diff --git a/src/Module/Followers.php b/src/Module/Followers.php
index 98e9f1e0e..56160aecf 100644
--- a/src/Module/Followers.php
+++ b/src/Module/Followers.php
@@ -29,7 +29,7 @@ class Followers extends BaseModule
 
 		$page = defaults($_REQUEST, 'page', null);
 
-		$followers = ActivityPub::getFollowers($owner, $page);
+		$followers = ActivityPub\Transmitter::getFollowers($owner, $page);
 
 		header('Content-Type: application/activity+json');
 		echo json_encode($followers);
diff --git a/src/Module/Following.php b/src/Module/Following.php
index 6023db4cb..71e6613f0 100644
--- a/src/Module/Following.php
+++ b/src/Module/Following.php
@@ -29,7 +29,7 @@ class Following extends BaseModule
 
 		$page = defaults($_REQUEST, 'page', null);
 
-		$Following = ActivityPub::getFollowing($owner, $page);
+		$Following = ActivityPub\Transmitter::getFollowing($owner, $page);
 
 		header('Content-Type: application/activity+json');
 		echo json_encode($Following);
diff --git a/src/Module/Outbox.php b/src/Module/Outbox.php
index f6bad56dd..681d1cccb 100644
--- a/src/Module/Outbox.php
+++ b/src/Module/Outbox.php
@@ -29,7 +29,7 @@ class Outbox extends BaseModule
 
 		$page = defaults($_REQUEST, 'page', null);
 
-		$outbox = ActivityPub::getOutbox($owner, $page);
+		$outbox = ActivityPub\Transmitter::getOutbox($owner, $page);
 
 		header('Content-Type: application/activity+json');
 		echo json_encode($outbox);
diff --git a/src/Protocol/ActivityPub.php b/src/Protocol/ActivityPub.php
index ef4a48479..a9f3217f9 100644
--- a/src/Protocol/ActivityPub.php
+++ b/src/Protocol/ActivityPub.php
@@ -92,148 +92,6 @@ class ActivityPub
 			stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
 	}
 
-	/**
-	 * @brief collects the lost of followers of the given owner
-	 *
-	 * @param array $owner Owner array
-	 * @param integer $page Page number
-	 *
-	 * @return array of owners
-	 */
-	public static function getFollowers($owner, $page = null)
-	{
-		$condition = ['rel' => [Contact::FOLLOWER, Contact::FRIEND], 'network' => Protocol::NATIVE_SUPPORT, 'uid' => $owner['uid'],
-			'self' => false, 'hidden' => false, 'archive' => false, 'pending' => false];
-		$count = DBA::count('contact', $condition);
-
-		$data = ['@context' => self::CONTEXT];
-		$data['id'] = System::baseUrl() . '/followers/' . $owner['nickname'];
-		$data['type'] = 'OrderedCollection';
-		$data['totalItems'] = $count;
-
-		// When we hide our friends we will only show the pure number but don't allow more.
-		$profile = Profile::getByUID($owner['uid']);
-		if (!empty($profile['hide-friends'])) {
-			return $data;
-		}
-
-		if (empty($page)) {
-			$data['first'] = System::baseUrl() . '/followers/' . $owner['nickname'] . '?page=1';
-		} else {
-			$list = [];
-
-			$contacts = DBA::select('contact', ['url'], $condition, ['limit' => [($page - 1) * 100, 100]]);
-			while ($contact = DBA::fetch($contacts)) {
-				$list[] = $contact['url'];
-			}
-
-			if (!empty($list)) {
-				$data['next'] = System::baseUrl() . '/followers/' . $owner['nickname'] . '?page=' . ($page + 1);
-			}
-
-			$data['partOf'] = System::baseUrl() . '/followers/' . $owner['nickname'];
-
-			$data['orderedItems'] = $list;
-		}
-
-		return $data;
-	}
-
-	/**
-	 * @brief Create list of following contacts
-	 *
-	 * @param array $owner Owner array
-	 * @param integer $page Page numbe
-	 *
-	 * @return array of following contacts
-	 */
-	public static function getFollowing($owner, $page = null)
-	{
-		$condition = ['rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::NATIVE_SUPPORT, 'uid' => $owner['uid'],
-			'self' => false, 'hidden' => false, 'archive' => false, 'pending' => false];
-		$count = DBA::count('contact', $condition);
-
-		$data = ['@context' => self::CONTEXT];
-		$data['id'] = System::baseUrl() . '/following/' . $owner['nickname'];
-		$data['type'] = 'OrderedCollection';
-		$data['totalItems'] = $count;
-
-		// When we hide our friends we will only show the pure number but don't allow more.
-		$profile = Profile::getByUID($owner['uid']);
-		if (!empty($profile['hide-friends'])) {
-			return $data;
-		}
-
-		if (empty($page)) {
-			$data['first'] = System::baseUrl() . '/following/' . $owner['nickname'] . '?page=1';
-		} else {
-			$list = [];
-
-			$contacts = DBA::select('contact', ['url'], $condition, ['limit' => [($page - 1) * 100, 100]]);
-			while ($contact = DBA::fetch($contacts)) {
-				$list[] = $contact['url'];
-			}
-
-			if (!empty($list)) {
-				$data['next'] = System::baseUrl() . '/following/' . $owner['nickname'] . '?page=' . ($page + 1);
-			}
-
-			$data['partOf'] = System::baseUrl() . '/following/' . $owner['nickname'];
-
-			$data['orderedItems'] = $list;
-		}
-
-		return $data;
-	}
-
-	/**
-	 * @brief Public posts for the given owner
-	 *
-	 * @param array $owner Owner array
-	 * @param integer $page Page numbe
-	 *
-	 * @return array of posts
-	 */
-	public static function getOutbox($owner, $page = null)
-	{
-		$public_contact = Contact::getIdForURL($owner['url'], 0, true);
-
-		$condition = ['uid' => $owner['uid'], 'contact-id' => $owner['id'], 'author-id' => $public_contact,
-			'wall' => true, 'private' => false, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT],
-			'deleted' => false, 'visible' => true];
-		$count = DBA::count('item', $condition);
-
-		$data = ['@context' => self::CONTEXT];
-		$data['id'] = System::baseUrl() . '/outbox/' . $owner['nickname'];
-		$data['type'] = 'OrderedCollection';
-		$data['totalItems'] = $count;
-
-		if (empty($page)) {
-			$data['first'] = System::baseUrl() . '/outbox/' . $owner['nickname'] . '?page=1';
-		} else {
-			$list = [];
-
-			$condition['parent-network'] = Protocol::NATIVE_SUPPORT;
-
-			$items = Item::select(['id'], $condition, ['limit' => [($page - 1) * 20, 20], 'order' => ['created' => true]]);
-			while ($item = Item::fetch($items)) {
-				$object = self::createObjectFromItemID($item['id']);
-				unset($object['@context']);
-				$list[] = $object;
-			}
-
-			if (!empty($list)) {
-				$data['next'] = System::baseUrl() . '/outbox/' . $owner['nickname'] . '?page=' . ($page + 1);
-			}
-
-			$data['partOf'] = System::baseUrl() . '/outbox/' . $owner['nickname'];
-
-			$data['orderedItems'] = $list;
-		}
-
-		return $data;
-	}
-
 	/**
 	 * Return the ActivityPub profile of the given user
 	 *
diff --git a/src/Protocol/ActivityPub/Processor.php b/src/Protocol/ActivityPub/Processor.php
new file mode 100644
index 000000000..bbf4d7b80
--- /dev/null
+++ b/src/Protocol/ActivityPub/Processor.php
@@ -0,0 +1,476 @@
+<?php
+/**
+ * @file src/Protocol/ActivityPub.php
+ */
+namespace Friendica\Protocol\ActivityPub;
+
+use Friendica\Database\DBA;
+use Friendica\Core\System;
+use Friendica\BaseObject;
+use Friendica\Util\Network;
+use Friendica\Util\HTTPSignature;
+use Friendica\Core\Protocol;
+use Friendica\Model\Conversation;
+use Friendica\Model\Contact;
+use Friendica\Model\APContact;
+use Friendica\Model\Item;
+use Friendica\Model\Profile;
+use Friendica\Model\Term;
+use Friendica\Model\User;
+use Friendica\Util\DateTimeFormat;
+use Friendica\Util\Crypto;
+use Friendica\Content\Text\BBCode;
+use Friendica\Content\Text\HTML;
+use Friendica\Util\JsonLD;
+use Friendica\Util\LDSignature;
+use Friendica\Core\Config;
+use Friendica\Protocol\ActivityPub;
+
+/**
+ * @brief ActivityPub Protocol class
+ */
+class Processor
+{
+	/**
+	 * @brief Converts mentions from Pleroma into the Friendica format
+	 *
+	 * @param string $body
+	 *
+	 * @return converted body
+	 */
+	private static function convertMentions($body)
+	{
+		$URLSearchString = "^\[\]";
+		$body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
+
+		return $body;
+	}
+
+	/**
+	 * @brief Constructs a string with tags for a given tag array
+	 *
+	 * @param array $tags
+	 * @param boolean $sensitive
+	 *
+	 * @return string with tags
+	 */
+	private static function constructTagList($tags, $sensitive)
+	{
+		if (empty($tags)) {
+			return '';
+		}
+
+		$tag_text = '';
+		foreach ($tags as $tag) {
+			if (in_array($tag['type'], ['Mention', 'Hashtag'])) {
