diff --git a/dist/files_opds-0.5.tar.gz b/dist/files_opds-0.5.tar.gz
new file mode 100644
index 0000000..dda5260
Binary files /dev/null and b/dist/files_opds-0.5.tar.gz differ
diff --git a/files_opds/admin.php b/files_opds/admin.php
index 575d9a2..8242395 100644
--- a/files_opds/admin.php
+++ b/files_opds/admin.php
@@ -25,6 +25,7 @@ $formats = array(
 
 $tmpl = new \OCP\Template('files_opds', 'admin');
 $tmpl->assign('feedSubtitle', Config::getApp('feed-subtitle', $l->t("%s OPDS catalog", $defaults->getName())));
+$tmpl->assign('isbndbKey', Config::getApp('isbndb-key', ''));
 $tmpl->assign('previewFormats', $formats);
 $tmpl->assign('cover-x', Config::getApp('cover-x', '200'));
 $tmpl->assign('cover-y', Config::getApp('cover-y', '200'));
diff --git a/files_opds/ajax/admin.php b/files_opds/ajax/admin.php
index 370fe2a..91d8a48 100644
--- a/files_opds/ajax/admin.php
+++ b/files_opds/ajax/admin.php
@@ -25,12 +25,14 @@ if (isset($_POST['opdsCoverX'])) {
 	$opdsThumbX = isset($_POST['opdsThumbX']) ? (int) $_POST['opdsThumbX'] : 36;
 	$opdsThumbY = isset($_POST['opdsThumbY']) ? (int) $_POST['opdsThumbY'] : 36;
 	$opdsFeedSubtitle = isset($_POST['opdsFeedSubtitle']) ? $_POST['opdsFeedSubtitle'] : $l->t("%s OPDS catalog", $defaults->getName());
+	$opdsIsbndbKey = isset($_POST['opdsIsbndbKey']) ? $_POST['opdsIsbndbKey'] : '';
 
 	Config::setApp('cover-x', $opdsCoverX);
 	Config::setApp('cover-y', $opdsCoverY);
 	Config::setApp('thumb-x', $opdsThumbX);
 	Config::setApp('thumb-y', $opdsThumbX);
 	Config::setApp('feed_subtitle', $opdsFeedSubtitle);
+	Config::setApp('isbndb-key', $opdsIsbndbKey);
 } else {
 	// set preview preferences
 	$opdsPreviewEpub = $_POST['opdsPreviewEpub'];
diff --git a/files_opds/appinfo/database.xml b/files_opds/appinfo/database.xml
index fda2e97..c689103 100644
--- a/files_opds/appinfo/database.xml
+++ b/files_opds/appinfo/database.xml
@@ -12,8 +12,8 @@
 				<!-- file ID, maps to OC file ID -->
 				<name>id</name>
 				<type>integer</type>
-				<default>0</default>
 				<notnull>true</notnull>
+				<primary>true</primary>
 				<length>11</length>
 			</field>
 
@@ -105,6 +105,22 @@
 				<notnull>true</notnull>
 				<length>1024</length>
 			</field>
+
+			<field>
+				<!-- rescan (rescan if passed) -->
+				<name>rescan</name>
+				<type>timestamp</type>
+				<default></default>
+				<notnull>false</notnull>
+			</field>
+
+			<index>
+				<name>opds_metadata_id_index</name>
+				<field>
+					<name>id</name>
+				</field>
+			</index>
+
 		</declaration>
 	</table>
 </database>	
diff --git a/files_opds/appinfo/info.xml b/files_opds/appinfo/info.xml
index 1613baf..f1f0524 100644
--- a/files_opds/appinfo/info.xml
+++ b/files_opds/appinfo/info.xml
@@ -4,11 +4,20 @@
         <name>OPDS catalog</name>
         <description>Personal OPDS catalog</description>
         <licence>AGPL</licence>
-	<version>0.4</version>
+	<version>0.5</version>
         <author>Frank de Lange</author>
         <requiremin>7.0</requiremin>
         <shipped>true</shipped>
         <default_enable/>
+        <repository type="git">https://github.com/Yetangitu/owncloud-apps</repository>
+        <bugs>https://github.com/Yetangitu/owncloud-apps/issues</bugs>
