| JavaTM 2 Platform Std. Ed. v1.6.0
javax.management.loading
Class MLet
java.lang.Object
 java.lang.ClassLoader
java.security.SecureClassLoader
java.net.URLClassLoader
javax.management.loading.MLet
- All Implemented Interfaces:
- Externalizable, Serializable, MLetMBean, MBeanRegistration
- Direct Known Subclasses:
- PrivateMLet
public class MLet - extends URLClassLoader
- implements MLetMBean, MBeanRegistration, Externalizable
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:
<MLET
CODE = class | OBJECT = serfile
ARCHIVE = "archiveList"
[CODEBASE = codebaseURL]
[NAME = mbeanname]
[VERSION = version]
>
[arglist]
</MLET>
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 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.
- 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:
- <
ARG TYPE=argumentType VALUE=value>
- 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.
- Since:
- 1.5
- See Also:
- Serialized Form
|
Constructor Summary |
MLet()
Constructs a new MLet using the default delegation parent ClassLoader. |
MLet(URL[] urls)
Constructs a new MLet for the specified URLs using the default
delegation parent ClassLoader. |
MLet(URL[] urls,
boolean delegateToCLR)
Constructs a new MLet for the specified URLs using the default
delegation parent ClassLoader. |
MLet(URL[] urls,
ClassLoader parent)
Constructs a new MLet for the given URLs. |
MLet(URL[] urls,
ClassLoader parent,
boolean delegateToCLR)
Constructs a new MLet for the given URLs. |
MLet(URL[] urls,
ClassLoader parent,
URLStreamHandlerFactory factory)
Constructs a new MLet for the specified URLs, parent class
loader, and URLStreamHandlerFactory. |
MLet(URL[] urls,
ClassLoader parent,
URLStreamHandlerFactory factory,
boolean delegateToCLR)
Constructs a new MLet for the specified URLs, parent class
loader, and URLStreamHandlerFactory. |
| Methods inherited from class java.lang.ClassLoader |
clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLoadedClass, findSystemClass, getPackage, getPackages, getParent, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
MLet
public MLet()
- Constructs a new MLet using the default delegation parent ClassLoader.
MLet
public MLet(URL[] urls)
- Constructs a new MLet for the specified URLs using the default
delegation parent ClassLoader. The URLs will be searched in
the order specified for classes and resources after first
searching in the parent class loader.
- Parameters:
urls - The URLs from which to load classes and resources.
MLet
public MLet(URL[] urls,
ClassLoader parent)
- Constructs a new MLet for the given URLs. The URLs will be
searched in the order specified for classes and resources
after first searching in the specified parent class loader.
The parent argument will be used as the parent class loader
for delegation.
- Parameters:
urls - The URLs from which to load classes and resources.parent - The parent class loader for delegation.
MLet
public MLet(URL[] urls,
ClassLoader parent,
URLStreamHandlerFactory factory)
- Constructs a new MLet for the specified URLs, parent class
loader, and URLStreamHandlerFactory. The parent argument will
be used as the parent class loader for delegation. The factory
argument will be used as the stream handler factory to obtain
protocol handlers when creating new URLs.
- Parameters:
urls - The URLs from which to load classes and resources.parent - The parent class loader for delegation.factory - The URLStreamHandlerFactory to use when creating URLs.
MLet
public MLet(URL[] urls,
boolean delegateToCLR)
- Constructs a new MLet for the specified URLs using the default
delegation parent ClassLoader. The URLs will be searched in
the order specified for classes and resources after first
searching in the parent class loader.
- Parameters:
urls - The URLs from which to load classes and resources.delegateToCLR - True if, when a class is not found in
either the parent ClassLoader or the URLs, the MLet should delegate
to its containing MBeanServer's ClassLoaderRepository.
MLet
public MLet(URL[] urls,
ClassLoader parent,
boolean delegateToCLR)
- Constructs a new MLet for the given URLs. The URLs will be
searched in the order specified for classes and resources
after first searching in the specified parent class loader.
The parent argument will be used as the parent class loader
for delegation.
- Parameters:
urls - The URLs from which to load classes and resources.parent - The parent class loader for delegation.delegateToCLR - True if, when a class is not found in
either the parent ClassLoader or the URLs, the MLet should delegate
to its containing MBeanServer's ClassLoaderRepository.
MLet
public MLet(URL[] urls,
ClassLoader parent,
URLStreamHandlerFactory factory,
boolean delegateToCLR)
- Constructs a new MLet for the specified URLs, parent class
loader, and URLStreamHandlerFactory. The parent argument will
be used as the parent class loader for delegation. The factory
argument will be used as the stream handler factory to obtain
protocol handlers when creating new URLs.
