content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.ambari.spi.upgrade;
  
  import java.util.List;
  import java.util.Set;
  
  import org.apache.ambari.annotations.UpgradeCheckInfo;
  import org.apache.ambari.server.AmbariException;
  
  /**
   * The {@link UpgradeCheck} is used before an upgrade in order to present the
   * administrator with a warning or a failure about an upgrade. All
   * implementations of this class should used the {@link UpgradeCheckInfo}
   * annotation to specify information about the check, such as its associated
   * upgrade type(s) and ordering.
   */
  public interface UpgradeCheck {
  
    /**
     * Gets the set of services that this check is associated with. If the check
     * is not associated with a particular service, then this should be an empty
     * set.
     *
     * @return a set of services which will determine whether this check is
     *         applicable, or an empty set.
     */
    Set<String> getApplicableServices();
  
    /**
     * Gets any additional qualifications which an upgrade check should run in
     * order to determine if it's applicable to the upgrade.
     *
     * @return a list of qualifications, or an empty list.
     */
    List<CheckQualification> getQualifications();
  
    /**
     * Executes check against given cluster.
     * @param request pre upgrade check request
     * @return TODO
     *
     * @throws AmbariException if server error happens
     */
    UpgradeCheckResult perform(UpgradeCheckRequest request)
        throws AmbariException;
  
    /**
     * The {@link UpgradeCheckDescription} which includes the name, description, and
     * success/failure messages for a {@link UpgradeCheck}.
     *
     * @return the check description.
     */
    UpgradeCheckDescription getCheckDescription();
  }