add get json for all progress_ratio and timestamp end-point

workers/sample-generator.py

@@ -262,7 +262,7 @@ def callback(channel, method, properties, body):
                              uuid=cfg['session']['current_uuid'],
                              step='sampler',
                              status=message,
-                             uuid_prefix='',
+                             uuid_prefix='meta',
                              info=uuid,
                              loglevel='INFO',
                              progress_ratio=0.9