001    /*
002        Licensed to the Apache Software Foundation (ASF) under one
003        or more contributor license agreements.  See the NOTICE file
004        distributed with this work for additional information
005        regarding copyright ownership.  The ASF licenses this file
006        to you under the Apache License, Version 2.0 (the
007        "License"); you may not use this file except in compliance
008        with the License.  You may obtain a copy of the License at
009    
010           http://www.apache.org/licenses/LICENSE-2.0
011    
012        Unless required by applicable law or agreed to in writing,
013        software distributed under the License is distributed on an
014        "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015        KIND, either express or implied.  See the License for the
016        specific language governing permissions and limitations
017        under the License.     
018     */
019    package org.apache.wiki.attachment;
020    
021    import java.io.IOException;
022    import java.io.InputStream;
023    
024    import org.apache.wiki.WikiContext;
025    import org.apache.wiki.api.exceptions.ProviderException;
026    
027    /**
028     *  Provides the data for an attachment.  Please note that there will
029     *  be a strong reference retained for the provider for each Attachment
030     *  it provides, so do try to keep the object light.  Also, reuse objects
031     *  if possible.
032     *  <p>
033     *  The Provider needs to be thread-safe.
034     *
035     *  @since  2.5.34
036     */
037    public interface DynamicAttachmentProvider
038    {
039        /**
040         *  Returns a stream of data for this attachment.  The stream will be
041         *  closed by AttachmentServlet.
042         *
043         *  @param context A Wiki Context
044         *  @param att The Attachment for which the data should be received.
045         *  @return InputStream for the data.
046         *  @throws ProviderException If something goes wrong internally
047         *  @throws IOException If something goes wrong when reading the data
048         */
049        InputStream getAttachmentData( WikiContext context, Attachment att )
050            throws ProviderException, IOException;
051    }