diff --git a/apps/dav/lib/comments/commentnode.php b/apps/dav/lib/comments/commentnode.php
new file mode 100644
index 0000000000..b78b4765ca
--- /dev/null
+++ b/apps/dav/lib/comments/commentnode.php
@@ -0,0 +1,211 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Comments;
+
+
+use OCP\Comments\IComment;
+use OCP\Comments\ICommentsManager;
+use OCP\ILogger;
+use OCP\IUserManager;
+use Sabre\DAV\Exception\MethodNotAllowed;
+use Sabre\DAV\PropPatch;
+
+class CommentNode implements \Sabre\DAV\INode, \Sabre\DAV\IProperties {
+	const NS_OWNCLOUD = 'http://owncloud.org/ns';
+
+	/** @var  IComment */
+	public $comment;
+
+	/** @var ICommentsManager */
+	protected $commentsManager;
+
+	/** @var  ILogger */
+	protected $logger;
+
+	/** @var array list of properties with key being their name and value their setter */
+	protected $properties = [];
+
+	/** @var IUserManager */
+	protected $userManager;
+
+	/**
+	 * CommentNode constructor.
+	 *
+	 * @param ICommentsManager $commentsManager
+	 * @param IComment $comment
+	 * @param IUserManager $userManager
+	 * @param ILogger $logger
+	 */
+	public function __construct(
+		ICommentsManager $commentsManager,
+		IComment $comment,
+		IUserManager $userManager,
+		ILogger $logger
+	) {
+		$this->commentsManager = $commentsManager;
+		$this->comment = $comment;
+		$this->logger = $logger;
+
+		$methods = get_class_methods($this->comment);
+		$methods = array_filter($methods, function($name){
+			return strpos($name, 'get') === 0;
+		});
+		foreach($methods as $getter) {
+			$name = '{'.self::NS_OWNCLOUD.'}' . lcfirst(substr($getter, 3));
+			$this->properties[$name] = $getter;
+		}
+		$this->userManager = $userManager;
+	}
+
+	/**
+	 * returns a list of all possible property names
+	 *
+	 * @return array
+	 */
+	static public function getPropertyNames() {
+		return [
+			'{http://owncloud.org/ns}id',
+			'{http://owncloud.org/ns}parentId',
+			'{http://owncloud.org/ns}topmostParentId',
+			'{http://owncloud.org/ns}childrenCount',
+			'{http://owncloud.org/ns}message',
+			'{http://owncloud.org/ns}verb',
+			'{http://owncloud.org/ns}actorType',
+			'{http://owncloud.org/ns}actorId',
+			'{http://owncloud.org/ns}actorDisplayName',
+			'{http://owncloud.org/ns}creationDateTime',
+			'{http://owncloud.org/ns}latestChildDateTime',
+			'{http://owncloud.org/ns}objectType',
+			'{http://owncloud.org/ns}objectId',
+		];
+	}
+
+	/**
+	 * Deleted the current node
+	 *
+	 * @return void
+	 */
+	function delete() {
+		$this->commentsManager->delete($this->comment->getId());
+	}
+
+	/**
+	 * Returns the name of the node.
+	 *
+	 * This is used to generate the url.
+	 *
+	 * @return string
+	 */
+	function getName() {
+		return $this->comment->getId();
+	}
+
+	/**
+	 * Renames the node
+	 *
+	 * @param string $name The new name
+	 * @throws MethodNotAllowed
+	 */
+	function setName($name) {
+		throw new MethodNotAllowed();
+	}
+
+	/**
+	 * Returns the last modification time, as a unix timestamp
+	 *
+	 * @return int
+	 */
+	function getLastModified() {
+		// we do not have a separate "mDateTime" field for updates currently.
+		return $this->comment->getCreationDateTime()->getTimestamp();
+	}
+
+	/**
+	 * update the comment's message
+	 *
+	 * @param $propertyValue
+	 * @return bool
+	 */
+	public function updateComment($propertyValue) {
+		try {
+			$this->comment->setMessage($propertyValue);
+			$this->commentsManager->save($this->comment);
+			return true;
+		} catch (\Exception $e) {
+			$this->logger->logException($e, ['app' => 'dav/comments']);
+			return false;
+		}
+	}
+
+	/**
+	 * Updates properties on this node.
+	 *
+	 * This method received a PropPatch object, which contains all the
+	 * information about the update.
+	 *
+	 * To update specific properties, call the 'handle' method on this object.
+	 * Read the PropPatch documentation for more information.
+	 *
+	 * @param PropPatch $propPatch
+	 * @return void
+	 */
+	function propPatch(PropPatch $propPatch) {
+		// other properties than 'message' are read only
+		$propPatch->handle('{'.self::NS_OWNCLOUD.'}message', [$this, 'updateComment']);
+		$propPatch->commit();
+	}
+
+	/**
+	 * Returns a list of properties for this nodes.
+	 *
+	 * The properties list is a list of propertynames the client requested,
+	 * encoded in clark-notation {xmlnamespace}tagname
+	 *
+	 * If the array is empty, it means 'all properties' were requested.
+	 *
+	 * Note that it's fine to liberally give properties back, instead of
+	 * conforming to the list of requested properties.
+	 * The Server class will filter out the extra.
+	 *
+	 * @param array $properties
+	 * @return array
+	 */
+	function getProperties($properties) {
+		$properties = array_keys($this->properties);
+
+		$result = [];
+		foreach($properties as $property) {
+			$getter = $this->properties[$property];
+			if(method_exists($this->comment, $getter)) {
+				$result[$property] = $this->comment->$getter();
+			}
+		}
+
+		if($this->comment->getActorType() === 'users') {
+			$user = $this->userManager->get($this->comment->getActorId());
+			$displayName = is_null($user) ? null : $user->getDisplayName();
+			$result['{' . self::NS_OWNCLOUD . '}actorDisplayName'] = $displayName;
+		}
+
+		return $result;
+	}
+}
diff --git a/apps/dav/lib/comments/commentsplugin.php b/apps/dav/lib/comments/commentsplugin.php
new file mode 100644
index 0000000000..59ce3f12f6
--- /dev/null
+++ b/apps/dav/lib/comments/commentsplugin.php
@@ -0,0 +1,243 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Comments;
+
+use OCP\Comments\IComment;
+use OCP\Comments\ICommentsManager;
+use OCP\IUserSession;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\DAV\Exception\ReportNotSupported;
+use Sabre\DAV\Exception\UnsupportedMediaType;
+use Sabre\DAV\Exception\NotFound;
+use Sabre\DAV\Server;
+use Sabre\DAV\ServerPlugin;
+use Sabre\DAV\Xml\Element\Response;
+use Sabre\DAV\Xml\Response\MultiStatus;
+use Sabre\HTTP\RequestInterface;
+use Sabre\HTTP\ResponseInterface;
+use Sabre\Xml\Writer;
+
+/**
+ * Sabre plugin to handle comments:
+ */
+class CommentsPlugin extends ServerPlugin {
+	// namespace
+	const NS_OWNCLOUD = 'http://owncloud.org/ns';
+
+	const REPORT_PARAM_LIMIT     = '{http://owncloud.org/ns}limit';
+	const REPORT_PARAM_OFFSET    = '{http://owncloud.org/ns}offset';
+	const REPORT_PARAM_TIMESTAMP = '{http://owncloud.org/ns}datetime';
+
+	/** @var ICommentsManager  */
+	protected $commentsManager;
+
+	/** @var \Sabre\DAV\Server $server */
+	private $server;
+
+	/** @var  \OCP\IUserSession */
+	protected $userSession;
+
+	/**
+	 * Comments plugin
+	 *
+	 * @param ICommentsManager $commentsManager
+	 * @param IUserSession $userSession
+	 */
+	public function __construct(ICommentsManager $commentsManager, IUserSession $userSession) {
+		$this->commentsManager = $commentsManager;
+		$this->userSession = $userSession;
+	}
+
+	/**
+	 * This initializes the plugin.
