diff --git a/src/utils/circular_vector.hpp b/src/utils/circular_vector.hpp
index ba185ec..f7ac8e5 100644
--- a/src/utils/circular_vector.hpp
+++ b/src/utils/circular_vector.hpp
@@ -4,7 +4,8 @@
 class CircularVector
 {
   public:
-    explicit CircularVector(size_t maxSizeIn) : maxSize(maxSizeIn)
+    explicit CircularVector(std::vector<T>& externalVec, size_t maxSizeIn) :
+        vec(externalVec), maxSize(maxSizeIn)
     {}
 
     template <class... Args>
@@ -53,7 +54,7 @@
     }
 
   private:
+    std::vector<T>& vec;
     size_t maxSize = 0;
     size_t idx = 0;
-    std::vector<T> vec;
 };
diff --git a/src/utils/labeled_tuple.hpp b/src/utils/labeled_tuple.hpp
index 71bf4b0..e6203dd 100644
--- a/src/utils/labeled_tuple.hpp
+++ b/src/utils/labeled_tuple.hpp
@@ -76,6 +76,11 @@
         return j;
     }
 
+    const tuple_type& to_tuple() const
+    {
+        return value;
+    }
+
     void from_json(const nlohmann::json& j)
     {
         from_json_all(j, std::make_index_sequence<sizeof...(Args)>());
diff --git a/src/utils/tstring.hpp b/src/utils/tstring.hpp
index e4529d8..67ad3c4 100644
--- a/src/utils/tstring.hpp
+++ b/src/utils/tstring.hpp
@@ -144,5 +144,45 @@
     }
 };
 
+struct MetricId
+{
+    static std::string str()
+    {
+        return "MetricId";
+    }
+};
+
+struct MetricProperty
+{
+    static std::string str()
+    {
+        return "MetricProperty";
+    }
+};
+
+struct MetricValue
+{
+    static std::string str()
+    {
+        return "MetricValue";
+    }
+};
+
+struct Timestamp
+{
+    static std::string str()
+    {
+        return "Timestamp";
+    }
+};
+
+struct Readings
+{
+    static std::string str()
+    {
+        return "Readings";
+    }
+};
+
 } // namespace tstring
 } // namespace utils