diff --git a/rbac/engine/classes/model/RbacUsers.php b/rbac/engine/classes/model/RbacUsers.php
index a6da34c66..6895d2ef0 100644
--- a/rbac/engine/classes/model/RbacUsers.php
+++ b/rbac/engine/classes/model/RbacUsers.php
@@ -401,6 +401,38 @@ class RbacUsers extends BaseRbacUsers
 
         return $array;
     }
+
+    /**
+     * Verify if user have the permission
+     *
+     * @param string $userUid
+     * @param string $permission
+     *
+     * @return bool
+     * @throws Exception
+     */
+    public function verifyPermission($userUid, $permission)
+    {
+        try {
+            $criteria = new Criteria('rbac');
+            $criteria->clearSelectColumns();
+            $criteria->add(PermissionsPeer::PER_CODE, $permission, Criteria::EQUAL);
+            $criteria->addJoin(UsersRolesPeer::ROL_UID, RolesPermissionsPeer::ROL_UID, Criteria::LEFT_JOIN);
+            $criteria->addJoin(RolesPermissionsPeer::PER_UID, PermissionsPeer::PER_UID, Criteria::LEFT_JOIN);
+            $criteria->add(UsersRolesPeer::USR_UID, $userUid, Criteria::EQUAL);
+
+            $response = false;
+            $permission = PermissionsPeer::doSelectOne($criteria);
+            if ($permission) {
+                $response = true;
+            }
+
+            return $response;
+        } catch (Exception $error) {
+            throw($error);
+        }
+
+    }
 }
 
