/*
* @(#)ActivationID.java 1.28 03/12/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.rmi.activation;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
import java.rmi.MarshalledObject;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.UnmarshalException;
import java.rmi.server.RemoteObject;
import java.rmi.server.RemoteObjectInvocationHandler;
import java.rmi.server.RemoteRef;
import java.rmi.server.RemoteStub;
import java.rmi.server.UID;
/**
* Activation makes use of special identifiers to denote remote
* objects that can be activated over time. An activation identifier
* (an instance of the class <code>ActivationID</code>) contains several
* pieces of information needed for activating an object:
* <ul>
* <li> a remote reference to the object's activator (a {@link
* java.rmi.server.RemoteRef RemoteRef}
* instance), and
* <li> a unique identifier (a {@link java.rmi.server.UID UID}
* instance) for the object. </ul> <p>
*
* An activation identifier for an object can be obtained by registering
* an object with the activation system. Registration is accomplished
* in a few ways: <ul>
* <li>via the <code>Activatable.register</code> method
* <li>via the first <code>Activatable</code> constructor (that takes
* three arguments and both registers and exports the object, and
* <li>via the first <code>Activatable.exportObject</code> method
* that takes the activation descriptor, object and port as arguments;
* this method both registers and exports the object. </ul>
*
* @author Ann Wollrath
* @version 1.28, 03/12/19
* @see Activatable
* @since 1.2
*/
public class ActivationID implements java.io.Serializable {
/**
* the object's activator
*/
private transient Activator activator;
/**
* the object's unique id
*/
private transient UID uid = new UID();
/** indicate compatibility with the Java 2 SDK v1.2 version of class */
private static final long serialVersionUID = -4608673054848209235L;
/**
* The constructor for <code>ActivationID</code> takes a single
* argument, activator, that specifies a remote reference to the
* activator responsible for activating the object associated with
* this identifier. An instance of <code>ActivationID</code> is globally
* unique.
*
* @param activator reference to the activator responsible for
* activating the object
* @since 1.2
*/
public ActivationID(Activator activator) {
this.activator = activator;
}
/**
* Activate the object for this id.
*
* @param force if true, forces the activator to contact the group
* when activating the object (instead of returning a cached reference);
* if false, returning a cached value is acceptable.
* @return the reference to the active remote object
* @exception ActivationException if activation fails
* @exception UnknownObjectException if the object is unknown
* @exception RemoteException if remote call fails
* @since 1.2
*/
public Remote activate(boolean force)
throws ActivationException, UnknownObjectException, RemoteException
{
try {
MarshalledObject mobj =
(MarshalledObject) activator.activate(this, force);
return (Remote) mobj.get();
} catch (RemoteException e) {
throw e;
} catch (IOException e) {
throw new UnmarshalException("activation failed", e);
} catch (ClassNotFoundException e) {
throw new UnmarshalException("activation failed", e);
}
}
/**
* Returns a hashcode for the activation id. Two identifiers that
* refer to the same remote object will have the same hash code.
*
* @see java.util.Hashtable
* @since 1.2
*/
public int hashCode() {
return uid.hashCode();
}
/**
* Compares two activation ids for content equality.
* Returns true if both of the following conditions are true:
* 1) the unique identifiers equivalent (by content), and
* 2) the activator specified in each identifier
* refers to the same remote object.
*
* @param obj the Object to compare with
* @return true if these Objects are equal; false otherwise.
* @see java.util.Hashtable
* @since 1.2
*/
public boolean equals(Object obj) {
if (obj instanceof ActivationID) {
ActivationID id = (ActivationID) obj;
return (uid.equals(id.uid) && activator.equals(id.activator));
} else {
return false;
}
}
/**
* <code>writeObject</code> for custom serialization.
*
* <p>This method writes this object's serialized form for
* this class as follows:
*
* <p>The <code>writeObject</code> method is invoked on
* <code>out</code> passing this object's unique identifier
* (a {@link java.rmi.server.UID UID} instance) as the argument.
*
* <p>Next, the {@link
* java.rmi.server.RemoteRef#getRefClass(java.io.ObjectOutput)
* getRefClass} method is invoked on the activator's
* <code>RemoteRef</code> instance to obtain its external ref
* type name. Next, the <code>writeUTF</code> method is
* invoked on <code>out</code> with the value returned by
* <code>getRefClass</code>, and then the
* <code>writeExternal</code> method is invoked on the
* <code>RemoteRef</code> instance passing <code>out</code>
* as the argument.
