diff --git a/CMakeLists.txt b/CMakeLists.txt
index 79d72e9..70dfe5b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,6 +8,7 @@ endif()
 
 project(webcc)
 
+option(WEBCC_ENABLE_REST "Enable REST support?" ON)
 option(WEBCC_ENABLE_SOAP "Enable SOAP support (need pugixml)?" ON)
 option(WEBCC_ENABLE_SSL "Enable SSL/HTTPS support (need OpenSSL)?" OFF)
 option(WEBCC_ENABLE_UNITTEST "Build unit test?" ON)
@@ -121,17 +122,18 @@ add_subdirectory(webcc)
 
 if(WEBCC_ENABLE_EXAMPLES)
     add_subdirectory(example/http_client)
-    add_subdirectory(example/http_async_client)
+    # add_subdirectory(example/http_async_client)
 
-    # For including jsoncpp as "json/json.h".
-    include_directories(${THIRD_PARTY_DIR}/src/jsoncpp)
+    if(WEBCC_ENABLE_REST)
+        # For including jsoncpp as "json/json.h".
+        include_directories(${THIRD_PARTY_DIR}/src/jsoncpp)
+        # REST examples need jsoncpp to parse and create JSON.
+        add_subdirectory(${THIRD_PARTY_DIR}/src/jsoncpp)
 
-    # REST examples need jsoncpp to parse and create JSON.
-    add_subdirectory(${THIRD_PARTY_DIR}/src/jsoncpp)
-
-    add_subdirectory(example/rest_book_server)
-    add_subdirectory(example/rest_book_client)
-    add_subdirectory(example/rest_book_async_client)
+        add_subdirectory(example/rest_book_server)
+        # add_subdirectory(example/rest_book_client)
+        # add_subdirectory(example/rest_book_async_client)
+    endif()
 
     if(WEBCC_ENABLE_SOAP)
         add_subdirectory(example/soap_calc_server)
@@ -143,8 +145,11 @@ if(WEBCC_ENABLE_EXAMPLES)
 
     if(WEBCC_ENABLE_SSL)
         add_subdirectory(example/http_ssl_client)
-        add_subdirectory(example/http_ssl_async_client)
-        add_subdirectory(example/github_rest_client)
+        # add_subdirectory(example/http_ssl_async_client)
+
+        if(WEBCC_ENABLE_REST)
+            # add_subdirectory(example/github_rest_client)
+        endif()
     endif()
 endif()
 
diff --git a/_clang-format b/_clang-format
index 0a7a576..255c975 100644
--- a/_clang-format
+++ b/_clang-format
@@ -1,7 +1,7 @@
 ---
 Language:        Cpp
 # BasedOnStyle:  Google
-AccessModifierOffset: -1
+AccessModifierOffset: -2
 AlignAfterOpenBracket: Align
 AlignConsecutiveAssignments: false
 AlignConsecutiveDeclarations: false
diff --git a/example/http_client/main.cc b/example/http_client/main.cc
index 8144650..bd608e0 100644
--- a/example/http_client/main.cc
+++ b/example/http_client/main.cc
@@ -1,29 +1,49 @@
 #include <iostream>
 
-#include "webcc/http_client.h"
+#include "webcc/http_client_session.h"  // TEST
 #include "webcc/logger.h"
 
-static void PrintError(const webcc::HttpClient& client) {
-  std::cout << webcc::DescribeError(client.error());
-  if (client.timed_out()) {
-    std::cout << " (timed out)";
-  }
-  std::cout << std::endl;
-}
-
 int main() {
   WEBCC_LOG_INIT("", webcc::LOG_CONSOLE);
 
