diff --git a/api.py b/api.py
index 463a765e47788b1a6eb0e97d1b38806b39ffb7c8..29dc418d7823b0807e50a0377395572687b20f41 100644
--- a/api.py
+++ b/api.py
@@ -27,7 +27,7 @@ except ImportError:
 from lib.read_status_logs import ReadLogger
 from lib.get_most_recent_status_logs import GetLatestLog
 from lib.read_and_filter_logs import ReadFilterLogger
-from lib.mongo_session import MongoSession
+from lib.mongo_helper import MongoSession
 
 # read 'n' parse the configuration
 with open("config.yaml", 'r') as yamlfile:
@@ -108,33 +108,36 @@ def _main(the_uuid):
 
 @api.route('/status/<session_id>')
 def taskstatus(session_id):
-    my_process_logger = ReadLogger(session_id=session_id, cfg=cfg)
+    my_process_logger = ReadLogger(session_id=session_id, cfg=cfg['mongo'])
     body = my_process_logger.main()
 
-    return Response(json.dumps(body, indent=4, sort_keys=True, default=str), mimetype='application/json')
+    return Response(json.dumps(body, sort_keys=True, default=str), mimetype='application/json'), 200
+    #return jsonify(body), 200
 
 
 @api.route('/status/<session_id>/latest')
 def lateststatus(session_id):
-    my_latest_log = GetLatestLog(session_id=session_id, cfg=cfg)
+    my_latest_log = GetLatestLog(session_id=session_id, cfg=cfg['mongo'])
     body = my_latest_log.main()
 
-    return Response(json.dumps(body, indent=4, sort_keys=True, default=str), mimetype='application/json')
+    return Response(json.dumps(body, sort_keys=True, default=str), mimetype='application/json'), 200
+    #return jsonify(body), 200
 
 
 @api.route('/status/<session_id>/<query_key>/<query_value>')
 def taskfilter(session_id, query_key, query_value):
-    my_task_filter = ReadFilterLogger(session_id=session_id, cfg=cfg, query_key=query_key, query_value=query_value)
+    my_task_filter = ReadFilterLogger(session_id=session_id, cfg=cfg['mongo'], query_key=query_key, query_value=query_value)
     body = my_task_filter.main()
 
-    return Response(json.dumps(body, indent=4, sort_keys=True, default=str), mimetype='application/json')
+    return Response(json.dumps(body, sort_keys=True, default=str), mimetype='application/json'), 200
+    #return jsonify(body), 200
 
 
 @api.route('/plot/<session_id>/<uuid>/<step>')
 def build_plot(session_id, uuid, step):
 
     img = io.BytesIO()
-    x, y = MongoSession(cfg=cfg).get_array_from_step(this_session_id=session_id, step_name=step, this_uuid=uuid)
+    x, y = MongoSession(cfg=cfg['mongo']).get_array_from_step(this_session_id=session_id, step_name=step, this_uuid=uuid)
     plt.clf()
     plt.plot(x, y, label=step)
     plt.savefig(img, format='png')
@@ -142,18 +145,18 @@ def build_plot(session_id, uuid, step):
 
     plot_url = base64.b64encode(img.getvalue()).decode()
 
-    return '<img src="data:image/png;base64,{}">'.format(plot_url)
+    return '<img src="data:image/png;base64,{}">'.format(plot_url), 200
 
 
 @api.route('/plot/<session_id>')
 def build_all_plot(session_id):
     img = io.BytesIO()
     plt.clf()
-    my_mongo_session = MongoSession(cfg=cfg)
+    my_mongo_session = MongoSession(cfg=cfg['mongo'])
     uuid_list = my_mongo_session.get_uuid_list_from_session_id(this_session_id=session_id)
     nb_uuids = len(uuid_list)
-    print('nb_uuid: ', nb_uuids)
-    print('uuid_list: ', uuid_list)
+    logging.debug('nb_uuid: ', nb_uuids)
+    logging.debug('uuid_list: ', uuid_list)
     if nb_uuids == 1:
         for step in ['main', 'metadata-processor', 'doc-enricher', 'doc-processor', 'doc-indexer',
                      'pre-reindexer-checker', 'reindexer', 'sampler']:
@@ -163,7 +166,8 @@ def build_all_plot(session_id):
                                                             step_name=step)
                 plt.plot(x, y, label=step)
             except Exception as _:
-                print('cannot get data from :' + step)
+                logging.error('cannot get data from :' + step)
+                return None, 404
         plt.legend()
         plt.xlabel('time')
         plt.ylabel('progress ratio')
@@ -182,14 +186,15 @@ def build_all_plot(session_id):
         response['info'] = 'please use <url/plot/session_id/uuid> end-point!'
         response['nb uuids'] = nb_uuids
         response['uuids list'] = uuid_list
-        return Response(json.dumps(response, indent=4, sort_keys=True, default=str), mimetype='application/json')
+        return Response(json.dumps(response, sort_keys=True, default=str), mimetype='application/json'), 400
+        #return jsonify(response), 400
 
