org.omg.PortableServer.ServantLocatorPackage

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1. Creating a Simple Servant Locator

import org.omg.PortableServer.ServantLocatorPackage;

public class MyServantLocator implements ServantLocatorPackage.ServantLocator {

    public MyServantLocator() {
        // Initialize the servant locator
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Return the servant for the given ID
        throw new ForwardRequest();
    }
}

2. Registering the Servant Locator with ORB

import org.omg.PortableServer.*;

public class RegisterServantLocator {

    public static void main(String[] args) {
        try {
            // Create and register the servant locator
            POA rootPOA = POAHelper.narrow(ORB.init(args, null).getRootPOA());
            rootPOA.setServantManager(new ServantManager());
            rootPOA.activate();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

3. Implementing ServantLocator for a Specific Servant Class

import org.omg.PortableServer.ServantLocatorPackage;

public class MyServantLocator implements ServantLocatorPackage.ServantLocator {

    private Class servantClass;

    public MyServantLocator(Class servantClass) {
        this.servantClass = servantClass;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Instantiate and return the servant of the given class
        try {
            return (Servant) servantClass.newInstance();
        } catch (Exception e) {
            throw new ForwardRequest();
        }
    }
}

4. Using a ServantLocator to Load Servants from a Database

import org.omg.PortableServer.ServantLocatorPackage;
import java.sql.*;

public class DatabaseServantLocator implements ServantLocatorPackage.ServantLocator {

    private Connection connection;

    public DatabaseServantLocator(Connection connection) {
        this.connection = connection;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Query the database for the servant data and instantiate the servant
        String servantClass = getServantClassFromDatabase(id);
        try {
            return (Servant) Class.forName(servantClass).newInstance();
        } catch (Exception e) {
            throw new ForwardRequest();
        }
    }

    private String getServantClassFromDatabase(ID id) {
        // Implement the logic to fetch the servant class name from the database
    }
}

5. Using a ServantLocator to Handle Exceptions

import org.omg.PortableServer.ServantLocatorPackage;

public class ExceptionHandlingServantLocator implements ServantLocatorPackage.ServantLocator {

    private Servant servant;

    public ExceptionHandlingServantLocator(Servant servant) {
        this.servant = servant;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        try {
            // Handle exceptions that may occur while instantiating the servant
            return servant;
        } catch (Exception e) {
            throw new ForwardRequest();
        }
    }
}

6. Using a ServantLocator to Create Singleton Servants

import org.omg.PortableServer.ServantLocatorPackage;

public class SingletonServantLocator implements ServantLocatorPackage.ServantLocator {

    private Servant servant;

    public SingletonServantLocator(Servant servant) {
        this.servant = servant;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Ensure that the servant is instantiated only once
        if (servant == null) {
            synchronized (this) {
                if (servant == null) {
                    servant = new Servant();
                }
            }
        }
        return servant;
    }
}

7. Using a ServantLocator to Dynamically Load Servants

import org.omg.PortableServer.ServantLocatorPackage;

public class DynamicServantLocator implements ServantLocatorPackage.ServantLocator {

    private String servantClass;

    public DynamicServantLocator(String servantClass) {
        this.servantClass = servantClass;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Dynamically load and instantiate the servant class
        try {
            return (Servant) Class.forName(servantClass).newInstance();
        } catch (Exception e) {
            throw new ForwardRequest();
        }
    }
}

8. Using a ServantLocator to Provide Different Implementations for Different IDs

import org.omg.PortableServer.ServantLocatorPackage;

public class MultiServantLocator implements ServantLocatorPackage.ServantLocator {

    private Map<ID, Servant> servants;

    public MultiServantLocator(Map<ID, Servant> servants) {
        this.servants = servants;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Return the servant associated with the given ID
        Servant servant = servants.get(id);
        if (servant == null) {
            throw new ForwardRequest();
        }
        return servant;
    }
}

9. Using a ServantLocator with a POAManager

import org.omg.PortableServer.*;

public class POAManagerServantLocator {

    public static void main(String[] args) {
        try {
            // Create a POAManager and register the servant locator with it
            POAManager poaManager = POAHelper.narrow(ORB.init(args, null).getRootPOA().getManager());
            poaManager.setServantLocator(new MyServantLocator());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

10. Using a ServantLocator with a Servantholder

import org.omg.PortableServer.ServantLocatorPackage;
import java.util.concurrent.ConcurrentHashMap;

public class ServantholderServantLocator implements ServantLocatorPackage.ServantLocator {

    private ConcurrentHashMap<ID, Servant> servants;

    public ServantholderServantLocator() {
        servants = new ConcurrentHashMap<>();
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Check if the servant is already in the servantholder, otherwise instantiate it
        Servant servant = servants.get(id);
        if (servant == null) {
            synchronized (servants) {
                if (servant == null) {
                    servant = new Servant();
                    servants.put(id, servant);
                }
            }
        }
        return servant;
    }
}

