package org.mag;

@Entity
@IdClass(Magazine.MagazineId.class)
public class Magazine {

    @Id private String isbn;
    @Id private String title;
    @Version private int version;

    private double price;   // defaults to @Basic
    private int copiesSold; // defaults to @Basic

    @OneToOne(fetch=FetchType.LAZY,
        cascade={CascadeType.PERSIST,CascadeType.REMOVE})
    private Article coverArticle;

    @OneToMany(cascade={CascadeType.PERSIST,CascadeType.REMOVE})
    @OrderBy
    private Collection<Article> articles;

    @ManyToOne(fetch=FetchType.LAZY, cascade=CascadeType.PERSIST)
    private Company publisher;

    @Transient private byte[] data;

    ...

    public static class MagazineId {
        ...
    }
}

@Entity
public class Article {

    @Id private long id;
    @Version private int version;

    private String title;   // defaults to @Basic
    private byte[] content; // defaults to @Basic

    @ManyToMany(cascade=CascadeType.PERSIST)
    @OrderBy("lastName, firstName")
    private Collection<Author> authors;

    ...
}


package org.mag.pub;

@Entity
public class Company {

    @Id private long id;
    @Version private int version;

    private String name;     // defaults to @Basic
    private double revenue;  // defaults to @Basic
    private Address address; // defaults to @Embedded

    @OneToMany(mappedBy="publisher", cascade=CascadeType.PERSIST)
    private Collection<Magazine> mags;

    @OneToMany(cascade={CascadeType.PERSIST,CascadeType.REMOVE})
    private Collection<Subscription> subscriptions;

    ...
}

@Entity
public class Author {

    @Id private long id;
    @Version private int version;

    private String firstName; // defaults to @Basic
    private double lastName;  // defaults to @Basic
    private Address address;  // defaults to @Embedded

    @ManyToMany(mappedBy="authors", cascade=CascadeType.PERSIST)
    private Collection<Article> arts;

    ...
}

@Embeddable
public class Address {

    private String street; // defaults to @Basic
    private String city;   // defaults to @Basic
    private String state;  // defaults to @Basic
    private String zip;    // defaults to @Basic

    ...
}


package org.mag.subscribe;

@MappedSuperclass
public abstract class Document {

    @Id private long id;
    @Version private int version;

    ...
}

@Entity
public class Contract
    extends Document {

    private String terms; // defaults to @Basic

    ...
}

@Entity
public class Subscription {

    @Id private long id;
    @Version private int version;

    private Date startDate; // defaults to @Basic
    private double payment; // defaults to @Basic

    @OneToMany(cascade={CascadeType.PERSIST,CascadeType.REMOVE})
    @MapKey(name="num")
    private Map<Long,LineItem> lineItems;

    ...

    @Entity
    public static class LineItem
        extends Contract {

        private String comments; // defaults to @Basic
        private double price;    // defaults to @Basic
        private long num;        // defaults to @Basic

        @ManyToOne
        private Magazine magazine;

        ...
    }
}

@Entity(name="Lifetime")
public class LifetimeSubscription
    extends Subscription {

    @Basic(fetch=FetchType.LAZY)
    private boolean getEliteClub() { ... }
    public void setEliteClub(boolean elite) { ... }

    ...
}

@Entity(name="Trial")
public class TrialSubscription
    extends Subscription {

    public Date getEndDate() { ... }
    public void setEndDate(Date end) { ... }

    ...
}

The same metadata declarations in XML:

<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm orm_1_0.xsd"
    version="1.0">
    <!-- declares a default access type for all entities -->
    <access-type>FIELD</access-type>
    <mapped-superclass class="org.mag.subscribe.Document">
        <attributes>
            <id name="id">
                <generated-value strategy="IDENTITY"/>
            </id>
            <version name="version"/>
        </attributes>
    </mapped-superclass>
    <entity class="org.mag.Magazine">
        <id-class="org.mag.Magazine$MagazineId"/>
        <attributes>
            <id name="isbn"/>
            <id name="title"/>
            <basic name="name"/>
            <basic name="price"/>
            <basic name="copiesSold"/>
            <version name="version"/>
            <many-to-one name="publisher" fetch="LAZY">
                <cascade>
                    <cascade-persist/>
                </cascade>
            </many-to-one>
            <one-to-many name="articles">
                <order-by/>
                <cascade>
                    <cascade-persist/>
                    <cascade-remove/>
                </cascade>
            </one-to-many>
            <one-to-one name="coverArticle" fetch="LAZY">
                <cascade>
                    <cascade-persist/>
                    <cascade-remove/>
                </cascade>
            </one-to-one>
            <transient name="data"/>
        </attributes>
    </entity>
    <entity class="org.mag.Article">
        <attributes>
            <id name="id"/>
            <basic name="title"/>
            <basic name="content"/>
            <version name="version"/>
            <many-to-many name="articles">
                <order-by>lastName, firstName</order-by>
            </many-to-many>
        </attributes>
    </entity>
    <entity class="org.mag.pub.Company">
        <attributes>
            <id name="id"/>
            <basic name="name"/>
            <basic name="revenue"/>
            <version name="version"/>
            <one-to-many name="mags" mapped-by="publisher">
                <cascade>
                    <cascade-persist/>
                </cascade>
            </one-to-many>
            <one-to-many name="subscriptions">
                <cascade>
                    <cascade-persist/>
                    <cascade-remove/>
                </cascade>
            </one-to-many>
        </attributes>
    </entity>
    <entity class="org.mag.pub.Author">
        <attributes>
            <id name="id"/>
            <basic name="firstName"/>
            <basic name="lastName"/>
            <version name="version"/>
            <many-to-many name="arts" mapped-by="authors">
                <cascade>
                    <cascade-persist/>
                </cascade>
            </many-to-many>
        </attributes>
    </entity>
    <entity class="org.mag.subcribe.Contract">
        <attributes>
            <basic name="terms"/>
        </attributes>
    </entity>
    <entity class="org.mag.subcribe.Subscription">
        <attributes>
            <id name="id"/>
            <basic name="payment"/>
            <basic name="startDate"/>
            <version name="version"/>
            <one-to-many name="items">
                <map-key name="num">
                <cascade>
                    <cascade-persist/>
                    <cascade-remove/>
                </cascade>
            </one-to-many>
        </attributes>
    </entity>
    <entity class="org.mag.subscribe.Subscription.LineItem">
        <attributes>
            <basic name="comments"/>
            <basic name="price"/>
            <basic name="num"/>
            <many-to-one name="magazine"/>
        </attributes>
    </entity>
    <entity class="org.mag.subscribe.LifetimeSubscription" name="Lifetime"
        access="PROPERTY">
        <attributes>
            <basic name="eliteClub" fetch="LAZY"/>
        </attributes>
    </entity>
    <entity class="org.mag.subscribe.TrialSubscription" name="Trial">
        <attributes>
            <basic name="endDate"/>
        </attributes>
    </entity>
    <embeddable class="org.mag.pub.Address">
        <attributes>
            <basic name="street"/>
            <basic name="city"/>
            <basic name="state"/>
            <basic name="zip"/>
        </attributes>
    </embeddable>
</entity-mappings>