 
 @api.route('/plot/<session_id>/<uuid>')
 def build_all_plot_using_uuid(session_id, uuid):
     img = io.BytesIO()
     plt.clf()
-    my_mongo_session = MongoSession(cfg=cfg)
+    my_mongo_session = MongoSession(cfg=cfg['mongo'])
 
     for step in ['main', 'metadata-processor', 'doc-enricher', 'doc-processor', 'doc-indexer',
                  'pre-reindexer-checker', 'reindexer', 'sampler']:
@@ -199,7 +204,9 @@ def build_all_plot_using_uuid(session_id, uuid):
                                                         step_name=step)
             plt.plot(x, y, label=step)
         except Exception as _:
-            print('cannot get data from :' + step)
+            logging.error('Cannot get data from :' + step)
+            return None, 404
+
     plt.legend()
     plt.xlabel('time')
     plt.ylabel('progress ratio')
@@ -211,13 +218,13 @@ def build_all_plot_using_uuid(session_id, uuid):
 
     plot_url = base64.b64encode(img.getvalue()).decode()
 
-    return '<img src="data:image/png;base64,{}">'.format(plot_url)
+    return '<img src="data:image/png;base64,{}">'.format(plot_url), 200
 
 
 @api.route('/json/<session_id>')
 def build_full_session_json(session_id):
     data = dict()
-    my_mongo_session = MongoSession(cfg=cfg)
+    my_mongo_session = MongoSession(cfg=cfg['mongo'])
     uuid_list = my_mongo_session.get_uuid_list_from_session_id(this_session_id=session_id)
     nb_uuids = len(uuid_list)
     print('nb_uuid: ', nb_uuids)
@@ -233,22 +240,29 @@ def build_full_session_json(session_id):
                                                          step_name=step,
                                                          this_uuid=uuid_list[0])
 
+                return Response(json.dumps(data, sort_keys=True, default=str), mimetype='application/json'), 200
+                #return jsonify(data), 200
+
+
             except Exception as _:
-                print('cannot get data from :' + step)
+                logging.error('cannot get data from :' + step)
+                return None, 404
 
-        return Response(json.dumps(data, indent=4, sort_keys=True, default=str), mimetype='application/json')
+        return Response(json.dumps(data, sort_keys=True, default=str), mimetype='application/json'), 200
+        #return jsonify(data), 200
     else:
         response = dict()
         response['info'] = 'please use <url/plot/session_id/uuid> end-point!'
         response['nb uuids'] = nb_uuids
         response['uuids list'] = uuid_list
-        return Response(json.dumps(response, indent=4, sort_keys=True, default=str), mimetype='application/json')
+        return Response(json.dumps(response, sort_keys=True, default=str), mimetype='application/json'), 400
+        #return jsonify(response), 400
 
 
 @api.route('/json/<session_id>/<uuid>')
 def build_full_session_json_using_one_uuid(session_id, uuid):
     data = dict()
-    my_mongo_session = MongoSession(cfg=cfg)
+    my_mongo_session = MongoSession(cfg=cfg['mongo'])
 
     for step in ['main', 'metadata-processor', 'doc-enricher', 'doc-processor', 'doc-indexer',
                  'pre-reindexer-checker', 'reindexer', 'sampler']:
@@ -258,11 +272,15 @@ def build_full_session_json_using_one_uuid(session_id, uuid):
                 my_mongo_session.get_array_from_step(this_session_id=session_id,
                                                      step_name=step,
                                                      this_uuid=uuid)
+            #return jsonify(data), 200
+            return Response(json.dumps(data, sort_keys=True, default=str), mimetype='application/json'), 200
 
         except Exception as _:
-            print('cannot get data from :' + step)
+            logging.error('Cannot get data from :' + step)
+            return None, 404
+
+    #return Response(json.dumps(data, indent=4, sort_keys=True, default=str), mimetype='application/json')
 