+        <homepage>https://github.com/Yetangitu/owncloud-apps</homepage>
+        <dependencies>
+            <php min-version="5.4" />
+            <database>pgsql</database>
+            <database>sqlite3</database>
+            <database>mysql</database>
+        </dependencies>
 	<ocsid>168132</ocsid>
 </info>
 
diff --git a/files_opds/js/admin.js b/files_opds/js/admin.js
index 598ce9f..dd95ca7 100644
--- a/files_opds/js/admin.js
+++ b/files_opds/js/admin.js
@@ -27,7 +27,8 @@ $(document).ready(function(){
                                 opdsCoverY : $('#opds-cover-y').val(),
                                 opdsThumbX : $('#opds-thumb-x').val(),
                                 opdsThumbY : $('#opds-thumb-y').val(),
-				opdsFeedSubtitle : $('#opds-feed-subtitle').val()
+				opdsFeedSubtitle : $('#opds-feed-subtitle').val(),
+				opdsIsbndbKey : $('#opds-isbndb-key').val()
                         };
                         OC.msg.startSaving('#opds-admin .msg');
                         $.post(OC.filePath('files_opds', 'ajax', 'admin.php'), data, opdsAdminCoverSettings.afterSave);
@@ -42,8 +43,8 @@ $(document).ready(function(){
         $('#opds-preview-opendocument').on("change", opdsAdminSettings.save);
         $('#opds-preview-msoffice').on("change", opdsAdminSettings.save);
 
-        $('#opds-cover-x,#opds-cover-y,#opds-thumb-x,#opds-thumb-y,#opds-feed-subtitle').blur(opdsAdminCoverSettings.save);
-        $('#opds-cover-x,#opds-cover-y,#opds-thumb-x,#opds-thumb-y,#opds-feed-subtitle').keypress(function( event ) {
+        $('#opds-cover-x,#opds-cover-y,#opds-thumb-x,#opds-thumb-y,#opds-feed-subtitle,#opds-isbndb-key').blur(opdsAdminCoverSettings.save);
+        $('#opds-cover-x,#opds-cover-y,#opds-thumb-x,#opds-thumb-y,#opds-feed-subtitle,#opds-isbndb-key').keypress(function( event ) {
                                                 if (event.which == 13) {
                                                   event.preventDefault();
                                                   opdsAdminCoverSettings.save();
diff --git a/files_opds/lib/google.php b/files_opds/lib/google.php
new file mode 100644
index 0000000..4de70ea
--- /dev/null
+++ b/files_opds/lib/google.php
@@ -0,0 +1,92 @@
+<?php
+
+/**
+ * ownCloud - Files_Opds App
+ *
+ * @author Frank de Lange
+ * @copyright 2014 Frank de Lange
+ *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ */
+
+namespace OCA\Files_Opds;
+
+/**
+ * Google class for OPDS
+ */
+class Google
+{
+        /**
+         * @brief get ISBN data for $isbn at Google (books)
+         *
+         * @param string $isbn ISBN to search for
+         * @param arrayref &$meta
+         * @return int $status (0 on success, ERRORCODE otherwise)
+         */
+        public static function get($isbn,&$meta) {
+                $command = 'https://www.googleapis.com/books/v1/volumes?q=isbn:' . $isbn;
+                $data = json_decode(file_get_contents($command),true);
+                if($data['totalItems'] > 0) {
+			self::parse($isbn,$meta);
+                        return true;
+                } else {
+			$meta['rescan'] = date("Y-m-d\TH:i:sP", time() + Isbn::RESCAN_NOT_FOUND);
+		}