+	 *
+	 * This function is called by Sabre\DAV\Server, after
+	 * addPlugin is called.
+	 *
+	 * This method should set up the required event subscriptions.
+	 *
+	 * @param Server $server
+	 * @return void
+	 */
+	function initialize(Server $server) {
+		$this->server = $server;
+		if(strpos($this->server->getRequestUri(), 'comments/') !== 0) {
+			return;
+		}
+
+		$this->server->xml->namespaceMap[self::NS_OWNCLOUD] = 'oc';
+
+		$this->server->xml->classMap['DateTime'] = function(Writer $writer, \DateTime $value) {
+			$writer->write($value->format('Y-m-d H:m:i'));
+		};
+
+		$this->server->on('report', [$this, 'onReport']);
+		$this->server->on('method:POST', [$this, 'httpPost']);
+	}
+
+	/**
+	 * POST operation on Comments collections
+	 *
+	 * @param RequestInterface $request request object
+	 * @param ResponseInterface $response response object
+	 * @return null|false
+	 */
+	public function httpPost(RequestInterface $request, ResponseInterface $response) {
+		$path = $request->getPath();
+
+		// Making sure the node exists
+		try {
+			$node = $this->server->tree->getNodeForPath($path);
+		} catch (NotFound $e) {
+			return null;
+		}
+
+		if ($node instanceof EntityCollection) {
+			$data = $request->getBodyAsString();
+
+			$comment = $this->createComment(
+				$node->getName(),
+				$node->getId(),
+				$data,
+				$request->getHeader('Content-Type')
+			);
+			$url = $request->getUrl() . '/' . urlencode($comment->getId());
+
+			$response->setHeader('Content-Location', $url);
+
+			// created
+			$response->setStatus(201);
+			return false;
+		}
+	}
+
+	/**
+	 * REPORT operations to look for comments
+	 *
+	 * @param string $reportName
+	 * @param [] $report
+	 * @param string $uri
+	 * @return bool
+	 * @throws NotFound
+	 * @throws ReportNotSupported
+	 */
+	public function onReport($reportName, $report, $uri) {
+		$node = $this->server->tree->getNodeForPath($uri);
+		if(!$node instanceof EntityCollection) {
+			throw new ReportNotSupported();
+		}
+		$args = ['limit' => 0, 'offset' => 0, 'datetime' => null];
+		$acceptableParameters = [
+			$this::REPORT_PARAM_LIMIT,
+			$this::REPORT_PARAM_OFFSET,
+			$this::REPORT_PARAM_TIMESTAMP
+		];
+		$ns = '{' . $this::NS_OWNCLOUD . '}';
+		foreach($report as $parameter) {
+			if(!in_array($parameter['name'], $acceptableParameters) || empty($parameter['value'])) {
+				continue;
+			}
+			$args[str_replace($ns, '', $parameter['name'])] = $parameter['value'];
+		}
+
+		if(!is_null($args['datetime'])) {
+			$args['datetime'] = new \DateTime($args['datetime']);
+		}
+
+		$results = $node->findChildren($args['limit'], $args['offset'], $args['datetime']);
+
+		$responses = [];
+		foreach($results as $node) {
+			$nodePath = $this->server->getRequestUri() . '/' . $node->comment->getId();
+			$resultSet = $this->server->getPropertiesForPath($nodePath, CommentNode::getPropertyNames());
+			if(isset($resultSet[0]) && isset($resultSet[0][200])) {
+				$responses[] = new Response(
+					$this->server->getBaseUri() . $nodePath,
+					[200 => $resultSet[0][200]],
+					200
+				);
+			}
+
+		}
+
+		$xml = $this->server->xml->write(
+			'{DAV:}multistatus',
+			new MultiStatus($responses)
+		);
+
+		$this->server->httpResponse->setStatus(207);
+		$this->server->httpResponse->setHeader('Content-Type', 'application/xml; charset=utf-8');
+		$this->server->httpResponse->setBody($xml);
+
+		return false;
+	}
+
+	/**
+	 * Creates a new comment
+	 *
+	 * @param string $objectType e.g. "files"
+	 * @param string $objectId e.g. the file id
+	 * @param string $data JSON encoded string containing the properties of the tag to create
+	 * @param string $contentType content type of the data
+	 * @return IComment newly created comment
+	 *
+	 * @throws BadRequest if a field was missing
+	 * @throws UnsupportedMediaType if the content type is not supported
+	 */
+	private function createComment($objectType, $objectId, $data, $contentType = 'application/json') {
+		if (explode(';', $contentType)[0] === 'application/json') {
+			$data = json_decode($data, true);
+		} else {
+			throw new UnsupportedMediaType();
+		}
+
+		$actorType = $data['actorType'];
+		$actorId = null;
+		if($actorType === 'users') {
+			$user = $this->userSession->getUser();
+			if(!is_null($user)) {
+				$actorId = $user->getUID();
+			}
+		}
+		if(is_null($actorId)) {
+			throw new BadRequest('Invalid actor "' .  $actorType .'"');
+		}
+
+		try {
+			$comment = $this->commentsManager->create($actorType, $actorId, $objectType, $objectId);
+			$properties = [
+				'message' => 'setMessage',
+				'verb' => 'setVerb',
+			];
+			foreach($properties as $property => $setter) {
+				$comment->$setter($data[$property]);
+			}
+			$this->commentsManager->save($comment);
+			return $comment;
+		} catch (\InvalidArgumentException $e) {
+			throw new BadRequest('Invalid input values', 0, $e);
+		}
+	}
+
+
+
+}
diff --git a/apps/dav/lib/comments/entitycollection.php b/apps/dav/lib/comments/entitycollection.php
new file mode 100644
index 0000000000..a93569f6e4
--- /dev/null
+++ b/apps/dav/lib/comments/entitycollection.php
@@ -0,0 +1,148 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Comments;
+
+use OCP\Comments\ICommentsManager;
+use OCP\Files\Folder;
+use OCP\ILogger;
+use OCP\IUserManager;
+use Sabre\DAV\Exception\NotFound;
+
+/**
+ * Class EntityCollection
+ *
+ * this represents a specific holder of comments, identified by an entity type
+ * (class member $name) and an entity id (class member $id).
+ *
+ * @package OCA\DAV\Comments
+ */
+class EntityCollection extends RootCollection {
+	/** @var  Folder */
+	protected $fileRoot;
+
+	/** @var  string */
+	protected $id;
+
+	/** @var  ILogger */
+	protected $logger;
+
+	/**
+	 * @param string $id
+	 * @param string $name
+	 * @param ICommentsManager $commentsManager
+	 * @param Folder $fileRoot
+	 * @param IUserManager $userManager
+	 * @param ILogger $logger
+	 */
+	public function __construct(
+		$id,
+		$name,
+		ICommentsManager $commentsManager,
+		Folder $fileRoot,
+		IUserManager $userManager,
+		ILogger $logger
+	) {
+		foreach(['id', 'name'] as $property) {
+			$$property = trim($$property);
+			if(empty($$property) || !is_string($$property)) {
+				throw new \InvalidArgumentException('"' . $property . '" parameter must be non-empty string');
+			}
+		}
+		$this->id = $id;
+		$this->name = $name;
+		$this->commentsManager = $commentsManager;
+		$this->fileRoot = $fileRoot;
+		$this->logger = $logger;
+		$this->userManager = $userManager;
+	}
+
+	/**
+	 * returns the ID of this entity
+	 *
+	 * @return string
+	 */
+	public function getId() {
+		return $this->id;
+	}
+
+	/**
+	 * Returns a specific child node, referenced by its name
+	 *
+	 * This method must throw Sabre\DAV\Exception\NotFound if the node does not
+	 * exist.