-  auto request = webcc::HttpRequest::New(webcc::kHttpGet, "/get",
-                                         "httpbin.org");
+  using namespace webcc;
+
+  HttpResponsePtr r;
+
+  HttpClientSession session;
+
+#if 0
+  r = session.Request(HttpRequestArgs("GET")
+                      .url("http://httpbin.org/get")  // Moved
+                      .parameters({ "key1", "value1", "key2", "value2" })  // Moved
+                      .headers({ "Accept", "application/json" })  // Moved
+                      .buffer_size(1000));
+
+  std::cout << r->content() << std::endl;
+
+  // If you want to create the args object firstly, there'll be an extra call
+  // to its move constructor.
+  //   - constructor: HttpRequestArgs("GET")
+  //   - move constructor: auto args = ... 
+  auto args = HttpRequestArgs("GET")
+      .url("http://httpbin.org/get")
+      .parameters({ "key1", "value1", "key2", "value2" })
+      .headers({ "Accept", "application/json" })
+      .buffer_size(1000);
+
+  r = session.Request(std::move(args));
+
+  r = session.Get("http://httpbin.org/get",
+                  { "key1", "value1", "key2", "value2" },
+                  { "Accept", "application/json" },
+                  HttpRequestArgs().buffer_size(1000));
+#endif
 
-  webcc::HttpClient client;
+  r = session.Post("http://httpbin.org/post", "{ 'key': 'value' }", true,
+                   { "Accept", "application/json" },
+                   HttpRequestArgs().buffer_size(1000));
 
-  if (client.Request(*request)) {
-    std::cout << client.response_content() << std::endl;
-  } else {
-    PrintError(client);
-  }
+  std::cout << r->content() << std::endl;
 
   return 0;
 }
diff --git a/example/http_ssl_client/main.cc b/example/http_ssl_client/main.cc
index 9244c9e..63762b8 100644
--- a/example/http_ssl_client/main.cc
+++ b/example/http_ssl_client/main.cc
@@ -4,25 +4,21 @@
 #include "webcc/logger.h"
 
 int main(int argc, char* argv[]) {
-  std::string host;
   std::string url;
 
   if (argc != 3) {
-    host = "www.boost.org";
-    url = "/LICENSE_1_0.txt";
+    url = "www.boost.org/LICENSE_1_0.txt";
   } else {
-    host = argv[1];
-    url = argv[2];
+    url = argv[1];
   }
 
-  std::cout << "Host: " << host << std::endl;
   std::cout << "URL:  " << url << std::endl;
   std::cout << std::endl;
 
   WEBCC_LOG_INIT("", webcc::LOG_CONSOLE);
 
   // Leave port to default value.
-  webcc::HttpRequest request(webcc::kHttpGet, url, host);
+  webcc::HttpRequest request(webcc::http::kGet, url);
 
   request.Prepare();
 
@@ -30,7 +26,7 @@ int main(int argc, char* argv[]) {
   // See HttpSslClient::Request() for more details.
   bool ssl_verify = false;
 
-  webcc::HttpSslClient client(2000, ssl_verify);
+  webcc::HttpSslClient client(ssl_verify, 2000);
 
   if (client.Request(request)) {
     //std::cout << client.response()->content() << std::endl;
diff --git a/unittest/CMakeLists.txt b/unittest/CMakeLists.txt
index 3c83354..793bcda 100644
--- a/unittest/CMakeLists.txt
+++ b/unittest/CMakeLists.txt
@@ -1,8 +1,14 @@
 # Unit test
 set(UT_SRCS
-    rest_service_manager_test.cc
+    url_test.cc
     )
 
+if(WEBCC_ENABLE_REST)
+	set(UT_SRCS ${UT_SRCS}
+		rest_service_manager_test.cc
+		)
+endif()
+
 set(UT_TARGET_NAME webcc_unittest)
 
 add_executable(${UT_TARGET_NAME} ${UT_SRCS})
diff --git a/unittest/rest_service_manager_test.cc b/unittest/rest_service_manager_test.cc
index e08d182..14a3917 100644
--- a/unittest/rest_service_manager_test.cc
+++ b/unittest/rest_service_manager_test.cc
@@ -1,6 +1,9 @@
-#include "webcc/rest_service_manager.h"
 #include "gtest/gtest.h"
 
+#include "webcc/rest_service_manager.h"
+
+// -----------------------------------------------------------------------------
+
 class TestRestService : public webcc::RestService {
  public:
   void Handle(const webcc::RestRequest& request,
@@ -9,6 +12,8 @@ class TestRestService : public webcc::RestService {
   }
 };
 