+				if (!empty($tag_text)) {
+					$tag_text .= ',';
+				}
+
+				$tag_text .= substr($tag['name'], 0, 1) . '[url=' . $tag['href'] . ']' . substr($tag['name'], 1) . '[/url]';
+			}
+		}
+
+		/// @todo add nsfw for $sensitive
+
+		return $tag_text;
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $attachments
+	 * @param array $item
+	 *
+	 * @return item array
+	 */
+	private static function constructAttachList($attachments, $item)
+	{
+		if (empty($attachments)) {
+			return $item;
+		}
+
+		foreach ($attachments as $attach) {
+			$filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
+			if ($filetype == 'image') {
+				$item['body'] .= "\n[img]".$attach['url'].'[/img]';
+			} else {
+				if (!empty($item["attach"])) {
+					$item["attach"] .= ',';
+				} else {
+					$item["attach"] = '';
+				}
+				if (!isset($attach['length'])) {
+					$attach['length'] = "0";
+				}
+				$item["attach"] .= '[attach]href="'.$attach['url'].'" length="'.$attach['length'].'" type="'.$attach['mediaType'].'" title="'.defaults($attach, 'name', '').'"[/attach]';
+			}
+		}
+
+		return $item;
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param array $activity
+	 * @param $body
+	 */
+	private static function createItem($activity, $body)
+	{
+		$item = [];
+		$item['verb'] = ACTIVITY_POST;
+		$item['parent-uri'] = $activity['reply-to-id'];
+
+		if ($activity['reply-to-id'] == $activity['id']) {
+			$item['gravity'] = GRAVITY_PARENT;
+			$item['object-type'] = ACTIVITY_OBJ_NOTE;
+		} else {
+			$item['gravity'] = GRAVITY_COMMENT;
+			$item['object-type'] = ACTIVITY_OBJ_COMMENT;
+		}
+
+		if (($activity['id'] != $activity['reply-to-id']) && !Item::exists(['uri' => $activity['reply-to-id']])) {
+			logger('Parent ' . $activity['reply-to-id'] . ' not found. Try to refetch it.');
+			self::fetchMissingActivity($activity['reply-to-id'], $activity);
+		}
+
+		self::postItem($activity, $item, $body);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param array $activity
+	 * @param $body
+	 */
+	private static function likeItem($activity, $body)
+	{
+		$item = [];
+		$item['verb'] = ACTIVITY_LIKE;
+		$item['parent-uri'] = $activity['object'];
+		$item['gravity'] = GRAVITY_ACTIVITY;
+		$item['object-type'] = ACTIVITY_OBJ_NOTE;
+
+		self::postItem($activity, $item, $body);
+	}
+
+	/**
+	 * @brief Delete items
+	 *
+	 * @param array $activity
+	 * @param $body
+	 */
+	private static function deleteItem($activity)
+	{
+		$owner = Contact::getIdForURL($activity['owner']);
+		$object = JsonLD::fetchElement($activity, 'object', 'id');
+		logger('Deleting item ' . $object . ' from ' . $owner, LOGGER_DEBUG);
+		Item::delete(['uri' => $object, 'owner-id' => $owner]);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param array $activity
+	 * @param $body
+	 */
+	private static function dislikeItem($activity, $body)
+	{
+		$item = [];
+		$item['verb'] = ACTIVITY_DISLIKE;
+		$item['parent-uri'] = $activity['object'];
+		$item['gravity'] = GRAVITY_ACTIVITY;
+		$item['object-type'] = ACTIVITY_OBJ_NOTE;
+
+		self::postItem($activity, $item, $body);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param array $activity
+	 * @param array $item
+	 * @param $body
+	 */
+	private static function postItem($activity, $item, $body)
+	{
+		/// @todo What to do with $activity['context']?
+
+		if (($item['gravity'] != GRAVITY_PARENT) && !Item::exists(['uri' => $item['parent-uri']])) {
+			logger('Parent ' . $item['parent-uri'] . ' not found, message will be discarded.', LOGGER_DEBUG);
+			return;
+		}
+
+		$item['network'] = Protocol::ACTIVITYPUB;
+		$item['private'] = !in_array(0, $activity['receiver']);
+		$item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
+		$item['owner-id'] = Contact::getIdForURL($activity['owner'], 0, true);
+		$item['uri'] = $activity['id'];
+		$item['created'] = $activity['published'];
+		$item['edited'] = $activity['updated'];
+		$item['guid'] = $activity['diaspora:guid'];
+		$item['title'] = HTML::toBBCode($activity['name']);
+		$item['content-warning'] = HTML::toBBCode($activity['summary']);
+		$item['body'] = self::convertMentions(HTML::toBBCode($activity['content']));
+		$item['location'] = $activity['location'];
+		$item['tag'] = self::constructTagList($activity['tags'], $activity['sensitive']);
+		$item['app'] = $activity['service'];
+		$item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
+
+		$item = self::constructAttachList($activity['attachments'], $item);
+
+		$source = JsonLD::fetchElement($activity, 'source', 'content', 'mediaType', 'text/bbcode');
+		if (!empty($source)) {
+			$item['body'] = $source;
+		}
+
+		$item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
+		$item['source'] = $body;
+		$item['conversation-href'] = $activity['context'];
+		$item['conversation-uri'] = $activity['conversation'];
+
+		foreach ($activity['receiver'] as $receiver) {
+			$item['uid'] = $receiver;
+			$item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
+
+			if (($receiver != 0) && empty($item['contact-id'])) {
+				$item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
+			}
+
+			$item_id = Item::insert($item);
+			logger('Storing for user ' . $item['uid'] . ': ' . $item_id);
+		}
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $url
+	 * @param $child
+	 */
+	private static function fetchMissingActivity($url, $child)
+	{
+		if (Config::get('system', 'ostatus_full_threads')) {
+			return;
+		}
+
+		$object = ActivityPub::fetchContent($url);
+		if (empty($object)) {
+			logger('Activity ' . $url . ' was not fetchable, aborting.');
+			return;
+		}
+
+		$activity = [];
+		$activity['@context'] = $object['@context'];
+		unset($object['@context']);
+		$activity['id'] = $object['id'];
+		$activity['to'] = defaults($object, 'to', []);
+		$activity['cc'] = defaults($object, 'cc', []);
+		$activity['actor'] = $child['author'];
+		$activity['object'] = $object;
+		$activity['published'] = $object['published'];
+		$activity['type'] = 'Create';
+
+		ActivityPub::processActivity($activity);
+		logger('Activity ' . $url . ' had been fetched and processed.');
+	}
+
+	/**
+	 * @brief perform a "follow" request
+	 *
+	 * @param array $activity
+	 */
+	private static function followUser($activity)
+	{
+		$actor = JsonLD::fetchElement($activity, 'object', 'id');
+		$uid = User::getIdForURL($actor);
+		if (empty($uid)) {
+			return;
+		}
+
+		$owner = User::getOwnerDataById($uid);
+
+		$cid = Contact::getIdForURL($activity['owner'], $uid);
+		if (!empty($cid)) {
+			$contact = DBA::selectFirst('contact', [], ['id' => $cid]);
+		} else {
+			$contact = false;
+		}
+
+		$item = ['author-id' => Contact::getIdForURL($activity['owner']),
+			'author-link' => $activity['owner']];
+
+		Contact::addRelationship($owner, $contact, $item);
+		$cid = Contact::getIdForURL($activity['owner'], $uid);
+		if (empty($cid)) {
+			return;
+		}
+
+		$contact = DBA::selectFirst('contact', ['network'], ['id' => $cid]);
+		if ($contact['network'] != Protocol::ACTIVITYPUB) {
+			Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
+		}
+
+		DBA::update('contact', ['hub-verify' => $activity['id']], ['id' => $cid]);
+		logger('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
+	}
+
+	/**
+	 * @brief Update the given profile
+	 *
+	 * @param array $activity
+	 */
+	private static function updatePerson($activity)
+	{
+		if (empty($activity['object']['id'])) {
+			return;
+		}
+
+		logger('Updating profile for ' . $activity['object']['id'], LOGGER_DEBUG);
+		APContact::getByURL($activity['object']['id'], true);
+	}
+
+	/**
+	 * @brief Delete the given profile
+	 *
+	 * @param array $activity
+	 */
+	private static function deletePerson($activity)
+	{
+		if (empty($activity['object']['id']) || empty($activity['object']['actor'])) {
+			logger('Empty object id or actor.', LOGGER_DEBUG);
+			return;
+		}
+
+		if ($activity['object']['id'] != $activity['object']['actor']) {
+			logger('Object id does not match actor.', LOGGER_DEBUG);
+			return;
+		}
+