 // Users
diff --git a/tests/unit/workflow/engine/src/ProcessMaker/BusinessModel/GroupTest.php b/tests/unit/workflow/engine/src/ProcessMaker/BusinessModel/GroupTest.php
new file mode 100644
index 000000000..d502ce5a1
--- /dev/null
+++ b/tests/unit/workflow/engine/src/ProcessMaker/BusinessModel/GroupTest.php
@@ -0,0 +1,131 @@
+<?php
+
+namespace ProcessMaker\BusinessModel;
+
+use Exception;
+use Tests\TestCase;
+
+class GroupTest extends TestCase
+{
+    /**
+     * @var Group
+     */
+    protected $group;
+
+    /**
+     * Return instance Group
+     *
+     * @return Group
+     */
+    public function getInstanceGroup()
+    {
+        return $this->group;
+    }
+
+    /**
+     * Set instance group
+     *
+     * @param Group $group
+     */
+    public function setInstanceGroup(Group $group)
+    {
+        $this->group = $group;
+    }
+
+    /**
+     * Sets up the unit tests.
+     */
+    protected function setUp()
+    {
+        parent::setUp();
+
+        //Move section
+        global $RBAC;
+        $RBAC->initRBAC();
+        $RBAC->loadUserRolePermission($RBAC->sSystem, '00000000000000000000000000000001');
+
+        $this->setInstanceGroup(new Group());
+    }
+
+    /**
+     * Information Group
+     *
+     * @return array Definition Data Group
+     */
+    public function testDataGroup()
+    {
+        $response = [
+            'GRP_TITLE' => 'Group Test Unit',
+            'GRP_STATUS' => 'ACTIVE'
+        ];
+        return $response;
+    }
+
+    /**
+     * Create group
+     *
+     * @depends testDataGroup
+     *
+     * @param array $dataGroup Information Group
+     *
+     * @return string group Uid
+     */
+    public function testCreate($dataGroup)
+    {
+        $response = $this->getInstanceGroup()->create($dataGroup);
+
+        $this->assertArrayHasKey('GRP_UID', $response);
+
+        return $response['GRP_UID'];
+    }
+
+    /**
+     * Get users from a group created recently.
+     *
+     * @depends testCreate
+     * @param string $groupUid Uid group
+     */
+    public function testGetUsersOfGroup($groupUid)
+    {
+        $response = $this->getInstanceGroup()->getUsers('USERS', $groupUid);
+        $this->assertCount(0, $response);
+    }
+
+    /**
+     * Get available users for assign to a group
+     *
+     * @depends testCreate
+     * @param string $groupUid Uid group
+     */
+    public function testGetUsersAvailable($groupUid)
+    {
+        $response = $this->getInstanceGroup()->getUsers('AVAILABLE-USERS', $groupUid);
+        $this->assertCount(1, $response);
+    }
+
+    /**
+     * Obtain assigned supervisors
+     *
+     * @depends testCreate
+     * @param string $groupUid Uid group
+     */
+    public function testGetUsersSupervisor($groupUid)
+    {
+        $response = $this->getInstanceGroup()->getUsers('SUPERVISOR', $groupUid);
+        $this->assertCount(0, $response);
+    }
+
+    /**
+     * Delete group
+     *
+     * @depends  testCreate
+     * @expectedException Exception
+     *
+     * @param string $groupUid Uid Group
+     */
+    public function testDelete($groupUid)
+    {
+        $this->getInstanceGroup()->delete($groupUid);
+        $this->getInstanceGroup()->getGroup($groupUid);
+    }
+}
diff --git a/workflow/engine/classes/model/GroupUser.php b/workflow/engine/classes/model/GroupUser.php
index bf082de4f..ef15c63c0 100644
--- a/workflow/engine/classes/model/GroupUser.php
+++ b/workflow/engine/classes/model/GroupUser.php
@@ -217,5 +217,99 @@ class GroupUser extends BaseGroupUser
         }
         return false;
     }
+
+    /**
+     * Load All users by groupUid
+     *
+     * @param $groupUid
+     * @param string $type
+     * @param string $filter
+     * @param string $sortField
+     * @param string $sortDir
+     * @param int $start
+     * @param int $limit
+     * @return array
+     * @throws Exception
+     */
+    public function getUsersbyGroup($groupUid, $type = 'USERS', $filter = '', $sortField = 'USR_USERNAME', $sortDir = 'ASC', $start = 0, $limit = null)
+    {
+        try {
