diff --git a/example/http_client/main.cc b/example/http_client/main.cc
index d4ccb1d..125248a 100644
--- a/example/http_client/main.cc
+++ b/example/http_client/main.cc
@@ -1,4 +1,5 @@
 #include <iostream>
+#include <thread>
 
 #include "webcc/http_client_session.h"
 #include "webcc/logger.h"
@@ -82,29 +83,11 @@ void Test(HttpClientSession& session) {
   }
 }
 
-void TestKeepAlive1(HttpClientSession& session) {
-  try {
-    auto r = session.Request(HttpRequestArgs{ "GET" }.
-                             url("http://httpbin.org/get").
-                             parameters({ "key1", "value1", "key2", "value2" }).
-                             headers({ "Accept", "application/json" }).
-                             buffer_size(1000));
-
-    std::cout << r->content() << std::endl;
-
-  } catch (const Exception& e) {
-    std::cout << "Exception: " << e.what() << std::endl;
-  }
-}
-
 void TestKeepAlive2(HttpClientSession& session) {
   try {
     auto r = session.Request(webcc::HttpRequestArgs("GET").
                              url("https://api.github.com/events").
                              ssl_verify(false).buffer_size(1500));
-
-    //std::cout << r->content() << std::endl;
-
   } catch (const Exception& e) {
     std::cout << "Exception: " << e.what() << std::endl;
   }
@@ -138,15 +121,31 @@ void TestKeepAlive4(HttpClientSession& session) {
 
 // -----------------------------------------------------------------------------
 
+void Sleep(int seconds) {
+  if (seconds > 0) {
+    LOG_INFO("Sleep %d seconds...", seconds);
+    std::this_thread::sleep_for(std::chrono::seconds(seconds));
+  }
+}
+
 int main() {
   WEBCC_LOG_INIT("", LOG_CONSOLE);
 
   HttpClientSession session;
 
-  GetBoostOrgLicense(session);
+  // TEST keep-alive.
+
+  try {
+    // Keep-Alive by default
+    session.Get("http://httpbin.org/get");
 
-  //TestKeepAlive1(session);
-  //TestKeepAlive1(session);
+    session.Get("http://httpbin.org/get", {}, { "Connection", "Close" });
+
+    session.Get("http://httpbin.org/get");
+
+  } catch (const Exception& e) {
+    std::cout << "Exception: " << e.what() << std::endl;
+  }
 
   return 0;
 }
diff --git a/example/soap_calc_server/calc_service.h b/example/soap_calc_server/calc_service.h
index 4fcf0bf..d8e5858 100644
--- a/example/soap_calc_server/calc_service.h
+++ b/example/soap_calc_server/calc_service.h
@@ -9,7 +9,7 @@ public:
   ~CalcService() override = default;
 
   bool Handle(const webcc::SoapRequest& soap_request,
-              webcc::SoapResponse* soap_response) override;
+              webcc::SoapResponse* soap_response) final;
 };
 
 #endif  // CALC_SERVICE_H_
diff --git a/webcc/http_client.cc b/webcc/http_client.cc
index b3f3f5b..32b99b5 100644
--- a/webcc/http_client.cc
+++ b/webcc/http_client.cc
@@ -1,5 +1,6 @@
 #include "webcc/http_client.h"
 
+#include "boost/algorithm/string.hpp"  // TODO: Remove
 #include "boost/date_time/posix_time/posix_time.hpp"
 
 #include "webcc/logger.h"
@@ -11,10 +12,10 @@ namespace webcc {
 
 HttpClient::HttpClient(std::size_t buffer_size, bool ssl_verify)
     : buffer_(buffer_size == 0 ? kBufferSize : buffer_size),
-      deadline_(io_context_),
+      timer_(io_context_),
       ssl_verify_(ssl_verify),
       timeout_seconds_(kMaxReadSeconds),
-      stopped_(false),
+      closed_(false),
       timed_out_(false),
       error_(kNoError) {
 }
@@ -33,13 +34,14 @@ bool HttpClient::Request(const HttpRequest& request,
   response_.reset(new HttpResponse());
   response_parser_.reset(new HttpResponseParser(response_.get()));
 