+
+                return false;
+        }
+
+        /**
+         * @brief parse Google response into OPDS $meta array
+         *
+         * @param array $data Google response (json_decoded into array)
+         * @param arrayref &$meta OPDS metadata array
+         * @return int errorcode (0 if success)
+         */
+        static function parse($data,&$meta) {
+                foreach ($data as $key => $value) {
+                        switch ($key) {
+                                case 'description':
+                                        $meta['description'] = $value;
+                                        if(array_key_exists('notes',$data)) {
+                                                $meta['description'] .= ((trim($value) == false) ? '' : "\n\n") . $data['notes'];
+                                        }
+                                        break;
+                                case 'subject_ids':
+                                        $meta['subjects'] = json_encode($value);
+                                        break;
+				/* rather pointless, ISBN is what brought us here in the first place and is alread set
+                                case 'industryIdentifiers':
+					foreach($value as $array) {
+						if ($array['type'] = 'ISBN_13') {
+							$isbn13 = $array['identifier'];
+						} elseif ($array['type'] = 'ISBN_10') {
+							$isbn10 = $array['identifier'];
+						}
+					}
+							
+                                        $meta['isbn'] = (isset($isbn13)) ? $isbn13 : $isbn10;
+                                        break;
+				*/
+                                case 'title':
+                                        $meta['title'] = $value;
+                                        break;
+                                case 'authors':
+                                        $meta['author'] = json_encode($value);
+                                        break;
+                                case 'language':
+                                        $meta['language'] = $value;
+                                        break;
+                                case 'publisher':
+                                        $meta['publisher'] = $value;
+                                        break;
+				case 'publishedDate':
+					$meta['date'] = $value;
+					break;
+                        }
+                }
+
+                return true;
+        }
+}
diff --git a/files_opds/lib/isbn.php b/files_opds/lib/isbn.php
new file mode 100644
index 0000000..b2a3e25
--- /dev/null
+++ b/files_opds/lib/isbn.php
@@ -0,0 +1,154 @@
+<?php
+
+/**
+ * ownCloud - Files_Opds App
+ *
+ * @author Frank de Lange
+ * @copyright 2014 Frank de Lange
+ *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ */
+
+namespace OCA\Files_Opds;
+
+/**
+ * ISBN class for OPDS
+ */
+class Isbn
+{
+	const SUCCESS = 0;
+	const REQUEST_LIMIT_EXCEEDED = -1;
+	const NOT_FOUND = -2;
+	const ERROR = -3;
+	const RESCAN_LIMIT_EXCEEDED = 86400;
+	const RESCAN_NOT_FOUND = 604800;
+	const RESCAN_ERROR = 86400;
+
+	/**
+	 * @brief try to find a valid ISBN in the given text, using a cascade of
+	 *         regexps. Can be optimized.