+            $validSorting = ['USR_UID', 'USR_USERNAME', 'USR_FIRSTNAME', 'USR_LASTNAME', 'USR_EMAIL', 'USR_STATUS'];
+            $response = [
+                'start' => !empty($start) ? $start : 0,
+                'limit' => !empty($limit) ? $limit : 0,
+                'filter' => !empty($filter) ? $filter : '',
+                'data' => []
+            ];
+
+
+            $criteria = new Criteria('workflow');
+            $criteria->add(UsersPeer::USR_STATUS, 'CLOSED', Criteria::NOT_EQUAL);
+            if ($type === 'AVAILABLE-USERS') {
+                $subQuery = 'SELECT ' . GroupUserPeer::USR_UID .
+                    ' FROM ' . GroupUserPeer::TABLE_NAME .
+                    ' WHERE ' . GroupUserPeer::GRP_UID . ' = "' . $groupUid . '" ' .
+                    'UNION SELECT "' . RBAC::GUEST_USER_UID . '"';
+
+                $criteria->add(UsersPeer::USR_UID, UsersPeer::USR_UID . " NOT IN ($subQuery)", Criteria::CUSTOM);
+            } else {
+                //USERS - SUPERVISOR
+                $criteria->addJoin(GroupUserPeer::USR_UID, UsersPeer::USR_UID, Criteria::LEFT_JOIN);
+                $criteria->add(GroupUserPeer::GRP_UID, $groupUid, Criteria::EQUAL);
+            }
+
+            if (!empty($filter)) {
+                $criteria->add($criteria->getNewCriterion(UsersPeer::USR_USERNAME, '%' . $filter . '%', Criteria::LIKE)->
+                addOr($criteria->getNewCriterion(UsersPeer::USR_FIRSTNAME, '%' . $filter . '%', Criteria::LIKE)->
+                addOr($criteria->getNewCriterion(UsersPeer::USR_LASTNAME, '%' . $filter . '%', Criteria::LIKE))));
+            }
+            $response['total'] = UsersPeer::doCount($criteria);
+
+            $criteria->addSelectColumn(UsersPeer::USR_UID);
+            $criteria->addSelectColumn(UsersPeer::USR_USERNAME);
+            $criteria->addSelectColumn(UsersPeer::USR_FIRSTNAME);
+            $criteria->addSelectColumn(UsersPeer::USR_LASTNAME);
+            $criteria->addSelectColumn(UsersPeer::USR_EMAIL);
+            $criteria->addSelectColumn(UsersPeer::USR_STATUS);
+
+            $sort = UsersPeer::USR_USERNAME;
+            if (!empty($sortField) && in_array($sortField, $validSorting, true)) {
+                $sort = UsersPeer::TABLE_NAME . '.' . $sortField;
+            }
+
+            if (!empty($sortDir) && strtoupper($sortDir) === 'DESC') {
+                $criteria->addDescendingOrderByColumn($sort);
+            } else {
+                $criteria->addAscendingOrderByColumn($sort);
+            }
+
+            if (!empty($start)) {
+                $criteria->setOffset((int)$start);
+            }
+
+            if (!empty($limit)) {
+                $criteria->setLimit((int)$limit);
+            }
+
+            $dataSet = UsersPeer::doSelectRS($criteria);
+            $dataSet->setFetchmode(ResultSet::FETCHMODE_ASSOC);
+            $userRbac = new RbacUsers();
+            while ($dataSet->next()) {
+                $row = $dataSet->getRow();
+                if ($type === 'SUPERVISOR') {
+                    if ($userRbac->verifyPermission($row['USR_UID'], 'PM_SUPERVISOR')) {
+                        $response['data'][] = $row;
+                    }
+                } else {
+                    $response['data'][] = $row;
+                }
+            }
+
+            return $response;
+
+        } catch (Exception $error) {
+            throw $error;
+        }
+    }
 }
 
diff --git a/workflow/engine/methods/groups/groups_Ajax.php b/workflow/engine/methods/groups/groups_Ajax.php
index b58ebfc0c..4b227b6dd 100644
--- a/workflow/engine/methods/groups/groups_Ajax.php
+++ b/workflow/engine/methods/groups/groups_Ajax.php
@@ -1,59 +1,33 @@
 <?php
-/**
- * groups_Ajax.php
- *
- * ProcessMaker Open Source Edition
- * Copyright (C) 2004 - 2008 Colosa Inc.23
- *
- * 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/>.
- *
- * For more information, contact Colosa Inc, 2566 Le Jeune Rd.,
- * Coral Gables, FL, 33134, USA, or email info@colosa.com.
- */
+
 if (($RBAC_Response = $RBAC->userCanAccess("PM_USERS")) != 1) {
     return $RBAC_Response;
 }
 $_POST['action'] = get_ajax_value('action');
 
