/*

  * 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.shiro.mgt;

 import org.apache.shiro.subject.Subject;

 /**

  * A {@code SubjectDAO} is responsible for persisting a Subject instance's internal state such that the Subject instance

  * can be recreated at a later time if necessary.

  * <p/>

  * Shiro's default {@code SecurityManager} implementations typically use a {@code SubjectDAO} in conjunction

  * with a {@link SubjectFactory}: after the {@code SubjectFactory} creates a {@code Subject} instance, the

  * {@code SubjectDAO} is used to persist that subject's state such that it can be accessed later if necessary.

  * <h3>Usage</h3>

  * It should be noted that this component is used by {@code SecurityManager} implementations to manage Subject

  * state persistence.  It does <em>not</em> make Subject instances accessible to the

  * application (e.g. via {@link org.apache.shiro.SecurityUtils#getSubject() SecurityUtils.getSubject()}).

  *

  * @see DefaultSubjectDAO

  * @since 1.2

  */

 public interface SubjectDAO {

     /**

      * Persists the specified Subject's state for later access.  If there is a no existing state persisted, this

      * persists it if possible (i.e. a create operation).  If there is existing state for the specified {@code Subject},

      * this method updates the existing state to reflect the current state (i.e. an update operation).

      *

      * @param subject the Subject instance for which its state will be created or updated.

      * @return the Subject instance to use after persistence is complete.  This can be the same as the method argument

      * if the underlying implementation does not need to make any Subject changes.

      */

     Subject save(Subject subject);

     /**

      * Removes any persisted state for the specified {@code Subject} instance.  This is a delete operation such that

      * the Subject's state will not be accessible at a later time.

      *

      * @param subject the Subject instance for which any persistent state should be deleted.

      */

     void delete(Subject subject);

 }