+// -----------------------------------------------------------------------------
+
 TEST(RestServiceManager, URL_RegexBasic) {
   webcc::RestServiceManager service_manager;
 
diff --git a/webcc/CMakeLists.txt b/webcc/CMakeLists.txt
index 567408b..dda4d58 100644
--- a/webcc/CMakeLists.txt
+++ b/webcc/CMakeLists.txt
@@ -15,27 +15,23 @@ include(GNUInstallDirs)
 
 set(HEADERS
     globals.h
-    http_async_client_base.h
-    http_async_client.h
+    # http_async_client_base.h
+    # http_async_client.h
     http_client_base.h
     http_client.h
-    http_session.h
+    http_client_session.h
+    http_connection.h
     http_message.h
     http_parser.h
     http_request.h
+    http_request_args.h
     http_request_handler.h
     http_request_parser.h
     http_response.h
     http_response_parser.h
     http_server.h
-    http_ssl_async_client.h
+    # http_ssl_async_client.h
     queue.h
-    rest_async_client.h
-    rest_client.h
-    rest_request_handler.h
-    rest_server.h
-    rest_service.h
-    rest_service_manager.h
     url.h
     utility.h
     version.h
@@ -43,11 +39,12 @@ set(HEADERS
 
 set(SOURCES
     globals.cc
-    http_async_client_base.cc
-    http_async_client.cc
+    # http_async_client_base.cc
+    # http_async_client.cc
     http_client_base.cc
     http_client.cc
-    http_session.cc
+    http_client_session.cc
+    http_connection.cc
     http_message.cc
     http_parser.cc
     http_request.cc
@@ -56,34 +53,41 @@ set(SOURCES
     http_response.cc
     http_response_parser.cc
     http_server.cc
-    http_ssl_async_client.cc
+    # http_ssl_async_client.cc
     logger.cc
-    rest_async_client.cc
-    rest_client.cc
-    rest_request_handler.cc
-    rest_service_manager.cc
-    rest_service.cc
     url.cc
     utility.cc
     )
 
-if(WEBCC_ENABLE_SSL)
-    set(HEADERS ${HEADERS}
-        http_ssl_client.h
-        # rest_ssl_async_client.h
-        rest_ssl_client.h
+if(WEBCC_ENABLE_REST)
+    set(REST_HEADERS
+       # rest_async_client.h
+        # rest_client.h
+        rest_request_handler.h
+        rest_server.h
+        rest_service.h
+        rest_service_manager.h
         )
-
-    set(SOURCES ${SOURCES}
-        http_ssl_client.cc
-        # rest_ssl_async_client.cc
-        rest_ssl_client.cc
+    set(REST_SOURCES
+       # rest_async_client.cc
+        # rest_client.cc
+        rest_request_handler.cc
+        rest_service_manager.cc
+        rest_service.cc
         )
+
+    set(HEADERS ${HEADERS} ${REST_HEADERS})
+    set(SOURCES ${SOURCES} ${REST_SOURCES})
+endif()
+
+if(WEBCC_ENABLE_SSL)
+    set(HEADERS ${HEADERS} http_ssl_client.h)
+    set(SOURCES ${SOURCES} http_ssl_client.cc)
 endif()
 
 if(WEBCC_ENABLE_SOAP)
     set(SOAP_HEADERS
-        soap_async_client.h
+        # soap_async_client.h
         soap_client.h
         soap_globals.h
         soap_message.h
@@ -97,7 +101,7 @@ if(WEBCC_ENABLE_SOAP)
         )
 
     set(SOAP_SOURCES
-        soap_async_client.cc
+        # soap_async_client.cc
         soap_client.cc
         soap_globals.cc
         soap_message.cc
diff --git a/webcc/globals.cc b/webcc/globals.cc
index 1db288a..ec9b726 100644
--- a/webcc/globals.cc
+++ b/webcc/globals.cc
@@ -1,15 +1,8 @@
 #include "webcc/globals.h"
 