-    return Response(json.dumps(data, indent=4, sort_keys=True, default=str), mimetype='application/json')
 
 
 if __name__ == '__main__':
diff --git a/docker-compose-workers.yml b/docker-compose-workers.yml
index 8bac4a1878c284c14c990502b1f483a480f92e3b..a4a5e41d7d3c32d4cc6464de73d758265574507a 100644
--- a/docker-compose-workers.yml
+++ b/docker-compose-workers.yml
@@ -104,28 +104,28 @@ services:
     # volumes:
     #   - ./config.yaml:/app/config.yaml:ro
 
-  metabase:
-    image: metabase/metabase
-#    restart: unless-stopped
-    ports:
-      - 3001:3000
-    volumes:
-      # declare your mount volume /host/dir:/container/dir
-      - /home/app/metabase-data:/metabase-data
-#    environment:
-#      MB_DB_TYPE: mongo
-#      MB_DB_DBNAME: indexerdb
-#      MB_DB_PORT: 27017
-#      MB_DB_USER: ${MONGO_USER}
-#      MB_DB_PASS: ${MONGO_PASSWORD}
-#      MB_DB_HOST: mongo
-    depends_on:
-      - mongo
-    links:
-      - mongo
+#   metabase:
+#     image: metabase/metabase
+# #    restart: unless-stopped
+#     ports:
+#       - 3001:3000
+#     volumes:
+#       # declare your mount volume /host/dir:/container/dir
+#       - metabase:/metabase-data
+# #    environment:
+# #      MB_DB_TYPE: mongo
+# #      MB_DB_DBNAME: indexerdb
+# #      MB_DB_PORT: 27017
+# #      MB_DB_USER: ${MONGO_USER}
+# #      MB_DB_PASS: ${MONGO_PASSWORD}
+# #      MB_DB_HOST: mongo
+#     depends_on:
+#       - mongo
+#     links:
+#       - mongo
 
 volumes:
   rabbitmq:
   working-directory:
   mongo:
-  metabase:
+  #metabase:
diff --git a/lib/get_most_recent_status_logs.py b/lib/get_most_recent_status_logs.py
index 69256e2ae47e1df42a00cad9d528227dde1521b2..8dc19434a46fe80bf2c7890fbcc4007f85859424 100644
--- a/lib/get_most_recent_status_logs.py
+++ b/lib/get_most_recent_status_logs.py
@@ -14,9 +14,9 @@ except ImportError:
     # Python 2.x fallback
     from argparse import Namespace
 try:
-    from lib.mongo_session import MongoSession
+    from lib.mongo_helper import MongoSession
 except ImportError:
-    from mongo_session import MongoSession
+    from mongo_helper import MongoSession
 
 fileDir = os.path.dirname(os.path.abspath(__file__))
 parentDir = os.path.dirname(fileDir)
diff --git a/lib/log_message.py b/lib/log_message.py
index 7c920a5f81ea3701823d7130d9bc979dd004c595..602421b81b329fa106c5c1621a4643f44bd0b7fa 100644
--- a/lib/log_message.py
+++ b/lib/log_message.py
@@ -4,36 +4,32 @@ import uuid as uuid_lib
 
 
 class LogMessage:
-    def __init__(self, session_id, uuid, step, status, uuid_prefix, info, loglevel, progress_ratio):
-        if(session_id.lower()) == 'new':
-            self.session_id = str(uuid_lib.uuid4())
-        else:
-            self.session_id = session_id
+    def __init__(self, session_id, uuid, step, status, uuid_suffix, info, loglevel, progress_ratio):
+        self.session_id = session_id
         self.uuid = uuid
         self.step = step
         self.status = status
         self.progress_ratio = progress_ratio
-        self.uuid_prefix = uuid_prefix
+        self.uuid_suffix = uuid_suffix
         self.info = info
         self.loglevel = loglevel
         self.timestamp = self.generate_timestamp()
 
