/**
 * A general interface for data objects that have some Stream-based file content. These objects may
 * be files on filesystems, web files received through http or emails stored in an email server.
 * All methods of DataObject are inherited. Additional is the <b>binary content</b> and the 
 * handling of the stream. For the extraction, both the InputStream 
 * returned by getContent() and
 * the RDF metadata returned by getMetadata() are important.
 */
public interface DataObjectFile extends DataObject {

        /**
         * Returns the byte size of the represented resource. This has been defined at
         * this global level due to the importance of this attribute for performance reasons.
         * @return the size of the binary resource in bytes, or a negative value when the
         * size is unknown or does not make sense for this particular DataObject implementation.
         */
        public long getSize();
     
        /**
         * Gets an InputStream containing the content represented by the DataObject.
         * The returned InputStream is required to support marking (markSupported()
         * returns true). Calling this method multiple times may references to
         * one-and-the-same InputStream instance. Care should therefore be taken to mark
         * and reset the stream when the stream's content is to be read again later.
         * 
         * @return An InputStream from which the content of the data object can be read.
         * @throws IOException If an I/O error occurred.
         */
        public InputStream getContent() throws IOException;

        /**
         * Instructs the DataObject that its content stream will most likely be used multiple
         * times in its entirety, making the mark-and-reset procedure difficult to work, 
         * and that it better should cache the entire contents.
         * @throws IOException when an IOException occured during caching of the content.
         */
 ´      public void cacheContent() throws IOException;
    
        /**
         * what is the mime-type of the content, if there is content?
         * This is set by the DataAccessor
         * @return null or a mimetype identifier like "text/plain"
         */
        public String getContentMimeType();

        /**
         * what is the character-encoding (using ansi identifiers like "UTF-8"
         * or "ISO-8859-1") of the content, if there is content. Will 
         * return null if not known or if content is null.
         * This is set by the DataAccessor
         * @return null or a encoding identifier like "UTF-8"
         */
        public String getContentEncoding();
}