-  stopped_ = false;
+  closed_ = false;
   timed_out_ = false;
   error_ = kNoError;
 
   BufferResizer buffer_resizer(&buffer_, buffer_size);
 
   if (connect) {
+    // No existing socket connection was specified, create a new one.
     if ((error_ = Connect(request)) != kNoError) {
       return false;
     }
@@ -56,6 +58,23 @@ bool HttpClient::Request(const HttpRequest& request,
   return true;
 }
 
+void HttpClient::Close() {
+  if (closed_) {
+    return;
+  }
+
+  closed_ = true;
+
+  LOG_INFO("Close socket...");
+
+  boost::system::error_code ec;
+  socket_->Close(&ec);
+
+  if (ec) {
+    LOG_ERRO("Socket close error (%s).", ec.message().c_str());
+  }
+}
+
 Error HttpClient::Connect(const HttpRequest& request) {
   if (request.url().scheme() == "https") {
     socket_.reset(new HttpSslSocket{ io_context_, ssl_verify_ });
@@ -89,7 +108,7 @@ Error HttpClient::DoConnect(const HttpRequest& request,
   // Determine whether a connection was successfully established.
   if (ec) {
     LOG_ERRO("Socket connect error (%s).", ec.message().c_str());
-    Stop();
+    Close();
     return kEndpointConnectError;
   }
 
@@ -113,7 +132,7 @@ Error HttpClient::WriteReqeust(const HttpRequest& request) {
 
   if (ec) {
     LOG_ERRO("Socket write error (%s).", ec.message().c_str());
-    Stop();
+    Close();
     return kSocketWriteError;
   }
 
@@ -125,8 +144,8 @@ Error HttpClient::WriteReqeust(const HttpRequest& request) {
 Error HttpClient::ReadResponse() {
   LOG_VERB("Read response (timeout: %ds)...", timeout_seconds_);
 
-  deadline_.expires_from_now(boost::posix_time::seconds(timeout_seconds_));
-  DoWaitDeadline();
+  timer_.expires_from_now(boost::posix_time::seconds(timeout_seconds_));
+  DoWaitTimer();
 
   Error error = kNoError;
   DoReadResponse(&error);
@@ -148,7 +167,8 @@ void HttpClient::DoReadResponse(Error* error) {
     LOG_VERB("Socket async read handler.");
 
     if (ec || length == 0) {
-      Stop();
+      StopTimer();
+      Close();
       *error = kSocketReadError;
       LOG_ERRO("Socket read error (%s).", ec.message().c_str());
       return;
@@ -158,7 +178,8 @@ void HttpClient::DoReadResponse(Error* error) {
 
     // Parse the response piece just read.
     if (!response_parser_->Parse(buffer_.data(), length)) {
-      Stop();
+      StopTimer();
+      Close();
       *error = kHttpError;
       LOG_ERRO("Failed to parse HTTP response.");
       return;
@@ -167,14 +188,23 @@ void HttpClient::DoReadResponse(Error* error) {
     if (response_parser_->finished()) {
       // Stop trying to read once all content has been received, because
       // some servers will block extra call to read_some().
-      Stop();  // TODO: Keep-Alive
+
+      StopTimer();
+
+      if (response_->IsConnectionKeepAlive()) {
+        // Close the timer but keep the socket connection.
+        LOG_INFO("Keep the socket connection alive.");
+      } else {
+        Close();
+      }
 
       LOG_INFO("Finished to read and parse HTTP response.");
 
+      // Stop reading.
       return;
     }
 
-    if (!stopped_) {
+    if (!closed_) {
       DoReadResponse(error);
     }
   };
@@ -187,17 +217,17 @@ void HttpClient::DoReadResponse(Error* error) {
   } while (ec == boost::asio::error::would_block);
 }
 
-void HttpClient::DoWaitDeadline() {
-  deadline_.async_wait(
-      std::bind(&HttpClient::OnDeadline, this, std::placeholders::_1));
+void HttpClient::DoWaitTimer() {
+  timer_.async_wait(
+      std::bind(&HttpClient::OnTimer, this, std::placeholders::_1));
 }
 
-void HttpClient::OnDeadline(boost::system::error_code ec) {
-  if (stopped_) {
+void HttpClient::OnTimer(boost::system::error_code ec) {
+  if (closed_) {
     return;
   }
 
