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package oracle.toplink.essentials.indirection;


/**
 * <b>Purpose</b>:
 * Define an interface for a Container that can also act as a TopLink
 * "indirection" object; i.e. the Container will only read its contents from
 * the database when necessary (typically, on receipt of the first
 * Container-related message).
 * <p>
 *
 * @see oracle.toplink.essentials.internal.indirection.TransparentIndirectionPolicy
 * @author Big Country
 * @since TOPLink/Java 2.5
 */
public interface IndirectContainer {

    /**
     * PUBLIC:
     * This is used by the indirection policy to build the
     * UOW clone of the container.
     * @return oracle.toplink.essentials.indirection.ValueHolderInterface A representation of the valueholder  * which this container uses
     */
    public ValueHolderInterface getValueHolder();

    /**
     * PUBLIC:
     * Return whether the contents have been read from the database.
     * This is used periodically by the indirection policy to determine whether
     * to trigger the database read.
     */
    public boolean isInstantiated();

    /**
     * PUBLIC:
     * Set the valueHolder.
     * This is used by the indirection policy to build the
     * UOW clone of the container.
     */
    public void setValueHolder(ValueHolderInterface valueHolder);
}