+$groups = new Groups();
+$groupWf = new Groupwf();
+
 switch ($_POST['action']) {
     case 'showUsers':
-
-        $oGroups = new Groups();
-        $oGroup = new Groupwf();
-        $aFields = $oGroup->load($_POST['sGroupUID']);
+        $fields = $groupWf->load($_POST['sGroupUID']);
         global $G_PUBLISH;
         $G_PUBLISH = new Publisher();
-        //$G_PUBLISH->AddContent('xmlform', 'xmlform', 'groups/groups_UsersListTitle', '', array('GRP_NAME' => $aFields['GRP_TITLE']));
-        $G_PUBLISH->AddContent('propeltable', 'groups/paged-table2', 'groups/groups_UsersList', $oGroups->getUsersGroupCriteria($_POST['sGroupUID']), array('GRP_UID' => $_POST['sGroupUID'],'GRP_NAME' => $aFields['GRP_TITLE']));
+        $G_PUBLISH->AddContent('propeltable', 'groups/paged-table2', 'groups/groups_UsersList', $groups->getUsersGroupCriteria($_POST['sGroupUID']), array('GRP_UID' => $_POST['sGroupUID'], 'GRP_NAME' => $fields['GRP_TITLE']));
         $oHeadPublisher = headPublisher::getSingleton();
-        $oHeadPublisher->addScriptCode("groupname=\"{$aFields["GRP_TITLE"]}\";");
+        $oHeadPublisher->addScriptCode("groupname=\"{$fields["GRP_TITLE"]}\";");
         G::RenderPage('publish', 'raw');
         break;
     case 'assignUser':
-        $oGroup = new Groups();
-        $oGroup->addUserToGroup($_POST['GRP_UID'], $_POST['USR_UID']);
+        $groups->addUserToGroup($_POST['GRP_UID'], $_POST['USR_UID']);
         break;
     case 'assignAllUsers':
-        $oGroup = new Groups();
-        $aUsers = explode(',', $_POST['aUsers']);
-        for ($i = 0; $i < count($aUsers); $i ++) {
-            $oGroup->addUserToGroup($_POST['GRP_UID'], $aUsers[$i]);
+        foreach (explode(',', $_POST['aUsers']) as $user) {
+            $groups->addUserToGroup($_POST['GRP_UID'], $user);
         }
         break;
     case 'ofToAssignUser':
-        $oGroup = new Groups();
-        $oGroup->removeUserOfGroup($_POST['GRP_UID'], $_POST['USR_UID']);
+        $groups->removeUserOfGroup($_POST['GRP_UID'], $_POST['USR_UID']);
         break;
     case 'verifyGroupname':
         $_POST['sOriginalGroupname'] = get_ajax_value('sOriginalGroupname');
@@ -61,13 +35,12 @@ switch ($_POST['action']) {
         if ($_POST['sOriginalGroupname'] == $_POST['sGroupname']) {
             echo '0';
         } else {
-            $oGroup = new Groupwf();
-            $oCriteria = $oGroup->loadByGroupname($_POST['sGroupname']);
+            $oCriteria = $groupWf->loadByGroupname($_POST['sGroupname']);
             $oDataset = GroupwfPeer::doSelectRS($oCriteria);
             $oDataset->setFetchmode(ResultSet::FETCHMODE_ASSOC);
             $oDataset->next();
             $aRow = $oDataset->getRow();
-            if (! $aRow) {
+            if (!$aRow) {
                 echo '0';
             } else {
                 echo '1';
@@ -75,16 +48,15 @@ switch ($_POST['action']) {
         }
         break;
     case 'groupsList':
-        $co = new Configurations();
-        $config = $co->getConfiguration('groupList', 'pageSize', '', $_SESSION['USER_LOGGED']);
-        $env = $co->getConfiguration('ENVIRONMENT_SETTINGS', '');
+        $config = new Configurations();
+        $config = $config->getConfiguration('groupList', 'pageSize', '', $_SESSION['USER_LOGGED']);
         $limit_size = isset($config['pageSize']) ? $config['pageSize'] : 20;
         $start = isset($_REQUEST['start']) ? $_REQUEST['start'] : 0;
         $limit = isset($_REQUEST['limit']) ? $_REQUEST['limit'] : $limit_size;
         $filter = isset($_REQUEST['textFilter']) ? $_REQUEST['textFilter'] : '';
 
-        $sortField = isset($_REQUEST["sort"])? $_REQUEST["sort"] : "";
-        $sortDir = isset($_REQUEST["dir"])? $_REQUEST["dir"] : "";
+        $sortField = isset($_REQUEST["sort"]) ? $_REQUEST["sort"] : "";
+        $sortDir = isset($_REQUEST["dir"]) ? $_REQUEST["dir"] : "";
 
         global $RBAC;
         if ($limit == $start) {
@@ -96,17 +68,15 @@ switch ($_POST['action']) {
         require_once PATH_CONTROLLERS . 'adminProxy.php';
         $uxList = adminProxy::getUxTypesList();
 
-        $groups = new Groupwf();
-
-        $data = $groups->getAllGroup($start, $limit, $filter, $sortField, $sortDir, true);
+        $data = $groupWf->getAllGroup($start, $limit, $filter, $sortField, $sortDir, true);
         $result = $data['rows'];
 