-  LOG_VERB("OnDeadline.");
+  LOG_VERB("On deadline timer.");
 
   // NOTE: Can't check this:
   //   if (ec == boost::asio::error::operation_aborted) {
@@ -205,39 +235,24 @@ void HttpClient::OnDeadline(boost::system::error_code ec) {
   //     return;
   //   }
 
-  if (deadline_.expires_at() <=
-      boost::asio::deadline_timer::traits_type::now()) {
+  if (timer_.expires_at() <= boost::asio::deadline_timer::traits_type::now()) {
     // The deadline has passed.
     // The socket is closed so that any outstanding asynchronous operations
     // are canceled.
     LOG_WARN("HTTP client timed out.");
     timed_out_ = true;
-    Stop();
+    Close();
     return;
   }
 
   // Put the actor back to sleep.
-  DoWaitDeadline();
+  DoWaitTimer();
 }
 
-void HttpClient::Stop() {
-  if (stopped_) {
-    return;
-  }
-
-  stopped_ = true;
-
-  LOG_INFO("Close socket...");
-
-  boost::system::error_code ec;
-  socket_->Close(&ec);
-
-  if (ec) {
-    LOG_ERRO("Socket close error (%s).", ec.message().c_str());
-  }
-
+void HttpClient::StopTimer() {
+  // Cancel any asynchronous operations that are waiting on the timer.
   LOG_INFO("Cancel deadline timer...");
-  deadline_.cancel();
+  timer_.cancel();
 }
 
 }  // namespace webcc
diff --git a/webcc/http_client.h b/webcc/http_client.h
index 5d34f03..989edce 100644
--- a/webcc/http_client.h
+++ b/webcc/http_client.h
@@ -18,9 +18,10 @@
 
 namespace webcc {
 
-class HttpSocketBase;
+class HttpClient;
+typedef std::shared_ptr<HttpClient> HttpClientPtr;
 
-// The base class of synchronous HTTP clients.
+// Synchronous HTTP & HTTPS client.
 // In synchronous mode, a request won't return until the response is received
 // or timeout occurs.
 // Please don't use the same client object in multiple threads.
@@ -46,6 +47,9 @@ public:
                std::size_t buffer_size = 0,
                bool connect = true);
 
+  // Close the socket.
+  void Close();
+
   HttpResponsePtr response() const { return response_; }
 
   int response_status() const {
@@ -58,11 +62,13 @@ public:
     return response_->content();
   }
 
+  bool closed() const { return closed_; }
+
   bool timed_out() const { return timed_out_; }
 
   Error error() const { return error_; }
 
-public:
+private:
   Error Connect(const HttpRequest& request);
 
   Error DoConnect(const HttpRequest& request, const std::string& default_port);
@@ -73,13 +79,15 @@ public:
 
   void DoReadResponse(Error* error);
 
-  void DoWaitDeadline();
-  void OnDeadline(boost::system::error_code ec);
+  void DoWaitTimer();
+  void OnTimer(boost::system::error_code ec);
 
-  void Stop();
+  void StopTimer();
 
+private:
   boost::asio::io_context io_context_;
 
+  // Socket connection.
   std::unique_ptr<HttpSocketBase> socket_;
 
   std::vector<char> buffer_;
@@ -88,7 +96,7 @@ public:
   std::unique_ptr<HttpResponseParser> response_parser_;
 
   // Timer for the timeout control.
-  boost::asio::deadline_timer deadline_;
+  boost::asio::deadline_timer timer_;
 
   // Verify the certificate of the peer (remote server) or not.
   // HTTPS only.
@@ -98,8 +106,8 @@ public:
   // Only for reading response from server.
   int timeout_seconds_;
 
-  // Request stopped due to timeout or socket error.
-  bool stopped_;
+  // Connection closed.
+  bool closed_;
 
   // If the error was caused by timeout or not.
   bool timed_out_;
diff --git a/webcc/http_client_pool.cc b/webcc/http_client_pool.cc
index 8843dcb..7aec182 100644
--- a/webcc/http_client_pool.cc
+++ b/webcc/http_client_pool.cc
@@ -1,16 +1,34 @@
 #include "webcc/http_client_pool.h"
 
