diff --git a/src/SearchLogInterface.php b/src/SearchLogInterface.php
new file mode 100644
index 0000000..8aee4cb
--- /dev/null
+++ b/src/SearchLogInterface.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace Drupal\search_log;
+
+/**
+ * It contains constants to manage global values.
+ */
+interface SearchLogInterface {
+
+  // Defining constants
+  const SEARCH_LOG_RESULT_UNKNOWN = 0;
+  const SEARCH_LOG_RESULT_SUCCESS = 1;
+  const SEARCH_LOG_RESULT_FAILED = -1;
+  const SEARCH_LOG_TERMS_LOWERCASE = 0;
+  const SEARCH_LOG_TERMS_UPPERCASE_FIRST = 1;
+  const SEARCH_LOG_TERMS_UPPERCASE_WORDS = 2;
+  const SEARCH_LOG_ADMIN_TERM_LENGTH = 50;
+  const SEARCH_LOG_ADMIN_ROWS = 40;
+  const SEARCH_LOG_DAY = 86400;
+}