+	 *
+	 * @param string $name
+	 * @return \Sabre\DAV\INode
+	 * @throws NotFound
+	 */
+	function getChild($name) {
+		try {
+			$comment = $this->commentsManager->get($name);
+			return new CommentNode($this->commentsManager, $comment, $this->userManager, $this->logger);
+		} catch (\OCP\Comments\NotFoundException $e) {
+			throw new NotFound();
+		}
+	}
+
+	/**
+	 * Returns an array with all the child nodes
+	 *
+	 * @return \Sabre\DAV\INode[]
+	 */
+	function getChildren() {
+		return $this->findChildren();
+	}
+
+	/**
+	 * Returns an array of comment nodes. Result can be influenced by offset,
+	 * limit and date time parameters.
+	 *
+	 * @param int $limit
+	 * @param int $offset
+	 * @param \DateTime|null $datetime
+	 * @return CommentNode[]
+	 */
+	function findChildren($limit = 0, $offset = 0, \DateTime $datetime = null) {
+		$comments = $this->commentsManager->getForObject($this->name, $this->id, $limit, $offset, $datetime);
+		$result = [];
+		foreach($comments as $comment) {
+			$result[] = new CommentNode($this->commentsManager, $comment, $this->userManager, $this->logger);
+		}
+		return $result;
+	}
+
+	/**
+	 * Checks if a child-node with the specified name exists
+	 *
+	 * @param string $name
+	 * @return bool
+	 */
+	function childExists($name) {
+		try {
+			$this->commentsManager->get($name);
+			return true;
+		} catch (\OCP\Comments\NotFoundException $e) {
+			return false;
+		}
+	}
+}
+
diff --git a/apps/dav/lib/comments/entitytypecollection.php b/apps/dav/lib/comments/entitytypecollection.php
new file mode 100644
index 0000000000..544838b89e
--- /dev/null
+++ b/apps/dav/lib/comments/entitytypecollection.php
@@ -0,0 +1,120 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Comments;
+
+use OCP\Comments\ICommentsManager;
+use OCP\Files\Folder;
+use OCP\ILogger;
+use OCP\IUserManager;
+use Sabre\DAV\Exception\Forbidden;
+use Sabre\DAV\Exception\MethodNotAllowed;
+
+/**
+ * Class EntityTypeCollection
+ *
+ * This is collection on the type of things a user can leave comments on, for
+ * example: 'files'.
+ *
+ * Its children are instances of EntityCollection (representing a specific
+ * object, for example the file by id).
+ *
+ * @package OCA\DAV\Comments
+ */
+class EntityTypeCollection extends RootCollection {
+	/** @var  Folder */
+	protected $fileRoot;
+
+	/** @var ILogger */
+	protected $logger;
+
+	/**
+	 * @param string $name
+	 * @param ICommentsManager $commentsManager
+	 * @param Folder $fileRoot
+	 * @param IUserManager $userManager
+	 * @param ILogger $logger
+	 */
+	public function __construct(
+		$name,
+		ICommentsManager $commentsManager,
+		Folder $fileRoot,
+		IUserManager $userManager,
+		ILogger $logger
+	) {
+		$name = trim($name);
+		if(empty($name) || !is_string($name)) {
+			throw new \InvalidArgumentException('"name" parameter must be non-empty string');
+		}
+		$this->name = $name;
+		$this->commentsManager = $commentsManager;
+		$this->fileRoot = $fileRoot;
+		$this->logger = $logger;
+		$this->userManager = $userManager;
+	}
+
+	/**
+	 * Returns a specific child node, referenced by its name
+	 *
+	 * This method must throw Sabre\DAV\Exception\NotFound if the node does not
+	 * exist.
+	 *
+	 * @param string $name
+	 * @return \Sabre\DAV\INode
+	 * @throws Forbidden
+	 */
+	function getChild($name) {
+		if(!$this->childExists($name)) {
+			throw new Forbidden('Entity does not exist or is not available');
+		}
+		return new EntityCollection(
+			$name,
+			$this->name,
+			$this->commentsManager,
+			$this->fileRoot,
+			$this->userManager,
+			$this->logger
+		);
+	}
+
+	/**
+	 * Returns an array with all the child nodes
+	 *
+	 * @return \Sabre\DAV\INode[]
+	 * @throws MethodNotAllowed
+	 */
+	function getChildren() {
+		throw new MethodNotAllowed('No permission to list folder contents');
+	}
+
+	/**
+	 * Checks if a child-node with the specified name exists
+	 *
+	 * @param string $name
+	 * @return bool
+	 */
+	function childExists($name) {
+		$nodes = $this->fileRoot->getById($name);
+		return !empty($nodes);
+	}
+
+
+}
diff --git a/apps/dav/lib/comments/rootcollection.php b/apps/dav/lib/comments/rootcollection.php
new file mode 100644
index 0000000000..aec8e65566
--- /dev/null
+++ b/apps/dav/lib/comments/rootcollection.php
@@ -0,0 +1,204 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Comments;
+
+use OCP\Comments\ICommentsManager;
+use OCP\Files\IRootFolder;
+use OCP\ILogger;
+use OCP\IUserManager;
+use OCP\IUserSession;
+use Sabre\DAV\Exception\NotAuthenticated;
+use Sabre\DAV\Exception\Forbidden;
+use Sabre\DAV\Exception\NotFound;
+use Sabre\DAV\ICollection;
+
+class RootCollection implements ICollection {
+
+	/** @var EntityTypeCollection[] */
+	private $entityTypeCollections = [];
+
+	/** @var ICommentsManager */
+	protected $commentsManager;
+
+	/** @var string */
+	protected $name = 'comments';
+
+	/** @var ILogger */
+	protected $logger;
+
+	/** @var IUserManager */
+	protected $userManager;
+	/**
+	 * @var IUserSession
+	 */
+	protected $userSession;
+	/**
+	 * @var IRootFolder
+	 */
+	protected $rootFolder;
+
+	/**
+	 * @param ICommentsManager $commentsManager
+	 * @param IUserManager $userManager
+	 * @param IUserSession $userSession
+	 * @param IRootFolder $rootFolder
+	 * @param ILogger $logger
+	 */
+	public function __construct(
+		ICommentsManager $commentsManager,
+		IUserManager $userManager,
+		IUserSession $userSession,
+		IRootFolder $rootFolder,
+		ILogger $logger)
+	{
+		$this->commentsManager = $commentsManager;
+		$this->logger = $logger;
+		$this->userManager = $userManager;
+		$this->userSession = $userSession;
+		$this->rootFolder = $rootFolder;
+	}
+
+	/**
+	 * initializes the collection. At this point of time, we need the logged in
+	 * user. Since it is not the case when the instance is created, we cannot
+	 * have this in the constructor.