+#include "webcc/logger.h"
+
 namespace webcc {
 
-HttpClientPtr HttpClientPool::Get(const Url& url) const {
-  for (const auto& client : clients_) {
-    return client;
+HttpClientPool::~HttpClientPool() {
+  LOG_INFO("Close socket for all (%u) connections in the pool.",
+           clients_.size());
+
+  for (auto& pair : clients_) {
+    pair.second->Close();
+  }
+}
+
+HttpClientPtr HttpClientPool::Get(const Key& key) const {
+  auto it = clients_.find(key);
+
+  if (it != clients_.end()) {
+    return it->second;
+  } else {
+    return HttpClientPtr{};
   }
-  return HttpClientPtr{};
 }
 
-void HttpClientPool::Add(HttpClientPtr client) {
-  clients_.push_back(client);
+void HttpClientPool::Add(const Key& key, HttpClientPtr client) {
+  clients_[key] = client;
+}
+
+void HttpClientPool::Remove(const Key& key) {
+  clients_.erase(key);
 }
 
 }  // namespace webcc
diff --git a/webcc/http_client_pool.h b/webcc/http_client_pool.h
index ed30c44..99ef36b 100644
--- a/webcc/http_client_pool.h
+++ b/webcc/http_client_pool.h
@@ -1,10 +1,7 @@
 #ifndef WEBCC_HTTP_CLIENT_POOL_H_
 #define WEBCC_HTTP_CLIENT_POOL_H_
 
-// HTTP client connection pool for keep-alive connections.
-
-#include <list>
-#include <memory>
+#include <map>
 #include <string>
 
 #include "webcc/http_client.h"
@@ -12,18 +9,51 @@
 
 namespace webcc {
 
-typedef std::shared_ptr<HttpClient> HttpClientPtr;
-
+// Connection pool for keep-alive connections.
 class HttpClientPool {
+public:
+  struct Key {
+    std::string scheme;
+    std::string host;
+    std::string port;
+
+    Key() = default;
+
+    explicit Key(const Url& url)
+        : scheme(url.scheme()), host(url.host()), port(url.port()) {
+    }
+
+    bool operator==(const Key& rhs) const {
+      return scheme == rhs.scheme && host == rhs.host && port == rhs.port;
+    }
+
+    bool operator<(const Key& rhs) const {
+      if (scheme < rhs.scheme) {
+        return true;
+      }
+      if (host < rhs.host) {
+        return true;
+      }
+      if (port < rhs.port) {
+        return true;
+      }
+      return false;
+    }
+  };
+
 public:
   HttpClientPool() = default;
 
-  HttpClientPtr Get(const Url& url) const;
+  ~HttpClientPool();
+
+  HttpClientPtr Get(const Key& key) const;
+
+  void Add(const Key& key, HttpClientPtr client);
 
-  void Add(HttpClientPtr client);
+  void Remove(const Key& key);
 
 private:
-  std::list<HttpClientPtr> clients_;
+  std::map<Key, HttpClientPtr> clients_;
 };
 
 }  // namespace webcc
diff --git a/webcc/http_client_session.cc b/webcc/http_client_session.cc
index d350cb5..9c70acb 100644
--- a/webcc/http_client_session.cc
+++ b/webcc/http_client_session.cc
@@ -1,12 +1,10 @@
 #include "webcc/http_client_session.h"
 
-#include "webcc/http_client.h"
 #include "webcc/url.h"
 
 namespace webcc {
 
-HttpClientSession::HttpClientSession()
-    : pool_(new HttpClientPool{}) {
+HttpClientSession::HttpClientSession() {
   InitHeaders();
 }
 
@@ -45,22 +43,39 @@ HttpResponsePtr HttpClientSession::Request(HttpRequestArgs&& args) {
 
   request.Prepare();
 
-  bool connect = false;
-  HttpClientPtr impl = pool_->Get(request.url());
+  const HttpClientPool::Key key{ request.url() };
+  bool new_created = false;
 