     @staticmethod
     def generate_timestamp():
-        print('timestamp generated')
-        datetime_without_timezone = datetime.datetime.now()
-        print("Original:", datetime_without_timezone)
-        timestamp_as_str = datetime_without_timezone.strftime("%Y-%m-%dT%H:%M:%S.%fZ")
-        return timestamp_as_str
+        return datetime.datetime.utcnow().strftime("%Y-%m-%dT%H:%M:%S.%fZ")
 
 
 if __name__ == '__main__':
-    my_message = LogMessage(session_id='new',
+
+    my_message = LogMessage(session_id='1234',
                             uuid='7c31bbee-9155-4a2d-964f-b13a9df5c542',
                             step='doc-enricher',
                             status='pending',
-                            uuid_prefix='meta',
-                            info='no info'
+                            uuid_suffix='meta',
+                            info='no info',
+                            loglevel='DEBUG',
+                            progress_ratio='0.12'
                             )
     print('my message.session_id :', my_message.session_id)
 
diff --git a/lib/mongo_session.py b/lib/mongo_helper.py
similarity index 86%
rename from lib/mongo_session.py
rename to lib/mongo_helper.py
index 0a8972cb2844a2c43848c4a362ed95ee6ec39803..4958e0ae0d95b5f09111bc164b7626d8c0ef7ff3 100644
--- a/lib/mongo_session.py
+++ b/lib/mongo_helper.py
@@ -2,13 +2,13 @@ from pymongo import MongoClient, errors, ASCENDING, DESCENDING
 import datetime
 import json
 import time
-
+from lib.my_logging import logging
 
 class MongoSession:
 
     def __init__(self, cfg):
         self.cfg = cfg
-        self.collection_name = cfg['mongo']['collection']
+        self.collection_name = cfg['collection']
         self.mongo_client = self.init_client_mongo()
         self.mongo_data_collection = self.set_mongo_collection(mongo_client=self.mongo_client,
                                                                mongo_collection=self.collection_name)
@@ -19,11 +19,11 @@ class MongoSession:
 
     def init_client_mongo(self):
         # init Mongo
-        mongo_hostname = self.cfg['mongo']['host']
-        mongo_port = self.cfg['mongo']['port']
-        mongo_database = self.cfg['mongo']['database']
-        mongo_user = self.cfg['mongo']['user']
-        mongo_pass = self.cfg['mongo']['password']
+        mongo_hostname = self.cfg['host']
+        mongo_port = self.cfg['port']
+        mongo_database = self.cfg['database']
+        mongo_user = self.cfg['user']
+        mongo_pass = self.cfg['password']
 
         while True:
             try:
@@ -32,7 +32,7 @@ class MongoSession:
                 db.authenticate(mongo_user, mongo_pass)
                 return db
             except errors.ServerSelectionTimeoutError:
-                print('Waiting for mongodb to be reachable...')
+                logging.info('Waiting for MongoDB to be reachable...')
                 time.sleep(5)
 
     @staticmethod
@@ -41,11 +41,11 @@ class MongoSession:
         return mongo_client[mongo_collection]
 
     def save_log_in_mongo(self, ch, method, body):
-        print('body: ', body)
+        logging.debug('body: ', body)
         try:
             body_object = json.loads(body.decode('utf-8'))
 
-            print('body session_id: ', body_object['session_id'])
+            logging.debug('body session_id: ', body_object['session_id'])
 
             timestamp = datetime.datetime.strptime(body_object["timestamp"], "%Y-%m-%dT%H:%M:%S.%fZ")
             float_progress_ratio = float(body_object["progress_ratio"])
@@ -55,12 +55,12 @@ class MongoSession:
                                                    "uuid": body_object["uuid"],
                                                    "step": body_object["step"],
                                                    "status": body_object["status"],
-                                                   "uuid_prefix": body_object["uuid_prefix"],
+                                                   "uuid_suffix": body_object["uuid_suffix"],
                                                    "info": body_object["info"],
                                                    "progress_ratio": float_progress_ratio,
                                                    "loglevel": body_object["loglevel"]})
         except Exception as exc:
-            print('[ERROR saving log]:', exc)
+            logging.error('[ERROR saving log]:', exc)
             ch.basic_nack(delivery_tag=method.delivery_tag, requeue=1)
 
