diff --git a/stacosys/conf/config.py b/stacosys/conf/config.py
index a4742d3..15a0ed2 100644
--- a/stacosys/conf/config.py
+++ b/stacosys/conf/config.py
@@ -4,59 +4,62 @@
 import profig
 
 # constants
-FLASK_APP = 'flask.app'
+FLASK_APP = "flask.app"
 
-DB_URL = 'main.db_url'
-DB_FILE = 'main.db_file'
-LANG = 'main.lang'
-COMMENT_POLLING = 'main.newcomment_polling'
+DB_URL = "main.db_url"
+DB_BACKUP_JSON_FILE = "main.db_backup_json_file"
+LANG = "main.lang"
+COMMENT_POLLING = "main.newcomment_polling"
 
-HTTP_HOST = 'http.host'
-HTTP_PORT = 'http.port'
+HTTP_HOST = "http.host"
+HTTP_PORT = "http.port"
 
-RSS_PROTO = 'rss.proto'
-RSS_FILE = 'rss.file'
+RSS_PROTO = "rss.proto"
+RSS_FILE = "rss.file"
 
-IMAP_POLLING = 'imap.polling'
-IMAP_SSL = 'imap.ssl'
-IMAP_HOST = 'imap.host'
-IMAP_PORT = 'imap.port'
-IMAP_LOGIN = 'imap.login'
-IMAP_PASSWORD = 'imap.password'
+IMAP_POLLING = "imap.polling"
+IMAP_SSL = "imap.ssl"
+IMAP_HOST = "imap.host"
+IMAP_PORT = "imap.port"
+IMAP_LOGIN = "imap.login"
+IMAP_PASSWORD = "imap.password"
 
-SMTP_STARTTLS = 'smtp.starttls'
-SMTP_HOST = 'smtp.host'
-SMTP_PORT = 'smtp.port'
-SMTP_LOGIN = 'smtp.login'
-SMTP_PASSWORD = 'smtp.password'
+SMTP_STARTTLS = "smtp.starttls"
+SMTP_HOST = "smtp.host"
+SMTP_PORT = "smtp.port"
+SMTP_LOGIN = "smtp.login"
+SMTP_PASSWORD = "smtp.password"
 
-SITE_NAME = 'site.name'
-SITE_URL = 'site.url'
-SITE_TOKEN = 'site.token'
-SITE_ADMIN_EMAIL = 'site.admin_email'
+SITE_NAME = "site.name"
+SITE_URL = "site.url"
+SITE_TOKEN = "site.token"
+SITE_ADMIN_EMAIL = "site.admin_email"
 
-# variable
-params = dict()
 
+class Config:
+    def __init__(self):
+        self._params = dict()
 
-def initialize(config_pathname, flask_app):
-    cfg = profig.Config(config_pathname)
-    cfg.sync()
-    params.update(cfg)
-    params.update({FLASK_APP: flask_app})
+    @classmethod
+    def load(cls, config_pathname):
+        cfg = profig.Config(config_pathname)
+        cfg.sync()
+        config = cls()
+        config._params.update(cfg)
+        return config
 
+    def exists(self, key):
+        return key in self._params
 
-def get(key):
-    return params[key]
+    def get(self, key):
+        return self._params[key] if key in self._params else None
 
+    def put(self, key, value):
+        self._params[key] = value
 
-def get_int(key):
-    return int(params[key])
+    def get_int(self, key):
+        return int(self._params[key])
 
+    def get_bool(self, key):
+        return self._params[key].lower() in ("yes", "true")
 
-def get_bool(key):
-    return params[key].lower() in ('yes', 'true', '1')
-
-
-def flaskapp():
-    return params[FLASK_APP]
diff --git a/tests/test_config.py b/tests/test_config.py
new file mode 100644
index 0000000..4b6d6f0
--- /dev/null
+++ b/tests/test_config.py
@@ -0,0 +1,57 @@
+#!/usr/bin/python
+# -*- coding: UTF-8 -*-
+
+import pytest
+import stacosys.conf.config as config
+
+EXPECTED_DB_URL = "sqlite:///db.sqlite"
+EXPECTED_HTTP_PORT = 8080
+EXPECTED_IMAP_PORT = "5000"
+EXPECTED_IMAP_LOGIN = "user"
+
+
+@pytest.fixture
+def conf():
+    conf = config.Config()
+    conf.put(config.DB_URL, EXPECTED_DB_URL)
+    conf.put(config.HTTP_PORT, EXPECTED_HTTP_PORT)
+    conf.put(config.IMAP_PORT, EXPECTED_IMAP_PORT)
+    conf.put(config.SMTP_STARTTLS, "yes")
+    conf.put(config.IMAP_SSL, "false")
+    return conf
+
+
+def test_exists(conf):
+    assert conf is not None
+    assert conf.exists(config.DB_URL)
+    assert not conf.exists(config.IMAP_HOST)
+
+
+def test_get(conf):
+    assert conf is not None
+    assert conf.get(config.DB_URL) == EXPECTED_DB_URL
+    assert conf.get(config.HTTP_PORT) == EXPECTED_HTTP_PORT
+    assert conf.get(config.HTTP_HOST) is None
+    assert conf.get(config.HTTP_PORT) == EXPECTED_HTTP_PORT
+    assert conf.get(config.IMAP_PORT) == EXPECTED_IMAP_PORT
+    assert conf.get_int(config.IMAP_PORT) == int(EXPECTED_IMAP_PORT)
+    try:
+        conf.get_int(config.HTTP_PORT)
+        assert False
+    except:
+        pass
+    assert conf.get_bool(config.SMTP_STARTTLS)
+    assert not conf.get_bool(config.IMAP_SSL)
+    try:
+        conf.get_bool(config.DB_URL)
+        assert False
+    except:
+        pass
+
+
+def test_put(conf):
+    assert conf is not None
+    assert not conf.exists(config.IMAP_LOGIN)
+    conf.put(config.IMAP_LOGIN, EXPECTED_IMAP_LOGIN)
+    assert conf.exists(config.IMAP_LOGIN)
+    assert conf.get(config.IMAP_LOGIN) == EXPECTED_IMAP_LOGIN