-  if (!impl) {
-    impl.reset(new HttpClient{ 0, args.ssl_verify_ });
-
-    connect = true;
+  HttpClientPtr client = pool_.Get(key);
+  if (!client) {
+    new_created = true;
+    client.reset(new HttpClient{ 0, args.ssl_verify_ });
+  } else {
+    new_created = false;
+    LOG_VERB("Reuse an existing connection.");
+  }
 
-    pool_->Add(impl);
+  if (!client->Request(request, args.buffer_size_, new_created)) {
+    throw Exception(client->error(), client->timed_out());
   }
 
-  if (!impl->Request(request, args.buffer_size_, connect)) {
-    throw Exception(impl->error(), impl->timed_out());
+  if (new_created) {
+    if (!client->closed()) {
+      pool_.Add(key, client);
+
+      LOG_VERB("Added connection to the pool (%s, %s, %s).",
+               key.scheme.c_str(), key.host.c_str(), key.port.c_str());
+    }
+  } else {
+    if (client->closed()) {
+      pool_.Remove(key);
+
+      LOG_VERB("Removed connection from the pool (%s, %s, %s).",
+               key.scheme.c_str(), key.host.c_str(), key.port.c_str());
+    }
   }
 
-  return impl->response();
+  return client->response();
 }
 
 HttpResponsePtr HttpClientSession::Get(const std::string& url,
@@ -85,7 +100,6 @@ HttpResponsePtr HttpClientSession::Post(const std::string& url,
 }
 
 void HttpClientSession::InitHeaders() {
-  // NOTE: C++11 requires a space between literal and string macro.
   headers_.Add(http::headers::kUserAgent, http::UserAgent());
 
   // TODO: Support gzip, deflate
@@ -93,7 +107,6 @@ void HttpClientSession::InitHeaders() {
 
   headers_.Add(http::headers::kAccept, "*/*");
 
-  // TODO
   headers_.Add(http::headers::kConnection, "Keep-Alive");
 }
 
diff --git a/webcc/http_client_session.h b/webcc/http_client_session.h
index 81095f0..a318922 100644
--- a/webcc/http_client_session.h
+++ b/webcc/http_client_session.h
@@ -52,7 +52,8 @@ private:
   // Headers for each request sent from this session.
   HttpHeaderDict headers_;
 
-  std::unique_ptr<HttpClientPool> pool_;
+  // Connection pool for keep-alive.
+  HttpClientPool pool_;
 };
 
 }  // namespace webcc
diff --git a/webcc/http_message.cc b/webcc/http_message.cc
index 6a6a294..10e440d 100644
--- a/webcc/http_message.cc
+++ b/webcc/http_message.cc
@@ -25,36 +25,68 @@ std::ostream& operator<<(std::ostream& os, const HttpMessage& message) {
 // -----------------------------------------------------------------------------
 
 void HttpHeaderDict::Add(const std::string& key, const std::string& value) {
-  for (HttpHeader& h : headers_) {
-    if (boost::iequals(h.first, key)) {
-      h.second = value;
-      return;
-    }
+  auto it = Find(key);
+  if (it != headers_.end()) {
+    it->second = value;
+  } else {
+    headers_.push_back({ key, value });
   }
-  headers_.push_back({ key, value });
 }
 
 void HttpHeaderDict::Add(std::string&& key, std::string&& value) {
-  for (HttpHeader& h : headers_) {
-    if (boost::iequals(h.first, key)) {
-      h.second = std::move(value);
-      return;
-    }
+  auto it = Find(key);
+  if (it != headers_.end()) {
+    it->second = std::move(value);
+  } else {
+    headers_.push_back({ std::move(key), std::move(value) });
+  }
+}
+
+const std::string& HttpHeaderDict::Get(const std::string& key,
+                                       bool* existed) const {
+  auto it = const_cast<HttpHeaderDict*>(this)->Find(key);
+
+  if (existed != nullptr) {
+    *existed = (it != headers_.end());
+  }
+
+  if (it != headers_.end()) {
+    return it->second;
   }
-  headers_.push_back({ std::move(key), std::move(value) });
+
+  static const std::string s_no_value;
+  return s_no_value;
 }
 