         ch.basic_ack(delivery_tag=method.delivery_tag)
@@ -69,8 +69,7 @@ class MongoSession:
         try:
             data = []
             request_result = self.mongo_data_collection.find({"session_id": this_session_id})
-            for res in request_result:
-                data.append(res)
+            data = list(request_result)
             return data
         except Exception as exc:
             print('[ERROR reading log]:', exc)
@@ -96,7 +95,7 @@ class MongoSession:
                     data['value'].append(res)
                 all_data.append(data)
             except Exception as exc:
-                print('[ERROR reading log]:', exc)
+                logging.error('[ERROR reading log]:', exc)
         return all_data
 
     def get_most_recent_log(self, this_session_id):
@@ -132,7 +131,7 @@ class MongoSession:
 
             return data_time, data_value
         except Exception as exc:
-            print('[ERROR reading log]:', exc)
+            logging.error('[ERROR reading log]:', exc)
 
 
 if __name__ == '__main__':
@@ -148,8 +147,6 @@ if __name__ == '__main__':
     cfg['mongo']['password'] = 'example'
     cfg['mongo']['collection'] = 'indexer_logs'
     this_session_id = 'bb0764fe-324e-4719-9214-dc4abc59fe50'
-    data_time, data_value = MongoSession(cfg=cfg).get_array_from_step(this_session_id, "doc-enricher")
+    data_time, data_value = MongoSession(cfg=cfg['mongo']).get_array_from_step(this_session_id, "doc-enricher")
     print('data_time: ', data_time)
     print('data_value: ', data_value)
-
-
diff --git a/lib/read_and_filter_logs.py b/lib/read_and_filter_logs.py
index 5687bcd32c0e9c21e16d3b50f59b30d309081cb0..35482d58c5530b15982320b80cc7b8bbb6a42b28 100644
--- a/lib/read_and_filter_logs.py
+++ b/lib/read_and_filter_logs.py
@@ -14,9 +14,9 @@ except ImportError:
     # Python 2.x fallback
     from argparse import Namespace
 try:
-    from lib.mongo_session import MongoSession
+    from lib.mongo_helper import MongoSession
 except ImportError:
-    from mongo_session import MongoSession
+    from mongo_helper import MongoSession
 
 fileDir = os.path.dirname(os.path.abspath(__file__))
 parentDir = os.path.dirname(fileDir)
diff --git a/lib/read_status_logs.py b/lib/read_status_logs.py
index a7c6063cd985d1aa497bd4a8bf5c120b04f4b1ce..e953b7932182dfde4d71566171ee2364a348e6e3 100644
--- a/lib/read_status_logs.py
+++ b/lib/read_status_logs.py
@@ -14,9 +14,9 @@ except ImportError:
     # Python 2.x fallback
     from argparse import Namespace
 try:
-    from lib.mongo_session import MongoSession
+    from lib.mongo_helper import MongoSession
 except ImportError:
-    from mongo_session import MongoSession
+    from mongo_helper import MongoSession
 