11. Using a ServantLocator with a ReferenceFactory

import org.omg.PortableServer.ServantLocatorPackage;
import org.omg.PortableServer.LifespanPolicyValue;

public class ReferenceFactoryServantLocator implements ServantLocatorPackage.ServantLocator {

    private ReferenceFactory referenceFactory;

    public ReferenceFactoryServantLocator(ReferenceFactory referenceFactory) {
        this.referenceFactory = referenceFactory;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Create a new servant using the reference factory
        Servant servant = referenceFactory.make_servant(id, LifespanPolicyValue.PERSISTENT);
        return servant;
    }
}

12. Using a ServantLocator with a ServantActivator

import org.omg.PortableServer.ServantLocatorPackage;

public class ServantActivatorServantLocator implements ServantLocatorPackage.ServantLocator {

    private ServantActivator servantActivator;

    public ServantActivatorServantLocator(ServantActivator servantActivator) {
        this.servantActivator = servantActivator;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Use the servant activator to create a new servant for the given ID
        Servant servant = servantActivator.incarnate(id, null);
        return servant;
    }
}

13. Using a ServantLocator with a ServantManager

import org.omg.PortableServer.ServantLocatorPackage;
import org.omg.PortableServer.POA;

public class ServantManagerServantLocator implements ServantLocatorPackage.ServantLocator {

    private ServantManager servantManager;
    private POA rootPOA;

    public ServantManagerServantLocator(ServantManager servantManager, POA rootPOA) {
        this.servantManager = servantManager;
        this.rootPOA = rootPOA;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Use the servant manager to create a new servant for the given ID
        Servant servant = servantManager.get_servant(id, rootPOA);
        return servant;
    }
}

14. Using a ServantLocator with a ServantRetentionPolicy

import org.omg.PortableServer.ServantLocatorPackage;

public class ServantRetentionPolicyServantLocator implements ServantLocatorPackage.ServantLocator {

    private ServantRetentionPolicy retentionPolicy;

    public ServantRetentionPolicyServantLocator(ServantRetentionPolicy retentionPolicy) {
        this.retentionPolicy = retentionPolicy;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Use the servant retention policy to determine how to handle the servant for the given ID
        Servant servant = retentionPolicy.get_servant(id);
        return servant;
    }
}

15. Using a ServantLocator with a ServantState

import org.omg.PortableServer.ServantLocatorPackage;

public class ServantStateServantLocator implements ServantLocatorPackage.ServantLocator {

    private ServantState state;

    public ServantStateServantLocator(ServantState state) {
        this.state = state;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Use the servant state to determine how to handle the servant for the given ID
        Servant servant = state.get_servant(id);
        return servant;
    }
}

16. Using a ServantLocator with a ServantTracker

import org.omg.PortableServer.ServantLocatorPackage;

public class ServantTrackerServantLocator implements ServantLocatorPackage.ServantLocator {

    private ServantTracker tracker;

    public ServantTrackerServantLocator(ServantTracker tracker) {
        this.tracker = tracker;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Use the servant tracker to determine how to handle the servant for the given ID
        Servant servant = tracker.get_servant(id);
        return servant;
    }
}

17. Using a ServantLocator with a ThreadPolicy

import org.omg.PortableServer.ServantLocatorPackage;

public class ThreadPolicyServantLocator implements ServantLocatorPackage.ServantLocator {

    private ThreadPolicy threadPolicy;

    public ThreadPolicyServantLocator(ThreadPolicy threadPolicy) {
        this.threadPolicy = threadPolicy;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Use the thread policy to determine how to handle the servant for the given ID
        Servant servant = threadPolicy.get_servant(id);
        return servant;
    }
}

18. Using a ServantLocator with an IDLType

import org.omg.PortableServer.ServantLocatorPackage;

public class IDLTypeServantLocator implements ServantLocatorPackage.ServantLocator {

    private IDLType type;

    public IDLTypeServantLocator(IDLType type) {
        this.type = type;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {
        // Use the IDL type to determine how to handle the servant for the given ID
        Servant servant = type.get_servant(id);
        return servant;
    }
}

19. Using a ServantLocator with a LifetimeControl

import org.omg.PortableServer.ServantLocatorPackage;

public class LifetimeControlServantLocator implements ServantLocatorPackage.ServantLocator {

    private LifetimeControl control;

    public LifetimeControlServantLocator(LifetimeControl control) {
        this.control = control;
    }

    @Override
    public Servant locate(ID id) throws ForwardRequest {