diff --git a/lib/iaddressbook.php b/lib/iaddressbook.php
new file mode 100644
index 0000000000000000000000000000000000000000..39205140361ca48499b6018f654c211d391af14e
--- /dev/null
+++ b/lib/iaddressbook.php
@@ -0,0 +1,72 @@
+<?php
+/**
+ * ownCloud
+ *
+ * @author Thomas Müller
+ * @copyright 2012 Thomas Müller thomas.mueller@tmit.eu
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or any later version.
+ *
+ * This library 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 AFFERO GENERAL PUBLIC LICENSE for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC {
+	interface IAddressBook {
+
+		/**
+		 * @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 string $pattern which should match within the $searchProperties
+		 * @param array $searchProperties defines the properties within the query pattern should match
+		 * @param array $options - for future use. One should always have options!
+		 * @return array of contacts which are arrays of key-value-pairs
+		 */
+		public function search($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 array $properties this array if key-value-pairs defines a contact
+		 * @return array representing the contact just created or updated
+		 */
+		public function createOrUpdate($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 getPermissions();
+
+		/**
+		 * @param object $id the unique identifier to a contact
+		 * @return bool successful or not
+		 */
+		public function delete($id);
+	}
+}
diff --git a/lib/public/contacts.php b/lib/public/contacts.php
index 5762fd28e02d93c44fa5774962cf4d63c709bf33..ab46614c8fd0018935fcd4f7721608930d96d8f1 100644
--- a/lib/public/contacts.php
+++ b/lib/public/contacts.php
@@ -28,76 +28,159 @@
 
 // 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;
+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.
+	 * 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.
 	 *
-	 * @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()) {
+	class Contacts {
 
-		// 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')),
-		);
-	}
+		/**
+		 * This function is used to search and find contacts within the users address books.
+		 * In case $pattern is empty all contacts will be returned.
+		 *
+		 * Example:
+		 *  Following function shows how to search for contacts for the name and the email address.
+		 *
+		 * 		public static function getMatchingRecipient($term) {
+		 *          // The API is not active -> nothing to do
+		 *			if (!\OCP\Contacts::isEnabled()) {
+		 *	    		return array();
+		 *			}
+		 *
+		 *			$result = \OCP\Contacts::search($term, array('FN', 'EMAIL'));
+		 *			$receivers = array();
+		 *			foreach ($result as $r) {
+		 *			    $id = $r['id'];
+		 *			    $fn = $r['FN'];
+		 *			    $email = $r['EMAIL'];
+		 *			    if (!is_array($email)) {
+		 *  		    	$email = array($email);
+		 *			    }
+		 *
+		 *			    // loop through all email addresses of this contact
+		 *			    foreach ($email as $e) {
+		 *	    		    $displayName = $fn . " <$e>";
+		 *		        	$receivers[] = array('id'    => $id,
+		 *			        'label' => $displayName,
+		 *			        'value' => $displayName);
+		 *			    }
+		 *			}
+		 *
+		 *			return $receivers;
+		 *		}
+		 *
+		 *
+		 * @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) {
+				$r = $address_book->search($pattern, $searchProperties, $options);
+				$result = array_merge($result, $r);
+			}
 
-	/**
-	 * This function can be used to delete the contact identified by the given id
-	 *
-	 * @param object $id the unique identifier to a contact
-	 * @return bool successful or not
-	 */
-	public static function delete($id) {
-		return false;
-	}
+			return $result;
+		}
 
-	/**
-	 * 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 $properties this array if key-value-pairs defines a contact
-	 * @return array representing the contact just created or updated
-	 */
-	public static function createOrUpdate($properties) {
+		/**
+		 * 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;
 
-		// 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'
-		);
-	}
+			$address_book = self::$address_books[$address_book_key];
+			if ($address_book->getPermissions() & \OCP\PERMISSION_DELETE)
+				return null;
 
