diff --git a/lib/public/contacts.php b/lib/public/contacts.php
index 5762fd28e0..51d4e03f00 100644
--- a/lib/public/contacts.php
+++ b/lib/public/contacts.php
@@ -26,78 +26,173 @@
  *
  */
 
+namespace OC {
+	interface AddressBook {
+
+		/**
+		 * @return string defining the technical unique key
+		 */
+		public function getKey();
+
+		/**
+		 * In comparison to getKey() this function returns a human readable (maybe translated) name
+		 * @return mixed
+		 */
+		public function getDisplayName();
+
+		/**
+		 * @param $pattern
+		 * @param $searchProperties
+		 * @param $options
+		 * @return mixed
+		 */
+		public function search($pattern, $searchProperties, $options);
+//			// dummy results
+//			return array(
+//				array('id' => 0, 'FN' => 'Thomas Müller', 'EMAIL' => 'a@b.c', 'GEO' => '37.386013;-122.082932'),
+//				array('id' => 5, 'FN' => 'Thomas Tanghus', 'EMAIL' => array('d@e.f', 'g@h.i')),
+//			);
+
+		/**
+		 * @param $properties
+		 * @return mixed
+		 */
+		public function createOrUpdate($properties);
+//			// dummy
+//			return array('id'    => 0, 'FN' => 'Thomas Müller', 'EMAIL' => 'a@b.c',
+//			             'PHOTO' => 'VALUE=uri:http://www.abc.com/pub/photos/jqpublic.gif',
+//			             'ADR'   => ';;123 Main Street;Any Town;CA;91921-1234'
+//			);
+
+		/**
+		 * @return mixed
+		 */
+		public function isReadOnly();
+
+		/**
+		 * @param $id
+		 * @return mixed
+		 */
+		public function delete($id);
+	}
+}
+
 // use OCP namespace for all classes that are considered public.
 // This means that they should be used by apps instead of the internal ownCloud classes
-namespace OCP;
-
-/**
- * This class provides access to the contacts app. Use this class exclusively if you want to access contacts.
- *
- * Contacts in general will be expressed as an array of key-value-pairs.
- * The keys will match the property names defined in https://tools.ietf.org/html/rfc2426#section-1
- *
- * Proposed workflow for working with contacts:
- *  - search for the contacts
- *  - manipulate the results array
- *  - createOrUpdate will save the given contacts overwriting the existing data
- *
- * For updating it is mandatory to keep the id.
- * Without an id a new contact will be created.
- *
- */
-class Contacts
-{
-	/**
-	 * This function is used to search and find contacts within the users address books.
-	 * In case $pattern is empty all contacts will be returned.
-	 *
-	 * @param string $pattern which should match within the $searchProperties
-	 * @param array $searchProperties defines the properties within the query pattern should match
-	 * @param array $options - for future use. One should always have options!
-	 * @return array of contacts which are arrays of key-value-pairs
-	 */
-	public static function search($pattern, $searchProperties = array(), $options = array()) {
-
-		// dummy results
-		return array(
-			array('id' => 0, 'FN' => 'Thomas Müller', 'EMAIL' => 'a@b.c', 'GEO' => '37.386013;-122.082932'),
-			array('id' => 5, 'FN' => 'Thomas Tanghus', 'EMAIL' => array('d@e.f', 'g@h.i')),
-		);
-	}
+namespace OCP {
 
