001    // Copyright 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.services.assets;
016    
017    import org.apache.tapestry5.ioc.Resource;
018    
019    import java.io.IOException;
020    import java.io.InputStream;
021    import java.io.OutputStream;
022    
023    /**
024     * An object, derived from a {@link Resource}, that can be streamed (ultimately, to a client web browser).
025     *
026     * @since 5.3
027     */
028    public interface StreamableResource
029    {
030        /**
031         * Describes the underlying {@link Resource} (or resources} for this streamble resource; expressly used
032         * as part of the object's {@code toString()}.
033         */
034        String getDescription();
035    
036        /**
037         * Indicates if the content is compressed, or compressable.
038         */
039        CompressionStatus getCompression();
040    
041        /**
042         * Returns the MIME content type, e.g., "image/jpeg".
043         */
044        String getContentType();
045    
046        /**
047         * The size, in bytes, of the underlying bytestream.
048         */
049        int getSize();
050    
051        /**
052         * Streams the resource's content to the provided stream. The caller is responsible for flushing or closing
053         * the output stream.
054         */
055        void streamTo(OutputStream os) throws IOException;
056    
057        /**
058         * Opens the content of the resource as an input stream; the caller is responsible for closing the stream
059         * after reading it.
060         *
061         * @return stream of the contents of the resource
062         * @throws IOException
063         */
064        InputStream openStream() throws IOException;
065    
066        /**
067         * Returns the time the resource was last modified, with accuracy to one second (so as to match
068         * the HTTP request/response date headers.
069         */
070        long getLastModified();
071    }