diff --git a/ActivityPubPlugin.php b/ActivityPubPlugin.php
index cc1e3d0..30d7884 100644
--- a/ActivityPubPlugin.php
+++ b/ActivityPubPlugin.php
@@ -1,4 +1,5 @@
 <?php
+require_once __DIR__ . DIRECTORY_SEPARATOR . "utils" . DIRECTORY_SEPARATOR . "postman.php";
 /**
  * GNU social - a federating social network
  *
@@ -45,12 +46,13 @@ class ActivityPubPlugin extends Plugin
          * @param URLMapper $m
          * @return void
          */
-        public function onRouterInitialized (URLMapper $m) {
+        public function onRouterInitialized (URLMapper $m)
+        {
                 ActivityPubURLMapperOverwrite::overwrite_variable ($m, ':nickname',
                                             ['action' => 'showstream'],
                                             ['nickname' => Nickname::DISPLAY_FMT],
-                                            'apactorprofile');
-
+                                            'apActorProfile');
+                
                 $m->connect (':nickname/liked.json',
                             ['action'    => 'apActorLikedCollection'],
                             ['nickname'  => Nickname::DISPLAY_FMT]);
@@ -77,7 +79,8 @@ class ActivityPubPlugin extends Plugin
          * @param array $versions
          * @return boolean true
          */
-        public function onPluginVersion (array &$versions) {
+        public function onPluginVersion (array &$versions)
+        {
                 $versions[] = [ 'name' => 'ActivityPub',
                                 'version' => GNUSOCIAL_VERSION,
                                 'author' => 'Daniel Supernault, Diogo Cordeiro',
@@ -88,6 +91,74 @@ class ActivityPubPlugin extends Plugin
 
                 return true;
         }
+
+        /**
+         * Make sure necessary tables are filled out.
+         */
+        function onCheckSchema ()
+        {
+            $schema = Schema::get ();
+            $schema->ensureTable ('Activitypub_profile', Activitypub_profile::schemaDef());
+            return true;
+        }
+        
+            /********************************************************
+             *                    Delivery Events                   *
+             ********************************************************/
+
+        /**
+         * Having established a remote subscription, send a notification to the
+         * remote ActivityPub profile's endpoint.
+         *
+         * @param Profile $profile  subscriber
+         * @param Profile $other    subscribee
+         * @return hook return value
+         * @throws Exception
+         */
+        function onEndSubscribe (Profile $profile, Profile $other)
+        {
+                if (!$profile->isLocal () || $other->isLocal ()) {
+                        return true;
+                }
+
+                try {
+                        $other = Activitypub_profile::fromProfile ($other);
+                } catch (Exception $e) {
+                        return true;
+                }
+
+                $postman = new Activitypub_postman ($profile, array ($other));
+
+                $postman->follow ();
+
+                return true;
+        }
+
+        /**
+         * Notify remote server on unsubscribe.
+         *
+         * @param Profile $profile
+         * @param Profile $other
+         * @return hook return value
+         */
+        function onEndUnsubscribe (Profile $profile, Profile $other)
+        {
+                if (!$profile->isLocal () || $other->isLocal ()) {
+                        return true;
+                }
+
+                try {
+                        $other = Activitypub_profile::fromProfile ($other);
+                } catch (Exception $e) {
+                        return true;
+                }
+
+                $postman = new Activitypub_postman ($profile, array ($other));
+
+                $postman->undo_follow ();
+
+                return true;
+        }
 }
 
 /**
@@ -127,7 +198,8 @@ class ActivityPubReturn
          * @param array $res
          * @return void
          */
-        static function answer ($res) {
+        static function answer ($res)
+        {
                 header ('Content-Type: application/activity+json');
                 echo json_encode ($res, JSON_UNESCAPED_SLASHES | (isset ($_GET["pretty"]) ? JSON_PRETTY_PRINT : null));
                 exit;
@@ -140,10 +212,11 @@ class ActivityPubReturn
          * @param int32 $code
          * @return void
          */
-        static function error ($m, $code = 500) {
+        static function error ($m, $code = 500)
+        {
                 http_response_code ($code);
                 header ('Content-Type: application/activity+json');
-                $res[] = Activitypub_error::errorMessageToObject ($m);
+                $res[] = Activitypub_error::error_message_to_array ($m);
                 echo json_encode ($res, JSON_UNESCAPED_SLASHES);
                 exit;
         }
diff --git a/actions/apactorfollowers.php b/actions/apactorfollowers.php
index ab1f8c8..8e32a10 100644
--- a/actions/apactorfollowers.php
+++ b/actions/apactorfollowers.php
@@ -46,7 +46,8 @@ class apActorFollowersAction extends ManagedAction
          *
          * @return void
          */
-        protected function handle () {
+        protected function handle ()
+        {
                 $nickname = $this->trimmed ('nickname');
                 try {
                         $user    = User::getByNickname ($nickname);
@@ -71,8 +72,7 @@ class apActorFollowersAction extends ManagedAction
                         $since = ($page - 1) * PROFILES_PER_MINILIST;
                         $limit = (($page - 1) == 0 ? 1 : $page) * PROFILES_PER_MINILIST;
                         $sub   = $profile->getSubscribers ($since, $limit);
-                }
-                catch(NoResultException $e) {
+                } catch (NoResultException $e) {
                         ActivityPubReturn::error ('This user has no followers.');
                 }
 