+	 *
+	 * @throws NotAuthenticated
+	 */
+	protected function initCollections() {
+		if(!empty($this->entityTypeCollections)) {
+			return;
+		}
+		$user = $this->userSession->getUser();
+		if(is_null($user)) {
+			throw new NotAuthenticated();
+		}
+		$userFolder = $this->rootFolder->getUserFolder($user->getUID());
+		$this->entityTypeCollections['files'] = new EntityTypeCollection(
+			'files',
+			$this->commentsManager,
+			$userFolder,
+			$this->userManager,
+			$this->logger
+		);
+	}
+
+	/**
+	 * Creates a new file in the directory
+	 *
+	 * @param string $name Name of the file
+	 * @param resource|string $data Initial payload
+	 * @return null|string
+	 * @throws Forbidden
+	 */
+	function createFile($name, $data = null) {
+		throw new Forbidden('Cannot create comments by id');
+	}
+
+	/**
+	 * Creates a new subdirectory
+	 *
+	 * @param string $name
+	 * @throws Forbidden
+	 */
+	function createDirectory($name) {
+		throw new Forbidden('Permission denied to create collections');
+	}
+
+	/**
+	 * Returns a specific child node, referenced by its name
+	 *
+	 * This method must throw Sabre\DAV\Exception\NotFound if the node does not
+	 * exist.
+	 *
+	 * @param string $name
+	 * @return \Sabre\DAV\INode
+	 * @throws NotFound
+	 */
+	function getChild($name) {
+		$this->initCollections();
+		if(isset($this->entityTypeCollections[$name])) {
+			return $this->entityTypeCollections[$name];
+		}
+		throw new NotFound('Entity type "' . $name . '" not found."');
+	}
+
+	/**
+	 * Returns an array with all the child nodes
+	 *
+	 * @return \Sabre\DAV\INode[]
+	 */
+	function getChildren() {
+		$this->initCollections();
+		return $this->entityTypeCollections;
+	}
+
+	/**
+	 * Checks if a child-node with the specified name exists
+	 *
+	 * @param string $name
+	 * @return bool
+	 */
+	function childExists($name) {
+		$this->initCollections();
+		return isset($this->entityTypeCollections[$name]);
+	}
+
+	/**
+	 * Deleted the current node
+	 *
+	 * @throws Forbidden
+	 */
+	function delete() {
+		throw new Forbidden('Permission denied to delete this collection');
+	}
+
+	/**
+	 * Returns the name of the node.
+	 *
+	 * This is used to generate the url.
+	 *
+	 * @return string
+	 */
+	function getName() {
+		return $this->name;
+	}
+
+	/**
+	 * Renames the node
+	 *
+	 * @param string $name The new name
+	 * @throws Forbidden
+	 */
+	function setName($name) {
+		throw new Forbidden('Permission denied to rename this collection');
+	}
+
+	/**
+	 * Returns the last modification time, as a unix timestamp
+	 *
+	 * @return int
+	 */
+	function getLastModified() {
+		return null;
+	}
+}
diff --git a/apps/dav/lib/rootcollection.php b/apps/dav/lib/rootcollection.php
index bfd1aefb05..b7c2995dba 100644
--- a/apps/dav/lib/rootcollection.php
+++ b/apps/dav/lib/rootcollection.php
@@ -70,6 +70,13 @@ class RootCollection extends SimpleCollection {
 			\OC::$server->getUserSession(),
 			\OC::$server->getGroupManager()
 		);
+		$commentsCollection = new Comments\RootCollection(
+			\OC::$server->getCommentsManager(),
+			\OC::$server->getUserManager(),
+			\OC::$server->getUserSession(),
+			\OC::$server->getRootFolder(),
+			\OC::$server->getLogger()
+		);
 
 		$usersCardDavBackend = new CardDavBackend($db, $userPrincipalBackend);
 		$usersAddressBookRoot = new AddressBookRoot($userPrincipalBackend, $usersCardDavBackend, 'principals/users');
@@ -91,6 +98,7 @@ class RootCollection extends SimpleCollection {
 						$systemAddressBookRoot]),
 				$systemTagCollection,
 				$systemTagRelationsCollection,
+				$commentsCollection,
 		];
 
 		parent::__construct('root', $children);
diff --git a/apps/dav/lib/server.php b/apps/dav/lib/server.php
index 78867ad2f4..a0ba9c1aa9 100644
--- a/apps/dav/lib/server.php
+++ b/apps/dav/lib/server.php
@@ -90,6 +90,12 @@ class Server {
 		// system tags plugins
 		$this->server->addPlugin(new \OCA\DAV\SystemTag\SystemTagPlugin(\OC::$server->getSystemTagManager()));
 
+		// comments plugin
+		$this->server->addPlugin(new \OCA\DAV\Comments\CommentsPlugin(
+			\OC::$server->getCommentsManager(),
+			\OC::$server->getUserSession()
+		));
+
 		// Finder on OS X requires Class 2 WebDAV support (locking), since we do
 		// not provide locking we emulate it using a fake locking plugin.
 		if($request->isUserAgent(['/WebDAVFS/'])) {
diff --git a/apps/dav/tests/unit/comments/commentnode.php b/apps/dav/tests/unit/comments/commentnode.php
new file mode 100644
index 0000000000..b224bee909
--- /dev/null
+++ b/apps/dav/tests/unit/comments/commentnode.php
@@ -0,0 +1,215 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Tests\Unit\Comments;
+
+use OCA\DAV\Comments\CommentNode;
+
+class CommentsNode extends \Test\TestCase {
+
+	protected $commentsManager;
+	protected $comment;
+	protected $node;
+	protected $userManager;
+	protected $logger;
+
+	public function setUp() {
+		parent::setUp();
+
+		$this->commentsManager = $this->getMock('\OCP\Comments\ICommentsManager');
+		$this->comment = $this->getMock('\OCP\Comments\IComment');
+		$this->userManager = $this->getMock('\OCP\IUserManager');
+		$this->logger = $this->getMock('\OCP\ILogger');
+
+		$this->node = new CommentNode($this->commentsManager, $this->comment, $this->userManager, $this->logger);
+	}
+
+	public function testDelete() {
+		$this->comment->expects($this->once())
+			->method('getId')
+			->will($this->returnValue('19'));
+
+		$this->commentsManager->expects($this->once())
+			->method('delete')
+			->with('19');
+
+		$this->node->delete();
+	}
+
+	public function testGetName() {
+		$id = '19';
+		$this->comment->expects($this->once())
+			->method('getId')
+			->will($this->returnValue($id));
+
+		$this->assertSame($this->node->getName(), $id);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\MethodNotAllowed
+	 */
+	public function testSetName() {
+		$this->node->setName('666');
+	}
+
+	public function testGetLastModified() {
+		$dateTime = new \DateTime('2016-01-10 18:48:00');
+		$this->comment->expects($this->once())
+			->method('getCreationDateTime')
+			->will($this->returnValue($dateTime));
+
+		$this->assertSame($this->node->getLastModified(), $dateTime->getTimestamp());
+	}
+
+	public function testUpdateComment() {
+		$msg = 'Hello Earth';
+
+		$this->comment->expects($this->once())
+			->method('setMessage')
+			->with($msg);
+
+		$this->commentsManager->expects($this->once())
+			->method('save')
+			->with($this->comment);
+