+	 *
+	 * @param string $text text to search through
+	 * @return string $hit ISBN on success, false otherwise
+	 */
+	public static function scan($text) {
+		if ($hits = preg_grep('/isbn/i',$text)) {
+			foreach ($hits as $hit) {
+				$hit = preg_replace('/.*ISBN(?:[ -]?1[03]:)?\s*([xX0-9-]{10,17}).*/i','$1',$hit,1);
+				//$hit = preg_replace('/isbn([ -]\(?1[03]\)?)?/i','',$hit);
+				$hit = preg_replace('/[^0-9X]/i','',$hit);
+				if(self::validate($hit)) {
+					return $hit;
+				}
+			}
+		}
+
+		/* single ISBN-13 targeted pattern */
+		if ($hits = preg_grep('/\d{3}[ -]?\d[ -]?\d{4}[ -]?\d{4}[ -]?\d/', $text)) {
+			foreach ($hits as $hit) {
+				$hit = preg_replace('/.*(\d{3}[ -]?\d[ -]?\d{4}[ -]?\d{4}[ -]?\d).*/','$1',$hit,1);
+				$hit = preg_replace('/[^0-9]/i','',$hit);
+				if(self::validate($hit)) {
+					return $hit;
+				}
+			}
+		}
+
+		/* single ISBN-10 targeted pattern */
+		if ($hits = preg_grep('/\d[\d -]{8,11}[\dX]/i', $text)) {
+			foreach ($hits as $hit) {
+				$hit = preg_replace('/.*(\d[\d -]{8,11}[\dX]).*/','$1',$hit,1);
+				$hit = preg_replace('/[^0-9X]/i','',$hit);
+				if(self::validate($hit)) {
+					return $hit;
+				}
+			}
+		}
+	
+		return false;
+	}
+
+	/**
+	 * @brief get metadata for given ISBN
+	 *
+	 * @param string $isbn ISBN to use
+	 * @param arrayref &$meta OPDS metadata
+	 * @return bool $success (true if metadata found)
+	 */
+        public static function get($isbn,&$meta) {
+		/* set ISBN in metadata; can be overwritten later with ISBN13 */
+		$meta['isbn'] = $isbn;
+		/* Try ISBNdb, then Google */
+		if (!(Isbn::SUCCESS == Isbndb::get($isbn,$meta)) && (!(Isbn::SUCCESS == Google::get($isbn,$meta)))) {
+			return false;
+		} else {
+			return true;
+		}
+        }
+
+	/**
+	 * @brief validate ISBN
+	 *
+	 * @param string $isbn ISBN to validate
+	 * @return bool true if ISBN is valid
+	 */
+        public static function validate($isbn) {
+                if (null === $isbn || '' === $isbn) {
+                        return false;
+                }
+
+                switch (strlen($isbn)) {
+                        case 10:
+                                return self::isIsbn10($isbn);
+                                break;
+                        case 13:
+                                return self::isIsbn13($isbn);
+                                break;
+                }
+		return false;
+        }
+
+	/**
+	 * @brief check for valid ISBN10
+	 * @param string $isbn ISBN to check
+	 * @return bool true if valid ISBN-10
+	 */
+        static function isIsbn10 ($isbn) {
+                $checksum = 0;
+                for ($i = 0; $i < 10; ++$i) {
+                        if (!isset($isbn{$i})) {
+                                return false;
+                        }
+                        if ('X' === $isbn{$i}) {
+                                $digit = 10;
+                        } elseif (ctype_digit($isbn{$i})) {
+                                $digit = $isbn{$i};
+                        } else {
+                                return false;
+                        }
+                        $checksum += $digit * intval(10 - $i);
+                }
+
+                return 0 === $checkSum % 11 ? true : false;
+        }
+
+	/**
+	 * @brief check for valid ISBN13
+	 * @param string $isbn ISBN to check
+	 * @return bool true if valid ISBN-13
+	 */
+        static function isIsbn13 ($isbn) {
+                $checksum = 0;
+                for ($i = 0; $i < 13; $i +=2) {
+                        $checksum += $isbn{$i};
+                }
+                for ($i = 1; $i < 12; $i +=2) {
+                        $checksum += $isbn{$i} * 3;
+                }
+
+                return 0 === $checkSum % 10 ? true : false;
+        }
+}
+
+
diff --git a/files_opds/lib/isbndb.php b/files_opds/lib/isbndb.php
new file mode 100644
index 0000000..9e4d2f3
--- /dev/null
+++ b/files_opds/lib/isbndb.php
@@ -0,0 +1,119 @@
+<?php
+
+/**
+ * ownCloud - Files_Opds App
+ *
+ * @author Frank de Lange
+ * @copyright 2014 Frank de Lange
+ *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ */
+
+namespace OCA\Files_Opds;
