1 /**
2 * This file Copyright (c) 2010-2015 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.dam.api;
35
36 import info.magnolia.dam.api.metadata.AssetMetadata;
37
38 import com.google.common.net.MediaType;
39 import java.util.Iterator;
40
41 /**
42 * An AssetProvider exposes {@link Folder}s and {@link Asset}s from a particular source.
43 * Specifics of the storage of these items are left to implementations.
44 *
45 * While most provider implementations will only use the {@link ItemKey#assetId} field of keys passed to the various
46 * get methods, the entire key object is passed for consistency and flexibility, making it possible to implement
47 * delegating/aggregating providers, for example.
48 */
49 public interface AssetProvider {
50
51 /**
52 * Return the AssetProvider identifier.
53 */
54 String getIdentifier();
55
56 /**
57 * Returns true if the provider supports the given {@link AssetProviderCapability}.
58 */
59 boolean supports(AssetProviderCapability capability);
60
61 /**
62 * Whether this provider supports the given {@link AssetMetadata} type.
63 */
64 boolean supports(Class<? extends AssetMetadata> metaData);
65
66 /**
67 * Whether this provider provides or allows the given MediaType.
68 * Some providers can be configured to only be used for a given set or subset of types.
69 */
70 boolean provides(MediaType mediaType);
71
72 /**
73 * Cast-less convenience method for {@link #getItem(ItemKey)}.
74 *
75 * @throws IllegalArgumentException if the key does not correspond to an Item of the Asset type.
76 */
77 Asset getAsset(ItemKey assetKey) throws AssetNotFoundException, IllegalItemKeyException;
78
79 /**
80 * Cast-less convenience method for {@link #getItem(ItemKey)}.
81 *
82 * @throws IllegalArgumentException if the key does not correspond to an Item of the Folder type.
83 */
84 Folder getFolder(ItemKey folderKey) throws AssetNotFoundException, IllegalItemKeyException;
85
86 /**
87 * Returns the item associated with the given {@link ItemKey}, regardless of its type.
88 *
89 * @throws IllegalArgumentException if the key does not correspond to an Item of the Folder or Asset type.
90 */
91 Item getItem(ItemKey itemKey) throws AssetNotFoundException, IllegalItemKeyException;
92
93 /**
94 * The top-most folder available from this AssetProvider. See notes at {@link Folder#isRoot()}.
95 */
96 Folder getRootFolder();
97
98 /**
99 * Returns an iterator over the results matching the given {@link AssetQuery}. Depending on the
100 * specific values of the {@link AssetQuery} and the {@link AssetProvider} implementation,
101 * this might list direct children, execute a query, ...
102 * It is up to the provider to validate the query - some combinations of criteria might not be supported by all
103 * providers.
104 * @see AssetProviderCapability
105 */
106 Iterator<Item> list(AssetQuery assetQuery);
107
108 /**
109 * Returns an appropriate {@link AssetRenderer} if this provider has specific renderers, or null if there is none.
110 * @see {@link AssetProviderRegistry#getRendererFor(Asset, com.google.common.net.MediaType)}, which is what client
111 * code should be using rather than this method here.
112 * TODO: overdoing it if we move this to abstract to hide it from client code ?
113 */
114 AssetRenderer getRendererFor(Asset asset, MediaType to);
115
116 /**
117 * Thrown when the given ItemKey can't be found.
118 */
119 static class AssetNotFoundException extends DamException {
120 public AssetNotFoundException(ItemKey itemKey) {
121 super("No Asset found for ItemKey <" + itemKey + ">");
122 }
123 }
124
125 /**
126 * Thrown when the given ItemKey isn't usable by the provider.
127 * Possible reasons are this ItemKey isn't mean for this provider, or points to an Asset outside the realm of this
128 * provider (if the provider has a "root path", for example).
129 */
130 static class IllegalItemKeyException extends DamException {
131 public IllegalItemKeyException(ItemKey itemKey, AssetProvider provider, String reason) {
132 super("ItemKey <" + itemKey + "> can not be handled by " + provider + " : " + reason);
133 }
134 }
135 }