+		$this->assertTrue($this->node->updateComment($msg));
+	}
+
+	public function testUpdateCommentException() {
+		$msg = null;
+
+		$this->comment->expects($this->once())
+			->method('setMessage')
+			->with($msg)
+			->will($this->throwException(new \Exception('buh!')));
+
+		$this->commentsManager->expects($this->never())
+			->method('save');
+
+		$this->logger->expects($this->once())
+			->method('logException');
+
+		$this->assertFalse($this->node->updateComment($msg));
+	}
+
+	public function testPropPatch() {
+		$propPatch = $this->getMockBuilder('Sabre\DAV\PropPatch')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$propPatch->expects($this->once())
+			->method('handle')
+			->with('{http://owncloud.org/ns}message');
+
+		$propPatch->expects($this->once())
+			->method('commit');
+
+		$this->node->propPatch($propPatch);
+	}
+
+	public function testGetProperties() {
+		$ns = '{http://owncloud.org/ns}';
+		$expected = [
+			$ns . 'id' => '123',
+			$ns . 'parentId' => '12',
+			$ns . 'topmostParentId' => '2',
+			$ns . 'childrenCount' => 3,
+			$ns . 'message' => 'such a nice file you have…',
+			$ns . 'verb' => 'comment',
+			$ns . 'actorType' => 'users',
+			$ns . 'actorId' => 'alice',
+			$ns . 'actorDisplayName' => 'Alice of Wonderland',
+			$ns . 'creationDateTime' => new \DateTime('2016-01-10 18:48:00'),
+			$ns . 'latestChildDateTime' => new \DateTime('2016-01-12 18:48:00'),
+			$ns . 'objectType' => 'files',
+			$ns . 'objectId' => '1848',
+		];
+
+		$this->comment->expects($this->once())
+			->method('getId')
+			->will($this->returnValue($expected[$ns . 'id']));
+
+		$this->comment->expects($this->once())
+			->method('getParentId')
+			->will($this->returnValue($expected[$ns . 'parentId']));
+
+		$this->comment->expects($this->once())
+			->method('getTopmostParentId')
+			->will($this->returnValue($expected[$ns . 'topmostParentId']));
+
+		$this->comment->expects($this->once())
+			->method('getChildrenCount')
+			->will($this->returnValue($expected[$ns . 'childrenCount']));
+
+		$this->comment->expects($this->once())
+			->method('getMessage')
+			->will($this->returnValue($expected[$ns . 'message']));
+
+		$this->comment->expects($this->once())
+			->method('getVerb')
+			->will($this->returnValue($expected[$ns . 'verb']));
+
+		$this->comment->expects($this->exactly(2))
+			->method('getActorType')
+			->will($this->returnValue($expected[$ns . 'actorType']));
+
+		$this->comment->expects($this->exactly(2))
+			->method('getActorId')
+			->will($this->returnValue($expected[$ns . 'actorId']));
+
+		$this->comment->expects($this->once())
+			->method('getCreationDateTime')
+			->will($this->returnValue($expected[$ns . 'creationDateTime']));
+
+		$this->comment->expects($this->once())
+			->method('getLatestChildDateTime')
+			->will($this->returnValue($expected[$ns . 'latestChildDateTime']));
+
+		$this->comment->expects($this->once())
+			->method('getObjectType')
+			->will($this->returnValue($expected[$ns . 'objectType']));
+
+		$this->comment->expects($this->once())
+			->method('getObjectId')
+			->will($this->returnValue($expected[$ns . 'objectId']));
+
+		$user = $this->getMockBuilder('\OCP\IUser')
+			->disableOriginalConstructor()
+			->getMock();
+		$user->expects($this->once())
+			->method('getDisplayName')
+			->will($this->returnValue($expected[$ns . 'actorDisplayName']));
+
+		$this->userManager->expects($this->once())
+			->method('get')
+			->with('alice')
+			->will($this->returnValue($user));
+
+		$properties = $this->node->getProperties(null);
+
+		foreach($properties as $name => $value) {
+			$this->assertTrue(isset($expected[$name]));
+			$this->assertSame($expected[$name], $value);
+			unset($expected[$name]);
+		}
+		$this->assertTrue(empty($expected));
+	}
+}
diff --git a/apps/dav/tests/unit/comments/commentsplugin.php b/apps/dav/tests/unit/comments/commentsplugin.php
new file mode 100644
index 0000000000..5fcccab90b
--- /dev/null
+++ b/apps/dav/tests/unit/comments/commentsplugin.php
@@ -0,0 +1,631 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Tests\Unit\Comments;
+
+use OC\Comments\Comment;
+use OCA\DAV\Comments\CommentsPlugin as CommentsPluginImplementation;
+
+class CommentsPlugin extends \Test\TestCase {
+	/** @var \Sabre\DAV\Server */
+	private $server;
+
+	/** @var \Sabre\DAV\Tree */
+	private $tree;
+
+	/** @var \OCP\Comments\ICommentsManager */
+	private $commentsManager;
+
+	/** @var  \OCP\IUserSession */
+	private $userSession;
+
+	/** @var CommentsPluginImplementation */
+	private $plugin;
+
+	public function setUp() {
+		parent::setUp();
+		$this->tree = $this->getMockBuilder('\Sabre\DAV\Tree')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$this->server = $this->getMockBuilder('\Sabre\DAV\Server')
+			->setConstructorArgs([$this->tree])
+			->setMethods(['getRequestUri'])
+			->getMock();
+
+		$this->commentsManager = $this->getMock('\OCP\Comments\ICommentsManager');
+		$this->userSession = $this->getMock('\OCP\IUserSession');
+
+		$this->plugin = new CommentsPluginImplementation($this->commentsManager, $this->userSession);
+	}
+
+	public function testCreateComment() {
+		$commentData = [
+			'actorType' => 'users',
+			'verb' => 'comment',
+			'message' => 'my first comment',
+		];
+
+		$comment = new Comment([
+			'objectType' => 'files',
+			'objectId' => '42',
+			'actorType' => 'users',
+			'actorId' => 'alice'
+		] + $commentData);
+		$comment->setId('23');
+
+		$path = 'comments/files/42';
+
+		$requestData = json_encode($commentData);
+
+		$user = $this->getMock('OCP\IUser');
+		$user->expects($this->once())
+			->method('getUID')
+			->will($this->returnValue('alice'));
+
+		$node = $this->getMockBuilder('\OCA\DAV\Comments\EntityCollection')
+			->disableOriginalConstructor()
+			->getMock();
+		$node->expects($this->once())
+			->method('getName')
+			->will($this->returnValue('files'));
+		$node->expects($this->once())
+			->method('getId')
+			->will($this->returnValue('42'));
+
+		$this->commentsManager->expects($this->once())
+			->method('create')
+			->with('users', 'alice', 'files', '42')
+			->will($this->returnValue($comment));
+
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->will($this->returnValue($user));
+
+		// technically, this is a shortcut. Inbetween EntityTypeCollection would
+		// be returned, but doing it exactly right would not be really
+		// unit-testing like, as it would require to haul in a lot of other
+		// things.