+
+/**
+ * ISBNdb class for OPDS
+ */
+class Isbndb
+{
+        /**
+         * @brief get ISBN data for $isbn at ISBNdb
+         *
+         * @param string $isbn ISBN to search for
+         * @param arrayref &$meta
+         * @return int $status (0 on success, ERRORCODE otherwise)
+         */
+        public static function get($isbn,&$meta) {
+                if ($keyString = Config::getApp('isbndb-key','')) {
+                        $keys = explode(',', $keyString);
+                        $key = $keys[rand(0,count($keys) - 1)];
+                        $data = false;
+                        $isbn = preg_replace('/[^0-9X]/i', '', $isbn);
+                        if (Isbn::validate($isbn)) {
+                                $command = 'http://isbndb.com/api/v2/json/' . $key . '/book/' . $isbn;
+                                $data = json_decode(file_get_contents($command),true);
+                                if (isset($data['error'])) {
+                                        Util::logWarn("ISBNDB: " . $data['error']);
+                                        if (!(stripos($data['error'], 'Daily request limit exceeded') === false)) {
+                                                return Isbn::REQUEST_LIMIT_EXCEEDED;
+                                        } elseif(!(stripos($data['error'], 'Unable to locate') === false))  {
+                                                return Isbn::NOT_FOUND;
+                                        } else {
+                                                return Isbn::ERROR;
+                                        }
+                                } else {
+                                        self::parse($data['data'][0],$meta);
+                                        return Isbn::SUCCESS;
+                                }
+                        }
+                }
+
+                return false;
+        }
+
+        /**
+         * @brief parse ISBNdb response into OPDS $meta array
+         *
+         * @param array $data ISBNdb response (json_decoded into array)
+         * @param arrayref &$meta OPDS metadata array
+         * @return int errorcode (0 if success)
+         */
+        static function parse($data,&$meta) {
+                /* did the call succeed? If not, schedule a rescan */
+                if (Isbn::REQUEST_LIMIT_EXCEEDED == $data) {
+                        $meta['rescan'] = date("Y-m-d\TH:i:sP", time() + Isbn::RESCAN_LIMIT_EXCEEDED);
+                        return false;
+                } elseif (Isbn::NOT_FOUND == $data) {
+                        $meta['rescan'] = date("Y-m-d\TH:i:sP", time() + Isbn::RESCAN_NOT_FOUND);
+                        return false;
+                } elseif (Isbn::ERROR == $data) {
+                        $meta['rescan'] = date("Y-m-d\TH:i:sP", time() + Isbn::RESCAN_ERROR);
+                        return false;
+                }
+
+                foreach ($data as $key => $value) {
+                        switch ($key) {
+                                case 'summary':
+                                        $meta['description'] = $value;
+                                        if(array_key_exists('notes',$data)) {
+                                                $meta['description'] .= ((trim($value) == false) ? '' : "\n\n") . $data['notes'];
+                                        }
+                                        break;
+                                case 'subject_ids':
+                                        $meta['subjects'] = json_encode($value);
+                                        break;
+                                case 'isbn10':
+                                        if(!(array_key_exists('isbn13', $data))) {
+                                                $meta['isbn'] = $value;
+                                        }
+                                        break;
+                                case 'isbn13':
+                                        $meta['isbn'] = $value;
+                                        break;
+                                case 'title':