+		$contacts = DBA::select('contact', ['id'], ['nurl' => normalise_link($activity['object']['id'])]);
+		while ($contact = DBA::fetch($contacts)) {
+			Contact::remove($contact["id"]);
+		}
+		DBA::close($contacts);
+
+		logger('Deleted contact ' . $activity['object']['id'], LOGGER_DEBUG);
+	}
+
+	/**
+	 * @brief Accept a follow request
+	 *
+	 * @param array $activity
+	 */
+	private static function acceptFollowUser($activity)
+	{
+		$actor = JsonLD::fetchElement($activity, 'object', 'actor');
+		$uid = User::getIdForURL($actor);
+		if (empty($uid)) {
+			return;
+		}
+
+		$owner = User::getOwnerDataById($uid);
+
+		$cid = Contact::getIdForURL($activity['owner'], $uid);
+		if (empty($cid)) {
+			logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
+			return;
+		}
+
+		$fields = ['pending' => false];
+
+		$contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
+		if ($contact['rel'] == Contact::FOLLOWER) {
+			$fields['rel'] = Contact::FRIEND;
+		}
+
+		$condition = ['id' => $cid];
+		DBA::update('contact', $fields, $condition);
+		logger('Accept contact request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
+	}
+
+	/**
+	 * @brief Reject a follow request
+	 *
+	 * @param array $activity
+	 */
+	private static function rejectFollowUser($activity)
+	{
+		$actor = JsonLD::fetchElement($activity, 'object', 'actor');
+		$uid = User::getIdForURL($actor);
+		if (empty($uid)) {
+			return;
+		}
+
+		$owner = User::getOwnerDataById($uid);
+
+		$cid = Contact::getIdForURL($activity['owner'], $uid);
+		if (empty($cid)) {
+			logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
+			return;
+		}
+
+		if (DBA::exists('contact', ['id' => $cid, 'rel' => Contact::SHARING, 'pending' => true])) {
+			Contact::remove($cid);
+			logger('Rejected contact request from contact ' . $cid . ' for user ' . $uid . ' - contact had been removed.', LOGGER_DEBUG);
+		} else {
+			logger('Rejected contact request from contact ' . $cid . ' for user ' . $uid . '.', LOGGER_DEBUG);
+		}
+	}
+
+	/**
+	 * @brief Undo activity like "like" or "dislike"
+	 *
+	 * @param array $activity
+	 */
+	private static function undoActivity($activity)
+	{
+		$activity_url = JsonLD::fetchElement($activity, 'object', 'id');
+		if (empty($activity_url)) {
+			return;
+		}
+
+		$actor = JsonLD::fetchElement($activity, 'object', 'actor');
+		if (empty($actor)) {
+			return;
+		}
+
+		$author_id = Contact::getIdForURL($actor);
+		if (empty($author_id)) {
+			return;
+		}
+
+		Item::delete(['uri' => $activity_url, 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
+	}
+
+	/**
+	 * @brief Activity to remove a follower
+	 *
+	 * @param array $activity
+	 */
+	private static function undoFollowUser($activity)
+	{
+		$object = JsonLD::fetchElement($activity, 'object', 'object');
+		$uid = User::getIdForURL($object);
+		if (empty($uid)) {
+			return;
+		}
+
+		$owner = User::getOwnerDataById($uid);
+
+		$cid = Contact::getIdForURL($activity['owner'], $uid);
+		if (empty($cid)) {
+			logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
+			return;
+		}
+
+		$contact = DBA::selectFirst('contact', [], ['id' => $cid]);
+		if (!DBA::isResult($contact)) {
+			return;
+		}
+
+		Contact::removeFollower($owner, $contact);
+		logger('Undo following request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
+	}
+}
diff --git a/src/Protocol/ActivityPub/Receiver.php b/src/Protocol/ActivityPub/Receiver.php
new file mode 100644
index 000000000..171771748
--- /dev/null
+++ b/src/Protocol/ActivityPub/Receiver.php
@@ -0,0 +1,596 @@
+<?php
+/**
+ * @file src/Protocol/ActivityPub.php
+ */
+namespace Friendica\Protocol\ActivityPub;
+
+use Friendica\Database\DBA;
+use Friendica\Core\System;
+use Friendica\BaseObject;
+use Friendica\Util\Network;
+use Friendica\Util\HTTPSignature;
+use Friendica\Core\Protocol;
+use Friendica\Model\Conversation;
+use Friendica\Model\Contact;
+use Friendica\Model\APContact;
+use Friendica\Model\Item;
+use Friendica\Model\Profile;
+use Friendica\Model\Term;
+use Friendica\Model\User;
+use Friendica\Util\DateTimeFormat;
+use Friendica\Util\Crypto;
+use Friendica\Content\Text\BBCode;
+use Friendica\Content\Text\HTML;
+use Friendica\Util\JsonLD;
+use Friendica\Util\LDSignature;
+use Friendica\Core\Config;
+use Friendica\Protocol\ActivityPub;
+
+/**
+ * @brief ActivityPub Protocol class
+ */
+class Receiver
+{
+	/**
+	 * @brief Checks if the web request is done for the AP protocol
+	 *
+	 * @return is it AP?
+	 */
+	public static function isRequest()
+	{
+		return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
+			stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $body
+	 * @param $header
+	 * @param integer $uid User ID
+	 */
+	public static function processInbox($body, $header, $uid)
+	{
+		$http_signer = HTTPSignature::getSigner($body, $header);
+		if (empty($http_signer)) {
+			logger('Invalid HTTP signature, message will be discarded.', LOGGER_DEBUG);
+			return;
+		} else {
+			logger('HTTP signature is signed by ' . $http_signer, LOGGER_DEBUG);
+		}
+
+		$activity = json_decode($body, true);
+
+		$actor = JsonLD::fetchElement($activity, 'actor', 'id');
+		logger('Message for user ' . $uid . ' is from actor ' . $actor, LOGGER_DEBUG);
+
+		if (empty($activity)) {
+			logger('Invalid body.', LOGGER_DEBUG);
+			return;
+		}
+
+		if (LDSignature::isSigned($activity)) {
+			$ld_signer = LDSignature::getSigner($activity);
+			if (empty($ld_signer)) {
+				logger('Invalid JSON-LD signature from ' . $actor, LOGGER_DEBUG);
+			}
+			if (!empty($ld_signer && ($actor == $http_signer))) {
+				logger('The HTTP and the JSON-LD signature belong to ' . $ld_signer, LOGGER_DEBUG);
+				$trust_source = true;
+			} elseif (!empty($ld_signer)) {
+				logger('JSON-LD signature is signed by ' . $ld_signer, LOGGER_DEBUG);
+				$trust_source = true;
+			} elseif ($actor == $http_signer) {
+				logger('Bad JSON-LD signature, but HTTP signer fits the actor.', LOGGER_DEBUG);
+				$trust_source = true;
+			} else {
+				logger('Invalid JSON-LD signature and the HTTP signer is different.', LOGGER_DEBUG);
+				$trust_source = false;
+			}
+		} elseif ($actor == $http_signer) {
+			logger('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', LOGGER_DEBUG);
+			$trust_source = true;
+		} else {
+			logger('No JSON-LD signature, different actor.', LOGGER_DEBUG);
+			$trust_source = false;
+		}
+
+		ActivityPub::processActivity($activity, $body, $uid, $trust_source);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param array $activity
+	 * @param integer $uid User ID
+	 * @param $trust_source
+	 *
+	 * @return 
+	 */
+	private static function prepareObjectData($activity, $uid, &$trust_source)
+	{
+		$actor = JsonLD::fetchElement($activity, 'actor', 'id');
+		if (empty($actor)) {
+			logger('Empty actor', LOGGER_DEBUG);
+			return [];
+		}
+
+		// Fetch all receivers from to, cc, bto and bcc
+		$receivers = ActivityPub::getReceivers($activity, $actor);
+
+		// When it is a delivery to a personal inbox we add that user to the receivers
+		if (!empty($uid)) {
+			$owner = User::getOwnerDataById($uid);
+			$additional = ['uid:' . $uid => $uid];
+			$receivers = array_merge($receivers, $additional);
+		}
+
+		logger('Receivers: ' . json_encode($receivers), LOGGER_DEBUG);
+
+		$object_id = JsonLD::fetchElement($activity, 'object', 'id');
+		if (empty($object_id)) {
+			logger('No object found', LOGGER_DEBUG);
+			return [];
+		}
+
+		// Fetch the content only on activities where this matters
+		if (in_array($activity['type'], ['Create', 'Announce'])) {
+			$object_data = ActivityPub::fetchObject($object_id, $activity['object'], $trust_source);
+			if (empty($object_data)) {
+				logger("Object data couldn't be processed", LOGGER_DEBUG);
+				return [];
+			}
+			// We had been able to retrieve the object data - so we can trust the source
+			$trust_source = true;
+		} elseif (in_array($activity['type'], ['Like', 'Dislike'])) {
+			// Create a mostly empty array out of the activity data (instead of the object).