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->returnValue($node));
+
+		$request = $this->getMockBuilder('Sabre\HTTP\RequestInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$response = $this->getMockBuilder('Sabre\HTTP\ResponseInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$request->expects($this->once())
+			->method('getPath')
+			->will($this->returnValue('/' . $path));
+
+		$request->expects($this->once())
+			->method('getBodyAsString')
+			->will($this->returnValue($requestData));
+
+		$request->expects($this->once())
+			->method('getHeader')
+			->with('Content-Type')
+			->will($this->returnValue('application/json'));
+
+		$request->expects($this->once())
+			->method('getUrl')
+			->will($this->returnValue('http://example.com/dav/' . $path));
+
+		$response->expects($this->once())
+			->method('setHeader')
+			->with('Content-Location', 'http://example.com/dav/' . $path . '/23');
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->httpPost($request, $response);
+	}
+
+	public function testCreateCommentInvalidObject() {
+		$commentData = [
+			'actorType' => 'users',
+			'verb' => 'comment',
+			'message' => 'my first comment',
+		];
+
+		$comment = new Comment([
+				'objectType' => 'files',
+				'objectId' => '666',
+				'actorType' => 'users',
+				'actorId' => 'alice'
+			] + $commentData);
+		$comment->setId('23');
+
+		$path = 'comments/files/666';
+
+		$user = $this->getMock('OCP\IUser');
+		$user->expects($this->never())
+			->method('getUID');
+
+		$node = $this->getMockBuilder('\OCA\DAV\Comments\EntityCollection')
+			->disableOriginalConstructor()
+			->getMock();
+		$node->expects($this->never())
+			->method('getName');
+		$node->expects($this->never())
+			->method('getId');
+
+		$this->commentsManager->expects($this->never())
+			->method('create');
+
+		$this->userSession->expects($this->never())
+			->method('getUser');
+
+		// technically, this is a shortcut. Inbetween EntityTypeCollection would
+		// be returned, but doing it exactly right would not be really
+		// unit-testing like, as it would require to haul in a lot of other
+		// things.
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->throwException(new \Sabre\DAV\Exception\NotFound()));
+
+		$request = $this->getMockBuilder('Sabre\HTTP\RequestInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$response = $this->getMockBuilder('Sabre\HTTP\ResponseInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$request->expects($this->once())
+			->method('getPath')
+			->will($this->returnValue('/' . $path));
+
+		$request->expects($this->never())
+			->method('getBodyAsString');
+
+		$request->expects($this->never())
+			->method('getHeader')
+			->with('Content-Type');
+
+		$request->expects($this->never())
+			->method('getUrl');
+
+		$response->expects($this->never())
+			->method('setHeader');
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->httpPost($request, $response);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\BadRequest
+	 */
+	public function testCreateCommentInvalidActor() {
+		$commentData = [
+			'actorType' => 'robots',
+			'verb' => 'comment',
+			'message' => 'my first comment',
+		];
+
+		$comment = new Comment([
+				'objectType' => 'files',
+				'objectId' => '42',
+				'actorType' => 'users',
+				'actorId' => 'alice'
+			] + $commentData);
+		$comment->setId('23');
+
+		$path = 'comments/files/42';
+
+		$requestData = json_encode($commentData);
+
+		$user = $this->getMock('OCP\IUser');
+		$user->expects($this->never())
+			->method('getUID');
+
+		$node = $this->getMockBuilder('\OCA\DAV\Comments\EntityCollection')
+			->disableOriginalConstructor()
+			->getMock();
+		$node->expects($this->once())
+			->method('getName')
+			->will($this->returnValue('files'));
+		$node->expects($this->once())
+			->method('getId')
+			->will($this->returnValue('42'));
+
+		$this->commentsManager->expects($this->never())
+			->method('create');
+
+		$this->userSession->expects($this->never())
+			->method('getUser');
+
+		// technically, this is a shortcut. Inbetween EntityTypeCollection would
+		// be returned, but doing it exactly right would not be really
+		// unit-testing like, as it would require to haul in a lot of other
+		// things.
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->returnValue($node));
+
+		$request = $this->getMockBuilder('Sabre\HTTP\RequestInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$response = $this->getMockBuilder('Sabre\HTTP\ResponseInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$request->expects($this->once())
+			->method('getPath')
+			->will($this->returnValue('/' . $path));
+
+		$request->expects($this->once())
+			->method('getBodyAsString')
+			->will($this->returnValue($requestData));
+
+		$request->expects($this->once())
+			->method('getHeader')
+			->with('Content-Type')
+			->will($this->returnValue('application/json'));
+
+		$request->expects($this->never())
+			->method('getUrl');
+
+		$response->expects($this->never())
+			->method('setHeader');
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->httpPost($request, $response);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\UnsupportedMediaType
+	 */
+	public function testCreateCommentUnsupportedMediaType() {
+		$commentData = [
+			'actorType' => 'users',
+			'verb' => 'comment',
+			'message' => 'my first comment',
+		];
+
+		$comment = new Comment([
+				'objectType' => 'files',
+				'objectId' => '42',
+				'actorType' => 'users',
+				'actorId' => 'alice'
+			] + $commentData);
+		$comment->setId('23');
+
+		$path = 'comments/files/42';
+
+		$requestData = json_encode($commentData);
+
+		$user = $this->getMock('OCP\IUser');
+		$user->expects($this->never())
+			->method('getUID');
+
+		$node = $this->getMockBuilder('\OCA\DAV\Comments\EntityCollection')
+			->disableOriginalConstructor()
+			->getMock();
+		$node->expects($this->once())
+			->method('getName')
+			->will($this->returnValue('files'));
+		$node->expects($this->once())
+			->method('getId')
+			->will($this->returnValue('42'));
+
+		$this->commentsManager->expects($this->never())
+			->method('create');
+
+		$this->userSession->expects($this->never())
+			->method('getUser');
+
+		// technically, this is a shortcut. Inbetween EntityTypeCollection would
+		// be returned, but doing it exactly right would not be really
+		// unit-testing like, as it would require to haul in a lot of other
+		// things.
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->returnValue($node));
+
+		$request = $this->getMockBuilder('Sabre\HTTP\RequestInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$response = $this->getMockBuilder('Sabre\HTTP\ResponseInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$request->expects($this->once())
+			->method('getPath')
+			->will($this->returnValue('/' . $path));
+
+		$request->expects($this->once())
+			->method('getBodyAsString')
+			->will($this->returnValue($requestData));
+
+		$request->expects($this->once())
+			->method('getHeader')
+			->with('Content-Type')
+			->will($this->returnValue('application/trumpscript'));
+
+		$request->expects($this->never())
+			->method('getUrl');
+
+		$response->expects($this->never())
+			->method('setHeader');
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->httpPost($request, $response);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\BadRequest
+	 */
+	public function testCreateCommentInvalidPayload() {
+		$commentData = [
+			'actorType' => 'users',
+			'verb' => '',
+			'message' => '',
+		];
+
+		$comment = new Comment([
+				'objectType' => 'files',
+				'objectId' => '42',
+				'actorType' => 'users',
+				'actorId' => 'alice',
+				'message' => 'dummy',
+				'verb' => 'dummy'
+			]);
+		$comment->setId('23');
+
+		$path = 'comments/files/42';
+
+		$requestData = json_encode($commentData);
+
+		$user = $this->getMock('OCP\IUser');
+		$user->expects($this->once())
+			->method('getUID')
+			->will($this->returnValue('alice'));
+
+		$node = $this->getMockBuilder('\OCA\DAV\Comments\EntityCollection')
+			->disableOriginalConstructor()
+			->getMock();
+		$node->expects($this->once())
+			->method('getName')
+			->will($this->returnValue('files'));
+		$node->expects($this->once())
+			->method('getId')
+			->will($this->returnValue('42'));
+
+		$this->commentsManager->expects($this->once())
+			->method('create')
+			->with('users', 'alice', 'files', '42')
+			->will($this->returnValue($comment));
+
+		$this->commentsManager->expects($this->any())
+			->method('setMessage')
+			->with('')
+			->will($this->throwException(new \InvalidArgumentException()));
+
+		$this->commentsManager->expects($this->any())
+			->method('setVerb')
+			->with('')
+			->will($this->throwException(new \InvalidArgumentException()));
+
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->will($this->returnValue($user));
+
+		// technically, this is a shortcut. Inbetween EntityTypeCollection would
+		// be returned, but doing it exactly right would not be really
+		// unit-testing like, as it would require to haul in a lot of other
+		// things.