         $totalRows = 0;
         $arrData = array();
         foreach ($result as $results) {
-            $totalRows ++;
-            $results['CON_VALUE'] = str_replace(array("<",">"
-            ), array("&lt;","&gt;"
+            $totalRows++;
+            $results['CON_VALUE'] = str_replace(array("<", ">"
+            ), array("&lt;", "&gt;"
             ), $results['GRP_TITLE']);
             $results['GRP_TASKS'] = isset($aTask[$results['GRP_UID']]) ? $aTask[$results['GRP_UID']] : 0;
             $arrData[] = $results;
@@ -120,8 +90,7 @@ switch ($_POST['action']) {
         echo G::json_encode($result);
         break;
     case 'exitsGroupName':
-        $oGroup = new Groupwf();
-        $oCriteria = $oGroup->loadByGroupname($_POST['GRP_NAME']);
+        $oCriteria = $groupWf->loadByGroupname($_POST['GRP_NAME']);
         $oDataset = GroupwfPeer::doSelectRS($oCriteria);
         $oDataset->setFetchmode(ResultSet::FETCHMODE_ASSOC);
         $oDataset->next();
@@ -134,9 +103,8 @@ switch ($_POST['action']) {
         $newGroup['GRP_STATUS'] = ($_POST['status'] == '1') ? 'ACTIVE' : 'INACTIVE';
         $newGroup['GRP_TITLE'] = trim($_POST['name']);
         unset($newGroup['GRP_UID']);
-        $group = new Groupwf();
-        $group->create($newGroup);
-        G::auditLog("CreateGroup", "Group Name: ".$newGroup['GRP_TITLE']." - Group Status: ".$newGroup['GRP_STATUS']);
+        $groupWf->create($newGroup);
+        G::auditLog("CreateGroup", "Group Name: " . $newGroup['GRP_TITLE'] . " - Group Status: " . $newGroup['GRP_STATUS']);
 
         echo '{success: true}';
 
@@ -145,18 +113,16 @@ switch ($_POST['action']) {
         $editGroup['GRP_UID'] = $_POST['grp_uid'];
         $editGroup['GRP_STATUS'] = ($_POST['status'] == '1') ? 'ACTIVE' : 'INACTIVE';
         $editGroup['GRP_TITLE'] = trim($_POST['name']);
-        $group = new Groupwf();
-        $group->update($editGroup);
-        G::auditLog("UpdateGroup", "Group Name: ".$editGroup['GRP_TITLE']." - Group ID: (".$_POST['grp_uid'].") - Group Status: ".$editGroup['GRP_STATUS']);
+        $groupWf->update($editGroup);
+        G::auditLog("UpdateGroup", "Group Name: " . $editGroup['GRP_TITLE'] . " - Group ID: (" . $_POST['grp_uid'] . ") - Group Status: " . $editGroup['GRP_STATUS']);
         echo '{success: true}';
         break;
     case 'deleteGroup':
-        $group = new Groupwf();
-        if (! isset($_POST['GRP_UID'])) {
+        if (!isset($_POST['GRP_UID'])) {
             return;
         }
-        $group->remove(urldecode($_POST['GRP_UID']));
-        G::auditLog("DeleteGroup", "Group Name: ".$_POST['GRP_NAME']." Group ID: (".$_POST['GRP_UID'].") ");
+        $groupWf->remove(urldecode($_POST['GRP_UID']));
+        G::auditLog("DeleteGroup", "Group Name: " . $_POST['GRP_NAME'] . " Group ID: (" . $_POST['GRP_UID'] . ") ");
         require_once 'classes/model/TaskUser.php';
         $oProcess = new TaskUser();
         $oCriteria = new Criteria('workflow');
@@ -175,7 +141,7 @@ switch ($_POST['action']) {
         $criteria->add(ProcessUserPeer::USR_UID, $_POST['GRP_UID']);
         $criteria->add(ProcessUserPeer::PU_TYPE, 'GROUP_SUPERVISOR');
         ProcessUserPeer::doDelete($criteria);
-        
+
         //Delete group users
         require_once 'classes/model/GroupUser.php';
         $criteria = new Criteria('workflow');
@@ -185,130 +151,36 @@ switch ($_POST['action']) {
         echo '{success: true}';
         break;
     case 'assignedMembers':
-
-        $co = new Configurations();
-        $config = $co->getConfiguration('groupList', 'pageSize', '', $_SESSION['USER_LOGGED']);
-        $env = $co->getConfiguration('ENVIRONMENT_SETTINGS', '');
-        $limit_size = isset($config['pageSize']) ? $config['pageSize'] : 20;
-        $start = isset($_REQUEST['start']) ? $_REQUEST['start'] : 0;
-        $limit = isset($_REQUEST['limit']) ? $_REQUEST['limit'] : $limit_size;
-        $filter = isset($_REQUEST['textFilter']) ? $_REQUEST['textFilter'] : '';
-
-        $sGroupUID = $_REQUEST['gUID'];
-
-        $aUsers = array();
-        $oCriteria = new Criteria('workflow');
-        $oCriteria->addSelectColumn('COUNT(*) AS CNT');
-        $oCriteria->addJoin(GroupUserPeer::USR_UID, UsersPeer::USR_UID, Criteria::LEFT_JOIN);
-        $oCriteria->add(GroupUserPeer::GRP_UID, $sGroupUID);
-        $oCriteria->add(UsersPeer::USR_STATUS, 'CLOSED', Criteria::NOT_EQUAL);
-        $filter = (isset($_POST['textFilter'])) ? $_POST['textFilter'] : '';
-        if ($filter != '') {
-            $oCriteria->add($oCriteria->getNewCriterion(UsersPeer::USR_USERNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_FIRSTNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_LASTNAME, '%' . $filter . '%', Criteria::LIKE))));
-        }
-        $oDataset = UsersPeer::DoSelectRs($oCriteria);
-        $oDataset->setFetchmode(ResultSet::FETCHMODE_ASSOC);
-        $oDataset->next();
-        $row = $oDataset->getRow();
-        $totalRows = $row['CNT'];
-
-        $oCriteria = new Criteria('workflow');
-        $oCriteria->addSelectColumn(GroupUserPeer::GRP_UID);
-        $oCriteria->addSelectColumn(UsersPeer::USR_UID);
-        $oCriteria->addSelectColumn(UsersPeer::USR_USERNAME);
-        $oCriteria->addSelectColumn(UsersPeer::USR_FIRSTNAME);
-        $oCriteria->addSelectColumn(UsersPeer::USR_LASTNAME);
-        $oCriteria->addSelectColumn(UsersPeer::USR_EMAIL);
-        $oCriteria->addSelectColumn(UsersPeer::USR_STATUS);
-        $oCriteria->addJoin(GroupUserPeer::USR_UID, UsersPeer::USR_UID, Criteria::LEFT_JOIN);
-        $oCriteria->add(GroupUserPeer::GRP_UID, $sGroupUID);
-        $oCriteria->add(UsersPeer::USR_STATUS, 'CLOSED', Criteria::NOT_EQUAL);
-        $filter = (isset($_POST['textFilter'])) ? $_POST['textFilter'] : '';
-        if ($filter != '') {
-            $oCriteria->add($oCriteria->getNewCriterion(UsersPeer::USR_USERNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_FIRSTNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_LASTNAME, '%' . $filter . '%', Criteria::LIKE))));
-        }
-        $oCriteria->setOffset($start);
-        $oCriteria->setLimit($limit);
-
-        $oDataset = UsersPeer::doSelectRS($oCriteria);
-        $oDataset->setFetchmode(ResultSet::FETCHMODE_ASSOC);
-        $arrData = array();
-        while ($oDataset->next()) {
-            $arrData[] = $oDataset->getRow();
-        }
-        G::header('Content-Type: application/json');
-        echo '{success: true, members: ' . G::json_encode($arrData) . ', total_users: ' . $totalRows . '}';
-        break;
     case 'availableMembers':
-        $co = new Configurations();
-        $config = $co->getConfiguration('groupList', 'pageSize', '', $_SESSION['USER_LOGGED']);
-        $env = $co->getConfiguration('ENVIRONMENT_SETTINGS', '');
+        $config = new Configurations();
+        $inputFilter = new InputFilter();
+
+        $config = $config->getConfiguration('groupList', 'pageSize', '', $_SESSION['USER_LOGGED']);
         $limit_size = isset($config['pageSize']) ? $config['pageSize'] : 20;
         $start = isset($_REQUEST['start']) ? $_REQUEST['start'] : 0;
         $limit = isset($_REQUEST['limit']) ? $_REQUEST['limit'] : $limit_size;
         $filter = isset($_REQUEST['textFilter']) ? $_REQUEST['textFilter'] : '';
+        $groupUid = $inputFilter->quoteSmart($_REQUEST['gUID'], Propel::getConnection("workflow")->getResource());
 
