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019package org.apache.james.mailbox.jpa.migrator.command;
020
021import javax.persistence.EntityManager;
022
023import org.apache.james.mailbox.jpa.migrator.exception.JpaMigrateException;
024
025/**
026 * A command that apply to James database the needed updates.
027 */
028public interface JpaMigrateCommand {
029    
030    /**
031     * Executes the needed SQL commands on the database via the provided JPA entity manager.
032     * A transaction on the provided entity manager must be begun by the caller.
033     * It is also the reponsibility of the caller to commit the opened transaction after
034     * calling the migrate method.
035     * 
036     * @param em the provided Entity Manager
037     * @throws JpaMigrateException
038     */
039    void migrate(EntityManager em) throws JpaMigrateException;
040
041}