+			// This way we later don't have to check for the existence of ech individual array element.
+			$object_data = ActivityPub::processObject($activity);
+			$object_data['name'] = $activity['type'];
+			$object_data['author'] = $activity['actor'];
+			$object_data['object'] = $object_id;
+			$object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
+		} else {
+			$object_data = [];
+			$object_data['id'] = $activity['id'];
+			$object_data['object'] = $activity['object'];
+			$object_data['object_type'] = JsonLD::fetchElement($activity, 'object', 'type');
+		}
+
+		$object_data = ActivityPub::addActivityFields($object_data, $activity);
+
+		$object_data['type'] = $activity['type'];
+		$object_data['owner'] = $actor;
+		$object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
+
+		logger('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], LOGGER_DEBUG);
+
+		return $object_data;
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param array $activity
+	 * @param $body
+	 * @param integer $uid User ID
+	 * @param $trust_source
+	 */
+	private static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
+	{
+		if (empty($activity['type'])) {
+			logger('Empty type', LOGGER_DEBUG);
+			return;
+		}
+
+		if (empty($activity['object'])) {
+			logger('Empty object', LOGGER_DEBUG);
+			return;
+		}
+
+		if (empty($activity['actor'])) {
+			logger('Empty actor', LOGGER_DEBUG);
+			return;
+
+		}
+
+		// $trust_source is called by reference and is set to true if the content was retrieved successfully
+		$object_data = ActivityPub::prepareObjectData($activity, $uid, $trust_source);
+		if (empty($object_data)) {
+			logger('No object data found', LOGGER_DEBUG);
+			return;
+		}
+
+		if (!$trust_source) {
+			logger('No trust for activity type "' . $activity['type'] . '", so we quit now.', LOGGER_DEBUG);
+		}
+
+		switch ($activity['type']) {
+			case 'Create':
+			case 'Announce':
+				ActivityPub::createItem($object_data, $body);
+				break;
+
+			case 'Like':
+				ActivityPub::likeItem($object_data, $body);
+				break;
+
+			case 'Dislike':
+				ActivityPub::dislikeItem($object_data, $body);
+				break;
+
+			case 'Update':
+				if (in_array($object_data['object_type'], ActivityPub::CONTENT_TYPES)) {
+					/// @todo
+				} elseif (in_array($object_data['object_type'], ActivityPub::ACCOUNT_TYPES)) {
+					ActivityPub::updatePerson($object_data, $body);
+				}
+				break;
+
+			case 'Delete':
+				if ($object_data['object_type'] == 'Tombstone') {
+					ActivityPub::deleteItem($object_data, $body);
+				} elseif (in_array($object_data['object_type'], ActivityPub::ACCOUNT_TYPES)) {
+					ActivityPub::deletePerson($object_data, $body);
+				}
+				break;
+
+			case 'Follow':
+				ActivityPub::followUser($object_data);
+				break;
+
+			case 'Accept':
+				if ($object_data['object_type'] == 'Follow') {
+					ActivityPub::acceptFollowUser($object_data);
+				}
+				break;
+
+			case 'Reject':
+				if ($object_data['object_type'] == 'Follow') {
+					ActivityPub::rejectFollowUser($object_data);
+				}
+				break;
+
+			case 'Undo':
+				if ($object_data['object_type'] == 'Follow') {
+					ActivityPub::undoFollowUser($object_data);
+				} elseif (in_array($object_data['object_type'], ActivityPub::ACTIVITY_TYPES)) {
+					ActivityPub::undoActivity($object_data);
+				}
+				break;
+
+			default:
+				logger('Unknown activity: ' . $activity['type'], LOGGER_DEBUG);
+				break;
+		}
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param array $activity
+	 * @param $actor
+	 *
+	 * @return 
+	 */
+	private static function getReceivers($activity, $actor)
+	{
+		$receivers = [];
+
+		// When it is an answer, we inherite the receivers from the parent
+		$replyto = JsonLD::fetchElement($activity, 'inReplyTo', 'id');
+		if (!empty($replyto)) {
+			$parents = Item::select(['uid'], ['uri' => $replyto]);
+			while ($parent = Item::fetch($parents)) {
+				$receivers['uid:' . $parent['uid']] = $parent['uid'];
+			}
+		}
+
+		if (!empty($actor)) {
+			$profile = APContact::getByURL($actor);
+			$followers = defaults($profile, 'followers', '');
+
+			logger('Actor: ' . $actor . ' - Followers: ' . $followers, LOGGER_DEBUG);
+		} else {
+			logger('Empty actor', LOGGER_DEBUG);
+			$followers = '';
+		}
+
+		foreach (['to', 'cc', 'bto', 'bcc'] as $element) {
+			if (empty($activity[$element])) {
+				continue;
+			}
+
+			// The receiver can be an array or a string
+			if (is_string($activity[$element])) {
+				$activity[$element] = [$activity[$element]];
+			}
+
+			foreach ($activity[$element] as $receiver) {
+				if ($receiver == ActivityPub::PUBLIC_COLLECTION) {
+					$receivers['uid:0'] = 0;
+				}
+
+				if (($receiver == ActivityPub::PUBLIC_COLLECTION) && !empty($actor)) {
+					// This will most likely catch all OStatus connections to Mastodon
+					$condition = ['alias' => [$actor, normalise_link($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
+						, 'archive' => false, 'pending' => false];
+					$contacts = DBA::select('contact', ['uid'], $condition);
+					while ($contact = DBA::fetch($contacts)) {
+						if ($contact['uid'] != 0) {
+							$receivers['uid:' . $contact['uid']] = $contact['uid'];
+						}
+					}
+					DBA::close($contacts);
+				}
+
+				if (in_array($receiver, [$followers, ActivityPub::PUBLIC_COLLECTION]) && !empty($actor)) {
+					$condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
+						'network' => Protocol::ACTIVITYPUB, 'archive' => false, 'pending' => false];
+					$contacts = DBA::select('contact', ['uid'], $condition);
+					while ($contact = DBA::fetch($contacts)) {
+						if ($contact['uid'] != 0) {
+							$receivers['uid:' . $contact['uid']] = $contact['uid'];
+						}
+					}
+					DBA::close($contacts);
+					continue;
+				}
+
+				$condition = ['self' => true, 'nurl' => normalise_link($receiver)];
+				$contact = DBA::selectFirst('contact', ['uid'], $condition);
+				if (!DBA::isResult($contact)) {
+					continue;
+				}
+				$receivers['uid:' . $contact['uid']] = $contact['uid'];
+			}
+		}
+
+		ActivityPub::switchContacts($receivers, $actor);
+
+		return $receivers;
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $cid
+	 * @param integer $uid User ID
+	 * @param $url
+	 */
+	private static function switchContact($cid, $uid, $url)
+	{
+		$profile = ActivityPub::probeProfile($url);
+		if (empty($profile)) {
+			return;
+		}
+
+		logger('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' from OStatus to ActivityPub');
+
+		$photo = $profile['photo'];
+		unset($profile['photo']);
+		unset($profile['baseurl']);
+
+		$profile['nurl'] = normalise_link($profile['url']);
+		DBA::update('contact', $profile, ['id' => $cid]);
+
+		Contact::updateAvatar($photo, $uid, $cid);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $receivers
+	 * @param $actor
+	 */
+	private static function switchContacts($receivers, $actor)
+	{
+		if (empty($actor)) {
+			return;
+		}
+
+		foreach ($receivers as $receiver) {
+			$contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => normalise_link($actor)]);
+			if (DBA::isResult($contact)) {
+				ActivityPub::switchContact($contact['id'], $receiver, $actor);
+			}
+
+			$contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [normalise_link($actor), $actor]]);
+			if (DBA::isResult($contact)) {
+				ActivityPub::switchContact($contact['id'], $receiver, $actor);
+			}
+		}
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $object_data
+	 * @param array $activity
+	 *
+	 * @return 
+	 */
+	private static function addActivityFields($object_data, $activity)