 fileDir = os.path.dirname(os.path.abspath(__file__))
 parentDir = os.path.dirname(fileDir)
diff --git a/main.py b/main.py
index e376f9f20e6de8a3bbcab2eb247c737aafd40819..23a4f1d0324b607a746f51c2e43eb8a405d8d271 100644
--- a/main.py
+++ b/main.py
@@ -184,7 +184,7 @@ def delete_dataset_from_dest_index(the_rabbit, the_cfg, the_uuid):
                              uuid=the_uuid,
                              step='main',
                              status='delete_dataset_from_dest_index',
-                             uuid_prefix='meta',
+                             uuid_suffix='meta',
                              info='no info',
                              loglevel='INFO',
                              progress_ratio=0.1
@@ -281,7 +281,7 @@ def main(cfg):
                                  uuid=uuid_to_log,
                                  step='main',
                                  status='Starting...',
-                                 uuid_prefix='meta',
+                                 uuid_suffix='meta',
                                  info='no info',
                                  loglevel='INFO',
                                  progress_ratio=0
@@ -305,7 +305,7 @@ def main(cfg):
                                       uuid=uuid_to_log,
                                       step='main',
                                       status='Terminated',
-                                      uuid_prefix='meta',
+                                      uuid_suffix='meta',
                                       info='no info',
                                       loglevel='INFO',
                                       progress_ratio=1
diff --git a/workers/doc-enricher.py b/workers/doc-enricher.py
index 6e91d0d2441607ee01e54fe358f095450e13484c..1d1f6b6cec1924cc79253b4fe8eb4f06bd30b7c4 100644
--- a/workers/doc-enricher.py
+++ b/workers/doc-enricher.py
@@ -246,7 +246,7 @@ def enrich_docs( channel, method, properties, body ):
                                  uuid=cfg['session']['current_uuid'],
                                  step='doc-enricher',
                                  status=status_message,
-                                 uuid_prefix='meta',
+                                 uuid_suffix='meta',
                                  info='no info',
                                  loglevel='INFO',
                                  progress_ratio=progress_rounded
@@ -287,7 +287,7 @@ def enrich_docs( channel, method, properties, body ):
                                      uuid=cfg['session']['current_uuid'],
                                      step='doc-enricher',
                                      status='done',
-                                     uuid_prefix='meta',
+                                     uuid_suffix='meta',
                                      info='no info',
                                      loglevel='INFO',
                                      progress_ratio=progress_rounded
diff --git a/workers/doc-indexer.py b/workers/doc-indexer.py
index 5d039187d2dd97a59acda4206607721f25a38bfa..0d10899340244a2ec124cfa9588e0862683c0cb8 100644
--- a/workers/doc-indexer.py
+++ b/workers/doc-indexer.py
@@ -132,7 +132,7 @@ def index_docs(channel, method, properties, body):
                              uuid=cfg['session']['current_uuid'],
                              step='doc-indexer',
                              status=status_message,
-                             uuid_prefix='meta',
+                             uuid_suffix='meta',
                              info='no info',
                              loglevel='INFO',
                              progress_ratio=progress_rounded
@@ -204,7 +204,7 @@ def index_docs(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='doc-indexer',
                                  status=rep,
-                                 uuid_prefix='meta',
+                                 uuid_suffix='meta',
                                  info='no info',
                                  loglevel='ERROR',
                                  progress_ratio=progress_rounded
@@ -231,7 +231,7 @@ def index_docs(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='doc-indexer',
                                  status='done',
-                                 uuid_prefix='meta',
+                                 uuid_suffix='meta',
                                  info='no info',
                                  loglevel='INFO',
                                  progress_ratio=progress_rounded
diff --git a/workers/doc-processor.py b/workers/doc-processor.py
index d1e952742c8ff015591a2440ef09abb53514b894..6b68703f2e11b2a6e763a6394bb7d691461e26c9 100644
--- a/workers/doc-processor.py
+++ b/workers/doc-processor.py
@@ -121,7 +121,7 @@ def process_docs( channel, method, properties, body ):
                              uuid=cfg['session']['current_uuid'],
                              step='doc-processor',
                              status=status_message,
-                             uuid_prefix='meta',
+                             uuid_suffix='meta',
                              info='no info',
                              loglevel='INFO',
                              progress_ratio=progress_rounded
@@ -165,7 +165,7 @@ def process_docs( channel, method, properties, body ):
                                  uuid=cfg['session']['current_uuid'],
                                  step='doc-processor',
                                  status='done',
-                                 uuid_prefix='meta',
+                                 uuid_suffix='meta',
                                  info='no info',
                                  loglevel='INFO',
                                  progress_ratio=progress_rounded
diff --git a/workers/metadata-processor.py b/workers/metadata-processor.py
index c772f9e7aba2e2f603a276231256bd85dae6431e..12d7eb55a434363d9aac05225cf34af71cab71bb 100644
--- a/workers/metadata-processor.py
+++ b/workers/metadata-processor.py
@@ -317,7 +317,7 @@ def callback( channel, method, properties, body ):
                              uuid=cfg['session']['current_uuid'],
                              step='metadata-processor',
                              status='Starting...',
-                             uuid_prefix='meta',
+                             uuid_suffix='meta',
                              info='no info',
                              loglevel='INFO',
                              progress_ratio=0
@@ -325,7 +325,7 @@ def callback( channel, method, properties, body ):
 
     json_body = json.dumps(log_message.__dict__)
 
-    print(" [x] json body : ", json_body)
+    logging.debug(" [x] json body : %s" % json_body)
 
     channel.basic_publish(exchange=exchange_logs_name,
                           routing_key=routing_key_logs,
@@ -391,7 +391,7 @@ def callback( channel, method, properties, body ):
                                          uuid=cfg['session']['current_uuid'],
                                          step='metadata-processor',
                                          status='sent task doc to enrich',
-                                         uuid_prefix='meta',
+                                         uuid_suffix='meta',
                                          info='no info',
                                          loglevel='INFO',
                                          progress_ratio=1
@@ -399,7 +399,7 @@ def callback( channel, method, properties, body ):
 
                 json_body = json.dumps(log_message.__dict__)
 
