activationgroup.java

Actual Java RMI implementation

	ActivationGroup createGroup(ActivationGroupID id,
				    final ActivationGroupDesc desc,
				    long incarnation)
        throws ActivationException
    {
	SecurityManager security = System.getSecurityManager();
	if (security != null)
	    security.checkSetFactory();
	    
	if (currGroup != null)
	    throw new ActivationException("group already exists");
	
	if (canCreate == false)
	    throw new ActivationException("group deactivated and " +
					  "cannot be recreated");

	try {
	    try {
		// load group's class
		String groupClassName = desc.getClassName();

		/*
		 * Fix for 4252236: resolution of the default
		 * activation group implementation name should be
		 * delayed until now.
		 */
		if (groupClassName == null) {
		    groupClassName = sun.rmi.server.ActivationGroupImpl.
			class.getName();
		}
		
		final String className = groupClassName;
		
		/*
		 * Fix for 4170955: Because the default group
		 * implementation is a sun.* class, the group class
		 * needs to be loaded in a privileged block of code.  
		 */
		Class cl;
		try {
		    cl = (Class) java.security.AccessController.
			doPrivileged(new PrivilegedExceptionAction() {
			    public Object run() throws ClassNotFoundException, 
				MalformedURLException 
			    {
				return RMIClassLoader.
				    loadClass(desc.getLocation(), className);
			    }
			});
		} catch (PrivilegedActionException pae) {
		    throw new ActivationException("Could not load default group " + 
						  "implementation class", 
						  pae.getException());
		}
		
		// create group
		Constructor constructor = cl.getConstructor(groupConstrParams);
		Object[] params = new Object[] { id, desc.getData() };

		Object obj = constructor.newInstance(params);
		if (obj instanceof ActivationGroup) {
		    currGroup = (ActivationGroup)obj;
		    currGroupID = id;
		    currSystem = id.getSystem();
		    currGroup.incarnation = incarnation;
		    currGroup.monitor =
			currSystem.activeGroup(id, currGroup, incarnation);
		    canCreate = false;
		} else {
		    throw new ActivationException("group not correct class: " +
						  obj.getClass().getName());
		}
	    } catch (java.lang.reflect.InvocationTargetException e) {
		e.getTargetException().printStackTrace();
		throw new ActivationException("exception in group constructor",
					      e.getTargetException());
		
	    } catch (ActivationException e) {
		throw e;
	    
	    } catch (Exception e) {
		throw new ActivationException("exception creating group", e);
	    }

	} catch (ActivationException e) {
	    destroyGroup();
	    canCreate = true;
	    throw e;
	}
	return currGroup;
    }

    /**
     * Returns the current activation group's identifier.  Returns null
     * if no group is currently active for this VM.
     * @return the activation group's identifier
     * @since 1.2 
     */
    public static synchronized ActivationGroupID currentGroupID() {
	return currGroupID;
    }

    /**
     * Returns the activation group identifier for the VM.  If an
     * activation group does not exist for this VM, a default
     * activation group is created. A group can be created only once,
     * so if a group has already become active and deactivated.
     *
     * @return the activation group identifier
     * @exception ActivationException if error occurs during group
     * creation, if security manager is not set, or if the group
     * has already been created and deactivated.
     */
    static synchronized ActivationGroupID internalCurrentGroupID()
	throws ActivationException
    {
	if (currGroupID == null)
	    throw new ActivationException("nonexistent group");

