Moving to root below branch label

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@2005 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/content/ContentStore.java

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+/*
+ * Copyright (C) 2005 Alfresco, Inc.
+ *
+ * Licensed under the Mozilla Public License version 1.1 
+ * with a permitted attribution clause. You may obtain a
+ * copy of the License at
+ *
+ *   http://www.alfresco.org/legal/license.txt
+ *
+ * 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.alfresco.repo.content;
+
+import java.util.Set;
+
+import org.alfresco.service.cmr.repository.ContentIOException;
+import org.alfresco.service.cmr.repository.ContentReader;
+import org.alfresco.service.cmr.repository.ContentStreamListener;
+import org.alfresco.service.cmr.repository.ContentWriter;
+
+/**
+ * Provides low-level retrieval of content
+ * {@link org.alfresco.service.cmr.repository.ContentReader readers} and
+ * {@link org.alfresco.service.cmr.repository.ContentWriter writers}.
+ * <p>
+ * Implementations of this interface should be soley responsible for
+ * providing persistence and retrieval of the content against a
+ * <code>content URL</code>.
+ * <p>
+ * The URL format is <b>store://year/month/day/GUID.bin</b> <br>
+ * <ul>
+ *   <li> <b>store://</b>: prefix identifying an Alfresco content stores
+ *                         regardless of the persistence mechanism. </li>
+ *   <li> <b>year</b>: year </li>
+ *   <li> <b>month</b>: 1-based month of the year </li>
+ *   <li> <b>day</b>: 1-based day of the month </li>
+ *   <li> <b>GUID</b>: A unique identifier </li>
+ * </ul>
+ * The old <b>file://</b> prefix must still be supported - and functionality
+ * around this can be found in the {@link org.alfresco.repo.content.AbstractContentStore}
+ * implementation.
+ * 
+ * @author Derek Hulley
+ */
+public interface ContentStore
+{
+    /** <b>store://</b> is the new prefix for all content URLs */
+    public static final String STORE_PROTOCOL = "store://";
+    
+    /**
+     * Check for the existence of content in the store.
+     * <p>
+     * The implementation of this may be more efficient than first getting a
+     * reader to {@link ContentReader#exists() check for existence}, although
+     * that check should also be performed.
+     * 
+     * @param contentUrl the path to the content
+     * @return Returns true if the content exists.
+     * @throws ContentIOException
+     * 
+     * @see ContentReader#exists()
+     */
+    public boolean exists(String contentUrl) throws ContentIOException;
+    
+    /**
+     * Get the accessor with which to read from the content
+     * at the given URL.  The reader is <b>stateful</b> and
+     * can <b>only be used once</b>.
+     * 
+     * @param contentUrl the path to where the content is located
+     * @return Returns a read-only content accessor for the given URL.  There may
+     *      be no content at the given URL, but the reader must still be returned.
+     *      The reader may implement the {@link RandomAccessContent random access interface}.
+     * @throws ContentIOException
+     *
+     * @see #exists(String)
+     * @see ContentReader#exists()
+     */
+    public ContentReader getReader(String contentUrl) throws ContentIOException;
+    
+    /**
+     * Get an accessor with which to write content to a location
+     * within the store.  The writer is <b>stateful</b> and can
+     * <b>only be used once</b>.  The location may be specified but must, in that case,
+     * be a valid and unused URL.
+     * <p>
+     * By supplying a reader to existing content, the store implementation may
+     * enable {@link RandomAccessContent random access}.  The store implementation
+     * can enable this by copying the existing content into the new location
+     * before supplying a writer onto the new content.
+     * 
+     * @param existingContentReader a reader onto any existing content for which
+     *      a writer is required - may be null
+     * @param newContentUrl an unused, valid URL to use - may be null.
+     * @return Returns a write-only content accessor, possibly implementing
+     *      the {@link RandomAccessContent random access interface}
+     * @throws ContentIOException if completely new content storage could not be
+     *      created
+     *
+     * @see ContentWriter#addListener(ContentStreamListener)
+     * @see ContentWriter#getContentUrl()
+     */
+    public ContentWriter getWriter(ContentReader existingContentReader, String newContentUrl) throws ContentIOException;
+
+    /**
+     * Get a set of all content in the store
+     * 
+     * @return Returns a complete set of the unique URLs of all available content
+     *      in the store
+     * @throws ContentIOException
+     */
+    public Set<String> getUrls() throws ContentIOException;
+    
+    /**
+     * Deletes the content at the given URL.
+     * <p>
+     * A delete cannot be forced since it is much better to have the
+     * file remain longer than desired rather than deleted prematurely.
+     * The store implementation should safeguard files for certain
+     * minimum period, in which case all files younger than a certain
+     * age will not be deleted.
+     * 
+     * @param contentUrl the URL of the content to delete
+     * @return Return true if the content was deleted (either by this or
+     *      another operation), otherwise false
+     * @throws ContentIOException
+     */
+    public boolean delete(String contentUrl) throws ContentIOException;
+}