001/*
002 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
003 *
004 * Project and contact information: http://www.cascading.org/
005 *
006 * This file is part of the Cascading project.
007 *
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *     http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020
021package cascading.management.annotation;
022
023import java.lang.annotation.ElementType;
024import java.lang.annotation.Retention;
025import java.lang.annotation.RetentionPolicy;
026import java.lang.annotation.Target;
027
028/**
029 * Property annotations can be used to send additional information about certain aspects of Cascading classes
030 * to the {@link cascading.management.DocumentService}.  The properties are present at runtime and allow a
031 * DocumentService to inspect, process or persist them.
032 * <p/>
033 * Property annotations can be applied to {@link cascading.tap.Tap}s, {@link cascading.scheme.Scheme}s,
034 * and any {@link cascading.operation.Operation} sub-classes (like Function or Aggregator).
035 * <p/>
036 * Property annotations can be applied to any method or field members, so that they can be accessed via
037 * java.lang.Class#getMethods() and java.lang.Class.getFields() respectively. If the member is protected/private,
038 * there will be an attempt to bypass the protected/private scope to retrieve the value.
039 * <p/>
040 * By default the {@link Visibility} is {@link Visibility#PUBLIC}, and optionality is {@code true}.
041 */
042@Retention(RetentionPolicy.RUNTIME)
043@Target({ElementType.METHOD, ElementType.FIELD})
044public @interface Property
045  {
046  /**
047   * The display name for the property value. Does not need to match the bean property or field name.
048   *
049   * @return the display name
050   */
051  String name();
052
053  /**
054   * The display visibility, see {@link Visibility}.
055   *
056   * @return the display visibility
057   */
058  Visibility visibility() default Visibility.PUBLIC;
059
060  /**
061   * Whether the field name and null should be displayed if the value is {@code null}.
062   * <p/>
063   * When {@code true}, no data (field name, visibility, and the {@code null} value are sent to the display. The property
064   * is ignored.
065   *
066   * @return whether the field should be displayed if {@code null}
067   */
068  boolean optional() default true;
069  }