-                print(" [x] json body : ", json_body)
+                logging.debug(" [x] json body: %s" % json_body)
 
                 channel.basic_publish(exchange=exchange_logs_name,
                                       routing_key=routing_key_logs,
@@ -441,7 +441,7 @@ def callback( channel, method, properties, body ):
                                  uuid=cfg['session']['current_uuid'],
                                  step='metadata-processor',
                                  status='sent task doc to index',
-                                 uuid_prefix='meta',
+                                 uuid_suffix='meta',
                                  info='no info',
                                  loglevel='INFO',
                                  progress_ratio=0.5
@@ -449,7 +449,7 @@ def callback( channel, method, properties, body ):
 
         json_body = json.dumps(log_message.__dict__)
 
-        print(" [x] json body : ", json_body)
+        logging.debug(" [x] json body: %s" % json_body)
 
         channel.basic_publish(exchange=exchange_logs_name,
                               routing_key=routing_key_logs,
@@ -464,7 +464,7 @@ def callback( channel, method, properties, body ):
                              uuid=cfg['session']['current_uuid'],
                              step='metadata-processor',
                              status='terminated',
-                             uuid_prefix='meta',
+                             uuid_suffix='meta',
                              info='no info',
                              loglevel='INFO',
                              progress_ratio=1
@@ -472,7 +472,7 @@ def callback( channel, method, properties, body ):
 
     json_body = json.dumps(log_message.__dict__)
 
-    print(" [x] json body : ", json_body)
+    logging.debug(" [x] json body: %s" % json_body)
 
     channel.basic_publish(exchange=exchange_logs_name,
                           routing_key=routing_key_logs,
diff --git a/workers/process-logger.py b/workers/process-logger.py
index 5eeea5d2943c0d587cb1fb213d33d437383f2b5e..e571b599992fc72472e8313f685e00c47066a5e5 100644
--- a/workers/process-logger.py
+++ b/workers/process-logger.py
@@ -7,7 +7,7 @@ fileDir = os.path.dirname(os.path.abspath(__file__))
 parentDir = os.path.dirname(fileDir)
 newPath = os.path.join(parentDir)
 sys.path.append(newPath)
-from lib.mongo_session import MongoSession
+from lib.mongo_helper import MongoSession
 
 
 try:
@@ -37,7 +37,7 @@ def main(cfg):
 
     channel.basic_qos(prefetch_count=1)
     channel.basic_consume(
-        on_message_callback=lambda ch, method, properties, body:  MongoSession(cfg).save_log_in_mongo(ch,
+        on_message_callback=lambda ch, method, properties, body:  MongoSession(cfg['mongo']).save_log_in_mongo(ch,
                                                                                                       method,
                                                                                                       body),
 