*
* @serialData The serialized data for this class comprises a
* <code>java.rmi.server.UID</code> (written with
* <code>ObjectOutput.writeObject</code>) followed by the
* external ref type name of the activator's
* <code>RemoteRef</code> instance (a string written with
* <code>ObjectOutput.writeUTF</code>), followed by the
* external form of the <code>RemoteRef</code> instance as
* written by its <code>writeExternal</code> method.
*
* <p>The external ref type name of the
* <code>RemoteRef</Code> instance is
* determined using the definitions of external ref type
* names specified in the {@link java.rmi.server.RemoteObject
* RemoteObject} <code>writeObject</code> method
* <b>serialData</b> specification. Similarly, the data
* written by the <code>writeExternal</code> method and read
* by the <code>readExternal</code> method of
* <code>RemoteRef</code> implementation classes
* corresponding to each of the defined external ref type
* names is specified in the {@link
* java.rmi.server.RemoteObject RemoteObject}
* <code>writeObject</code> method <b>serialData</b>
* specification.
**/
private void writeObject(java.io.ObjectOutputStream out)
throws IOException, ClassNotFoundException
{
out.writeObject(uid);
RemoteRef ref;
if (activator instanceof RemoteObject) {
ref = ((RemoteObject) activator).getRef();
} else if (Proxy.isProxyClass(activator.getClass())) {
InvocationHandler handler = Proxy.getInvocationHandler(activator);
if (!(handler instanceof RemoteObjectInvocationHandler)) {
throw new InvalidObjectException(
"unexpected invocation handler");
}
ref = ((RemoteObjectInvocationHandler) handler).getRef();
} else {
throw new InvalidObjectException("unexpected activator type");
}
out.writeUTF(ref.getRefClass(out));
ref.writeExternal(out);
}
/**
* <code>readObject</code> for custom serialization.
*
* <p>This method reads this object's serialized form for this
* class as follows:
*
* <p>The <code>readObject</code> method is invoked on
* <code>in</code> to read this object's unique identifier
* (a {@link java.rmi.server.UID UID} instance).
*
* <p>Next, the <code>readUTF</code> method is invoked on
* <code>in</code> to read the external ref type name of the
* <code>RemoteRef</code> instance for this object's
* activator. Next, the <code>RemoteRef</code>
* instance is created of an implementation-specific class
* corresponding to the external ref type name (returned by
* <code>readUTF</code>), and the <code>readExternal</code>
* method is invoked on that <code>RemoteRef</code> instance
* to read the external form corresponding to the external
* ref type name.
*
* <p>Note: If the external ref type name is
* <code>"UnicastRef"</code>, <code>"UnicastServerRef"</code>,
* <code>"UnicastRef2"</code>, <code>"UnicastServerRef2"</code>,
* or <code>"ActivatableRef"</code>, a corresponding
* implementation-specific class must be found, and its
* <code>readExternal</code> method must read the serial data
* for that external ref type name as specified to be written
* in the <b>serialData</b> documentation for this class.
* If the external ref type name is any other string (of non-zero
* length), a <code>ClassNotFoundException</code> will be thrown,
* unless the implementation provides an implementation-specific
* class corresponding to that external ref type name, in which
* case the <code>RemoteRef</code> will be an instance of
* that implementation-specific class.
*/
private void readObject(java.io.ObjectInputStream in)
throws IOException, ClassNotFoundException
{
uid = (UID)in.readObject();
try {
Class refClass = Class.forName(RemoteRef.packagePrefix + "." +
in.readUTF());
RemoteRef ref = (RemoteRef) refClass.newInstance();
ref.readExternal(in);
activator = (Activator)
Proxy.newProxyInstance(null,
new Class[]{ Activator.class },
new RemoteObjectInvocationHandler(ref));
} catch (InstantiationException e) {
throw (IOException)
new InvalidObjectException(
"Unable to create remote reference").initCause(e);
} catch (IllegalAccessException e) {
throw (IOException)
new InvalidObjectException(
"Unable to create remote reference").initCause(e);
}
}
}
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