diff --git a/actions/apactorfollowing.php b/actions/apactorfollowing.php
index b0b3884..f5bc75f 100644
--- a/actions/apactorfollowing.php
+++ b/actions/apactorfollowing.php
@@ -46,7 +46,8 @@ class apActorFollowingAction extends ManagedAction
          *
          * @return void
          */
-        protected function handle () {
+        protected function handle ()
+        {
                 $nickname = $this->trimmed ('nickname');
                 try {
                         $user    = User::getByNickname ($nickname);
@@ -70,7 +71,7 @@ class apActorFollowingAction extends ManagedAction
                 try {
                         $since = ($page - 1) * PROFILES_PER_MINILIST;
                         $limit = (($page - 1) == 0 ? 1 : $page) * PROFILES_PER_MINILIST;
-                        $sub = $profile->getSubscribed($since, $limit);
+                        $sub   = $profile->getSubscribed ($since, $limit);
                 } catch (NoResultException $e) {
                         ActivityPubReturn::error ('This user is not following anyone.');
                 }
diff --git a/actions/apactorinbox.php b/actions/apactorinbox.php
index d0a90e5..b662368 100644
--- a/actions/apactorinbox.php
+++ b/actions/apactorinbox.php
@@ -76,8 +76,8 @@ class apActorInboxAction extends ManagedAction
 
                 // Get valid Actor object
                 try {
-                        require_once dirname (__DIR__) . DIRECTORY_SEPARATOR . "utils" . DIRECTORY_SEPARATOR . "discovery.php";
-                        $actor_profile = new Activitypub_Discovery;
+                        require_once dirname (__DIR__) . DIRECTORY_SEPARATOR . "utils" . DIRECTORY_SEPARATOR . "explorer.php";
+                        $actor_profile = new Activitypub_explorer;
                         $actor_profile = $actor_profile->lookup ($data->actor);
                         $actor_profile = $actor_profile[0];
                 } catch (Exception $e) {
diff --git a/actions/apactorlikedcollection.php b/actions/apactorlikedcollection.php
index c3cf045..c6b128f 100644
--- a/actions/apactorlikedcollection.php
+++ b/actions/apactorlikedcollection.php
@@ -46,7 +46,8 @@ class apActorLikedCollectionAction extends ManagedAction
          *
          * @return void
          */
-        protected function handle () {
+        protected function handle ()
+        {
                 $nickname = $this->trimmed ('nickname');
                 try {
                         $user    = User::getByNickname ($nickname);
@@ -96,13 +97,14 @@ class apActorLikedCollectionAction extends ManagedAction
          * Take a fave object and turns it in a pretty array to be used
          * as a plugin answer
          *
-         * @param \Fave $fave_object
+         * @param Fave $fave_object
          * @return array pretty array representating a Fave
          */
-        protected function pretty_fave ($fave_object) {
+        protected function pretty_fave ($fave_object)
+        {
                 $res = array("uri" => $fave_object->uri,
                              "created" => $fave_object->created,
-                             "object" => Activitypub_notice::noticeToObject (Notice::getByID ($fave_object->notice_id)));
+                             "object" => Activitypub_notice::notice_to_array (Notice::getByID ($fave_object->notice_id)));
 
                 return $res;
         }
@@ -114,10 +116,11 @@ class apActorLikedCollectionAction extends ManagedAction
          * @param int32 $limit
          * @param int32 $since_id
          * @param int32 $max_id
-         * @return \Fave fetchable fave collection
+         * @return Fave fetchable fave collection
          */
         private static function fetch_faves ($user_id, $limit = 40, $since_id = null,
-                                             $max_id = null) {
+                                             $max_id = null)
+        {
                 $fav = new Fave ();
 
                 $fav->user_id = $user_id;
diff --git a/actions/apactorprofile.php b/actions/apactorprofile.php
index 4216909..f026728 100644
--- a/actions/apactorprofile.php
+++ b/actions/apactorprofile.php
@@ -47,7 +47,8 @@ class apActorProfileAction extends ManagedAction
          *
          * @return void
          */
-        protected function handle() {
+        protected function handle()
+        {
                 $nickname = $this->trimmed ('nickname');
                 try {
                         $user    = User::getByNickname ($nickname);
@@ -57,7 +58,7 @@ class apActorProfileAction extends ManagedAction
                         ActivityPubReturn::error ('Invalid username.', 404);
                 }
 
