServer server

paramLoader

protected PrimitiveClassLoader paramLoader

Constructor Detail

MLet

public MLet()

MLet

public MLet(java.net.URL[] urls)

MLet

public MLet(java.net.URL[] urls,
            java.lang.ClassLoader parent)

MLet

public MLet(java.net.URL[] urls,
            java.lang.ClassLoader parent,
            java.net.URLStreamHandlerFactory factory)

Method Detail

getMBeansFromURL

public java.util.Set getMBeansFromURL(java.net.URL url)
                               throws ServiceNotFoundException

Description copied from interface: MLetMBean

Loads a text file containing MLET tags that define the MBeans to be added to the agent. The location of the text file is specified by a URL. The MBeans specified in the MLET file will be instantiated and registered by the MBeanServer.

Specified by:

getMBeansFromURL in interface MLetMBean

Following copied from interface: javax.management.loading.MLetMBean

Parameters:

url - The URL of the text file to be loaded as String object.

Returns:

A set containing one entry per MLET tag in the m-let text file loaded. Each entry specifies either the ObjectInstance for the created MBean, or a throwable object (that is, an error or an exception) if the MBean could not be created.

Throws:

ServiceNotFoundException - One of the following errors has occurred: The m-let text file does not contain an MLET tag, the m-let text file is not found, a mandatory attribute of the MLET tag is not specified, the value of url is null.

getMBeansFromURL

public java.util.Set getMBeansFromURL(java.lang.String url)
                               throws ServiceNotFoundException

Description copied from interface: MLetMBean

Loads a text file containing MLET tags that define the MBeans to be added to the agent. The location of the text file is specified by a URL. The MBeans specified in the MLET file will be instantiated and registered by the MBeanServer.

Specified by:

getMBeansFromURL in interface MLetMBean

Following copied from interface: javax.management.loading.MLetMBean

Parameters:

url - The URL of the text file to be loaded as String object.

Returns:

A set containing one entry per MLET tag in the m-let text file loaded. Each entry specifies either the ObjectInstance for the created MBean, or a throwable object (that is, an error or an exception) if the MBean could not be created.

Throws:

ServiceNotFoundException - One of the following errors has occurred: The m-let text file does not contain an MLET tag, the m-let text file is not found, a mandatory attribute of the MLET tag is not specified, the value of url is malformed.

addURL

public void addURL(java.net.URL url)

Description copied from interface: MLetMBean

Appends the specified URL to the list of URLs to search for classes and resources.

Specified by:

addURL in interface MLetMBean

Overrides:

addURL in class java.net.URLClassLoader

addURL

public void addURL(java.lang.String url)
            throws ServiceNotFoundException

Description copied from interface: MLetMBean

Appends the specified URL to the list of URLs to search for classes and resources.

Specified by:

addURL in interface MLetMBean

Following copied from interface: javax.management.loading.MLetMBean

Throws:

ServiceNotFoundException - The specified URL is malformed.

getLibraryDirectory

public java.lang.String getLibraryDirectory()

Description copied from interface: MLetMBean

Gets the current directory used by the library loader for storing native libraries before they are loaded into memory.

Specified by:

getLibraryDirectory in interface MLetMBean

Following copied from interface: javax.management.loading.MLetMBean

Returns:

The current directory used by the library loader.

setLibraryDirectory

public void setLibraryDirectory(java.lang.String ld)

Description copied from interface: MLetMBean

Sets the directory used by the library loader for storing native libraries before they are loaded into memory.

Specified by:

setLibraryDirectory in interface MLetMBean

preRegister

public ObjectName preRegister(MBeanServer server,
                              ObjectName objName)
                       throws java.lang.Exception

get server & objectName & classLoaderRepository

Specified by:

preRegister in interface MBeanRegistration

Parameters:

server -

objName -

Returns:

Throws:

java.lang.Exception -

postRegister

public void postRegister(java.lang.Boolean success)

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.

Specified by:

postRegister in interface MBeanRegistration

Following copied from interface: javax.management.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 java.lang.Exception

Description copied from interface: MBeanRegistration

Allows the MBean to perform any operations it needs before being de-registered by the MBean server.

Specified by:

preDeregister in interface MBeanRegistration

Following copied from interface: javax.management.MBeanRegistration

Throws:

java.lang.Exception - This exception should 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 de-registered in the MBean server.

Specified by:

postDeregister in interface MBeanRegistration

createMBean

protected ObjectInstance createMBean(MLetObject mlet)

doCreate a MBean by the offered mlet

Parameters:

mlet -

Returns:

ObjectInstance of the created MBean

getMLetURLs

protected java.net.URL[] getMLetURLs(MLetObject mlet,
                                     java.lang.String defaultCodeBase)

get the jar urls, so can add it the the classloader path

loadClass

public java.lang.Class loadClass(java.lang.String name)
                          throws java.lang.ClassNotFoundException

Overrides:

loadClass in class java.lang.ClassLoader

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception