javax.management.remote.generic.ObjectWrapping Maven / Gradle / Ivy

/*
 * @(#)file      ObjectWrapping.java
 * @(#)author    Sun Microsystems, Inc.
 * @(#)version   1.12
 * @(#)lastedit  07/03/08
 * @(#)build     @BUILD_TAG_PLACEHOLDER@
 *
 * 
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package javax.management.remote.generic;

import javax.management.MBeanServerConnection;
import java.io.IOException;
import java.io.Serializable;

/**
 * An interface that defines how to wrap parameters that use a
 * non-default class loader.  A {@link GenericConnector} can specify
 * an instance of this interface to define a connection-specific
 * wrapping.
 *
 * Certain parameters to {@link
 * javax.management.MBeanServerConnection MBeanServerConnection}
 * methods have to be wrapped because their class loader is not
 * necessarily known to the remote connector server.
 *
 * For example, when calling {@link
 * javax.management.MBeanServerConnection#setAttribute setAttribute} on an MBean
 * X, the attribute value v to be set might be of a
 * class that is known to X's class loader but not to the
 * class loader of the connector server.  If v were not
 * wrapped, the connector server would receive it at the same time as
 * it received other information such as X's
 * ObjectName.  The whole request would fail because of
 * the inability to find the v's class.
 *
 * Object wrapping solves this problem by encoding v
 * inside an object of a type that is known to the connector server,
 * such as byte[] or String.  Then
 * v is recreated using X's class loader, which the
 * connector server can know once X's name has been
 * successfully received.
 *
 * An instance of this class can be communicated to the Generic
 * Connector or Generic Connector Server using the attribute {@link
 * GenericConnector#OBJECT_WRAPPING}.
 *
 * The default ObjectWrapping wraps objects in a byte
 * array that contains the output of {@link
 * java.io.ObjectOutputStream#writeObject(Object)
 * ObjectOutputStream.writeObject} for the given object in a new
 * ObjectOutputStream.
 */
public interface ObjectWrapping {
    /**
     * Wraps an object.
     *
     * @param obj the object to be wrapped.
     * @return the wrapped object.
     * @exception IOException if the object cannot be wrapped
     * for some reason.
     */
    public Object wrap(Object obj) throws IOException;

    /**
     * Unwraps an object.
     *
     * @param wrapped the wrapped object to be unwrapped.
     * @param cloader the class loader to be used to load the object's
     * class.  Can be null, meaning the bootstrap class loader.
     * @return the unwrapped object.
     * @exception ClassNotFoundException if the class that the
     * unwrapped object should have is not known to the given class
     * loader.
     * @exception IOException if the object cannot be unwrapped
     * for some reason.
     */
    public Object unwrap(Object wrapped, ClassLoader cloader)
	    throws IOException, ClassNotFoundException;

}