	return currGroupID;
    }

    /**
     * Set the activation system for the VM.  The activation system can
     * only be set it if no group is currently active. If the activation
     * system is not set via this call, then the <code>getSystem</code>
     * method attempts to obtain a reference to the
     * <code>ActivationSystem</code> by looking up the name
     * "java.rmi.activation.ActivationSystem" in the Activator's
     * registry. By default, the port number used to look up the
     * activation system is defined by
     * <code>ActivationSystem.SYSTEM_PORT</code>. This port can be overridden
     * by setting the property <code>java.rmi.activation.port</code>.
     *
     * <p>If there is a security manager, this method first
     * calls the security manager's <code>checkSetFactory</code> method.
     * This could result in a SecurityException.
     *
     * @param system remote reference to the <code>ActivationSystem</code>
     * @exception ActivationException if activation system is already set
     * @exception SecurityException if permission to set the activation system is denied.
     * (Note: The default implementation of the security manager 
     * <code>checkSetFactory</code>
     * method requires the RuntimePermission "setFactory")
     * @see SecurityManager#checkSetFactory
     * @since 1.2
     */
    public static synchronized void setSystem(ActivationSystem system)
	throws ActivationException
    {
	SecurityManager security = System.getSecurityManager();
	if (security != null)
	    security.checkSetFactory();
	
	if (currSystem != null)
	    throw new ActivationException("activation system already set");

	currSystem = system;
    }

    /**
     * Returns the activation system for the VM. The activation system
     * may be set by the <code>setSystem</code> method. If the
     * activation system is not set via the <code>setSystem</code>
     * method, then the <code>getSystem</code> method attempts to
     * obtain a reference to the <code>ActivationSystem</code> by
     * looking up the name "java.rmi.activation.ActivationSystem" in
     * the Activator's registry. By default, the port number used to
     * look up the activation system is defined by
     * <code>ActivationSystem.SYSTEM_PORT</code>. This port can be
     * overridden by setting the property
     * <code>java.rmi.activation.port</code>.
     *
     * @return the activation system for the VM/group
     * @exception ActivationException if activation system cannot be
     *  obtained or is not bound
     * (means that it is not running)
     * @since 1.2
     */
    public static synchronized ActivationSystem getSystem()
	throws ActivationException
    {
	if (currSystem == null) {
	    try {
		int port;
		port = ((Integer)java.security.AccessController.doPrivileged(
                    new GetIntegerAction("java.rmi.activation.port",
					 ActivationSystem.SYSTEM_PORT))).intValue();
		currSystem = (ActivationSystem)
		    Naming.lookup("//:" + port +
				  "/java.rmi.activation.ActivationSystem");
	    } catch (Exception e) {
		throw new ActivationException("ActivationSystem not running",
					      e);
	    }
	}
	return currSystem;
    }

    /**
     * This protected method is necessary for subclasses to
     * make the <code>activeObject</code> callback to the group's
     * monitor. The call is simply forwarded to the group's
     * <code>ActivationMonitor</code>.
     *
     * @param id the object's identifier
     * @param mobj a marshalled object containing the remote object's stub
     * @exception UnknownObjectException if object is not registered
     * @exception RemoteException if call informing monitor fails
     * @exception ActivationException if an activation error occurs
     * @since 1.2
     */
    protected void activeObject(ActivationID id, MarshalledObject mobj)
	throws ActivationException, UnknownObjectException, RemoteException
    {
	monitor.activeObject(id, mobj);
    }

    /**
     * This protected method is necessary for subclasses to
     * make the <code>inactiveGroup</code> callback to the group's
     * monitor. The call is simply forwarded to the group's
     * <code>ActivationMonitor</code>. Also, the current group
     * for the VM is set to null.
     *
     * @exception UnknownGroupException if group is not registered
     * @exception RemoteException if call informing monitor fails
     * @since 1.2
     */
    protected void inactiveGroup()
	throws UnknownGroupException, RemoteException
    {
	try {
	    monitor.inactiveGroup(groupID, incarnation);
	} finally {
	    destroyGroup();
	}
    }

    /**
     * Destroys the current group.
     */
    private static synchronized void destroyGroup() {
	currGroup = null;
	currGroupID = null;
	// NOTE: don't set currSystem to null since it may be needed
    }

    /**
     * Returns the current group for the VM.
     * @exception ActivationException if current group is null (not active)
     */
    static synchronized ActivationGroup currentGroup()
	throws ActivationException
    {
	if (currGroup == null) {
	    throw new ActivationException("group is not active");
	}
	return currGroup;
    }
    
}