-                $res = Activitypub_profile::profileToObject ($profile);
+                $res = Activitypub_profile::profile_to_array ($profile);
 
                 ActivityPubReturn::answer ($res);
         }
diff --git a/actions/apsharedinbox.php b/actions/apsharedinbox.php
index b3684db..2f8321e 100644
--- a/actions/apsharedinbox.php
+++ b/actions/apsharedinbox.php
@@ -1,10 +1,5 @@
 <?php
-
-require_once dirname (__DIR__) . DIRECTORY_SEPARATOR . "utils" . DIRECTORY_SEPARATOR . "discovery.php";
-use Activitypub_Discovery;
-use ActivityPubReturn;
-use Activitypub_notice;
-
+require_once dirname (__DIR__) . DIRECTORY_SEPARATOR . "utils" . DIRECTORY_SEPARATOR . "explorer.php";
 /**
  * GNU social - a federating social network
  *
@@ -67,14 +62,11 @@ class apSharedInboxAction extends ManagedAction
                 if (!isset($data->actor)) {
                         ActivityPubReturn::error ("Actor was not specified.");
                 }
-                if (!isset($data->to)) {
-                        ActivityPubReturn::error ("To was not specified.");
-                }
                 if (!isset($data->object)) {
                         ActivityPubReturn::error ("Object was not specified.");
                 }
 
-                $discovery = new Activitypub_Discovery;
+                $discovery = new Activitypub_explorer;
 
                 // Get valid Actor object
                 try {
@@ -84,37 +76,42 @@ class apSharedInboxAction extends ManagedAction
                         ActivityPubReturn::error ("Invalid Actor.", 404);
                 }
 
+                unset ($discovery);
+
                 // Public To:
                 $public_to = array ("https://www.w3.org/ns/activitystreams#Public",
                                     "Public",
                                     "as:Public");
 
-                $to_profiles = array ();
-                // Generate To objects
-                if (is_array ($data->to)) {
-                        // Remove duplicates from To actors set
-                        array_unique ($data->to);
-                        foreach ($data->to as $to_url) {
-                                try {
-                                        $to_profiles = array_merge ($to_profiles, $discovery->lookup ($to_url));
-                                } catch (Exception $e) {
-                                        // XXX: Invalid actor found, not sure how we handle those
-                                }
-                        }
-                } else if (empty ($data->to) || in_array ($data->to, $public_to)) {
-                        // No need to do anything else at this point, let's just break out the if
-                } else {
-                        try {
-                                $to_profiles[]= $discovery->lookup ($data->to);
-                        } catch (Exception $e) {
-                                ActivityPubReturn::error ("Invalid Actor.", 404);
-                        }
-                }
-                unset ($discovery);
-
                 // Process request
                 switch ($data->type) {
                         case "Create":
+                                if (!isset($data->to)) {
+                                        ActivityPubReturn::error ("To was not specified.");
+                                }
+                                $discovery = new Activitypub_Discovery;
+                                $to_profiles = array ();
+                                // Generate To objects
+                                if (is_array ($data->to)) {
+                                        // Remove duplicates from To actors set
+                                        array_unique ($data->to);
+                                        foreach ($data->to as $to_url) {
+                                                try {
+                                                        $to_profiles = array_merge ($to_profiles, $discovery->lookup ($to_url));
+                                                } catch (Exception $e) {
+                                                        // XXX: Invalid actor found, not sure how we handle those
+                                                }
+                                        }
+                                } else if (empty ($data->to) || in_array ($data->to, $public_to)) {
+                                        // No need to do anything else at this point, let's just break out the if
+                                } else {
+                                        try {
+                                                $to_profiles[]= $discovery->lookup ($data->to);
+                                        } catch (Exception $e) {
+                                                ActivityPubReturn::error ("Invalid Actor.", 404);
+                                        }
+                                }
+                                unset ($discovery);
                                 require_once __DIR__ . DIRECTORY_SEPARATOR . "inbox" . DIRECTORY_SEPARATOR . "Create.php";
                                 break;
                         case "Follow":
@@ -126,6 +123,9 @@ class apSharedInboxAction extends ManagedAction
                         case "Announce":
                                 require_once __DIR__ . DIRECTORY_SEPARATOR . "inbox" . DIRECTORY_SEPARATOR . "Announce.php";
                                 break;
+                        case "Undo":
+                                require_once __DIR__ . DIRECTORY_SEPARATOR . "inbox" . DIRECTORY_SEPARATOR . "Undo.php";
+                                break;
                         default:
                                 ActivityPubReturn::error ("Invalid type value.");
                 }
diff --git a/actions/inbox/Announce.php b/actions/inbox/Announce.php
index 461b463..d1470c2 100644
--- a/actions/inbox/Announce.php
+++ b/actions/inbox/Announce.php
@@ -30,8 +30,8 @@ if (!defined ('GNUSOCIAL')) {
 }
 
