diff --git a/lib/inc/drogon/HttpViewData.h b/lib/inc/drogon/HttpViewData.h
index 7f15ab13..626e1b67 100755
--- a/lib/inc/drogon/HttpViewData.h
+++ b/lib/inc/drogon/HttpViewData.h
@@ -24,19 +24,19 @@
 #include <stdio.h>
 #include <stdarg.h>
 
-typedef std::unordered_map<std::string, any> ViewDataMap;
 namespace drogon
 {
+
 /// This class represents the data set displayed in views.
 class HttpViewData
 {
   public:
     /// The function template is used to get an item in the data set by the @param key.
     template <typename T>
-    const T get(const std::string &key, T &&nullVal = T()) const
+    const T &get(const std::string &key, T &&nullVal = T()) const
     {
-        auto it = viewData_.find(key);
-        if (it != viewData_.end())
+        auto it = _viewData.find(key);
+        if (it != _viewData.end())
         {
             try
             {
@@ -53,11 +53,11 @@ class HttpViewData
     /// Insert an item identified by the @param key into the data set;
     void insert(const std::string &key, any &&obj)
     {
-        viewData_[key] = std::move(obj);
+        _viewData[key] = std::move(obj);
     }
     void insert(const std::string &key, const any &obj)
     {
-        viewData_[key] = obj;
+        _viewData[key] = obj;
     }
 
     /// Insert an item identified by the @param key into the data set; The item will be converted to a string.
@@ -66,7 +66,7 @@ class HttpViewData
     {
         std::stringstream ss;
         ss << val;
-        viewData_[key] = ss.str();
+        _viewData[key] = ss.str();
     }
 
     /// Insert a formated string identified by the @param key.
@@ -110,17 +110,18 @@ class HttpViewData
             }
         }
         va_end(ap);
-        viewData_[key] = std::move(strBuffer);
+        _viewData[key] = std::move(strBuffer);
     }
 
     /// Get the 'any' object by the @param key.
     any &operator[](const std::string &key) const
     {
-        return viewData_[key];
+        return _viewData[key];
     }
 
   protected:
-    mutable ViewDataMap viewData_;
+    typedef std::unordered_map<std::string, any> ViewDataMap;
+    mutable ViewDataMap _viewData;
 };
 
 } // namespace drogon
diff --git a/lib/inc/drogon/Session.h b/lib/inc/drogon/Session.h
index 7c87cdc3..1ea10dff 100755
--- a/lib/inc/drogon/Session.h
+++ b/lib/inc/drogon/Session.h
@@ -20,48 +20,47 @@
 #include <thread>
 #include <drogon/config.h>
 
-typedef std::map<std::string, any> SessionMap;
 namespace drogon
 {
+    
 class Session
 {
   public:
     template <typename T>
-    T get(const std::string &key) const
+    const T &get(const std::string &key, T &&nullVal = T()) const
     {
-        std::lock_guard<std::mutex> lck(mutex_);
-        auto it = sessionMap_.find(key);
-        if (it != sessionMap_.end())
+        std::lock_guard<std::mutex> lck(_mutex);
+        auto it = _sessionMap.find(key);
+        if (it != _sessionMap.end())
         {
             return *(any_cast<T>(&(it->second)));
         }
-        T tmp;
-        return tmp;
+        return nullVal;
     };
     any &operator[](const std::string &key)
     {
-        std::lock_guard<std::mutex> lck(mutex_);
-        return sessionMap_[key];
+        std::lock_guard<std::mutex> lck(_mutex);
+        return _sessionMap[key];
     };
     void insert(const std::string &key, const any &obj)
     {
-        std::lock_guard<std::mutex> lck(mutex_);
-        sessionMap_[key] = obj;
+        std::lock_guard<std::mutex> lck(_mutex);
+        _sessionMap[key] = obj;
     };
     void insert(const std::string &key, any &&obj)
     {
-        std::lock_guard<std::mutex> lck(mutex_);
-        sessionMap_[key] = std::move(obj);
+        std::lock_guard<std::mutex> lck(_mutex);
+        _sessionMap[key] = std::move(obj);
     }
     void erase(const std::string &key)
     {
-        std::lock_guard<std::mutex> lck(mutex_);
-        sessionMap_.erase(key);
+        std::lock_guard<std::mutex> lck(_mutex);
+        _sessionMap.erase(key);
     }
     bool find(const std::string &key)
     {
-        std::lock_guard<std::mutex> lck(mutex_);
-        if (sessionMap_.find(key) == sessionMap_.end())
+        std::lock_guard<std::mutex> lck(_mutex);
+        if (_sessionMap.find(key) == _sessionMap.end())
         {
             return false;
         }
@@ -69,14 +68,16 @@ class Session
     }
     void clear()
     {
-        std::lock_guard<std::mutex> lck(mutex_);
-        sessionMap_.clear();
+        std::lock_guard<std::mutex> lck(_mutex);
+        _sessionMap.clear();
     }
 
   protected:
-    SessionMap sessionMap_;
-    int timeoutInterval_;
-    mutable std::mutex mutex_;
+    typedef std::map<std::string, any> SessionMap;
+    SessionMap _sessionMap;
+    mutable std::mutex _mutex;
 };
+
 typedef std::shared_ptr<Session> SessionPtr;
+
 } // namespace drogon