EmbeddingEUROPA

Ways to run EUROPA

Embedding EUROPA

EUROPA comes with a tool called makeproject, which will generate C++ and Java projects for you.

They both illustrate how you can perform the full application cycle :

1. Initialize EUROPA
2. Load/Modify model and initial state descriptions
3. Invoke a solver
4. Extract plan results from the Plan Database
5. Repeat steps 2-4 as many times as needed
6. Shutdown EUROPA

Using the C++ API

Take a look at the main() program that makeproject generates for the C++ project : Main.cc

The [interface is the official interface for EUROPA clients, it is the recommended way to use EUROPA. This interface is very straightforward and allows you to run the entire application cycle described above. This abstraction layer will isolate your client code from most changes in the internals of the EUROPA implementation, it is also designed for easy mapping to other languages using [SWIG](http://www.swig.org SWIG)(PSEngine).

If you're planning to write your application in a language other than C++, the corresponding binding for this interface should be either already available in the EUROPA distribution, or relatively easy to add (currently only Java bindings are bundled with the EUROPA distribution, but we have plans to add Python and any other languages that are popular with the EUROPA user community).

Using the JAVA API

The interface is automatically mapped to Java using [SWIG](http://www.swig.org SWIG) PSEngine.

Take a look at the main() program that makeproject generates for the Java project : Main.java

makeproject uses a combination of Java and BeanShell scripting to achieve its goal, if you put everything together in a single Java program it would look something like this :

import org.ops.ui.util.LibraryLoader;
import psengine.*;

class Main
{
    public static void main(String args[])
    {
        String debugMode = args[0];
        String nddlFilename = args[1];

        PSEngine europa = makePSEngine(debugMode);
        europa.start();
        europa.executeScript("nddl",nddlFilename,true/*isFile*/);        
        runSolver(europa);
        europa.shutdown();
   }
	
    /*
     * debugMode = "g" for debug, "o" for optimized
     */
    static PSEngine makePSEngine(String debugMode)
    {
        PSEngine psEngine;
        LibraryLoader.loadLibrary("System_"+debugMode);
        psEngine = PSEngine.makeInstance();

        return psEngine;
    }	

    static void runSolver(PSEngine europa)
    {
        String plannerConfig = "PlannerConfig.xml";
        int startHorizon=0, endHorizon=100;

	PSSolver solver = europa.createSolver(plannerConfig);
	solver.configure(startHorizon,endHorizon);

        int maxSteps = 1000;
        for (int i = 0; !solver.isExhausted() && !solver.isTimedOut() && i<maxSteps; i = solver->getStepCount()) {
            solver.step();
            if (solver.getFlaws().size() == 0)
                break; // we're done!
        }
        
        if (solver->isExhausted())    debugMsg("Solver was exhausted after " + i + " steps");	  
	else if (solver.isTimedOut()) debugMsg("Solver timed out after " + i + " steps");
	else                          debugMsg("Main","Solver finished after " << i << " steps");
    }

    static void debugMsg(String msg)
    {
        System.out.println(msg);
    }
}

Building your own project

If you don't want to use the infrastructure generated by Makeproject Page, you will need to :

• C++ API
• Add the directories $EUROPA_HOME/include and $EUROPA_HOME/include/PLASMA to your include path
• Link in the EUROPA libraries from $EUROPA_HOME/lib.
• Java API
• Add $EUROPA_HOME/lib/PSEngine.jar to your classpath.
• If you want to use EUROPA's UI components also add $EUROPA_HOME/lib/PSUISwing.jar

In both cases, make sure $EUROPA_HOME/lib is in your LD_LIBRARY_PATH (or on your PATH if you're on Windows)