--- /dev/null
+<?php
+// Own namespace
+namespace Org\Mxchange\CoreFramework\Filesystem\File;
+
+// Import framework stuff
+use Org\Mxchange\CoreFramework\Filesystem\Filesystem;
+
+/**
+ * A virtual file system interface
+ *
+ * @author Roland Haeder <webmaster@ship-simu.org>
+ * @version 0.0.0
+ * @copyright Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2020 Core Developer Team
+ * @license GNU GPL 3.0 or any newer version
+ * @link http://www.ship-simu.org
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+interface BinaryFile extends Filesystem {
+ /**
+ * Reads the file header
+ *
+ * @return void
+ */
+ function readFileHeader ();
+
+ /**
+ * Flushes the file header
+ *
+ * @return void
+ */
+ function flushFileHeader ();
+
+ /**
+ * Determines whether the EOF has been reached
+ *
+ * @return $isEndOfFileReached Whether the EOF has been reached
+ */
+ function isEndOfFileReached ();
+
+ /**
+ * Getter for header size
+ *
+ * @return $totalEntries Size of file header
+ */
+ function getHeaderSize ();
+
+ /**
+ * Setter for header size
+ *
+ * @param $headerSize Size of file header
+ * @return void
+ */
+ function setHeaderSize (int $headerSize);
+
+ /**
+ * Getter for header array
+ *
+ * @return $totalEntries Size of file header
+ */
+ function getHeader ();
+
+ /**
+ * Setter for header
+ *
+ * @param $header Array for a file header
+ * @return void
+ */
+ function setHeader (array $header);
+
+ /**
+ * Initializes counter for valid entries, arrays for damaged entries and
+ * an array for gap seek positions. If you call this method on your own,
+ * please re-analyze the file structure. So you are better to call
+ * analyzeFileStructure() instead of this method.
+ *
+ * @return void
+ */
+ function initCountersGapsArray ();
+
+ /**
+ * Updates seekPosition attribute from file to avoid to much access on file.
+ *
+ * @return void
+ */
+ function updateSeekPosition ();
+
+ /**
+ * Getter for total entries
+ *
+ * @return $totalEntries Total entries in this file
+ */
+ function getCounter ();
+
+ /**
+ * "Getter" for file size
+ *
+ * @return $fileSize Size of currently loaded file
+ */
+ function getFileSize ();
+
+ /**
+ * Searches for next suitable gap the given length of data can fit in
+ * including padding bytes.
+ *
+ * @param $length Length of raw data
+ * @return $seekPosition Found next gap's seek position
+ */
+ function searchNextGap (int $length);
+
+ /**
+ * Writes given value to the file and returns a hash and gap position for it
+ *
+ * @param $groupId Group identifier
+ * @param $value Value to be added to the stack
+ * @return $data Hash and gap position
+ */
+ function writeValueToFile (string $groupId, string $rawData);
+
+ /**
+ * Writes given raw data to the file and returns a gap position and length
+ *
+ * @param $groupId Group identifier
+ * @param $hash Hash from encoded value
+ * @param $encoded Encoded value to be written to the file
+ * @return $data Gap position and length of the raw data
+ */
+ function writeDataToFreeGap (string $groupId, string $hash, string $encoded);
+
+ /**
+ * Writes data at given position
+ *
+ * @param $seekPosition Seek position
+ * @param $data Data to be written
+ * @param $flushHeader Whether to flush the header (default: flush)
+ * @return void
+ */
+ function writeData (int $seekPosition, string $data, bool $flushHeader = true);
+
+ /**
+ * Writes at given position by seeking to it.
+ *
+ * @param $seekPosition Seek position in file
+ * @param $dataStream Data to be written
+ * @return mixed Number of writes bytes or false on error
+ * @throws InvalidArgumentException If a parameter is not valid
+ */
+ function writeAtPosition (int $seekPosition, string $dataStream);
+
+}