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package org.apache.james.imap.jpa.migrator.command;

import javax.persistence.EntityManager;

import org.apache.james.imap.jpa.migrator.exception.JpaMigrateException;

/**
 * A command that apply to James database the needed updates.
 */
public interface JpaMigrateCommand {
    
    /**
     * Executes the needed SQL commands on the database via the provided JPA entity manager.
     * A transaction on the provided entity manager must be begun by the caller.
     * It is also the reponsibility of the caller to commit the opened transaction after
     * calling the migrate method.
     * 
     * @param em the provided Entity Manager
     * @throws JpaMigrateException
     */
    void migrate(EntityManager em) throws JpaMigrateException;

}