 try {
-        Notice::getByUri ($data->object)->repeat ($actor_profile, "api");
+        Notice::getByUri ($data->object)->repeat ($actor_profile, "ActivityPub");
         ActivityPubReturn::answer ("Notice repeated successfully.");
-} catch(Exception $ex) {
-        ActivityPubReturn::error ($ex->getMessage (), 403);
+} catch (Exception $e) {
+        ActivityPubReturn::error ($e->getMessage (), 403);
 }
diff --git a/actions/inbox/Create.php b/actions/inbox/Create.php
index f121300..4bffcaf 100644
--- a/actions/inbox/Create.php
+++ b/actions/inbox/Create.php
@@ -32,7 +32,7 @@ if (!defined ('GNUSOCIAL')) {
 $valid_object_types = array ("Note");
 
 // Validate data
-if (! (isset($data->object->type) && in_array ($data->object->type, $valid_object_types))) {
+if (!(isset ($data->object->type) && in_array ($data->object->type, $valid_object_types))) {
         ActivityPubReturn::error ("Invalid Object type.");
 }
 if (!isset ($data->object->content)) {
@@ -51,17 +51,17 @@ $act->context = new ActivityContext ();
 // Is this a reply?
 if (isset ($data->object->reply_to)) {
         $reply_to = Notice::getByUri ($data->object->reply_to);
-        $act->context->replyToID  = $reply_to->getUri ();
+        $act->context->replyToID = $reply_to->getUri ();
         $act->context->replyToUrl = $data->object->reply_to;
 } else {
         $reply_to = null;
 }
 
-$act->context->attention = common_get_attentions($content, $actor_profile, $reply_to);
+$act->context->attention = common_get_attentions ($content, $actor_profile, $reply_to);
 
 foreach ($to_profiles as $to)
 {
-        $act->context->attention[$to->getUri()] = "http://activitystrea.ms/schema/1.0/person";
+        $act->context->attention[$to->getUri ()] = "http://activitystrea.ms/schema/1.0/person";
 }
 
 // Reject notice if it is too long (without the HTML)
@@ -70,7 +70,7 @@ if (Notice::contentTooLong ($content)) {
         ActivityPubReturn::error ("That's too long. Maximum notice size is %d character.");
 }
 
-$options = array ('source' => 'web', 'uri' => $data->id);
+$options = array ('source' => 'ActivityPub', 'uri' => $data->id);
 // $options gets filled with possible scoping settings
 ToSelector::fillActivity ($this, $act, $options);
 
@@ -86,7 +86,7 @@ try {
                   "id"     => $data->id,
                   "type"   => "Create",
                   "actor"  => $data->actor,
-                  "object" => Activitypub_notice::noticeToObject (Notice::saveActivity ($act, $actor_profile, $options)));
+                  "object" => Activitypub_notice::notice_to_array (Notice::saveActivity ($act, $actor_profile, $options)));
         ActivityPubReturn::answer ($res);
 } catch (Exception $e) {
         ActivityPubReturn::error ($e->getMessage ());
diff --git a/actions/inbox/Delete.php b/actions/inbox/Delete.php
index 32f97c1..44a3936 100644
--- a/actions/inbox/Delete.php
+++ b/actions/inbox/Delete.php
@@ -31,7 +31,11 @@ if (!defined ('GNUSOCIAL')) {
 
 try {
         Activitypub_notice::getByUri ($data->object)->deleteAs ($actor_profile);
-        ActivityPubReturn::answer ("Notice deleted successfully.");
-} catch(Exception $ex) {
-        ActivityPubReturn::error ($ex->getMessage (), 403);
+        $res = array ("@context" => "https://www.w3.org/ns/activitystreams",
+                  "type"   => "Delete",
+                  "actor"  => $data->actor,
+                  "object" => $data->object);
+        ActivityPubReturn::answer ($res);
+} catch (Exception $e) {
+        ActivityPubReturn::error ($e->getMessage (), 403);
 }
diff --git a/actions/inbox/Follow.php b/actions/inbox/Follow.php
index 9fdd81f..1ff819f 100644
--- a/actions/inbox/Follow.php
+++ b/actions/inbox/Follow.php
@@ -29,10 +29,15 @@ if (!defined ('GNUSOCIAL')) {
         exit (1);
 }
 