-namespace webcc {
-
-// -----------------------------------------------------------------------------
+#include "boost/algorithm/string.hpp"
 
-const std::string kHttpHead = "HEAD";
-const std::string kHttpGet = "GET";
-const std::string kHttpPost = "POST";
-const std::string kHttpPatch = "PATCH";
-const std::string kHttpPut = "PUT";
-const std::string kHttpDelete = "DELETE";
+namespace webcc {
 
 // -----------------------------------------------------------------------------
 
diff --git a/webcc/globals.h b/webcc/globals.h
index 00f9e6d..657355c 100644
--- a/webcc/globals.h
+++ b/webcc/globals.h
@@ -1,7 +1,9 @@
 #ifndef WEBCC_GLOBALS_H_
 #define WEBCC_GLOBALS_H_
 
+#include <cassert>
 #include <string>
+#include <vector>
 
 #include "webcc/version.h"
 
@@ -25,6 +27,9 @@
   TypeName(const TypeName&) = delete; \
   TypeName& operator=(const TypeName&) = delete;
 
+// Default user agent.
+#define USER_AGENT "Webcc/" WEBCC_VERSION
+
 namespace webcc {
 
 // -----------------------------------------------------------------------------
@@ -45,9 +50,47 @@ const int kMaxReadSeconds = 30;
 // when dumped/logged.
 const std::size_t kMaxDumpSize = 2048;
 
+// Default ports.
+const char* const kPort80 = "80";
+const char* const kPort443 = "443";
+
+// Client side error codes.
+enum Error {
+  kNoError = 0,  // i.e., OK
+
+  kHostResolveError,
+  kEndpointConnectError,
+  kHandshakeError,  // HTTPS handshake
+  kSocketReadError,
+  kSocketWriteError,
+
+  // HTTP error.
+  // E.g., failed to parse HTTP response (invalid content length, etc.).
+  kHttpError,
+
+  // Server error.
+  // E.g., HTTP status 500 + SOAP Fault element.
+  kServerError,
+
+  // XML parsing error.
+  kXmlError,
+};
+
+// Return a descriptive message for the given error code.
+const char* DescribeError(Error error);
+
 // HTTP headers.
 namespace http {
 
+// HTTP methods (verbs) in string.
+// Don't use enum to avoid converting back and forth.
+const char* const kHead   = "HEAD";
+const char* const kGet    = "GET";
+const char* const kPost   = "POST";
+const char* const kPatch  = "PATCH";
+const char* const kPut    = "PUT";
+const char* const kDelete = "DELETE";
+
 // HTTP response status.
 // This is not a full list.
 // Full list: https://en.wikipedia.org/wiki/List_of_HTTP_status_codes
@@ -94,6 +137,7 @@ const char* const kTextXml = "text/xml";
 
 }  // namespace media_types
 
+// TODO: Rename to encodings?
 namespace charsets {
 
 const char* const kUtf8 = "utf-8";
@@ -102,45 +146,6 @@ const char* const kUtf8 = "utf-8";
 
 }  // namespace http
 
-// Default ports.
-const char* const kHttpPort = "80";
-const char* const kHttpSslPort = "443";
-
-// HTTP methods (verbs) in string ("HEAD", "GET", etc.).
-// NOTE: Don't use enum to avoid converting back and forth.
-// TODO: Add enum.
-extern const std::string kHttpHead;
-extern const std::string kHttpGet;
-extern const std::string kHttpPost;
-extern const std::string kHttpPatch;
-extern const std::string kHttpPut;
-extern const std::string kHttpDelete;
-
-// Client side error codes.
-enum Error {
-  kNoError = 0,  // i.e., OK
-
-  kHostResolveError,
-  kEndpointConnectError,
-  kHandshakeError,  // HTTPS handshake
-  kSocketReadError,
-  kSocketWriteError,
-
-  // HTTP error.
-  // E.g., failed to parse HTTP response (invalid content length, etc.).
-  kHttpError,
-
-  // Server error.
-  // E.g., HTTP status 500 + SOAP Fault element.
-  kServerError,
-
-  // XML parsing error.
-  kXmlError,
-};
-
-// Return a descriptive message for the given error code.
-const char* DescribeError(Error error);
-
 }  // namespace webcc
 