-        $inputFilter = new InputFilter();
-        $subQuery = "SELECT " . GroupUserPeer::USR_UID .
-                    " FROM " . GroupUserPeer::TABLE_NAME .
-                    " WHERE " . GroupUserPeer::GRP_UID . " = '" .
-                    $inputFilter->quoteSmart($_REQUEST['gUID'], Propel::getConnection("workflow")) . "'\n" .
-                    "UNION SELECT '" . RBAC::GUEST_USER_UID . "'";
+        $groupUsers = new GroupUser();
+        $type = $_POST['action'] === 'assignedMembers' ? 'USERS' : 'AVAILABLE-USERS';
+        $data = $groupUsers->getUsersbyGroup($groupUid, $type, $filter, 'USR_USERNAME', 'ASC', $start, $limit);
 
-        $aUsers = array();
-        $oCriteria = new Criteria('workflow');
-        $oCriteria->addSelectColumn('COUNT(*) AS CNT');
-        $oCriteria->add(UsersPeer::USR_STATUS, 'CLOSED', Criteria::NOT_EQUAL);
-        $oCriteria->add(UsersPeer::USR_UID, UsersPeer::USR_UID . " NOT IN ($subQuery)", Criteria::CUSTOM);
-        $filter = (isset($_POST['textFilter'])) ? $_POST['textFilter'] : '';
-        if ($filter != '') {
-            $oCriteria->add($oCriteria->getNewCriterion(UsersPeer::USR_USERNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_FIRSTNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_LASTNAME, '%' . $filter . '%', Criteria::LIKE))));
-        }
-        $oDataset = UsersPeer::DoSelectRs($oCriteria);
-        $oDataset->setFetchmode(ResultSet::FETCHMODE_ASSOC);
-        $oDataset->next();
-        $row = $oDataset->getRow();
-        $totalRows = $row['CNT'];
-
-        $oCriteria = new Criteria('workflow');
-        $oCriteria->addSelectColumn(UsersPeer::USR_UID);
-        $oCriteria->addSelectColumn(UsersPeer::USR_USERNAME);
-        $oCriteria->addSelectColumn(UsersPeer::USR_FIRSTNAME);
-        $oCriteria->addSelectColumn(UsersPeer::USR_LASTNAME);
-        $oCriteria->addSelectColumn(UsersPeer::USR_EMAIL);
-        $oCriteria->addSelectColumn(UsersPeer::USR_STATUS);
-        $oCriteria->add(UsersPeer::USR_STATUS, 'CLOSED', Criteria::NOT_EQUAL);
-        $oCriteria->add(UsersPeer::USR_UID, UsersPeer::USR_UID . " NOT IN ($subQuery)", Criteria::CUSTOM);
-        $filter = (isset($_POST['textFilter'])) ? $_POST['textFilter'] : '';
-        if ($filter != '') {
-            $oCriteria->add($oCriteria->getNewCriterion(UsersPeer::USR_USERNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_FIRSTNAME, '%' . $filter . '%', Criteria::LIKE)->addOr($oCriteria->getNewCriterion(UsersPeer::USR_LASTNAME, '%' . $filter . '%', Criteria::LIKE))));
-        }
-        $oCriteria->addAscendingOrderByColumn(UsersPeer::USR_USERNAME);
-        $oCriteria->setOffset($start);
-        $oCriteria->setLimit($limit);
-        $oDataset = UsersPeer::doSelectRS($oCriteria);
-        $oDataset->setFetchmode(ResultSet::FETCHMODE_ASSOC);
-        $arrData = array();
-        while ($oDataset->next()) {
-            $arrData[] = $oDataset->getRow();
-        }
         G::header('Content-Type: application/json');
-        echo '{success: true, members: ' . G::json_encode($arrData) . ', total_users: ' . $totalRows . '}';
+        echo '{success: true, members: ' . G::json_encode($data["data"]) . ', total_users: ' . $data["total"] . '}';
         break;
     case 'assignUsersToGroupsMultiple':
         $GRP_UID = $_POST['GRP_UID'];
         $uUIDs = explode(',', $_POST['USR_UID']);
-        $oGroup = new Groups();
         foreach ($uUIDs as $USR_UID) {
-            $oGroup->addUserToGroup($GRP_UID, $USR_UID);
+            $groups->addUserToGroup($GRP_UID, $USR_UID);
         }
         break;
     case 'deleteUsersToGroupsMultiple':
         $GRP_UID = $_POST['GRP_UID'];
         $uUIDs = explode(',', $_POST['USR_UID']);
-        $oGroup = new Groups();
         foreach ($uUIDs as $USR_UID) {
-            $oGroup->removeUserOfGroup($GRP_UID, $USR_UID);
+            $groups->removeUserOfGroup($GRP_UID, $USR_UID);
         }
         break;
     case 'updatePageSize':
diff --git a/workflow/engine/src/ProcessMaker/BusinessModel/Group.php b/workflow/engine/src/ProcessMaker/BusinessModel/Group.php
index 95684a4b4..63082315b 100644
--- a/workflow/engine/src/ProcessMaker/BusinessModel/Group.php
+++ b/workflow/engine/src/ProcessMaker/BusinessModel/Group.php
@@ -1,6 +1,12 @@
 <?php
+
 namespace ProcessMaker\BusinessModel;
 
+use Exception;
+use GroupUser;
+use Groupwf;
+use ProcessMaker\BusinessModel\Process;
+
 class Group
 {
     private $arrayFieldDefinition = array(
@@ -29,7 +35,7 @@ class Group
             foreach ($this->arrayFieldDefinition as $key => $value) {
                 $this->arrayFieldNameForException[$value["fieldNameAux"]] = $key;
             }
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -47,7 +53,7 @@ class Group
             $this->formatFieldNameInUppercase = $flag;
 
             $this->setArrayFieldNameForException($this->arrayFieldNameForException);
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -65,7 +71,7 @@ class Group
             foreach ($arrayData as $key => $value) {
                 $this->arrayFieldNameForException[$key] = $this->getFieldNameByFormatFieldName($value);
             }
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -81,7 +87,7 @@ class Group
     {
         try {
             return ($this->formatFieldNameInUppercase)? strtoupper($fieldName) : strtolower($fieldName);
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -117,7 +123,7 @@ class Group
             } else {
                 return false;
             }
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -133,12 +139,12 @@ class Group
     public function throwExceptionIfNotExistsGroup($groupUid, $fieldNameForException)
     {
         try {
-            $group = new \Groupwf();
+            $group = new Groupwf();
 
             if (!$group->GroupwfExists($groupUid)) {
-                throw new \Exception(\G::LoadTranslation("ID_GROUP_DOES_NOT_EXIST", array($fieldNameForException, $groupUid)));
+                throw new Exception(\G::LoadTranslation("ID_GROUP_DOES_NOT_EXIST", array($fieldNameForException, $groupUid)));
             }
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -156,9 +162,9 @@ class Group
     {
         try {
             if ($this->existsTitle($groupTitle, $groupUidExclude)) {
-                throw new \Exception(\G::LoadTranslation("ID_GROUP_TITLE_ALREADY_EXISTS", array($fieldNameForException, $groupTitle)));
+                throw new Exception(\G::LoadTranslation("ID_GROUP_TITLE_ALREADY_EXISTS", array($fieldNameForException, $groupTitle)));
             }
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -166,38 +172,39 @@ class Group
     /**
      * Create Group
      *
-     * @param array $arrayData Data
+     * @param array $arrayData Information of group
      *
-     * return array Return data of the new Group created
+     * @return array Return data of the new Group created
+     * @throws Exception
      */
     public function create($arrayData)
     {
         try {
             $arrayData = array_change_key_case($arrayData, CASE_UPPER);
 
-            unset($arrayData["GRP_UID"]);
+            unset($arrayData['GRP_UID']);
 
             //Verify data
-            $process = new \ProcessMaker\BusinessModel\Process();
+            $process = new Process();
 
             $process->throwExceptionIfDataNotMetFieldDefinition($arrayData, $this->arrayFieldDefinition, $this->arrayFieldNameForException, true);
 
-            $this->throwExceptionIfExistsTitle($arrayData["GRP_TITLE"], $this->arrayFieldNameForException["groupTitle"]);
+            $this->throwExceptionIfExistsTitle($arrayData['GRP_TITLE'], $this->arrayFieldNameForException['groupTitle']);
 