-bool HttpHeaderDict::Has(const std::string& key) const {
-  for (const HttpHeader& h : headers_) {
-    if (boost::iequals(h.first, key)) {
-      return true;
+std::vector<HttpHeader>::iterator HttpHeaderDict::Find(const std::string& key) {
+  auto it = headers_.begin();
+  for (; it != headers_.end(); ++it) {
+    if (boost::iequals(it->first, key)) {
+      break;
     }
   }
-  return false;
+  return it;
 }
 
 // -----------------------------------------------------------------------------
 
+bool HttpMessage::IsConnectionKeepAlive() const {
+  bool existed = false;
+  const std::string& connection =
+      GetHeader(http::headers::kConnection, &existed);
+
+  if (!existed) {
+    // Keep-Alive is by default for HTTP/1.1.
+    return true;
+  }
+
+  if (boost::iequals(connection, "Keep-Alive")) {
+    return true;
+  }
+
+  return false;
+}
+
 // See: https://tools.ietf.org/html/rfc7231#section-3.1.1.1
 void HttpMessage::SetContentType(const std::string& media_type,
                                  const std::string& charset) {
diff --git a/webcc/http_message.h b/webcc/http_message.h
index 8c442c9..017f4f1 100644
--- a/webcc/http_message.h
+++ b/webcc/http_message.h
@@ -14,36 +14,45 @@ namespace webcc {
 
 // -----------------------------------------------------------------------------
 
-typedef std::pair<std::string, std::string> HttpHeader;
-
 class HttpMessage;
-
 std::ostream& operator<<(std::ostream& os, const HttpMessage& message);
 
 // -----------------------------------------------------------------------------
 
+typedef std::pair<std::string, std::string> HttpHeader;
+
 class HttpHeaderDict {
 public:
   std::size_t size() const {
     return headers_.size();
   }
 
+  const std::vector<HttpHeader>& data() const {
+    return headers_;
+  }
+
   void Add(const std::string& key, const std::string& value);
 
   void Add(std::string&& key, std::string&& value);
 
-  bool Has(const std::string& key) const;
-
-  const HttpHeader& Get(std::size_t i) const {
-    assert(i < size());
-    return headers_[i];
+  bool Has(const std::string& key) const {
+    return const_cast<HttpHeaderDict*>(this)->Find(key) != headers_.end();
   }
 
-  const std::vector<HttpHeader>& data() const {
-    return headers_;
+  // Get header by index.
+  const HttpHeader& Get(std::size_t index) const {
+    assert(index < size());
+    return headers_[index];
   }
 
+  // Get header value by key.
+  // If there's no such header with the given key, besides return empty, the
+  // optional |existed| parameter will be set to false.
+  const std::string& Get(const std::string& key, bool* existed = nullptr) const;
+
 private:
+  std::vector<HttpHeader>::iterator Find(const std::string& key);
+
   std::vector<HttpHeader> headers_;
 };
 
@@ -73,6 +82,8 @@ public:
     return content_;
   }
 
+  bool IsConnectionKeepAlive() const;
+
   void SetHeader(const std::string& key, const std::string& value) {
     headers_.Add(key, value);
   }
@@ -81,11 +92,15 @@ public:
     headers_.Add(std::move(key), std::move(value));
   }
 
+  const std::string& GetHeader(const std::string& key,
+                               bool* existed = nullptr) const {
+    return headers_.Get(key, existed);
+  }
+
   // E.g., "text/html", "application/json; charset=utf-8", etc.
   void SetContentType(const std::string& media_type,
                       const std::string& charset);
 
-  // TODO: Remove parameter |set_length|.
   void SetContent(std::string&& content, bool set_length);
 
   // Make the message (e.g., update start line).
diff --git a/webcc/rest_request_handler.h b/webcc/rest_request_handler.h
index a7d421f..3c65a0b 100644
--- a/webcc/rest_request_handler.h
+++ b/webcc/rest_request_handler.h
@@ -19,7 +19,7 @@ public:
   bool Bind(RestServicePtr service, const std::string& url, bool is_regex);
 
 private:
-  void HandleConnection(HttpConnectionPtr connection) override;
+  void HandleConnection(HttpConnectionPtr connection) final;
 