- Parameters:
urls - The URLs from which to load classes and resources.parent - The parent class loader for delegation.factory - The URLStreamHandlerFactory to use when creating URLs.delegateToCLR - True if, when a class is not found in
either the parent ClassLoader or the URLs, the MLet should delegate
to its containing MBeanServer's ClassLoaderRepository.
addURL
public void addURL(URL url)
- 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 URLClassLoader
- Parameters:
url - the URL to be added to the search path of URLs
addURL
public void addURL(String url)
throws ServiceNotFoundException
- Appends the specified URL to the list of URLs to search for classes and
resources.
- Specified by:
addURL in interface MLetMBean
- Parameters:
url - the URL to add.
- Throws:
ServiceNotFoundException - The specified URL is malformed.
getURLs
public URL[] getURLs()
- Returns the search path of URLs for loading classes and resources.
This includes the original list of URLs specified to the constructor,
along with any URLs subsequently appended by the addURL() method.
- Specified by:
getURLs in interface MLetMBean- Overrides:
getURLs in class URLClassLoader
- Returns:
- the search path of URLs for loading classes and resources.
getMBeansFromURL
public Set<Object> getMBeansFromURL(URL url)
throws ServiceNotFoundException
- Loads a text file containing MLET tags that define the MBeans to
be added to the MBean server. The location of the text file is specified by
a URL. The MBeans specified in the MLET file will be instantiated and
registered in the MBean server.
- Specified by:
getMBeansFromURL in interface MLetMBean
- Parameters:
url - The URL of the text file to be loaded as URL 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.
IllegalStateException - MLet MBean is not registered with an MBeanServer.
getMBeansFromURL
public Set<Object> getMBeansFromURL(String url)
throws ServiceNotFoundException
- Loads a text file containing MLET tags that define the MBeans to
be added to the MBean server. The location of the text file is specified by
a URL. The MBeans specified in the MLET file will be instantiated and
registered in the MBean server.
- Specified by:
getMBeansFromURL in interface 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 url is
malformed.
IllegalStateException - MLet MBean is not registered
with an MBeanServer.
getLibraryDirectory
public String getLibraryDirectory()
- 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
- Returns:
- The current directory used by the library loader.
- Throws:
UnsupportedOperationException - if this implementation
does not support storing native libraries in this way.- See Also:
setLibraryDirectory(java.lang.String)
setLibraryDirectory
public void setLibraryDirectory(String libdir)
- Sets the directory used by the library loader for storing
native libraries before they are loaded into memory.
- Specified by:
setLibraryDirectory in interface MLetMBean
- Parameters:
libdir - The directory used by the library loader.
- Throws:
UnsupportedOperationException - if this implementation
does not support storing native libraries in this way.- See Also:
getLibraryDirectory()
preRegister
public ObjectName preRegister(MBeanServer server,
ObjectName name)
throws Exception
- Allows the m-let to perform any operations it needs before
being registered in the MBean server. If the ObjectName is
null, the m-let provides a default name for its registration
<defaultDomain>:type=MLet
- Specified by:
preRegister in interface MBeanRegistration
- Parameters:
server - The MBean server in which the m-let will be registered.name - The object name of the m-let.
- Returns:
- The name of the m-let registered.
- Throws:
Exception - This exception should be caught by the MBean server and re-thrown
as an MBeanRegistrationException.
postRegister
public void postRegister(Boolean registrationDone)
- Allows the m-let 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
- Parameters:
registrationDone - Indicates whether or not the m-let has
been successfully registered in the MBean server. The value
false means that either the registration phase has failed.
preDeregister
public void preDeregister()
throws Exception
- Allows the m-let to perform any operations it needs before being unregistered
by the MBean server.
- Specified by:
preDeregister in interface MBeanRegistration
- Throws:
java.langException - This exception should be caught
by the MBean server and re-thrown as an
MBeanRegistrationException.
Exception - This exception will be caught by
the MBean server and re-thrown as an MBeanRegistrationException.
postDeregister
public void postDeregister()
- Allows the m-let to perform any operations needed after having been
unregistered in the MBean server.
- Specified by:
postDeregister in interface MBeanRegistration
writeExternal
public void writeExternal(ObjectOutput out)
throws IOException,
UnsupportedOperationException
Save this MLet's contents to the given ObjectOutput.