-	/**
-	 * Check if contacts are available (e.g. contacts app enabled)
-	 *
-	 * @return bool true if enabled, false if not
-	 */
-	public static function isEnabled() {
-		return false;
-	}
+			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->getPermissions() & \OCP\PERMISSION_CREATE)
+				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\IAddressBook $address_book
+		 */
+		public static function registerAddressBook(\OC\IAddressBook $address_book) {
+			self::$address_books[$address_book->getKey()] = $address_book;
+		}
+
+		/**
+		 * @param \OC\IAddressBook $address_book
+		 */
+		public static function unregisterAddressBook(\OC\IAddressBook $address_book) {
+			unset(self::$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 $result;
+		}
+
+		/**
+		 * removes all registered address book instances
+		 */
+		public static function clear() {
+			self::$address_books = array();
+		}
+
+		/**
+		 * @var \OC\IAddressBook[] which holds all registered address books
+		 */
+		private static $address_books = array();
+	}
 }
diff --git a/tests/lib/public/contacts.php b/tests/lib/public/contacts.php
new file mode 100644
index 0000000000000000000000000000000000000000..23994667a26a50622345a76747ae246acd626b1b
--- /dev/null
+++ b/tests/lib/public/contacts.php
@@ -0,0 +1,125 @@
+<?php
+/**
+ * ownCloud
+ *
+ * @author Thomas Müller
+ * @copyright 2012 Thomas Müller thomas.mueller@tmit.eu
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or any later version.
+ *
+ * This library 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 AFFERO GENERAL PUBLIC LICENSE for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+OC::autoload('OCP\Contacts');
+
+class Test_Contacts extends PHPUnit_Framework_TestCase
+{
+
+	public function setUp() {
+
+		OCP\Contacts::clear();
+	}
+
+	public function tearDown() {
+	}
+
+	public function testDisabledIfEmpty() {
+		// pretty simple
+		$this->assertFalse(OCP\Contacts::isEnabled());
+	}
+
+	public function testEnabledAfterRegister() {
+		// create mock for the addressbook
+		$stub = $this->getMock("SimpleAddressBook", array('getKey'));
+
+		// we expect getKey to be called twice:
+		// first time on register
+		// second time on un-register
+		$stub->expects($this->exactly(2))
+			->method('getKey');
+
+		// not enabled before register
+		$this->assertFalse(OCP\Contacts::isEnabled());
+
+		// register the address book
+		OCP\Contacts::registerAddressBook($stub);
+
+		// contacts api shall be enabled
+		$this->assertTrue(OCP\Contacts::isEnabled());
+
+		// unregister the address book
+		OCP\Contacts::unregisterAddressBook($stub);
+
+		// not enabled after register
+		$this->assertFalse(OCP\Contacts::isEnabled());
+	}
+
+	public function testAddressBookEnumeration() {
+		// create mock for the addressbook
+		$stub = $this->getMock("SimpleAddressBook", array('getKey', 'getDisplayName'));
+
+		// setup return for method calls
+		$stub->expects($this->any())
+			->method('getKey')
+			->will($this->returnValue('SIMPLE_ADDRESS_BOOK'));
+		$stub->expects($this->any())
+			->method('getDisplayName')
+			->will($this->returnValue('A very simple Addressbook'));
+
+		// register the address book
+		OCP\Contacts::registerAddressBook($stub);
+		$all_books = OCP\Contacts::getAddressBooks();
+
+		$this->assertEquals(1, count($all_books));
+		$this->assertEquals('A very simple Addressbook', $all_books['SIMPLE_ADDRESS_BOOK']);
+	}
+
+	public function testSearchInAddressBook() {
+		// create mock for the addressbook
+		$stub1 = $this->getMock("SimpleAddressBook1", array('getKey', 'getDisplayName', 'search'));
+		$stub2 = $this->getMock("SimpleAddressBook2", array('getKey', 'getDisplayName', 'search'));
+
+		$searchResult1 = array(
+			array('id' => 0, 'FN' => 'Frank Karlitschek', 'EMAIL' => 'a@b.c', 'GEO' => '37.386013;-122.082932'),
+			array('id' => 5, 'FN' => 'Klaas Freitag', 'EMAIL' => array('d@e.f', 'g@h.i')),
+		);
+		$searchResult2 = array(
+			array('id' => 0, 'FN' => 'Thomas Müller', 'EMAIL' => 'a@b.c'),
+			array('id' => 5, 'FN' => 'Thomas Tanghus', 'EMAIL' => array('d@e.f', 'g@h.i')),
+		);
+
+		// setup return for method calls for $stub1
+		$stub1->expects($this->any())->method('getKey')->will($this->returnValue('SIMPLE_ADDRESS_BOOK1'));
+		$stub1->expects($this->any())->method('getDisplayName')->will($this->returnValue('Address book ownCloud Inc'));
+		$stub1->expects($this->any())->method('search')->will($this->returnValue($searchResult1));
+
+		// setup return for method calls for $stub2
+		$stub2->expects($this->any())->method('getKey')->will($this->returnValue('SIMPLE_ADDRESS_BOOK2'));
+		$stub2->expects($this->any())->method('getDisplayName')->will($this->returnValue('Address book ownCloud Community'));
+		$stub2->expects($this->any())->method('search')->will($this->returnValue($searchResult2));
+
+		// register the address books
+		OCP\Contacts::registerAddressBook($stub1);
+		OCP\Contacts::registerAddressBook($stub2);
+		$all_books = OCP\Contacts::getAddressBooks();
+
+		// assert the count - doesn't hurt
+		$this->assertEquals(2, count($all_books));
+
+		// perform the search
+		$result = OCP\Contacts::search('x', array());
+
+		// we expect 4 hits
+		$this->assertEquals(4, count($result));
+
+	}
+}