processexecutionengineimpl.java

开发owl的API,提供了W3C规定标准接口,是目前比较少的API.

// The MIT License
//
// Copyright (c) 2004 Evren Sirin
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

/*
 * Created on Dec 29, 2003
 *
 */
package org.mindswap.owls.process.execution.impl;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.mindswap.owls.OWLSFactory;
import org.mindswap.owls.process.AtomicProcess;
import org.mindswap.owls.process.CompositeProcess;
import org.mindswap.owls.process.ControlConstruct;
import org.mindswap.owls.process.DataFlow;
import org.mindswap.owls.process.Process;
import org.mindswap.owls.process.ProcessComponentList;
import org.mindswap.owls.process.Sequence;
import org.mindswap.owls.process.Split;
import org.mindswap.owls.process.SplitJoin;
import org.mindswap.owls.process.Unordered;
import org.mindswap.owls.process.ValueMap;
import org.mindswap.owls.process.execution.ProcessExecutionEngine;
import org.mindswap.owls.process.execution.ProcessExecutionListener;

/**
 * @author Evren Sirin
 *
 */
public class ProcessExecutionEngineImpl implements ProcessExecutionEngine {
	protected List executionListeners = new ArrayList();

	/**
	 * 
	 */
	public ProcessExecutionEngineImpl() {
	}

	public void notifyListeners(String msg) {
		Iterator i = executionListeners.iterator();
		while(i.hasNext()) {
			ProcessExecutionListener l = (ProcessExecutionListener) i.next();
			l.printMessage(msg);
		}
	}
	
	public void setCurrentExecuteService(Process p) {
		Iterator i = executionListeners.iterator();
		while (i.hasNext()) {
			ProcessExecutionListener l = (ProcessExecutionListener) i.next();
			l.setCurrentExecuteService(p);
		}
	}
	
	public void finishExecution(int retCode) {
		Iterator i = executionListeners.iterator();
		while (i.hasNext())
		{
			ProcessExecutionListener l = (ProcessExecutionListener) i.next();
			l.finishExecution(retCode);
		}
	}

	/* (non-Javadoc)
	 * @see org.mindswap.owls.process.execution.ProcessExecutionEngine#addExecutionListener(org.mindswap.owls.process.execution.ProcessExecutionListener)
	 */
	public void addExecutionListener(ProcessExecutionListener listener) {
		executionListeners.add(listener);	
	}

	public ValueMap execute(Process p) throws Exception { return execute(p, OWLSFactory.createValueMap()); }
	
	public ValueMap execute(Process p, ValueMap values) throws Exception {
		ValueMap valueMap = OWLSFactory.createValueMap();
		
		setCurrentExecuteService(p);
		
		valueMap.addMap(values);
		valueMap.addMap(p.getDefaultValues());	
		valueMap.retainValues(p.getInputs());
		if(p instanceof AtomicProcess) {
			valueMap = executeAtomic((AtomicProcess) p, valueMap);
		}
		else if(p instanceof CompositeProcess) {			
			valueMap = executeConstruct(((CompositeProcess) p).getComposedOf(), valueMap, p.getDataFlow());
		}
		valueMap.retainValues(p.getOutputs());
		
		notifyListeners("[DONE]");
		
		return valueMap;			
	}

	private ValueMap executeAtomic(AtomicProcess p, ValueMap values) throws Exception { 		
		return  p.getGrounding().invoke(values);	
	}

	private ValueMap executeConstruct(ControlConstruct c, ValueMap values, DataFlow dataFlow) throws Exception {
		if(c instanceof Sequence)
			return executeOrdered(c, values, dataFlow);
		else if(c instanceof Unordered)
			// Unordered says it doesn't matter in which orders subelements
			// are executed so the initial order is also ok. By checking
			// preconditions We could also
			// check different orderings and find the one that is
			return executeOrdered(c, values, dataFlow);
		else if(c instanceof Split)
			return executeParallel(c, values, dataFlow, false);
		else if(c instanceof SplitJoin)
			return executeParallel(c, values, dataFlow, true);
				
		return null;
	}
	
	private ValueMap executeOrdered(ControlConstruct s, ValueMap values, DataFlow dataFlow) throws Exception {
		ValueMap allValues = OWLSFactory.createValueMap();
		allValues.addMap(values);
		
		ProcessComponentList processList = s.getComponents(); 
 
		for(int i = 0; i < processList.size(); i++) {
			Process process = (Process) processList.get(i);
					
			allValues.applyDataFlow(dataFlow);
			ValueMap result = execute(process, allValues);
			
			boolean success = (result != null);
			if(!success) {
				notifyListeners("[ERROR]\n");
				notifyListeners("Execution Stopped"); 
				finishExecution(ProcessExecutionListener.EXEC_ERROR); // done
				return null;
			}
			else {
				allValues.addMap(result);		
				allValues.applyDataFlow(dataFlow);				
			}
		}
	
		return allValues;
	}
	
	class ProcessExecutionThread extends Thread {
		Process process;
		ValueMap values;
		ValueMap result;
		
		ProcessExecutionThread(Process process, ValueMap values) {
			this.process = process;
			this.values  = values;
		}
		
		public void run() {
			try {
				result = execute(process, values);
			} catch (Exception e) {
				notifyListeners("A thread in parallel execution failed for process " + process);				
			}	
		}
		
		public boolean isSuccess() {
			return (result != null);
		}
		
		public ValueMap getResult() {
			return result;
		}
	}
	
	private ValueMap executeParallel(ControlConstruct s, ValueMap values, DataFlow dataFlow, boolean join) {
		ValueMap allValues = OWLSFactory.createValueMap();
		allValues.addMap(values);
		
		ProcessComponentList processList = s.getComponents(); 
		ProcessExecutionThread[] threads = new ProcessExecutionThread[processList.size()];
			
		for(int i = 0; i < processList.size(); i++) {
			DataFlow df = OWLSFactory.createDataFlow();
			df.addAll(dataFlow);
			df.addAll(s.getDataFlow());
			
			Process process = (Process) processList.get(i);
			threads[i] = new ProcessExecutionThread(process, allValues);
			
			setCurrentExecuteService(process);
			threads[i].run();
		}
		
		if(join) {
			for(int i = 0; i < processList.size(); i++) {
				try {
					threads[i].join();
				} catch (InterruptedException e) {
					notifyListeners("[ERROR]\n");
					notifyListeners("Execution Stopped\n"); 
					finishExecution(ProcessExecutionListener.EXEC_ERROR); // done
					return null;					
				}
			}
		}		
		
		notifyListeners("Execution completed\n");
		return allValues;
	}	
}