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->returnValue($node));
+
+		$request = $this->getMockBuilder('Sabre\HTTP\RequestInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$response = $this->getMockBuilder('Sabre\HTTP\ResponseInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$request->expects($this->once())
+			->method('getPath')
+			->will($this->returnValue('/' . $path));
+
+		$request->expects($this->once())
+			->method('getBodyAsString')
+			->will($this->returnValue($requestData));
+
+		$request->expects($this->once())
+			->method('getHeader')
+			->with('Content-Type')
+			->will($this->returnValue('application/json'));
+
+		$request->expects($this->never())
+			->method('getUrl');
+
+		$response->expects($this->never())
+			->method('setHeader');
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->httpPost($request, $response);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\ReportNotSupported
+	 */
+	public function testOnReportInvalidNode() {
+		$path = 'totally/unrelated/13';
+
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->returnValue($this->getMock('\Sabre\DAV\INode')));
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->onReport('', [], '/' . $path);
+	}
+
+	public function testOnReportDateTimeEmpty() {
+		$path = 'comments/files/42';
+
+		$parameters = [
+			[
+				'name'  => '{http://owncloud.org/ns}limit',
+				'value' => 5,
+			],
+			[
+				'name'  => '{http://owncloud.org/ns}offset',
+				'value' => 10,
+			],
+			[
+				'name' => '{http://owncloud.org/ns}datetime',
+				'value' => '',
+			]
+		];
+
+		$node = $this->getMockBuilder('\OCA\DAV\Comments\EntityCollection')
+			->disableOriginalConstructor()
+			->getMock();
+		$node->expects($this->once())
+			->method('findChildren')
+			->with(5, 10, null)
+			->will($this->returnValue([]));
+
+		$response = $this->getMockBuilder('Sabre\HTTP\ResponseInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$response->expects($this->once())
+			->method('setHeader')
+			->with('Content-Type', 'application/xml; charset=utf-8');
+
+		$response->expects($this->once())
+			->method('setStatus')
+			->with(207);
+
+		$response->expects($this->once())
+			->method('setBody');
+
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->returnValue($node));
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->server->httpResponse = $response;
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->onReport('', $parameters, '/' . $path);
+	}
+
+	public function testOnReport() {
+		$path = 'comments/files/42';
+
+		$parameters = [
+			[
+				'name'  => '{http://owncloud.org/ns}limit',
+				'value' => 5,
+			],
+			[
+				'name'  => '{http://owncloud.org/ns}offset',
+				'value' => 10,
+			],
+			[
+				'name' => '{http://owncloud.org/ns}datetime',
+				'value' => '2016-01-10 18:48:00',
+			]
+		];
+
+		$node = $this->getMockBuilder('\OCA\DAV\Comments\EntityCollection')
+			->disableOriginalConstructor()
+			->getMock();
+		$node->expects($this->once())
+			->method('findChildren')
+			->with(5, 10, new \DateTime($parameters[2]['value']))
+			->will($this->returnValue([]));
+
+		$response = $this->getMockBuilder('Sabre\HTTP\ResponseInterface')
+			->disableOriginalConstructor()
+			->getMock();
+
+		$response->expects($this->once())
+			->method('setHeader')
+			->with('Content-Type', 'application/xml; charset=utf-8');
+
+		$response->expects($this->once())
+			->method('setStatus')
+			->with(207);
+
+		$response->expects($this->once())
+			->method('setBody');
+
+		$this->tree->expects($this->any())
+			->method('getNodeForPath')
+			->with('/' . $path)
+			->will($this->returnValue($node));
+
+		$this->server->expects($this->any())
+			->method('getRequestUri')
+			->will($this->returnValue($path));
+		$this->server->httpResponse = $response;
+		$this->plugin->initialize($this->server);
+
+		$this->plugin->onReport('', $parameters, '/' . $path);
+	}
+
+
+
+}
diff --git a/apps/dav/tests/unit/comments/entitycollection.php b/apps/dav/tests/unit/comments/entitycollection.php
new file mode 100644
index 0000000000..81442c7a87
--- /dev/null
+++ b/apps/dav/tests/unit/comments/entitycollection.php
@@ -0,0 +1,113 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Tests\Unit\Comments;
+
+class EntityCollection extends \Test\TestCase {
+
+	protected $commentsManager;
+	protected $folder;
+	protected $userManager;
+	protected $logger;
+	protected $collection;
+
+	public function setUp() {
+		parent::setUp();
+
+		$this->commentsManager = $this->getMock('\OCP\Comments\ICommentsManager');
+		$this->folder = $this->getMock('\OCP\Files\Folder');
+		$this->userManager = $this->getMock('\OCP\IUserManager');
+		$this->logger = $this->getMock('\OCP\ILogger');
+
+		$this->collection = new \OCA\DAV\Comments\EntityCollection(
+			'19',
+			'files',
+			$this->commentsManager,
+			$this->folder,
+			$this->userManager,
+			$this->logger
+		);
+	}
+
+	public function testGetId() {
+		$this->assertSame($this->collection->getId(), '19');
+	}
+
+	public function testGetChild() {
+		$this->commentsManager->expects($this->once())
+			->method('get')
+			->with('55')
+			->will($this->returnValue($this->getMock('\OCP\Comments\IComment')));
+
+		$node = $this->collection->getChild('55');
+		$this->assertTrue($node instanceof \OCA\DAV\Comments\CommentNode);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\NotFound
+	 */
+	public function testGetChildException() {
+		$this->commentsManager->expects($this->once())
+			->method('get')
+			->with('55')
+			->will($this->throwException(new \OCP\Comments\NotFoundException()));
+
+		$this->collection->getChild('55');
+	}
+
+	public function testGetChildren() {
+		$this->commentsManager->expects($this->once())
+			->method('getForObject')
+			->with('files', '19')
+			->will($this->returnValue([$this->getMock('\OCP\Comments\IComment')]));
+
+		$result = $this->collection->getChildren();
+
+		$this->assertSame(count($result), 1);
+		$this->assertTrue($result[0] instanceof \OCA\DAV\Comments\CommentNode);
+	}
+
+	public function testFindChildren() {
+		$dt = new \DateTime('2016-01-10 18:48:00');
+		$this->commentsManager->expects($this->once())
+			->method('getForObject')
+			->with('files', '19', 5, 15, $dt)
+			->will($this->returnValue([$this->getMock('\OCP\Comments\IComment')]));
+
+		$result = $this->collection->findChildren(5, 15, $dt);
+
+		$this->assertSame(count($result), 1);
+		$this->assertTrue($result[0] instanceof \OCA\DAV\Comments\CommentNode);
+	}
+
+	public function testChildExistsTrue() {
+		$this->assertTrue($this->collection->childExists('44'));
+	}
+
+	public function testChildExistsFalse() {
+		$this->commentsManager->expects($this->once())
+			->method('get')
+			->with('44')
+			->will($this->throwException(new \OCP\Comments\NotFoundException()));
+
+		$this->assertFalse($this->collection->childExists('44'));
+	}
+}
diff --git a/apps/dav/tests/unit/comments/entitytypecollection.php b/apps/dav/tests/unit/comments/entitytypecollection.php
new file mode 100644
index 0000000000..72e90a5713
--- /dev/null
+++ b/apps/dav/tests/unit/comments/entitytypecollection.php
@@ -0,0 +1,94 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Tests\Unit\Comments;