             //Create
-            $group = new \Groupwf();
+            $group = new Groupwf();
 
             $groupUid = $group->create($arrayData);
 
             //Return
-            $arrayData = array_merge(array("GRP_UID" => $groupUid), $arrayData);
+            $arrayData = array_merge(['GRP_UID' => $groupUid], $arrayData);
 
             if (!$this->formatFieldNameInUppercase) {
                 $arrayData = array_change_key_case($arrayData, CASE_LOWER);
             }
 
             return $arrayData;
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -205,10 +212,11 @@ class Group
     /**
      * Update Group
      *
-     * @param string $groupUid  Unique id of Group
-     * @param array  $arrayData Data
+     * @param string $groupUid Unique id of group
+     * @param array $arrayData information of group
      *
-     * return array Return data of the Group updated
+     * @return array Return data of the Group updated
+     * @throws Exception
      */
     public function update($groupUid, $arrayData)
     {
@@ -216,32 +224,32 @@ class Group
             $arrayData = array_change_key_case($arrayData, CASE_UPPER);
 
             //Verify data
-            $process = new \ProcessMaker\BusinessModel\Process();
+            $process = new Process();
 
-            $this->throwExceptionIfNotExistsGroup($groupUid, $this->arrayFieldNameForException["groupUid"]);
+            $this->throwExceptionIfNotExistsGroup($groupUid, $this->arrayFieldNameForException['groupUid']);
 
             $process->throwExceptionIfDataNotMetFieldDefinition($arrayData, $this->arrayFieldDefinition, $this->arrayFieldNameForException, false);
 
-            if (isset($arrayData["GRP_TITLE"])) {
-                $this->throwExceptionIfExistsTitle($arrayData["GRP_TITLE"], $this->arrayFieldNameForException["groupTitle"], $groupUid);
+            if (isset($arrayData['GRP_TITLE'])) {
+                $this->throwExceptionIfExistsTitle($arrayData['GRP_TITLE'], $this->arrayFieldNameForException['groupTitle'], $groupUid);
             }
 
             //Update
-            $group = new \Groupwf();
+            $group = new Groupwf();
 
-            $arrayData["GRP_UID"] = $groupUid;
+            $arrayData['GRP_UID'] = $groupUid;
 
             $result = $group->update($arrayData);
 
             //Return
-            unset($arrayData["GRP_UID"]);
+            unset($arrayData['GRP_UID']);
 
             if (!$this->formatFieldNameInUppercase) {
                 $arrayData = array_change_key_case($arrayData, CASE_LOWER);
             }
 
             return $arrayData;
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -262,11 +270,11 @@ class Group
             $arrayTotalTasksByGroup = $this->getTotalTasksByGroup($groupUid);
 
             if (isset($arrayTotalTasksByGroup[$groupUid]) && $arrayTotalTasksByGroup[$groupUid] > 0) {
-                throw new \Exception(\G::LoadTranslation("ID_GROUP_CANNOT_DELETE_WHILE_ASSIGNED_TO_TASK"));
+                throw new Exception(\G::LoadTranslation("ID_GROUP_CANNOT_DELETE_WHILE_ASSIGNED_TO_TASK"));
             }
 
             //Delete
-            $group = new \Groupwf();
+            $group = new Groupwf();
 
             $result = $group->remove($groupUid);
 
@@ -291,7 +299,7 @@ class Group
             $criteria->add(\ProcessUserPeer::PU_TYPE, "GROUP_SUPERVISOR");
 
             \ProcessUserPeer::doDelete($criteria);
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -312,7 +320,7 @@ class Group
             $criteria->addSelectColumn(\GroupwfPeer::GRP_LDAP_DN);
             $criteria->addSelectColumn(\GroupwfPeer::GRP_UX);
             return $criteria;
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -359,7 +367,7 @@ class Group
 
             //Return
             return $arrayData;
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -406,7 +414,7 @@ class Group
 
             //Return
             return $arrayData;
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -428,7 +436,7 @@ class Group
                 $this->getFieldNameByFormatFieldName("GRP_USERS")  => $record["GRP_USERS"],
                 $this->getFieldNameByFormatFieldName("GRP_TASKS")  => $record["GRP_TASKS"]
             );
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -452,7 +460,7 @@ class Group
             $numRecTotal = 0;
 
             //Verify data
-            $process = new \ProcessMaker\BusinessModel\Process();
+            $process = new Process();
 
             $process->throwExceptionIfDataNotMetPagerVarDefinition(array("start" => $start, "limit" => $limit), $this->arrayFieldNameForException);
 
@@ -561,7 +569,7 @@ class Group
                 $filterName => (!is_null($arrayFilterData) && is_array($arrayFilterData) && isset($arrayFilterData["filter"]))? $arrayFilterData["filter"] : "",
                 "data"      => $arrayGroup
             );
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -600,7 +608,7 @@ class Group
 
             //Return
             return $this->getGroupDataFromRecord($row);
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -656,7 +664,7 @@ class Group
             }
 
             return $criteria;
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -679,7 +687,7 @@ class Group
                 $this->getFieldNameByFormatFieldName("USR_EMAIL")     => $record["USR_EMAIL"] . "",
                 $this->getFieldNameByFormatFieldName("USR_STATUS")    => $record["USR_STATUS"]
             );
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             throw $e;
         }
     }
@@ -708,123 +716,41 @@ class Group
     }
 