+	{
+		if (!empty($activity['published']) && empty($object_data['published'])) {
+			$object_data['published'] = $activity['published'];
+		}
+
+		if (!empty($activity['updated']) && empty($object_data['updated'])) {
+			$object_data['updated'] = $activity['updated'];
+		}
+
+		if (!empty($activity['inReplyTo']) && empty($object_data['parent-uri'])) {
+			$object_data['parent-uri'] = JsonLD::fetchElement($activity, 'inReplyTo', 'id');
+		}
+
+		if (!empty($activity['instrument'])) {
+			$object_data['service'] = JsonLD::fetchElement($activity, 'instrument', 'name', 'type', 'Service');
+		}
+		return $object_data;
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $object_id
+	 * @param $object
+	 * @param $trust_source
+	 *
+	 * @return 
+	 */
+	private static function fetchObject($object_id, $object = [], $trust_source = false)
+	{
+		if (!$trust_source || is_string($object)) {
+			$data = ActivityPub::fetchContent($object_id);
+			if (empty($data)) {
+				logger('Empty content for ' . $object_id . ', check if content is available locally.', LOGGER_DEBUG);
+				$data = $object_id;
+			} else {
+				logger('Fetched content for ' . $object_id, LOGGER_DEBUG);
+			}
+		} else {
+			logger('Using original object for url ' . $object_id, LOGGER_DEBUG);
+			$data = $object;
+		}
+
+		if (is_string($data)) {
+			$item = Item::selectFirst([], ['uri' => $data]);
+			if (!DBA::isResult($item)) {
+				logger('Object with url ' . $data . ' was not found locally.', LOGGER_DEBUG);
+				return false;
+			}
+			logger('Using already stored item for url ' . $object_id, LOGGER_DEBUG);
+			$data = ActivityPub::createNote($item);
+		}
+
+		if (empty($data['type'])) {
+			logger('Empty type', LOGGER_DEBUG);
+			return false;
+		}
+
+		if (in_array($data['type'], ActivityPub::CONTENT_TYPES)) {
+			return ActivityPub::processObject($data);
+		}
+
+		if ($data['type'] == 'Announce') {
+			if (empty($data['object'])) {
+				return false;
+			}
+			return ActivityPub::fetchObject($data['object']);
+		}
+
+		logger('Unhandled object type: ' . $data['type'], LOGGER_DEBUG);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $object
+	 *
+	 * @return 
+	 */
+	private static function processObject($object)
+	{
+		if (empty($object['id'])) {
+			return false;
+		}
+
+		$object_data = [];
+		$object_data['object_type'] = $object['type'];
+		$object_data['id'] = $object['id'];
+
+		if (!empty($object['inReplyTo'])) {
+			$object_data['reply-to-id'] = JsonLD::fetchElement($object, 'inReplyTo', 'id');
+		} else {
+			$object_data['reply-to-id'] = $object_data['id'];
+		}
+
+		$object_data['published'] = defaults($object, 'published', null);
+		$object_data['updated'] = defaults($object, 'updated', $object_data['published']);
+
+		if (empty($object_data['published']) && !empty($object_data['updated'])) {
+			$object_data['published'] = $object_data['updated'];
+		}
+
+		$actor = JsonLD::fetchElement($object, 'attributedTo', 'id');
+		if (empty($actor)) {
+			$actor = defaults($object, 'actor', null);
+		}
+
+		$object_data['diaspora:guid'] = defaults($object, 'diaspora:guid', null);
+		$object_data['owner'] = $object_data['author'] = $actor;
+		$object_data['context'] = defaults($object, 'context', null);
+		$object_data['conversation'] = defaults($object, 'conversation', null);
+		$object_data['sensitive'] = defaults($object, 'sensitive', null);
+		$object_data['name'] = defaults($object, 'title', null);
+		$object_data['name'] = defaults($object, 'name', $object_data['name']);
+		$object_data['summary'] = defaults($object, 'summary', null);
+		$object_data['content'] = defaults($object, 'content', null);
+		$object_data['source'] = defaults($object, 'source', null);
+		$object_data['location'] = JsonLD::fetchElement($object, 'location', 'name', 'type', 'Place');
+		$object_data['attachments'] = defaults($object, 'attachment', null);
+		$object_data['tags'] = defaults($object, 'tag', null);
+		$object_data['service'] = JsonLD::fetchElement($object, 'instrument', 'name', 'type', 'Service');
+		$object_data['alternate-url'] = JsonLD::fetchElement($object, 'url', 'href');
+		$object_data['receiver'] = ActivityPub::getReceivers($object, $object_data['owner']);
+
+		// Common object data:
+
+		// Unhandled
+		// @context, type, actor, signature, mediaType, duration, replies, icon
+
+		// Also missing: (Defined in the standard, but currently unused)
+		// audience, preview, endTime, startTime, generator, image
+
+		// Data in Notes:
+
+		// Unhandled
+		// contentMap, announcement_count, announcements, context_id, likes, like_count
+		// inReplyToStatusId, shares, quoteUrl, statusnetConversationId
+
+		// Data in video:
+
+		// To-Do?
+		// category, licence, language, commentsEnabled
+
+		// Unhandled
+		// views, waitTranscoding, state, support, subtitleLanguage
+		// likes, dislikes, shares, comments
+
+		return $object_data;
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param $url
+	 * @param $child
+	 */
+	private static function fetchMissingActivity($url, $child)
+	{
+		if (Config::get('system', 'ostatus_full_threads')) {
+			return;
+		}
+
+		$object = ActivityPub::fetchContent($url);
+		if (empty($object)) {
+			logger('Activity ' . $url . ' was not fetchable, aborting.');
+			return;
+		}
+
+		$activity = [];
+		$activity['@context'] = $object['@context'];
+		unset($object['@context']);
+		$activity['id'] = $object['id'];
+		$activity['to'] = defaults($object, 'to', []);
+		$activity['cc'] = defaults($object, 'cc', []);
+		$activity['actor'] = $child['author'];
+		$activity['object'] = $object;
+		$activity['published'] = $object['published'];
+		$activity['type'] = 'Create';
+
+		ActivityPub::processActivity($activity);
+		logger('Activity ' . $url . ' had been fetched and processed.');
+	}
+}
diff --git a/src/Protocol/ActivityPub/Transmitter.php b/src/Protocol/ActivityPub/Transmitter.php
new file mode 100644
index 000000000..7155d8309
--- /dev/null
+++ b/src/Protocol/ActivityPub/Transmitter.php
@@ -0,0 +1,831 @@
+<?php
+/**
+ * @file src/Protocol/ActivityPub/Transmitter.php
+ */
+namespace Friendica\Protocol\ActivityPub;
+
+use Friendica\Database\DBA;
+use Friendica\Core\System;
+use Friendica\BaseObject;
+use Friendica\Util\HTTPSignature;
+use Friendica\Core\Protocol;
+use Friendica\Model\Conversation;
+use Friendica\Model\Contact;
+use Friendica\Model\APContact;
+use Friendica\Model\Item;
+use Friendica\Model\Term;
+use Friendica\Model\User;
+use Friendica\Util\DateTimeFormat;
+use Friendica\Content\Text\BBCode;
+use Friendica\Util\JsonLD;
+use Friendica\Util\LDSignature;
+use Friendica\Protocol\ActivityPub;
+use Friendica\Model\Profile;
+
+/**
+ * @brief ActivityPub Transmitter Protocol class
+ */
+class Transmitter
+{
+	/**
+	 * @brief collects the lost of followers of the given owner
+	 *
+	 * @param array $owner Owner array
+	 * @param integer $page Page number
+	 *
+	 * @return array of owners
+	 */
+	public static function getFollowers($owner, $page = null)
+	{
+		$condition = ['rel' => [Contact::FOLLOWER, Contact::FRIEND], 'network' => Protocol::NATIVE_SUPPORT, 'uid' => $owner['uid'],
+			'self' => false, 'hidden' => false, 'archive' => false, 'pending' => false];
+		$count = DBA::count('contact', $condition);
+
+		$data = ['@context' => ActivityPub::CONTEXT];
+		$data['id'] = System::baseUrl() . '/followers/' . $owner['nickname'];
+		$data['type'] = 'OrderedCollection';
+		$data['totalItems'] = $count;
+
+		// When we hide our friends we will only show the pure number but don't allow more.