+                                        if(!(array_key_exists('title_long',$data))) {
+                                                $meta['title'] = $value;
+                                        }
+                                        break;
+                                case 'title_long':
+                                        $meta['title'] = $value;
+                                        break;
+                                case 'author_data':
+                                        $meta['author'] = json_encode(array_column($value, 'name','id'));
+                                        break;
+                                case 'language':
+                                        $meta['language'] = $value;
+                                        break;
+                               case 'publisher_name':
+                                        $meta['publisher'] = $value;
+                                        if(array_key_exists('publisher_text',$data)) {
+                                                $meta['publisher'] .= ((trim($value) == false) ? '' : ', ') . $data['publisher_text'];
+                                        }
+                                        break;
+                        }
+                }
+
+                return true;
+        }
+}
diff --git a/files_opds/lib/meta.php b/files_opds/lib/meta.php
index 76d460b..1ebdca8 100644
--- a/files_opds/lib/meta.php
+++ b/files_opds/lib/meta.php
@@ -40,6 +40,7 @@ class Meta
 		$meta['copyright'] = '';
 		$meta['description'] = '';
 		$meta['subjects'] = '';
+		$meta['rescan'] = null;
 
 		return $meta;
 	}
@@ -65,20 +66,45 @@ class Meta
 	 * @return OC_DB_StatementWrapper
 	 */
 	protected static function save($meta) {
-		$sql = "INSERT INTO *PREFIX*opds_metadata (`id`, `updated`, `date`, `author`, `title`, `language`, `publisher`, `isbn`, `copyright`, `description`, `subjects`) VALUES (?,?,?,?,?,?,?,?,?,?,?)";
-		$args = array(
-			$meta['id'],
-			$meta['updated'],
-			$meta['date'],
-			$meta['author'],
-			$meta['title'],
-			$meta['language'],
-			$meta['publisher'],
-			$meta['isbn'],
-			$meta['copyright'],
-			$meta['description'],
-			$meta['subjects']
-			);
+		$sql = "SELECT `id` FROM *PREFIX*opds_metadata WHERE `id`=?";
+		$args = array($meta['id']);
+		$query = \OCP\DB::prepare($sql);
+		$result = $query->execute($args);
+		$data = $result->fetchRow();
+		if (isset($data['id'])) {
+			$sql = "UPDATE *PREFIX*opds_metadata SET `updated`=?, `date`=?, `author`=?, `title`=?, `language`=?, `publisher`=?, `isbn`=?, `copyright`=?, `description`=?, `subjects`=?, `rescan`=? WHERE id=?";
+			$args = array(
+				$meta['updated'],
+				$meta['date'],
+				$meta['author'],
+				$meta['title'],
+				$meta['language'],
+				$meta['publisher'],
+				$meta['isbn'],
+				$meta['copyright'],
+				$meta['description'],
+				$meta['subjects'],
+				$meta['rescan'],
+				$meta['id']
+				);
+
+		} else {
+			$sql = "INSERT INTO *PREFIX*opds_metadata (`id`, `updated`, `date`, `author`, `title`, `language`, `publisher`, `isbn`, `copyright`, `description`, `subjects`, `rescan`) VALUES (?,?,?,?,?,?,?,?,?,?,?,?)";
+			$args = array(
+				$meta['id'],
+				$meta['updated'],
+				$meta['date'],
+				$meta['author'],
+				$meta['title'],
+				$meta['language'],
+				$meta['publisher'],
+				$meta['isbn'],
+				$meta['copyright'],
+				$meta['description'],
+				$meta['subjects'],
+				$meta['rescan']
+				);
+		}
 		$query = \OCP\DB::prepare($sql);
 
 		return $query->execute($args);
@@ -93,7 +119,10 @@ class Meta
          * @return array of metadata
          */
         public static function get($id) {
-		if (!($meta = self::load($id))) {
+		if (!($meta = self::load($id)) || (isset($meta['rescan']) && time() > $meta['rescan'])) {
+			if(isset($meta['rescan'])) {
+				$meta['rescan'] = null;
+			}
 			$meta = self::scan($id);
                 }
 		return $meta;
@@ -101,8 +130,6 @@ class Meta
 
 	/**
 	 * @brief scan files for metadata
-	 * PLAN: use search_lucene to extract metadata? Does not seem to support PDF1.6? 
-	 *       solution: first ask search_lucene, if no data then scan file?