   RestServiceManager service_manager_;
 };
diff --git a/webcc/rest_server.h b/webcc/rest_server.h
index 0a55d89..b99a1cb 100644
--- a/webcc/rest_server.h
+++ b/webcc/rest_server.h
@@ -32,7 +32,7 @@ public:
   }
 
 private:
-  HttpRequestHandler* GetRequestHandler() override {
+  HttpRequestHandler* GetRequestHandler() final {
     return &request_handler_;
   }
 
diff --git a/webcc/rest_service_manager.h b/webcc/rest_service_manager.h
index 740aafc..6b031a0 100644
--- a/webcc/rest_service_manager.h
+++ b/webcc/rest_service_manager.h
@@ -33,7 +33,7 @@ public:
 
 private:
   class ServiceItem {
- public:
+  public:
     ServiceItem(RestServicePtr _service, const std::string& _url,
                 bool _is_regex)
         : service(_service), url(_url), is_regex(_is_regex) {
diff --git a/webcc/soap_message.h b/webcc/soap_message.h
index cc19c4c..96882ed 100644
--- a/webcc/soap_message.h
+++ b/webcc/soap_message.h
@@ -38,7 +38,7 @@ public:
   // Parse from SOAP XML.
   bool FromXml(const std::string& xml_string);
 
-public:
+protected:
   // Convert to SOAP body XML.
   virtual void ToXmlBody(pugi::xml_node xbody) = 0;
 
diff --git a/webcc/soap_request.h b/webcc/soap_request.h
index 06f36eb..3408452 100644
--- a/webcc/soap_request.h
+++ b/webcc/soap_request.h
@@ -21,9 +21,9 @@ public:
   // Get parameter value by key.
   const std::string& GetParameter(const std::string& key) const;
 
-public:
-  void ToXmlBody(pugi::xml_node xbody) override;
-  bool FromXmlBody(pugi::xml_node xbody) override;
+protected:
+  void ToXmlBody(pugi::xml_node xbody) final;
+  bool FromXmlBody(pugi::xml_node xbody) final;
 
 private:
   std::vector<SoapParameter> parameters_;
diff --git a/webcc/soap_request_handler.h b/webcc/soap_request_handler.h
index 6a3c367..3d92a84 100644
--- a/webcc/soap_request_handler.h
+++ b/webcc/soap_request_handler.h
@@ -28,7 +28,7 @@ public:
   bool Bind(SoapServicePtr service, const std::string& url);
 
 private:
-  void HandleConnection(HttpConnectionPtr connection) override;
+  void HandleConnection(HttpConnectionPtr connection) final;
 
   SoapServicePtr GetServiceByUrl(const std::string& url);
 
diff --git a/webcc/soap_response.h b/webcc/soap_response.h
index 14d5f4c..f3afcce 100644
--- a/webcc/soap_response.h
+++ b/webcc/soap_response.h
@@ -50,7 +50,7 @@ public:
   //   - composer(xxxResponse);
   // The composer then add proper children to xxxResponse as the result.
   class Composer {
- public:
+  public:
     void operator()(pugi::xml_node xresponse) {
       Compose(xresponse);
     }
@@ -127,10 +127,10 @@ public:
 
   // TODO: Set fault from server.
 
-public:
-  void ToXmlBody(pugi::xml_node xbody) override;
+protected:
+  void ToXmlBody(pugi::xml_node xbody) final;
 
-  bool FromXmlBody(pugi::xml_node xbody) override;
+  bool FromXmlBody(pugi::xml_node xbody) final;
 
 private:
   // Fault element if any.
diff --git a/webcc/soap_server.h b/webcc/soap_server.h
index 79a81b3..e497e92 100644
--- a/webcc/soap_server.h
+++ b/webcc/soap_server.h
@@ -37,7 +37,7 @@ public:
   }
 
 private:
-  HttpRequestHandler* GetRequestHandler() override {
+  HttpRequestHandler* GetRequestHandler() final {
     return &request_handler_;
   }
 
diff --git a/webcc/soap_service.h b/webcc/soap_service.h
index 8b34ada..d029bac 100644
--- a/webcc/soap_service.h
+++ b/webcc/soap_service.h
@@ -19,7 +19,7 @@ public:
   virtual bool Handle(const SoapRequest& soap_request,
                       SoapResponse* soap_response) = 0;
 
-public:
+protected:
   http::Status http_status_ = http::Status::kOK;
 };