diff --git a/workers/reindexer.py b/workers/reindexer.py
index 75fb6aae51dc24fa896af1441fda5b7cc336d678..43f9909ef96079c33e9e009b1023da407182b6c4 100644
--- a/workers/reindexer.py
+++ b/workers/reindexer.py
@@ -39,7 +39,7 @@ def create_sampling_task(cfg, channel, uuid):
                              uuid=cfg['session']['current_uuid'],
                              step='reindexer',
                              status='create sampling task',
-                             uuid_prefix='full',
+                             uuid_suffix='full',
                              info=uuid,
                              loglevel='INFO',
                              progress_ratio=0.8
@@ -98,7 +98,7 @@ def on_msg_callback(channel, method, properties, body):
                              uuid=cfg['session']['current_uuid'],
                              step='reindexer',
                              status='starting',
-                             uuid_prefix='full',
+                             uuid_suffix='full',
                              info=uuid,
                              loglevel='INFO',
                              progress_ratio=0
@@ -175,7 +175,7 @@ def on_msg_callback(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='pre-reindexer-checker',
                                  status='Documents are still being pushed to the source index',
-                                 uuid_prefix='full',
+                                 uuid_suffix='full',
                                  info=uuid,
                                  loglevel='INFO',
                                  progress_ratio=ratio
@@ -204,7 +204,7 @@ def on_msg_callback(channel, method, properties, body):
                              uuid=cfg['session']['current_uuid'],
                              step='reindexer',
                              status=message,
-                             uuid_prefix='full',
+                             uuid_suffix='full',
                              info=uuid,
                              loglevel='INFO',
                              progress_ratio=0.2
@@ -236,7 +236,7 @@ def on_msg_callback(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='reindexer',
                                  status=message,
-                                 uuid_prefix='full',
+                                 uuid_suffix='full',
                                  info=uuid,
                                  loglevel='ERROR',
                                  progress_ratio=None
@@ -270,7 +270,7 @@ def on_msg_callback(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='reindexer',
                                  status='refreshed indices',
-                                 uuid_prefix='meta',
+                                 uuid_suffix='meta',
                                  info=uuid,
                                  loglevel='INFO',
                                  progress_ratio=0.6
@@ -299,7 +299,7 @@ def on_msg_callback(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='reindexer',
                                  status=exc,
-                                 uuid_prefix='full',
+                                 uuid_suffix='full',
                                  info=uuid,
                                  loglevel='ERROR',
                                  progress_ratio=None
@@ -372,7 +372,7 @@ def on_msg_callback(channel, method, properties, body):
                                      uuid=cfg['session']['current_uuid'],
                                      step='reindexer',
                                      status=message,
-                                     uuid_prefix='full',
+                                     uuid_suffix='full',
                                      info=uuid,
                                      loglevel='INFO',
                                      progress_ratio=0.9
@@ -400,7 +400,7 @@ def on_msg_callback(channel, method, properties, body):
                                      uuid=cfg['session']['current_uuid'],
                                      step='reindexer',
                                      status=message,
-                                     uuid_prefix='meta',
+                                     uuid_suffix='meta',
                                      info=uuid,
                                      loglevel='INFO',
                                      progress_ratio=1
@@ -432,7 +432,7 @@ def on_msg_callback(channel, method, properties, body):
                              uuid=cfg['session']['current_uuid'],
                              step='reindexer',
                              status=message,
-                             uuid_prefix='',
+                             uuid_suffix='',
                              info=uuid,
                              loglevel='INFO',
                              progress_ratio=1
diff --git a/workers/sample-generator.py b/workers/sample-generator.py
index 511aaa47eb18ae6709910590c41b863dbbe287e7..37c8d74aa3ceb265eae29e4ea8ba17197072c0ed 100644
--- a/workers/sample-generator.py
+++ b/workers/sample-generator.py
@@ -187,7 +187,7 @@ def callback(channel, method, properties, body):
                              uuid=cfg['session']['current_uuid'],
                              step='sampler',
                              status=message,
-                             uuid_prefix='meta',
+                             uuid_suffix='meta',
                              info=uuid,
                              loglevel='INFO',
                              progress_ratio=0
@@ -221,7 +221,7 @@ def callback(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='sampler',
                                  status=exc,
-                                 uuid_prefix='full',
+                                 uuid_suffix='full',
                                  info=uuid,
                                  loglevel='ERROR',
                                  progress_ratio=0
@@ -262,7 +262,7 @@ def callback(channel, method, properties, body):
                              uuid=cfg['session']['current_uuid'],
                              step='sampler',
                              status=message,
-                             uuid_prefix='meta',
+                             uuid_suffix='meta',
                              info=uuid,
                              loglevel='INFO',
                              progress_ratio=0.9
@@ -296,7 +296,7 @@ def callback(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='sampler',
                                  status='Removing lock for dataset',
-                                 uuid_prefix='full',
+                                 uuid_suffix='full',
                                  info=uuid,
                                  loglevel='INFO',
                                  progress_ratio=1
@@ -322,7 +322,7 @@ def callback(channel, method, properties, body):
                                  uuid=cfg['session']['current_uuid'],
                                  step='sampler',
                                  status=rep,
-                                 uuid_prefix='full',
+                                 uuid_suffix='full',
                                  info=uuid,
                                  loglevel='ERROR',
                                  progress_ratio=0
@@ -350,7 +350,7 @@ def callback(channel, method, properties, body):
     #                          uuid=cfg['session']['current_uuid'],
     #                          step='sampler',
     #                          status=message,
-    #                          uuid_prefix='meta',
+    #                          uuid_suffix='meta',
     #                          info=uuid,
     #                          loglevel='INFO',
     #                          progress_ratio=1