 	 *
 	 * @param int $id fileid
 	 * @return array $meta metadata
@@ -110,16 +137,19 @@ class Meta
 	public static function scan($id) {
 		$meta = self::create($id);
 		$path = \OC\Files\Filesystem::getLocalFile(\OC\Files\Filesystem::getPath($id));
-		
-		switch (strtolower(substr(strrchr($path, "."), 1))) {
-			case 'epub':
-				self::epub($path,$meta);
-				break;
-			case 'pdf':
-				self::pdf($path,$meta);
-				break;
-		}
 
+		/* try to call function named 'type' with signature type($path,$meta)
+		 * eg, pdf(), epub(), etc
+		 */
+		$type = strtolower(substr(strrchr($path, "."), 1));
+		if(is_callable(array(__CLASS__, $type))) {
+			try {
+				self::$type($path,$meta);
+			} catch (Exception $e) {
+				Util::logWarn("no metadata scanner for format " . $type);
+			}
+		}
+		
 		/* if title is not set, assume metadata was invalid or not present
 		 * use filename as title
 		 */
@@ -127,7 +157,7 @@ class Meta
 			$info = pathinfo($path);
 			$meta['title'] = basename($path,'.'.$info['extension']);
 		}
-		// self::save($meta);
+		self::save($meta);
 		return $meta;
 	}
 
@@ -137,21 +167,23 @@ class Meta
 	 *
 	 * @param string $path path to epub
 	 * @param arrayref $meta reference to array of metadata
-	 * @return bool $success (true if metadata found)
 	 */
 	public static function epub($path,&$meta) {
+		$success = false;
 		$epub = new Epub($path);
-		$meta['author'] = json_encode($epub->Authors());
-		$meta['title'] = $epub->Title();
-		$meta['date'] = $epub->Date();
-		$meta['publisher'] = $epub->Publisher();
-		$meta['copyright'] = $epub->Copyright();
-		$meta['language'] = $epub->Language();
-		$meta['description'] = strip_tags($epub->Description());
-		$meta['isbn'] = $epub->ISBN();
-		$meta['subjects'] = $epub->Subjects();
-
-		return true;
+		/* first try ISBN */
+		if(!(($isbn = $epub->ISBN()) && (Isbn::get($isbn, $meta)))) {
+			/* use EPUB internal metadata instead */
+			$meta['author'] = json_encode($epub->Authors());
+			$meta['title'] = $epub->Title();
+			$meta['date'] = $epub->Date();
+			$meta['publisher'] = $epub->Publisher();
+			$meta['copyright'] = $epub->Copyright();
+			$meta['language'] = $epub->Language();
+			$meta['description'] = strip_tags($epub->Description());
+			$meta['isbn'] = $epub->ISBN();
+			$meta['subjects'] = json_encode($epub->Subjects());
+		}
 	}
 
 	/**
@@ -159,10 +191,45 @@ class Meta
 	 *
 	 * @param string $path path to pdf
 	 * @param arrayref $meta reference to array of metadata
-	 * @return bool $success (true if metadata found)
 	 */
 	public static function pdf($path,&$meta) {
+		if(\OC_Util::runningOnWindows()) {
+			/* not supported when running on Windows due to use of exec() */
+			return;
+		}
 
-		return false;
+		/* first, try to get metadata through ISBN */
+		$command = ['pdftotext -l 10 "','" -'];
+		$output=array();
+		exec($command[0] . $path . $command[1], $output);
+		if (!(($output) && ($isbn = Isbn::scan($output)) && (Isbn::get($isbn,$meta)))) {
+			/* No ISBN, try PDF metadata */
+			$output=array();
+			$command = ["pdfinfo '","'|grep -we '^\(Title\|Author\|Subject\|Keywords\|CreationDate\|ModDate\)'"];
+			exec($command[0] . $path . $command[1], $output);
+			foreach($output as $data) {
+				list($key, $value) = explode(':',$data,2);
+				$value = trim($value);
+			}
+
+			if (!($value == '')) {
+				switch ($key) {
+					case 'Title':