     /**
-     * Get all Users of a Group
+     * Get all users of a group
      *
-     * @param string $option          Option (USERS, AVAILABLE-USERS)
-     * @param string $groupUid        Unique id of Group
-     * @param array  $arrayFilterData Data of the filters
-     * @param string $sortField       Field name to sort
-     * @param string $sortDir         Direction of sorting (ASC, DESC)
-     * @param int    $start           Start
-     * @param int    $limit           Limit
+     * @param string $option types USERS|AVAILABLE-USERS|SUPERVISOR
+     * @param string $groupUid Unique id of Group
+     * @param array $arrayFilterData Data of the filters
+     * @param string $sortField Field name to sort
+     * @param string $sortDir Direction of sorting (ASC, DESC)
+     * @param int $start start
+     * @param int $limit limit
      *
-     * return array Return an array with all Users of a Group
+     * @return array Return an array with all Users of a Group
+     * @throws Exception
      */
-    public function getUsers($option, $groupUid, $arrayFilterData = null, $sortField = null, $sortDir = null, $start = null, $limit = null)
+    public function getUsers($option, $groupUid, $arrayFilterData = [], $sortField = 'USR_USERNAME', $sortDir = 'ASC', $start = 0, $limit = null)
     {
         try {
-            $arrayUser = array();
-
             //Verify data
-            $process = new \ProcessMaker\BusinessModel\Process();
+            $process = new Process();
 
-            $this->throwExceptionIfNotExistsGroup($groupUid, $this->arrayFieldNameForException["groupUid"]);
+            $this->throwExceptionIfNotExistsGroup($groupUid, $this->arrayFieldNameForException['groupUid']);
+            $process->throwExceptionIfDataNotMetPagerVarDefinition(['start' => $start, 'limit' => $limit], $this->arrayFieldNameForException);
 
-            $process->throwExceptionIfDataNotMetPagerVarDefinition(array("start" => $start, "limit" => $limit), $this->arrayFieldNameForException);
+            $filter = isset($arrayFilterData['filter']) ? $arrayFilterData['filter'] : '';
 
-            //Get data
-            if (!is_null($limit) && $limit . "" == "0") {
-                return $arrayUser;
+            $groupUsers = new GroupUser();
+            $data = $groupUsers->getUsersbyGroup($groupUid, $option, $filter, $sortField, $sortDir, $start, $limit);
+
+            $response = [];
+            foreach ($data['data'] as $user)
+            {
+                $response[] = $this->getUserDataFromRecord($user);
             }
 
-            //SQL
-            switch ($option) {
-                case "SUPERVISOR":
-                    $flagPermission = true;
-                    //Criteria for Supervisor
-                    $criteria = $this->getUserCriteria($groupUid, $arrayFilterData);
-                    break;
-                case "USERS":
-                    //Criteria
-                    $criteria = $this->getUserCriteria($groupUid, $arrayFilterData);
-                    break;
-                case "AVAILABLE-USERS":
-                    //Get Uids
-                    $arrayUid = array();
-
-                    $criteria = $this->getUserCriteria($groupUid);
-
-                    $rsCriteria = \UsersPeer::doSelectRS($criteria);
-                    $rsCriteria->setFetchmode(\ResultSet::FETCHMODE_ASSOC);
-
-                    while ($rsCriteria->next()) {
-                        $row = $rsCriteria->getRow();
-
-                        $arrayUid[] = $row["USR_UID"];
-                    }
-
-                    //Criteria
-                    $criteria = $this->getUserCriteria("", $arrayFilterData, $arrayUid);
-                    break;
-            }
-
-            //SQL
-            if (!is_null($sortField) && trim($sortField) != "") {
-                $sortField = strtoupper($sortField);
-
-                if (in_array($sortField, array("USR_UID", "USR_USERNAME", "USR_FIRSTNAME", "USR_LASTNAME", "USR_EMAIL", "USR_STATUS"))) {
-                    $sortField = \UsersPeer::TABLE_NAME . "." . $sortField;
-                } else {
-                    $sortField = \UsersPeer::USR_USERNAME;
-                }
-            } else {
-                $sortField = \UsersPeer::USR_USERNAME;
-            }
-
-            if (!is_null($sortDir) && trim($sortDir) != "" && strtoupper($sortDir) == "DESC") {
-                $criteria->addDescendingOrderByColumn($sortField);
-            } else {
-                $criteria->addAscendingOrderByColumn($sortField);
-            }
-
-            if (!is_null($start)) {
-                $criteria->setOffset((int)($start));
-            }
-
-            if (!is_null($limit)) {
-                $criteria->setLimit((int)($limit));
-            }
-
-            $rsCriteria = \UsersPeer::doSelectRS($criteria);
-            $rsCriteria->setFetchmode(\ResultSet::FETCHMODE_ASSOC);
-
-            if (isset($flagPermission) && $flagPermission) {
-
-                while ($rsCriteria->next()) {
-                    $row = $rsCriteria->getRow();
-
-                    $aPermissions =   $this->loadUserRolePermission("PROCESSMAKER", $row['USR_UID']);
-                    $bInclude = false;
-
-                    foreach ($aPermissions as $aPermission) {
-                        if ($aPermission['PER_CODE'] == 'PM_SUPERVISOR') {
-                            $bInclude = true;
-                        }
-                    }
-                    if ($bInclude) {
-                        $arrayUser[] = $this->getUserDataFromRecord($row);
-                    }
-                }
-            } else {
-                while ($rsCriteria->next()) {
-                    $row = $rsCriteria->getRow();
-
-                    $arrayUser[] = $this->getUserDataFromRecord($row);
-                }
-            }
-            //Return
-            return $arrayUser;
-        } catch (\Exception $e) {
+            return $response;
+        } catch (Exception $e) {
             throw $e;
         }
     }