EJB und Services

package at.aydin.lab.ejb.legacy;

import javax.ejb.*;
import java.rmi.RemoteException;

public interface OrderHome extends EJBHome {
    OrderRemote create() throws CreateException, RemoteException;
}

package at.aydin.lab.ejb.legacy;

import javax.ejb.EJBObject;
import java.rmi.RemoteException;

// Design Pattern: Remote Facade
// Zweck: Grobgranulare Remote-Schnittstelle reduziert verteilte Einzelaufrufe.
public interface OrderRemote extends EJBObject {
    String placeOrder(String sku, int quantity) throws RemoteException;
}

package at.aydin.lab.ejb.modern;

import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/orders")
public class OrderController {
    private final OrderService service;
    public OrderController(OrderService service) {
        this.service = service;
    }

    @PostMapping
    public String order(@RequestParam String sku, @RequestParam int quantity) {
        return service.placeOrder(sku, quantity);
    }
}

package at.aydin.lab.ejb.legacy;

import javax.ejb.*;

// Design Pattern: Session Facade
// Zweck: Bündelt fachlichen Bestellablauf in einer serverseitigen Session-Komponente.
public class OrderSessionBean implements SessionBean {
    public String placeOrder(String sku, int quantity) {
        return "ORDERED " + quantity + " x " + sku;
    }

    public void ejbCreate() {
    }

    public void ejbActivate() {
    }

    public void ejbPassivate() {
    }

    public void ejbRemove() {
    }

    public void setSessionContext(SessionContext context) {
    }
}

package at.aydin.lab.ejb.modern;

import org.springframework.stereotype.Service;

// Design Pattern: Service Layer
// Zweck: Fachlogik ist containerleicht, lokal testbar und nicht an RemoteObject gebunden.
@Service
public class OrderService {
    public String placeOrder(String sku, int quantity) {
        if (quantity <= 0) throw new IllegalArgumentException("quantity");
        return "ORDERED " + quantity + " x " + sku;
    }
}

package at.aydin.lab.ejb.legacy;

import javax.ejb.*;

// Design Pattern: Session Facade
// Zweck: Bündelt fachlichen Bestellablauf in einer serverseitigen Session-Komponente.
public class OrderSessionBean implements SessionBean {
    public String placeOrder(String sku, int quantity) {
        return "ORDERED " + quantity + " x " + sku;
    }

    public void ejbCreate() {
    }

    public void ejbActivate() {
    }

    public void ejbPassivate() {
    }

    public void ejbRemove() {
    }

    public void setSessionContext(SessionContext context) {
    }
}

package at.aydin.lab.ejb.modern;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class OrderApplication {
    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }
}