Not all implementations support this method. Those that do not
throw UnsupportedOperationException. A subclass may
override this method to support it or to change the format of
the written data.
The format of the written data is not specified, but if
an implementation supports writeExternal(java.io.ObjectOutput) it must
also support readExternal(java.io.ObjectInput) in such a way that what is
written by the former can be read by the latter.
- Specified by:
writeExternal in interface Externalizable
- Parameters:
out - The object output stream to write to.
- Throws:
IOException - If a problem occurred while writing.
UnsupportedOperationException - If this
implementation does not support this operation.
readExternal
public void readExternal(ObjectInput in)
throws IOException,
ClassNotFoundException,
UnsupportedOperationException
Restore this MLet's contents from the given ObjectInput.
Not all implementations support this method. Those that do not
throw UnsupportedOperationException. A subclass may
override this method to support it or to change the format of
the read data.
The format of the read data is not specified, but if an
implementation supports readExternal(java.io.ObjectInput) it must also
support writeExternal(java.io.ObjectOutput) in such a way that what is
written by the latter can be read by the former.
- Specified by:
readExternal in interface Externalizable
- Parameters:
in - The object input stream to read from.
- Throws:
IOException - if a problem occurred while reading.
ClassNotFoundException - if the class for the object
being restored cannot be found.
UnsupportedOperationException - if this
implementation does not support this operation.
loadClass
public Class<?> loadClass(String name,
ClassLoaderRepository clr)
throws ClassNotFoundException
Load a class, using the given ClassLoaderRepository if
the class is not found in this MLet's URLs. The given
ClassLoaderRepository can be null, in which case a ClassNotFoundException occurs immediately if the class is not
found in this MLet's URLs.
- Parameters:
name - The name of the class we want to load.clr - The ClassLoaderRepository that will be used to search
for the given class, if it is not found in this
ClassLoader. May be null.
- Returns:
- The resulting Class object.
- Throws:
ClassNotFoundException - The specified class could not be
found in this ClassLoader nor in the given
ClassLoaderRepository.
findClass
protected Class<?> findClass(String name)
throws ClassNotFoundException
- This is the main method for class loaders that is being redefined.
- Overrides:
findClass in class URLClassLoader
- Parameters:
name - The name of the class.
- Returns:
- The resulting Class object.
- Throws:
ClassNotFoundException - The specified class could not be
found.
findLibrary
protected String findLibrary(String libname)
- Returns the absolute path name of a native library. The VM
invokes this method to locate the native libraries that belong
to classes loaded with this class loader. Libraries are
searched in the JAR files using first just the native library
name and if not found the native library name together with
the architecture-specific path name
(
OSName/OSArch/OSVersion/lib/nativelibname), i.e.
the library stat on Solaris SPARC 5.7 will be searched in the JAR file as:
- libstat.so
- SunOS/sparc/5.7/lib/libstat.so
the library stat on Windows NT 4.0 will be searched in the JAR file as:
- stat.dll
- WindowsNT/x86/4.0/lib/stat.dll
More specifically, let nativelibname be the result of
System.mapLibraryName(libname). Then the following names are
searched in the JAR files, in order:
nativelibname
<os.name>/<os.arch>/<os.version>/lib/nativelibname
where <X> means System.getProperty(X) with any
spaces in the result removed, and / stands for the
file separator character (File.separator).
If this method returns null, i.e. the libraries
were not found in any of the JAR files loaded with this class
loader, the VM searches the library along the path specified
as the java.library.path property.
- Overrides:
findLibrary in class ClassLoader
- Parameters:
libname - The library name.
- Returns:
- The absolute path of the native library.
- See Also:
System.loadLibrary(String),
System.mapLibraryName(String)
check
protected URL check(String version,
URL codebase,
String jarfile,
MLetContent mlet)
throws Exception
This method is to be overridden when extending this service to
support caching and versioning. It is called from getMBeansFromURL when the version,
codebase, and jarfile have been extracted from the MLet file,
and can be used to verify that it is all right to load the
given MBean, or to replace the given URL with a different one.
The default implementation of this method returns
codebase unchanged.
- Parameters:
version - The version number of the .jar
file stored locally.codebase - The base URL of the remote .jar file.jarfile - The name of the .jar file to be loaded.mlet - The MLetContent instance that
represents the MLET tag.
- Returns:
- the codebase to use for the loaded MBean. The returned
value should not be null.
- Throws:
Exception - if the MBean is not to be loaded for some
reason. The exception will be added to the set returned by
getMBeansFromURL.
Copyright 2003 Sun Microsystems, Inc. All rights reserved
|