+
+use OCA\DAV\Comments\EntityCollection as EntityCollectionImplemantation;
+
+class EntityTypeCollection extends \Test\TestCase {
+
+	protected $commentsManager;
+	protected $folder;
+	protected $userManager;
+	protected $logger;
+	protected $collection;
+
+	public function setUp() {
+		parent::setUp();
+
+		$this->commentsManager = $this->getMock('\OCP\Comments\ICommentsManager');
+		$this->folder = $this->getMock('\OCP\Files\Folder');
+		$this->userManager = $this->getMock('\OCP\IUserManager');
+		$this->logger = $this->getMock('\OCP\ILogger');
+
+		$this->collection = new \OCA\DAV\Comments\EntityTypeCollection(
+			'files',
+			$this->commentsManager,
+			$this->folder,
+			$this->userManager,
+			$this->logger
+		);
+	}
+
+	public function testChildExistsYes() {
+		$this->folder->expects($this->once())
+			->method('getById')
+			->with('17')
+			->will($this->returnValue([$this->getMock('\OCP\Files\Node')]));
+		$this->assertTrue($this->collection->childExists('17'));
+	}
+
+	public function testChildExistsNo() {
+		$this->folder->expects($this->once())
+			->method('getById')
+			->will($this->returnValue([]));
+		$this->assertFalse($this->collection->childExists('17'));
+	}
+
+	public function testGetChild() {
+		$this->folder->expects($this->once())
+			->method('getById')
+			->with('17')
+			->will($this->returnValue([$this->getMock('\OCP\Files\Node')]));
+
+		$ec = $this->collection->getChild('17');
+		$this->assertTrue($ec instanceof EntityCollectionImplemantation);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\Forbidden
+	 */
+	public function testGetChildException() {
+		$this->folder->expects($this->once())
+			->method('getById')
+			->with('17')
+			->will($this->returnValue([]));
+
+		$this->collection->getChild('17');
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\MethodNotAllowed
+	 */
+	public function testGetChildren() {
+		$this->collection->getChildren();
+	}
+}
diff --git a/apps/dav/tests/unit/comments/rootcollection.php b/apps/dav/tests/unit/comments/rootcollection.php
new file mode 100644
index 0000000000..369006e715
--- /dev/null
+++ b/apps/dav/tests/unit/comments/rootcollection.php
@@ -0,0 +1,160 @@
+<?php
+/**
+ * @author Arthur Schiwon <blizzz@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\Tests\Unit\Comments;
+
+use OCA\DAV\Comments\EntityTypeCollection as EntityTypeCollectionImplementation;
+
+class RootCollection extends \Test\TestCase {
+
+	protected $commentsManager;
+	protected $userManager;
+	protected $logger;
+	protected $collection;
+	protected $userSession;
+	protected $rootFolder;
+	protected $user;
+
+	public function setUp() {
+		parent::setUp();
+
+		$this->user = $this->getMock('\OCP\IUser');
+
+		$this->commentsManager = $this->getMock('\OCP\Comments\ICommentsManager');
+		$this->userManager = $this->getMock('\OCP\IUserManager');
+		$this->userSession = $this->getMock('\OCP\IUserSession');
+		$this->rootFolder = $this->getMock('\OCP\Files\IRootFolder');
+		$this->logger = $this->getMock('\OCP\ILogger');
+
+		$this->collection = new \OCA\DAV\Comments\RootCollection(
+			$this->commentsManager,
+			$this->userManager,
+			$this->userSession,
+			$this->rootFolder,
+			$this->logger
+		);
+	}
+
+	protected function prepareForInitCollections() {
+		$this->user->expects($this->any())
+			->method('getUID')
+			->will($this->returnValue('alice'));
+
+		$this->userSession->expects($this->once())
+			->method('getUser')
+			->will($this->returnValue($this->user));
+
+		$this->rootFolder->expects($this->once())
+			->method('getUserFolder')
+			->with('alice')
+			->will($this->returnValue($this->getMock('\OCP\Files\Folder')));
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\Forbidden
+	 */
+	public function testCreateFile() {
+		$this->collection->createFile('foo');
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\Forbidden
+	 */
+	public function testCreateDirectory() {
+		$this->collection->createDirectory('foo');
+	}
+
+	public function testGetChild() {
+		$this->prepareForInitCollections();
+		$etc = $this->collection->getChild('files');
+		$this->assertTrue($etc instanceof EntityTypeCollectionImplementation);
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\NotFound
+	 */
+	public function testGetChildInvalid() {
+		$this->prepareForInitCollections();
+		$this->collection->getChild('robots');
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\NotAuthenticated
+	 */
+	public function testGetChildNoAuth() {
+		$this->collection->getChild('files');
+	}
+
+	public function testGetChildren() {
+		$this->prepareForInitCollections();
+		$children = $this->collection->getChildren();
+		$this->assertFalse(empty($children));
+		foreach($children as $child) {
+			$this->assertTrue($child instanceof EntityTypeCollectionImplementation);
+		}
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\NotAuthenticated
+	 */
+	public function testGetChildrenNoAuth() {
+		$this->collection->getChildren();
+	}
+
+	public function testChildExistsYes() {
+		$this->prepareForInitCollections();
+		$this->assertTrue($this->collection->childExists('files'));
+	}
+
+	public function testChildExistsNo() {
+		$this->prepareForInitCollections();
+		$this->assertFalse($this->collection->childExists('robots'));
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\NotAuthenticated
+	 */
+	public function testChildExistsNoAuth() {
+		$this->collection->childExists('files');
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\Forbidden
+	 */
+	public function testDelete() {
+		$this->collection->delete();
+	}
+
+	public function testGetName() {
+		$this->assertSame('comments', $this->collection->getName());
+	}
+
+	/**
+	 * @expectedException \Sabre\DAV\Exception\Forbidden
+	 */
+	public function testSetName() {
+		$this->collection->setName('foobar');
+	}
+
+	public function testGetLastModified() {
+		$this->assertSame(null, $this->collection->getLastModified());
+	}
+}
diff --git a/lib/private/comments/comment.php b/lib/private/comments/comment.php
index 1e1514a587..75964603f9 100644
--- a/lib/private/comments/comment.php
+++ b/lib/private/comments/comment.php
@@ -284,9 +284,9 @@ class Comment implements IComment {
 	}
 
 	/**
-	 * returns the timestamp of the most recent child
+	 * returns the DateTime of the most recent child, if set, otherwise null
 	 *
-	 * @return int
+	 * @return \DateTime|null
 	 * @since 9.0.0
 	 */
 	public function getLatestChildDateTime() {
diff --git a/lib/private/comments/manager.php b/lib/private/comments/manager.php
index 64013a9e11..64977c4889 100644
--- a/lib/private/comments/manager.php
+++ b/lib/private/comments/manager.php
@@ -58,7 +58,9 @@ class Manager implements ICommentsManager {
 		$data['parent_id'] = strval($data['parent_id']);
 		$data['topmost_parent_id'] = strval($data['topmost_parent_id']);
 		$data['creation_timestamp'] = new \DateTime($data['creation_timestamp']);
-		$data['latest_child_timestamp'] = new \DateTime($data['latest_child_timestamp']);
+		if (!is_null($data['latest_child_timestamp'])) {
+			$data['latest_child_timestamp'] = new \DateTime($data['latest_child_timestamp']);
+		}
 		$data['children_count'] = intval($data['children_count']);
 		return $data;
 	}