+		$profile = Profile::getByUID($owner['uid']);
+		if (!empty($profile['hide-friends'])) {
+			return $data;
+		}
+
+		if (empty($page)) {
+			$data['first'] = System::baseUrl() . '/followers/' . $owner['nickname'] . '?page=1';
+		} else {
+			$list = [];
+
+			$contacts = DBA::select('contact', ['url'], $condition, ['limit' => [($page - 1) * 100, 100]]);
+			while ($contact = DBA::fetch($contacts)) {
+				$list[] = $contact['url'];
+			}
+
+			if (!empty($list)) {
+				$data['next'] = System::baseUrl() . '/followers/' . $owner['nickname'] . '?page=' . ($page + 1);
+			}
+
+			$data['partOf'] = System::baseUrl() . '/followers/' . $owner['nickname'];
+
+			$data['orderedItems'] = $list;
+		}
+
+		return $data;
+	}
+
+	/**
+	 * @brief Create list of following contacts
+	 *
+	 * @param array $owner Owner array
+	 * @param integer $page Page numbe
+	 *
+	 * @return array of following contacts
+	 */
+	public static function getFollowing($owner, $page = null)
+	{
+		$condition = ['rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::NATIVE_SUPPORT, 'uid' => $owner['uid'],
+			'self' => false, 'hidden' => false, 'archive' => false, 'pending' => false];
+		$count = DBA::count('contact', $condition);
+
+		$data = ['@context' => ActivityPub::CONTEXT];
+		$data['id'] = System::baseUrl() . '/following/' . $owner['nickname'];
+		$data['type'] = 'OrderedCollection';
+		$data['totalItems'] = $count;
+
+		// When we hide our friends we will only show the pure number but don't allow more.
+		$profile = Profile::getByUID($owner['uid']);
+		if (!empty($profile['hide-friends'])) {
+			return $data;
+		}
+
+		if (empty($page)) {
+			$data['first'] = System::baseUrl() . '/following/' . $owner['nickname'] . '?page=1';
+		} else {
+			$list = [];
+
+			$contacts = DBA::select('contact', ['url'], $condition, ['limit' => [($page - 1) * 100, 100]]);
+			while ($contact = DBA::fetch($contacts)) {
+				$list[] = $contact['url'];
+			}
+
+			if (!empty($list)) {
+				$data['next'] = System::baseUrl() . '/following/' . $owner['nickname'] . '?page=' . ($page + 1);
+			}
+
+			$data['partOf'] = System::baseUrl() . '/following/' . $owner['nickname'];
+
+			$data['orderedItems'] = $list;
+		}
+
+		return $data;
+	}
+
+	/**
+	 * @brief Public posts for the given owner
+	 *
+	 * @param array $owner Owner array
+	 * @param integer $page Page numbe
+	 *
+	 * @return array of posts
+	 */
+	public static function getOutbox($owner, $page = null)
+	{
+		$public_contact = Contact::getIdForURL($owner['url'], 0, true);
+
+		$condition = ['uid' => $owner['uid'], 'contact-id' => $owner['id'], 'author-id' => $public_contact,
+			'wall' => true, 'private' => false, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT],
+			'deleted' => false, 'visible' => true];
+		$count = DBA::count('item', $condition);
+
+		$data = ['@context' => ActivityPub::CONTEXT];
+		$data['id'] = System::baseUrl() . '/outbox/' . $owner['nickname'];
+		$data['type'] = 'OrderedCollection';
+		$data['totalItems'] = $count;
+
+		if (empty($page)) {
+			$data['first'] = System::baseUrl() . '/outbox/' . $owner['nickname'] . '?page=1';
+		} else {
+			$list = [];
+
+			$condition['parent-network'] = Protocol::NATIVE_SUPPORT;
+
+			$items = Item::select(['id'], $condition, ['limit' => [($page - 1) * 20, 20], 'order' => ['created' => true]]);
+			while ($item = Item::fetch($items)) {
+				$object = self::createObjectFromItemID($item['id']);
+				unset($object['@context']);
+				$list[] = $object;
+			}
+
+			if (!empty($list)) {
+				$data['next'] = System::baseUrl() . '/outbox/' . $owner['nickname'] . '?page=' . ($page + 1);
+			}
+
+			$data['partOf'] = System::baseUrl() . '/outbox/' . $owner['nickname'];
+
+			$data['orderedItems'] = $list;
+		}
+
+		return $data;
+	}
+
+	/**
+	 * Return the ActivityPub profile of the given user
+	 *
+	 * @param integer $uid User ID
+	 * @return profile array
+	 */
+	public static function profile($uid)
+	{
+		$condition = ['uid' => $uid, 'blocked' => false, 'account_expired' => false,
+			'account_removed' => false, 'verified' => true];
+		$fields = ['guid', 'nickname', 'pubkey', 'account-type', 'page-flags'];
+		$user = DBA::selectFirst('user', $fields, $condition);
+		if (!DBA::isResult($user)) {
+			return [];
+		}
+
+		$fields = ['locality', 'region', 'country-name'];
+		$profile = DBA::selectFirst('profile', $fields, ['uid' => $uid, 'is-default' => true]);
+		if (!DBA::isResult($profile)) {
+			return [];
+		}
+
+		$fields = ['name', 'url', 'location', 'about', 'avatar'];
+		$contact = DBA::selectFirst('contact', $fields, ['uid' => $uid, 'self' => true]);
+		if (!DBA::isResult($contact)) {
+			return [];
+		}
+
+		$data = ['@context' => ActivityPub::CONTEXT];
+		$data['id'] = $contact['url'];
+		$data['diaspora:guid'] = $user['guid'];
+		$data['type'] = ActivityPub::ACCOUNT_TYPES[$user['account-type']];
+		$data['following'] = System::baseUrl() . '/following/' . $user['nickname'];
+		$data['followers'] = System::baseUrl() . '/followers/' . $user['nickname'];
+		$data['inbox'] = System::baseUrl() . '/inbox/' . $user['nickname'];
+		$data['outbox'] = System::baseUrl() . '/outbox/' . $user['nickname'];
+		$data['preferredUsername'] = $user['nickname'];
+		$data['name'] = $contact['name'];
+		$data['vcard:hasAddress'] = ['@type' => 'vcard:Home', 'vcard:country-name' => $profile['country-name'],
+			'vcard:region' => $profile['region'], 'vcard:locality' => $profile['locality']];
+		$data['summary'] = $contact['about'];
+		$data['url'] = $contact['url'];
+		$data['manuallyApprovesFollowers'] = in_array($user['page-flags'], [Contact::PAGE_NORMAL, Contact::PAGE_PRVGROUP]);
+		$data['publicKey'] = ['id' => $contact['url'] . '#main-key',
+			'owner' => $contact['url'],
+			'publicKeyPem' => $user['pubkey']];
+		$data['endpoints'] = ['sharedInbox' => System::baseUrl() . '/inbox'];
+		$data['icon'] = ['type' => 'Image',
+			'url' => $contact['avatar']];
+
+		// tags: https://kitty.town/@inmysocks/100656097926961126.json
+		return $data;
+	}
+
+	/**
+	 * @brief Returns an array with permissions of a given item array
+	 *
+	 * @param array $item
+	 *
+	 * @return array with permissions
+	 */
+	private static function fetchPermissionBlockFromConversation($item)
+	{
+		if (empty($item['thr-parent'])) {
+			return [];
+		}
+
+		$condition = ['item-uri' => $item['thr-parent'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
+		$conversation = DBA::selectFirst('conversation', ['source'], $condition);
+		if (!DBA::isResult($conversation)) {
+			return [];
+		}
+
+		$activity = json_decode($conversation['source'], true);
+
+		$actor = JsonLD::fetchElement($activity, 'actor', 'id');
+		$profile = APContact::getByURL($actor);
+
+		$item_profile = APContact::getByURL($item['author-link']);
+		$exclude[] = $item['author-link'];
+
+		if ($item['gravity'] == GRAVITY_PARENT) {
+			$exclude[] = $item['owner-link'];
+		}
+
+		$permissions['to'][] = $actor;
+
+		foreach (['to', 'cc', 'bto', 'bcc'] as $element) {
+			if (empty($activity[$element])) {
+				continue;
+			}
+			if (is_string($activity[$element])) {
+				$activity[$element] = [$activity[$element]];
+			}
+
+			foreach ($activity[$element] as $receiver) {
+				if ($receiver == $profile['followers'] && !empty($item_profile['followers'])) {
+					$receiver = $item_profile['followers'];
+				}
+				if (!in_array($receiver, $exclude)) {
+					$permissions[$element][] = $receiver;
+				}
+			}
+		}
+		return $permissions;
+	}
+
+	/**
+	 * @brief Creates an array of permissions from an item thread
+	 *
+	 * @param array $item
+	 *
+	 * @return permission array
+	 */
+	public static function createPermissionBlockForItem($item)
+	{
+		$data = ['to' => [], 'cc' => []];
+
+		$data = array_merge($data, self::fetchPermissionBlockFromConversation($item));
+
