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 */
019package org.apache.wiki.attachment;
020
021import java.io.IOException;
022import java.io.InputStream;
023
024import org.apache.wiki.WikiContext;
025import 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 */
037public 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}