+// Validate Object
+if (!is_string ($data->object)) {
+        ActivityPubReturn::error ("Invalid Object object, URL expected.");
+}
+
 // Get valid Object profile
 try {
-        $object_profile = new Activitypub_Discovery;
-        $object_profile = $object_profile->lookup ($data->object);
+        $object_profile = new Activitypub_explorer;
+        $object_profile = $object_profile->lookup ($data->object)[0];
 } catch(Exception $e) {
         ActivityPubReturn::error ("Invalid Object Actor URL.", 404);
 }
@@ -40,10 +45,14 @@ try {
 try {
         if (!Subscription::exists ($actor_profile, $object_profile)) {
                 Subscription::start ($actor_profile, $object_profile);
-                ActivityPubReturn::answer ("You are now following this person.");
+                $res = array ("@context" => "https://www.w3.org/ns/activitystreams",
+                          "type"   => "Follow",
+                          "actor"  => $data->actor,
+                          "object" => $data->object);
+                ActivityPubReturn::answer ($res);
         } else {
                 ActivityPubReturn::error ("Already following.", 409);
         }
-} catch (Exception $ex) {
+} catch (Exception $e) {
         ActivityPubReturn::error ("Invalid Object Actor URL.", 404);
 }
diff --git a/actions/inbox/Like.php b/actions/inbox/Like.php
index 2ae552d..7c64e81 100644
--- a/actions/inbox/Like.php
+++ b/actions/inbox/Like.php
@@ -31,7 +31,11 @@ if (!defined ('GNUSOCIAL')) {
 
 try {
         Fave::addNew ($actor_profile, Notice::getByUri ($data->object));
-        ActivityPubReturn::answer ("Notice favorited successfully.");
-} catch (Exception $ex) {
-        ActivityPubReturn::error ($ex->getMessage (), 403);
+        $res = array ("@context" => "https://www.w3.org/ns/activitystreams",
+                  "type"   => "Like",
+                  "actor"  => $data->actor,
+                  "object" => $data->object);
+        ActivityPubReturn::answer ($res);
+} catch (Exception $e) {
+        ActivityPubReturn::error ($e->getMessage (), 403);
 }
diff --git a/actions/inbox/Undo.php b/actions/inbox/Undo.php
index c976d19..86731e0 100644
--- a/actions/inbox/Undo.php
+++ b/actions/inbox/Undo.php
@@ -1,7 +1,4 @@
 <?php
-
-use Activitypub_Discovery;
-
 /**
  * GNU social - a federating social network
  *
@@ -45,10 +42,10 @@ case "Like":
                         ActivityPubReturn::error ("Object Notice URL was not specified.");
                 }
 
-                Fave::removeEntry ($actor_profile, Notice::getByUri($data->object->object));
+                Fave::removeEntry ($actor_profile, Notice::getByUri ($data->object->object));
                 ActivityPubReturn::answer ("Notice disfavorited successfully.");
         } catch (Exception $e) {
-                ActivityPubReturn::error ($e->getMessage(), 403);
+                ActivityPubReturn::error ($e->getMessage (), 403);
         }
         break;
 case "Follow":
@@ -58,8 +55,8 @@ case "Follow":
         }
         // Get valid Object profile
         try {
-                $object_profile = new Activitypub_Discovery;
-                $object_profile = $object_profile->lookup ($data->object->object);
+                $object_profile = new Activitypub_explorer;
+                $object_profile = $object_profile->lookup ($data->object->object)[0];
         } catch (Exception $e) {
                 ActivityPubReturn::error ("Invalid Object Actor URL.", 404);
         }
@@ -71,7 +68,7 @@ case "Follow":
                 } else {
                         ActivityPubReturn::error ("You are not following this person already.", 409);
                 }
-        } catch (Exception $ex) {
+        } catch (Exception $e) {
                 ActivityPubReturn::error ("Invalid Object Actor URL.", 404);
         }
         break;
diff --git a/classes/Activitypub_attachment.php b/classes/Activitypub_attachment.php
index 61f617b..691277b 100644
--- a/classes/Activitypub_attachment.php
+++ b/classes/Activitypub_attachment.php
@@ -41,10 +41,11 @@ class Activitypub_attachment extends Managed_DataObject
         /**
          * Generates a pretty array from an Attachment object
          *
-         * @param \Attachment $attachment
+         * @param Attachment $attachment
          * @return pretty array to be used in a response
          */
-        public static function attachmentToObject ($attachment) {
+        public static function attachment_to_array ($attachment)
+        {
                 $res = [
                         '@context'  => [
                                 "https://www.w3.org/ns/activitystreams",
diff --git a/classes/Activitypub_error.php b/classes/Activitypub_error.php
index 69e74bc..b14299b 100644
--- a/classes/Activitypub_error.php
+++ b/classes/Activitypub_error.php
@@ -44,7 +44,8 @@ class Activitypub_error extends Managed_DataObject
          * @param string $m
          * @return pretty array to be used in a response
          */
-        public static function errorMessageToObject ($m) {
+        public static function error_message_to_array ($m)
+        {
                 $res = [
                         'error'=> $m
                 ];
diff --git a/classes/Activitypub_notice.php b/classes/Activitypub_notice.php
index 1fc8daf..8868dd9 100644
--- a/classes/Activitypub_notice.php
+++ b/classes/Activitypub_notice.php
@@ -42,19 +42,20 @@ class Activitypub_notice extends Managed_DataObject
         /**
          * Generates a pretty notice from a Notice object
          *
-         * @param \Notice $notice
+         * @param Notice $notice
          * @return pretty array to be used in a response
          */
-        public static function noticeToObject ($notice) {
+        public static function notice_to_array ($notice)
+        {
                 $attachments = array ();
                 foreach($notice->attachments () as $attachment) {
-                        $attachments[] = Activitypub_attachment::attachmentToObject ($attachment);
+                        $attachments[] = Activitypub_attachment::attachment_to_array ($attachment);
                 }
 