+		$actor_profile = APContact::getByURL($item['author-link']);
+
+		$terms = Term::tagArrayFromItemId($item['id'], TERM_MENTION);
+
+		$contacts[$item['author-link']] = $item['author-link'];
+
+		if (!$item['private']) {
+			$data['to'][] = ActivityPub::PUBLIC_COLLECTION;
+			if (!empty($actor_profile['followers'])) {
+				$data['cc'][] = $actor_profile['followers'];
+			}
+
+			foreach ($terms as $term) {
+				$profile = APContact::getByURL($term['url'], false);
+				if (!empty($profile) && empty($contacts[$profile['url']])) {
+					$data['cc'][] = $profile['url'];
+					$contacts[$profile['url']] = $profile['url'];
+				}
+			}
+		} else {
+			$receiver_list = Item::enumeratePermissions($item);
+
+			$mentioned = [];
+
+			foreach ($terms as $term) {
+				$cid = Contact::getIdForURL($term['url'], $item['uid']);
+				if (!empty($cid) && in_array($cid, $receiver_list)) {
+					$contact = DBA::selectFirst('contact', ['url'], ['id' => $cid, 'network' => Protocol::ACTIVITYPUB]);
+					$data['to'][] = $contact['url'];
+					$contacts[$contact['url']] = $contact['url'];
+				}
+			}
+
+			foreach ($receiver_list as $receiver) {
+				$contact = DBA::selectFirst('contact', ['url'], ['id' => $receiver, 'network' => Protocol::ACTIVITYPUB]);
+				if (empty($contacts[$contact['url']])) {
+					$data['cc'][] = $contact['url'];
+					$contacts[$contact['url']] = $contact['url'];
+				}
+			}
+		}
+
+		$parents = Item::select(['id', 'author-link', 'owner-link', 'gravity'], ['parent' => $item['parent']]);
+		while ($parent = Item::fetch($parents)) {
+			// Don't include data from future posts
+			if ($parent['id'] >= $item['id']) {
+				continue;
+			}
+
+			$profile = APContact::getByURL($parent['author-link'], false);
+			if (!empty($profile) && empty($contacts[$profile['url']])) {
+				$data['cc'][] = $profile['url'];
+				$contacts[$profile['url']] = $profile['url'];
+			}
+
+			if ($item['gravity'] != GRAVITY_PARENT) {
+				continue;
+			}
+
+			$profile = APContact::getByURL($parent['owner-link'], false);
+			if (!empty($profile) && empty($contacts[$profile['url']])) {
+				$data['cc'][] = $profile['url'];
+				$contacts[$profile['url']] = $profile['url'];
+			}
+		}
+		DBA::close($parents);
+
+		if (empty($data['to'])) {
+			$data['to'] = $data['cc'];
+			$data['cc'] = [];
+		}
+
+		return $data;
+	}
+
+	/**
+	 * @brief Fetches a list of inboxes of followers of a given user
+	 *
+	 * @param integer $uid User ID
+	 *
+	 * @return array of follower inboxes
+	 */
+	public static function fetchTargetInboxesforUser($uid)
+	{
+		$inboxes = [];
+
+		$condition = ['uid' => $uid, 'network' => Protocol::ACTIVITYPUB, 'archive' => false, 'pending' => false];
+
+		if (!empty($uid)) {
+			$condition['rel'] = [Contact::FOLLOWER, Contact::FRIEND];
+		}
+
+		$contacts = DBA::select('contact', ['notify', 'batch'], $condition);
+		while ($contact = DBA::fetch($contacts)) {
+			$contact = defaults($contact, 'batch', $contact['notify']);
+			$inboxes[$contact] = $contact;
+		}
+		DBA::close($contacts);
+
+		return $inboxes;
+	}
+
+	/**
+	 * @brief Fetches an array of inboxes for the given item and user
+	 *
+	 * @param array $item
+	 * @param integer $uid User ID
+	 *
+	 * @return array with inboxes
+	 */
+	public static function fetchTargetInboxes($item, $uid)
+	{
+		$permissions = self::createPermissionBlockForItem($item);
+		if (empty($permissions)) {
+			return [];
+		}
+
+		$inboxes = [];
+
+		if ($item['gravity'] == GRAVITY_ACTIVITY) {
+			$item_profile = APContact::getByURL($item['author-link']);
+		} else {
+			$item_profile = APContact::getByURL($item['owner-link']);
+		}
+
+		foreach (['to', 'cc', 'bto', 'bcc'] as $element) {
+			if (empty($permissions[$element])) {
+				continue;
+			}
+
+			foreach ($permissions[$element] as $receiver) {
+				if ($receiver == $item_profile['followers']) {
+					$inboxes = self::fetchTargetInboxesforUser($uid);
+				} else {
+					$profile = APContact::getByURL($receiver);
+					if (!empty($profile)) {
+						$target = defaults($profile, 'sharedinbox', $profile['inbox']);
+						$inboxes[$target] = $target;
+					}
+				}
+			}
+		}
+
+		return $inboxes;
+	}
+
+	/**
+	 * @brief Returns the activity type of a given item
+	 *
+	 * @param array $item
+	 *
+	 * @return activity type
+	 */
+	public static function getTypeOfItem($item)
+	{
+		if ($item['verb'] == ACTIVITY_POST) {
+			if ($item['created'] == $item['edited']) {
+				$type = 'Create';
+			} else {
+				$type = 'Update';
+			}
+		} elseif ($item['verb'] == ACTIVITY_LIKE) {
+			$type = 'Like';
+		} elseif ($item['verb'] == ACTIVITY_DISLIKE) {
+			$type = 'Dislike';
+		} elseif ($item['verb'] == ACTIVITY_ATTEND) {
+			$type = 'Accept';
+		} elseif ($item['verb'] == ACTIVITY_ATTENDNO) {
+			$type = 'Reject';
+		} elseif ($item['verb'] == ACTIVITY_ATTENDMAYBE) {
+			$type = 'TentativeAccept';
+		} else {
+			$type = '';
+		}
+
+		return $type;
+	}
+
+	/**
+	 * @brief Creates an activity array for a given item id
+	 *
+	 * @param integer $item_id
+	 * @param boolean $object_mode Is the activity item is used inside another object?
+	 *
+	 * @return array of activity
+	 */
+	public static function createActivityFromItem($item_id, $object_mode = false)
+	{
+		$item = Item::selectFirst([], ['id' => $item_id, 'parent-network' => Protocol::NATIVE_SUPPORT]);
+
+		if (!DBA::isResult($item)) {
+			return false;
+		}
+
+		$condition = ['item-uri' => $item['uri'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
+		$conversation = DBA::selectFirst('conversation', ['source'], $condition);
+		if (DBA::isResult($conversation)) {
+			$data = json_decode($conversation['source']);
+			if (!empty($data)) {
+				return $data;
+			}
+		}
+
+		$type = self::getTypeOfItem($item);
+
+		if (!$object_mode) {
+			$data = ['@context' => ActivityPub::CONTEXT];
+
+			if ($item['deleted'] && ($item['gravity'] == GRAVITY_ACTIVITY)) {
+				$type = 'Undo';
+			} elseif ($item['deleted']) {
+				$type = 'Delete';
+			}
+		} else {
+			$data = [];
+		}
+
+		$data['id'] = $item['uri'] . '#' . $type;
+		$data['type'] = $type;
+		$data['actor'] = $item['author-link'];
+
+		$data['published'] = DateTimeFormat::utc($item["created"]."+00:00", DateTimeFormat::ATOM);
+
+		if ($item["created"] != $item["edited"]) {
+			$data['updated'] = DateTimeFormat::utc($item["edited"]."+00:00", DateTimeFormat::ATOM);
+		}
+
+		$data['context'] = self::fetchContextURLForItem($item);
+
+		$data = array_merge($data, self::createPermissionBlockForItem($item));
+
+		if (in_array($data['type'], ['Create', 'Update', 'Announce', 'Delete'])) {
+			$data['object'] = self::createNote($item);
+		} elseif ($data['type'] == 'Undo') {
+			$data['object'] = self::createActivityFromItem($item_id, true);
+		} else {
+			$data['object'] = $item['thr-parent'];
+		}
+
+		$owner = User::getOwnerDataById($item['uid']);
+
+		if (!$object_mode) {
+			return LDSignature::sign($data, $owner);
+		} else {
+			return $data;
+		}
+	}
+
+	/**
+	 * @brief Creates an object array for a given item id
+	 *
+	 * @param integer $item_id
+	 *
+	 * @return object array
+	 */
+	public static function createObjectFromItemID($item_id)
+	{
+		$item = Item::selectFirst([], ['id' => $item_id, 'parent-network' => Protocol::NATIVE_SUPPORT]);
+
+		if (!DBA::isResult($item)) {
+			return false;
+		}
+
+		$data = ['@context' => ActivityPub::CONTEXT];
+		$data = array_merge($data, self::createNote($item));
+
+		return $data;
+	}
+
+	/**
+	 * @brief Returns a tag array for a given item array
+	 *
+	 * @param array $item
+	 *
+	 * @return array of tags
+	 */
+	private static function createTagList($item)
+	{
+		$tags = [];
+
+		$terms = Term::tagArrayFromItemId($item['id'], TERM_MENTION);
+		foreach ($terms as $term) {
+			$contact = Contact::getDetailsByURL($term['url']);
+			if (!empty($contact['addr'])) {