 	/**
-	 * This function can be used to delete the contact identified by the given id
+	 * This class provides access to the contacts app. Use this class exclusively if you want to access contacts.
 	 *
-	 * @param object $id the unique identifier to a contact
-	 * @return bool successful or not
-	 */
-	public static function delete($id) {
-		return false;
-	}
-
-	/**
-	 * This function is used to create a new contact if 'id' is not given or not present.
-	 * Otherwise the contact will be updated by replacing the entire data set.
+	 * Contacts in general will be expressed as an array of key-value-pairs.
+	 * The keys will match the property names defined in https://tools.ietf.org/html/rfc2426#section-1
 	 *
-	 * @param array $properties this array if key-value-pairs defines a contact
-	 * @return array representing the contact just created or updated
-	 */
-	public static function createOrUpdate($properties) {
-
-		// dummy
-		return array('id'    => 0, 'FN' => 'Thomas Müller', 'EMAIL' => 'a@b.c',
-		             'PHOTO' => 'VALUE=uri:http://www.abc.com/pub/photos/jqpublic.gif',
-		             'ADR'   => ';;123 Main Street;Any Town;CA;91921-1234'
-		);
-	}
-
-	/**
-	 * Check if contacts are available (e.g. contacts app enabled)
+	 * Proposed workflow for working with contacts:
+	 *  - search for the contacts
+	 *  - manipulate the results array
+	 *  - createOrUpdate will save the given contacts overwriting the existing data
+	 *
+	 * For updating it is mandatory to keep the id.
+	 * Without an id a new contact will be created.
 	 *
-	 * @return bool true if enabled, false if not
 	 */
-	public static function isEnabled() {
-		return false;
-	}
+	class Contacts {
 
-}
+		/**
+		 * This function is used to search and find contacts within the users address books.
+		 * In case $pattern is empty all contacts will be returned.
+		 *
+		 * @param string $pattern which should match within the $searchProperties
+		 * @param array $searchProperties defines the properties within the query pattern should match
+		 * @param array $options - for future use. One should always have options!
+		 * @return array of contacts which are arrays of key-value-pairs
+		 */
+		public static function search($pattern, $searchProperties = array(), $options = array()) {
+
+			$result = array();
+			foreach(self::$address_books as $address_book) {
+				$result = $result + $address_book->search($pattern, $searchProperties, $options);
+			}
+
+			return $result;
+		}
+
+		/**
+		 * This function can be used to delete the contact identified by the given id
+		 *
+		 * @param object $id the unique identifier to a contact
+		 * @param $address_book_key
+		 * @return bool successful or not
+		 */
+		public static function delete($id, $address_book_key) {
+			if (!array_key_exists($address_book_key, self::$address_books))
+				return null;
+
+			$address_book = self::$address_books[$address_book_key];
+			if ($address_book->isReadOnly())
+				return null;
+
+			return $address_book->delete($id);
+		}
+
+		/**
+		 * This function is used to create a new contact if 'id' is not given or not present.
+		 * Otherwise the contact will be updated by replacing the entire data set.
+		 *
+		 * @param array $properties this array if key-value-pairs defines a contact
+		 * @param $address_book_key string to identify the address book in which the contact shall be created or updated
+		 * @return array representing the contact just created or updated
+		 */
+		public static function createOrUpdate($properties, $address_book_key) {
+
+			if (!array_key_exists($address_book_key, self::$address_books))
+				return null;
+
+			$address_book = self::$address_books[$address_book_key];
+			if ($address_book->isReadOnly())
+				return null;
+
+			return $address_book->createOrUpdate($properties);
+		}
+
+		/**
+		 * Check if contacts are available (e.g. contacts app enabled)
+		 *
+		 * @return bool true if enabled, false if not
+		 */
+		public static function isEnabled() {
+			return !empty(self::$address_books);
+		}
+
+		/**
+		 * @param \OC\AddressBook $address_book
+		 */
+		public static function registerAddressBook(\OC\AddressBook $address_book) {
+			self::$address_books[$address_book->getKey()] = $address_book;
+		}
+
+		/**
+		 * @param \OC\AddressBook $address_book
+		 */
+		public static function unregisterAddressBook(\OC\AddressBook $address_book) {
+			unset(self::$address_books[$address_book->getKey()]);
+		}
+
+		/**
+		 * @return array
+		 */
+		public static function getAddressBooks() {
+			$result = array();
+			foreach(self::$address_books as $address_book) {
+				$result[$address_book->getKey()] = $address_book->getDisplayName();
+			}
+
+			return $result;
+		}
+
+		/**
+		 * @var \OC\AddressBook[] which holds all registered address books
+		 */
+		private static $address_books = array();
+	}
+}
\ No newline at end of file