                 $tags = array ();
                 foreach($notice->getTags()as $tag) {
                         if ($tag != "") {       // Hacky workaround to avoid stupid outputs
-                                $tags[] = Activitypub_tag::tagNameToObject ($tag);
+                                $tags[] = Activitypub_tag::tag_to_array ($tag);
                         }
                 }
 
diff --git a/classes/Activitypub_profile.php b/classes/Activitypub_profile.php
index 3ec1344..3c5f93e 100644
--- a/classes/Activitypub_profile.php
+++ b/classes/Activitypub_profile.php
@@ -37,15 +37,47 @@ if (!defined ('GNUSOCIAL')) {
  * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
  * @link      http://www.gnu.org/software/social/
  */
-class Activitypub_profile extends Managed_DataObject
+class Activitypub_profile extends Profile
 {
+        public $__table = 'Activitypub_profile';
+
+        protected $_profile = null;
+
+        /**
+         * Return table definition for Schema setup and DB_DataObject usage.
+         *
+         * @return array array of column definitions
+         */
+        static function schemaDef ()
+        {
+            return array (
+                'fields' => array (
+                    'uri' => array ('type' => 'varchar', 'length' => 191, 'not null' => true),
+                    'profile_id' => array ('type' => 'integer'),
+                    'inboxuri' => array ('type' => 'varchar', 'length' => 191),
+                    'sharedInboxuri' => array ('type' => 'varchar', 'length' => 191),
+                    'created' => array ('type' => 'datetime', 'not null' => true),
+                    'modified' => array ('type' => 'datetime', 'not null' => true),
+                ),
+                'primary key' => array ('uri'),
+                'unique keys' => array (
+                    'Activitypub_profile_profile_id_key' => array ('profile_id'),
+                    'Activitypub_profile_inboxuri_key' => array ('inboxuri'),
+                ),
+                'foreign keys' => array (
+                    'Activitypub_profile_profile_id_fkey' => array ('profile', array ('profile_id' => 'id')),
+                ),
+            );
+        }
+
         /**
          * Generates a pretty profile from a Profile object
          *
-         * @param \Profile $profile
+         * @param Profile $profile
          * @return pretty array to be used in a response
          */
-        public static function profileToObject($profile) {
+        public static function profile_to_array ($profile)
+        {
                 $url = $profile->getURL ();
                 $res = [
                         '@context'        => [
@@ -68,7 +100,7 @@ class Activitypub_profile extends Managed_DataObject
                         'following_count' => $profile->subscriptionCount (),
                         'liked'           => "{$url}/liked.json",
                         'liked_count'     => Fave::countByProfile ($profile),
-                        'summary'         => $profile->getDescription (),
+                        'summary'         => ($desc = $profile->getDescription ()) == null ? "" : $desc,
                         'url'             => $profile->getURL (),
                         'avatar'          => [
                                 'type'   => 'Image',
@@ -79,4 +111,92 @@ class Activitypub_profile extends Managed_DataObject
                 ];
                 return $res;
         }
+
+        /**
+         * Insert the current objects variables into the database
+         *
+         * @access public
+         * @throws ServerException
+         */
+        public function doInsert ()
+        {
+                $profile = new Profile ();
+
+                $profile->created = $this->created = $this->modified = common_sql_now ();
+
+                $fields = array (