+						$meta['title'] = $value;
+						break;
+					case 'Author':
+						$meta['author'] = $value;
+						break;
+					case 'Subject':
+					case 'Keywords':
+						$meta['subjects'] .= $value;
+						break;
+					case 'CreationDate':
+					case 'ModDate':
+						$meta['date'] = strtotime($value); 
+						break;
+				}
+			}
+		}
 	}
 }
diff --git a/files_opds/templates/admin.php b/files_opds/templates/admin.php
index d8f4886..13f60ce 100644
--- a/files_opds/templates/admin.php
+++ b/files_opds/templates/admin.php
@@ -23,10 +23,16 @@ function checkBox($format) {
 
 <div class="section" id="opds-admin">
         <h2><?php p($l->t('OPDS')); ?><span class="msg"></span></h2>
-        <div>
-                <label for="opds-feed-subtitle"><?php p($l->t('Feed subtitle:')) ?></label>
-                <input type="text" id="opds-feed-subtitle" title="<?php p($l->t("Enter subtitle for OPDS catalog.")); ?>" value="<?php p($_['feedSubtitle']) ?>" />
-        </div>
+	<table>
+        <tr>
+                <td><label for="opds-feed-subtitle"><?php p($l->t('Feed subtitle:')) ?></label></td>
+                <td><input type="text" id="opds-feed-subtitle" title="<?php p($l->t("Enter subtitle for OPDS catalog.")); ?>" value="<?php p($_['feedSubtitle']) ?>" /></td>
+        </tr>
+        <tr>
+                <td><label for="opds-isbndb-key"><?php p($l->t('ISBNdb key:')) ?></label></td>
+                <td><input type="text" id="opds-isbndb-key" title="<?php p($l->t("Enter ISBNdb key to use for metadata lookup. Leave blank to disable ISBNdb lookup.")); ?>" value="<?php p($_['isbndbKey']) ?>" /></td>
+        </tr>
+	</table>
 	<br>
 	<p><?php p($l->t('Enable preview for:')); ?></p>
 	<div class="indent">
diff --git a/files_opds/templates/part.feed.acquisition.php b/files_opds/templates/part.feed.acquisition.php
index 83c18eb..b0bff3d 100644
--- a/files_opds/templates/part.feed.acquisition.php
+++ b/files_opds/templates/part.feed.acquisition.php
@@ -3,15 +3,21 @@
     <updated><?php p(date("Y-m-d\TH:i:sP",strtotime($_['file']['meta']['updated']))); ?></updated>
     <id>id:<?php p($_['file']['id']); ?></id>
     <dcterms:extent><?php p($_['file']['humansize']); ?></dcterms:extent>
-    <dc:language><?php p($_['file']['meta']['language']); ?></dc:language>
     <?php foreach (json_decode($_['file']['meta']['author'],true) as $author): ?>
     <author>
       <name><?php p($author); ?></name>
     </author>
-    <dc:identifier>urn:isbn:<?php p($_['file']['meta']['isbn']); ?></dc:identifier>
-    <dc:publisher><?php p($_['file']['meta']['publisher']); ?></dc:publisher>
-    <dc:issued><?php p($_['file']['meta']['date']); ?></dc:issued>
     <?php endforeach; ?>
+    <?php if($_['file']['meta']['isbn']): ?>
+    <dc:identifier>urn:isbn:<?php p($_['file']['meta']['isbn']); ?></dc:identifier>
+    <?php endif; ?>
+    <?php if($_['file']['meta']['publisher']): ?>
+    <dc:publisher><?php p($_['file']['meta']['publisher']); ?></dc:publisher>
+    <?php endif; ?>
+    <?php if($_['file']['meta']['language']): ?>
+    <dc:language><?php p($_['file']['meta']['language']); ?></dc:language>
+    <?php endif; ?>
+    <dc:issued><?php p(date("Y-m-d\TH:i:sP",strtotime($_['file']['meta']['date']))); ?></dc:issued>
     <link type="<?php p($_['file']['mimetype']); ?>"
         rel="alternate"
         href="?id=<?php p($_['file']['id']); ?>"/>