+				$mention = '@' . $contact['addr'];
+			} else {
+				$mention = '@' . $term['url'];
+			}
+
+			$tags[] = ['type' => 'Mention', 'href' => $term['url'], 'name' => $mention];
+		}
+		return $tags;
+	}
+
+	/**
+	 * @brief Fetches the "context" value for a givem item array from the "conversation" table
+	 *
+	 * @param array $item
+	 *
+	 * @return string with context url
+	 */
+	private static function fetchContextURLForItem($item)
+	{
+		$conversation = DBA::selectFirst('conversation', ['conversation-href', 'conversation-uri'], ['item-uri' => $item['parent-uri']]);
+		if (DBA::isResult($conversation) && !empty($conversation['conversation-href'])) {
+			$context_uri = $conversation['conversation-href'];
+		} elseif (DBA::isResult($conversation) && !empty($conversation['conversation-uri'])) {
+			$context_uri = $conversation['conversation-uri'];
+		} else {
+			$context_uri = str_replace('/objects/', '/context/', $item['parent-uri']);
+		}
+		return $context_uri;
+	}
+
+	/**
+	 * @brief Creates a note/article object array
+	 *
+	 * @param array $item
+	 *
+	 * @return object array
+	 */
+	private static function createNote($item)
+	{
+		if (!empty($item['title'])) {
+			$type = 'Article';
+		} else {
+			$type = 'Note';
+		}
+
+		if ($item['deleted']) {
+			$type = 'Tombstone';
+		}
+
+		$data = [];
+		$data['id'] = $item['uri'];
+		$data['type'] = $type;
+
+		if ($item['deleted']) {
+			return $data;
+		}
+
+		$data['summary'] = null; // Ignore by now
+
+		if ($item['uri'] != $item['thr-parent']) {
+			$data['inReplyTo'] = $item['thr-parent'];
+		} else {
+			$data['inReplyTo'] = null;
+		}
+
+		$data['diaspora:guid'] = $item['guid'];
+		$data['published'] = DateTimeFormat::utc($item["created"]."+00:00", DateTimeFormat::ATOM);
+
+		if ($item["created"] != $item["edited"]) {
+			$data['updated'] = DateTimeFormat::utc($item["edited"]."+00:00", DateTimeFormat::ATOM);
+		}
+
+		$data['url'] = $item['plink'];
+		$data['attributedTo'] = $item['author-link'];
+		$data['actor'] = $item['author-link'];
+		$data['sensitive'] = false; // - Query NSFW
+		$data['context'] = self::fetchContextURLForItem($item);
+
+		if (!empty($item['title'])) {
+			$data['name'] = BBCode::convert($item['title'], false, 7);
+		}
+
+		$data['content'] = BBCode::convert($item['body'], false, 7);
+		$data['source'] = ['content' => $item['body'], 'mediaType' => "text/bbcode"];
+
+		if (!empty($item['signed_text']) && ($item['uri'] != $item['thr-parent'])) {
+			$data['diaspora:comment'] = $item['signed_text'];
+		}
+
+		$data['attachment'] = []; // @ToDo
+		$data['tag'] = self::createTagList($item);
+		$data = array_merge($data, self::createPermissionBlockForItem($item));
+
+		return $data;
+	}
+
+	/**
+	 * @brief Transmits a profile deletion to a given inbox
+	 *
+	 * @param integer $uid User ID
+	 * @param string $inbox Target inbox
+	 */
+	public static function transmitProfileDeletion($uid, $inbox)
+	{
+		$owner = User::getOwnerDataById($uid);
+		$profile = APContact::getByURL($owner['url']);
+
+		$data = ['@context' => 'https://www.w3.org/ns/activitystreams',
+			'id' => System::baseUrl() . '/activity/' . System::createGUID(),
+			'type' => 'Delete',
+			'actor' => $owner['url'],
+			'object' => self::profile($uid),
+			'published' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
+			'to' => [ActivityPub::PUBLIC_COLLECTION],
+			'cc' => []];
+
+		$signed = LDSignature::sign($data, $owner);
+
+		logger('Deliver profile deletion for user ' . $uid . ' to ' . $inbox .' via ActivityPub', LOGGER_DEBUG);
+		HTTPSignature::transmit($signed, $inbox, $uid);
+	}
+
+	/**
+	 * @brief Transmits a profile change to a given inbox
+	 *
+	 * @param integer $uid User ID
+	 * @param string $inbox Target inbox
+	 */
+	public static function transmitProfileUpdate($uid, $inbox)
+	{
+		$owner = User::getOwnerDataById($uid);
+		$profile = APContact::getByURL($owner['url']);
+
+		$data = ['@context' => 'https://www.w3.org/ns/activitystreams',
+			'id' => System::baseUrl() . '/activity/' . System::createGUID(),
+			'type' => 'Update',
+			'actor' => $owner['url'],
+			'object' => self::profile($uid),
+			'published' => DateTimeFormat::utcNow(DateTimeFormat::ATOM),
+			'to' => [$profile['followers']],
+			'cc' => []];
+
+		$signed = LDSignature::sign($data, $owner);
+
+		logger('Deliver profile update for user ' . $uid . ' to ' . $inbox .' via ActivityPub', LOGGER_DEBUG);
+		HTTPSignature::transmit($signed, $inbox, $uid);
+	}
+
+	/**
+	 * @brief Transmits a given activity to a target
+	 *
+	 * @param array $activity
+	 * @param string $target Target profile
+	 * @param integer $uid User ID
+	 */
+	public static function transmitActivity($activity, $target, $uid)
+	{
+		$profile = APContact::getByURL($target);
+
+		$owner = User::getOwnerDataById($uid);
+
+		$data = ['@context' => 'https://www.w3.org/ns/activitystreams',
+			'id' => System::baseUrl() . '/activity/' . System::createGUID(),
+			'type' => $activity,
+			'actor' => $owner['url'],
+			'object' => $profile['url'],
+			'to' => $profile['url']];
+
+		logger('Sending activity ' . $activity . ' to ' . $target . ' for user ' . $uid, LOGGER_DEBUG);
+
+		$signed = LDSignature::sign($data, $owner);
+		HTTPSignature::transmit($signed, $profile['inbox'], $uid);
+	}
+
+	/**
+	 * @brief Transmit a message that the contact request had been accepted
+	 *
+	 * @param string $target Target profile
+	 * @param $id
+	 * @param integer $uid User ID
+	 */
+	public static function transmitContactAccept($target, $id, $uid)
+	{
+		$profile = APContact::getByURL($target);
+
+		$owner = User::getOwnerDataById($uid);
+		$data = ['@context' => 'https://www.w3.org/ns/activitystreams',
+			'id' => System::baseUrl() . '/activity/' . System::createGUID(),
+			'type' => 'Accept',
+			'actor' => $owner['url'],
+			'object' => ['id' => $id, 'type' => 'Follow',
+				'actor' => $profile['url'],
+				'object' => $owner['url']],
+			'to' => $profile['url']];
+
+		logger('Sending accept to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
+
+		$signed = LDSignature::sign($data, $owner);
+		HTTPSignature::transmit($signed, $profile['inbox'], $uid);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param string $target Target profile
+	 * @param $id
+	 * @param integer $uid User ID
+	 */
+	public static function transmitContactReject($target, $id, $uid)
+	{
+		$profile = APContact::getByURL($target);
+
+		$owner = User::getOwnerDataById($uid);
+		$data = ['@context' => 'https://www.w3.org/ns/activitystreams',
+			'id' => System::baseUrl() . '/activity/' . System::createGUID(),
+			'type' => 'Reject',
+			'actor' => $owner['url'],
+			'object' => ['id' => $id, 'type' => 'Follow',
+				'actor' => $profile['url'],
+				'object' => $owner['url']],
+			'to' => $profile['url']];
+
+		logger('Sending reject to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
+
+		$signed = LDSignature::sign($data, $owner);
+		HTTPSignature::transmit($signed, $profile['inbox'], $uid);
+	}
+
+	/**
+	 * @brief 
+	 *
+	 * @param string $target Target profile
+	 * @param integer $uid User ID
+	 */
+	public static function transmitContactUndo($target, $uid)
+	{
+		$profile = APContact::getByURL($target);
+
+		$id = System::baseUrl() . '/activity/' . System::createGUID();
+
+		$owner = User::getOwnerDataById($uid);
+		$data = ['@context' => 'https://www.w3.org/ns/activitystreams',
+			'id' => $id,
+			'type' => 'Undo',
+			'actor' => $owner['url'],
+			'object' => ['id' => $id, 'type' => 'Follow',
+				'actor' => $owner['url'],
+				'object' => $profile['url']],
+			'to' => $profile['url']];
+
+		logger('Sending undo to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
+
+		$signed = LDSignature::sign($data, $owner);
+		HTTPSignature::transmit($signed, $profile['inbox'], $uid);
+	}
+}