+                            'uri'      => 'profileurl',
+                            'nickname' => 'nickname',
+                            'fullname' => 'fullname',
+                            'bio'      => 'bio'
+                            );
+
+                foreach ($fields as $af => $pf) {
+                        $profile->$pf = $this->$af;
+                }
+
+                $this->profile_id = $profile->insert ();
+                if ($this->profile_id === false) {
+                        $profile->query ('ROLLBACK');
+                        throw new ServerException ('Profile insertion failed.');
+                }
+
+                $ok = $this->insert ();
+
+                if ($ok === false) {
+                        $profile->query ('ROLLBACK');
+                        throw new ServerException ('Cannot save ActivityPub profile.');
+                }
+        }
+
+        /**
+         * Fetch the locally stored profile for this Activitypub_profile
+         * @return Profile
+         * @throws NoProfileException if it was not found
+         */
+        public function localProfile ()
+        {
+                $profile = Profile::getKV ('id', $this->profile_id);
+                if (!$profile instanceof Profile) {
+                        throw new NoProfileException ($this->profile_id);
+                }
+                return $profile;
+        }
+
+        /**
+         * Generates an Activitypub_profile from a Profile
+         *
+         * @param Profile $profile
+         * @return Activitypub_profile
+         * @throws Exception if no Activitypub_profile exists for given Profile
+         */
+        static function fromProfile (Profile $profile)
+        {
+                $profile_id = $profile->getID ();
+
+                $aprofile = Activitypub_profile::getKV ('profile_id', $profile_id);
+                if (!$aprofile instanceof Activitypub_profile) {
+                        throw new Exception('No Activitypub_profile for Profile ID: '.$profile_id);
+                }
+
+                foreach ($profile as $key => $value) {
+                        $aprofile->$key = $value;
+                }
+
+                return $aprofile;
+        }
+
+        /**
+         * Returns sharedInbox if possible, inbox otherwise
+         *
+         * @return string Inbox URL
+         */
+        public function getInbox ()
+        {
+                if (is_null ($this->sharedInboxuri)) {
+                        return $this->inboxuri;
+                }
+
+                return $this->sharedInboxuri;
+        }
 }
diff --git a/classes/Activitypub_tag.php b/classes/Activitypub_tag.php
index e72a73c..9f27a96 100644
--- a/classes/Activitypub_tag.php
+++ b/classes/Activitypub_tag.php
@@ -41,10 +41,11 @@ class Activitypub_tag extends Managed_DataObject
         /**
          * Generates a pretty tag from a Tag object
          *
-         * @param \Tag $tag
+         * @param Tag $tag
          * @return pretty array to be used in a response
          */
-        public static function tagNameToObject ($tag) {
+        public static function tag_to_array ($tag)
+        {
                 $res = [
                 '@context'          => [
                 "https://www.w3.org/ns/activitystreams",
diff --git a/utils/discovery.php b/utils/explorer.php
similarity index 73%
rename from utils/discovery.php
rename to utils/explorer.php
index 4fe5c25..cbf9d38 100644
--- a/utils/discovery.php
+++ b/utils/explorer.php
@@ -1,7 +1,4 @@
 <?php
-
-use Profile;
-
 /**
  * GNU social - a federating social network
  *
@@ -39,7 +36,7 @@ if (!defined ('GNUSOCIAL')) {
  * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
  * @link      http://www.gnu.org/software/social/
  */
-class Activitypub_Discovery
+class Activitypub_explorer
 {
         private $discovered_actor_profiles = array ();
 
