trunk/workflowmodel-api/src/main/java/net/sf/taverna/t2/monitor/MonitorNode.java

/*******************************************************************************
 * Copyright (C) 2007 The University of Manchester   
 * 
 *  Modifications to the initial code base are copyright of their
 *  respective authors, or their employers as appropriate.
 * 
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2.1 of
 *  the License, or (at your option) any later version.
 *    
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *    
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 ******************************************************************************/
package net.sf.taverna.t2.monitor;

import java.util.Date;
import java.util.Set;

/**
 * A single node in the Monitor tree, containing an optional arbitrary workflow
 * object and a set of properties which may or may not be mutable. For tree
 * traversal operations the top level monitor tree must be used, instances of
 * this class are not aware of the surrounding tree structure.
 * 
 * @author Tom Oinn
 * 
 */
public interface MonitorNode {

	/**
	 * Each monitor node can reference zero or one workflow object. This is the
	 * object which is providing any properties the node exposes, so is likely
	 * to be a workflow or processor but could be anything.
	 * 
	 * @return the workflow object providing this node's properties, or null if
	 *         there is no directly corresponding workflow object. Note that
	 *         this workflow object can be anything, and may not be a top level
	 *         workflow object at all.
	 */
	public Object getWorkflowObject();

	/**
	 * Each monitor node has an identity corresponding to the identifier stack
	 * of the data flowing through the workflow object that created it. This
	 * string array also defines its position in the monitor tree.
	 */
	public String[] getOwningProcess();

	/**
	 * Each monitor node exposes a set of properties, which may or may not be
	 * mutable
	 */
	public Set<? extends MonitorableProperty<?>> getProperties();

	/**
	 * Each node has a creation date
	 */
	public Date getCreationDate();

	/**
	 * Properties can be added to the monitor node after creation if required,
	 * although this should be used only when necessary to avoid race conditions
	 */
	public void addMonitorableProperty(MonitorableProperty<?> newProperty);

	/**
	 * Nodes can persist in the tree after they have expired, in which case this
	 * will return true.
	 */
	public boolean hasExpired();

}