@@ -49,7 +46,7 @@ class Activitypub_Discovery
          * so that there is no erroneous data
          *
          * @param string $url User's url
-         * @return array of \Profile objects
+         * @return array of Profile objects
          */
         public function lookup ($url)
         {
@@ -64,13 +61,16 @@ class Activitypub_Discovery
          * $discovered_actor_profiles array
          *
          * @param string $url User's url
-         * @return array of \Profile objects
+         * @return array of Profile objects
          */
         private function _lookup ($url)
         {
                 // First check if we already have it locally and, if so, return it
                 // If the local fetch fails: grab it remotely, store locally and return
-                $this->grab_local_user ($url) || $this->grab_remote_user($url);
+                if (! ($this->grab_local_user ($url) || $this->grab_remote_user ($url))) {
+                    throw new Exception ("User not found");
+                }
+
 
                 return $this->discovered_actor_profiles;
         }
@@ -84,7 +84,7 @@ class Activitypub_Discovery
          */
         private function grab_local_user ($url)
         {
-                if (($actor_profile = Profile::getKV ("profileurl", $url)) != false) {
+                if (($actor_profile = self::get_profile_by_url ($url)) != false) {
                         $this->discovered_actor_profiles[]= $actor_profile;
                         return true;
                 } else {
@@ -115,14 +115,15 @@ class Activitypub_Discovery
          * @param string $url User's url
          * @return boolean success state
          */
-        private function grab_remote_user ($url) {
+        private function grab_remote_user ($url)
+        {
                 $client    = new HTTPClient ();
                 $headers   = array();
                 $headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
                 $headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
                 $response  = $client->get ($url, $headers);
-                if (!$response->isOk()) {
-                    throw new NoResultException ("Invalid Actor URL.");
+                if (!$response->isOk ()) {
+                    throw new Exception ("Invalid Actor URL.");
                 }
                 $res = json_decode ($response->getBody (), JSON_UNESCAPED_SLASHES);
                 if (isset ($res["orderedItems"])) { // It's a potential collection of actors!!!
@@ -148,17 +149,21 @@ class Activitypub_Discovery
          * Save remote user profile in local instance
          *
          * @param array $res remote response
-         * @return \Profile remote Profile object
+         * @return Profile remote Profile object
          */
-        private function store_profile ($res) {
-                $profile             = new Profile;
-                $profile->profileurl = $res["url"];
-                $profile->nickname   = $res["nickname"];
-                $profile->fullname   = $res["display_name"];
-                $profile->bio        = substr ($res["summary"], 0, 1000);
-                $profile->insert ();
+        private function store_profile ($res)
+        {
+                $aprofile                 = new Activitypub_profile;
+                $aprofile->uri            = $res["url"];
+                $aprofile->nickname       = $res["nickname"];
+                $aprofile->fullname       = $res["display_name"];
+                $aprofile->bio            = substr ($res["summary"], 0, 1000);
+                $aprofile->inboxuri       = $res["inbox"];
+                $aprofile->sharedInboxuri = $res["sharedInbox"];
 
-                return $profile;
+                $aprofile->doInsert ();
+
+                return $aprofile->localProfile ();
         }
 
         /**
@@ -168,11 +173,37 @@ class Activitypub_Discovery
          * @param array $res remote response
          * @return boolean success state
          */
-        private function validate_remote_response ($res) {
-                if (!isset ($res["url"], $res["nickname"], $res["display_name"], $res["summary"])) {
+        private function validate_remote_response ($res)
+        {
+                if (!isset ($res["url"], $res["nickname"], $res["display_name"], $res["summary"], $res["inbox"], $res["sharedInbox"])) {
                         return false;
                 }
 
                 return true;
         }
+
+        /**
+         * Get a profile from it's profileurl
+         * Unfortunately GNU Social cache is not truly reliable when handling
+         * potential ActivityPub remote profiles, as so it is important to use
+         * this hacky workaround (at least for now)
+         *
+         * @param string $v URL
+         * @return boolean|Profile false if fails | Profile object if successful
+         */
+        static function get_profile_by_url ($v)
+        {
+                $i = Managed_DataObject::getcached(Profile, "profileurl", $v);
+                if (empty ($i)) { // false = cache miss
+                        $i = new Profile;
+                        $result = $i->get ("profileurl", $v);
+                        if ($result) {
+                                // Hit!
+                                $i->encache();
+                        } else {
+                            return false;
+                        }
+                }
+                return $i;
+        }
 }
diff --git a/utils/postman.php b/utils/postman.php
new file mode 100644
index 0000000..4fa69fb
--- /dev/null
+++ b/utils/postman.php
@@ -0,0 +1,91 @@
+<?php
+/**
+ * GNU social - a federating social network
+ *
+ * ActivityPubPlugin implementation for GNU Social
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @author    Daniel Supernault <danielsupernault@gmail.com>
+ * @copyright 2018 Free Software Foundation http://fsf.org
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      https://www.gnu.org/software/social/
+ */
+if (!defined ('GNUSOCIAL')) {
+        exit (1);
+}
+
+/**
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://www.gnu.org/software/social/
+ */
+class Activitypub_postman
+{
+        private $actor;
+        private $to = array ();
+        private $client;
+        private $headers;
+
+        /**
+         * Create a postman to deliver something to someone
+         *
+         * @param Activitypub_profile $to array of destinataries
+         */
+        public function __construct ($from, $to)
+        {
+                $this->actor = $from;
+                $this->to = $to;
+                $this->headers = array();
+                $this->headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+                $this->headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
+        }
+
+        /**
+         * Send a follow notification to remote instance
+         */
+        public function follow ()
+        {
+                $this->client = new HTTPClient ();
+                $data = array ("@context" => "https://www.w3.org/ns/activitystreams",
+                          "type"   => "Follow",
+                          "actor"  => $this->actor->getUrl (),
+                          "object" => $this->to[0]->getUrl ());
+                $this->client->setBody (json_encode ($data));
+                $response = $this->client->post ($this->to[0]->getInbox (), $this->headers);
+        }
+
+        /**
+         * Send a Undo Follow notification to remote instance
+         */
+        public function undo_follow ()
+        {
+                $this->client = new HTTPClient ();
+                $data = array ("@context" => "https://www.w3.org/ns/activitystreams",
+                            "type"   => "Undo",
+                            "actor"  => $this->actor->getUrl (),
+                            "object" => array (
+                                "type" => "Follow",
+                                "object" => $this->to[0]->getUrl ()
+                            )
+                        );
+                $this->client->setBody (json_encode ($data));
+                $response = $this->client->post ($this->to[0]->getInbox (), $this->headers);
+        }
+}