 #endif  // WEBCC_GLOBALS_H_
diff --git a/webcc/http_client.h b/webcc/http_client.h
index b76736d..55eea20 100644
--- a/webcc/http_client.h
+++ b/webcc/http_client.h
@@ -14,7 +14,7 @@ class HttpClient : public HttpClientBase {
 
  private:
   Error Connect(const HttpRequest& request) final {
-    return DoConnect(request, kHttpPort);
+    return DoConnect(request, kPort80);
   }
 
   void SocketConnect(const Endpoints& endpoints,
diff --git a/webcc/http_client_session.cc b/webcc/http_client_session.cc
new file mode 100644
index 0000000..8d78009
--- /dev/null
+++ b/webcc/http_client_session.cc
@@ -0,0 +1,80 @@
+#include "webcc/http_client_session.h"
+
+#include "webcc/http_client.h"
+#include "webcc/http_request.h"
+#include "webcc/url.h"
+
+namespace webcc {
+
+HttpClientSession::HttpClientSession() {
+  InitHeaders();
+}
+
+HttpResponsePtr HttpClientSession::Request(HttpRequestArgs&& args) {
+  assert(args.parameters_.size() % 2 == 0);
+  assert(args.headers_.size() % 2 == 0);
+
+  HttpRequest request(args.method_, args.url_, args.parameters_);
+
+  if (!args.data_.empty()) {
+    request.SetContent(std::move(args.data_), true);
+
+    // TODO: charset/encoding
+    if (args.json_) {
+      request.SetContentType(http::media_types::kApplicationJson, "");
+    }
+  }
+
+  // Apply the session-level headers.
+  for (const HttpHeader& h : headers_.data()) {
+    request.SetHeader(h.first, h.second);
+  }
+
+  // Apply the request-level headers.
+  // This will overwrite the session-level headers.
+  for (std::size_t i = 1; i < args.headers_.size(); i += 2) {
+    request.SetHeader(std::move(args.headers_[i - 1]),
+                      std::move(args.headers_[i]));
+  }
+
+  request.Prepare();
+
+  HttpClient client;
+  if (!client.Request(request, args.buffer_size_)) {
+    return HttpResponsePtr{};
+  }
+
+  return client.response();
+}
+
+HttpResponsePtr HttpClientSession::Get(const std::string& url,
+                                       std::vector<std::string>&& parameters,
+                                       std::vector<std::string>&& headers,
+                                       HttpRequestArgs&& args) {
+  return Request(args.method(http::kGet).url(url)
+                 .parameters(std::move(parameters))
+                 .headers(std::move(headers)));
+}
+
+HttpResponsePtr HttpClientSession::Post(const std::string& url,
+                                        std::string&& data, bool json,
+                                        std::vector<std::string>&& headers,
+                                        HttpRequestArgs&& args) {
+  return Request(args.method(http::kPost).url(url).data(std::move(data))
+                 .json(json).headers(std::move(headers)));
+}
+
+void HttpClientSession::InitHeaders() {
+  // NOTE: C++11 requires a space between literal and string macro.
+  headers_.Add(http::headers::kUserAgent, USER_AGENT);
+
+  // TODO: Support gzip, deflate
+  headers_.Add(http::headers::kAcceptEncoding, "identity");
+
+  headers_.Add(http::headers::kAccept, "*/*");
+
+  // TODO: Support Keep-Alive connection.
+  //headers_.Add(http::headers::kConnection, "close");
+}
+
+}  // namespace webcc
diff --git a/webcc/http_client_session.h b/webcc/http_client_session.h
new file mode 100644
index 0000000..4df7142
--- /dev/null
+++ b/webcc/http_client_session.h
@@ -0,0 +1,43 @@
+#ifndef WEBCC_HTTP_CLIENT_SESSION_H_
+#define WEBCC_HTTP_CLIENT_SESSION_H_
+
+#include <string>
+#include <vector>
+
+#include "webcc/http_request_args.h"
+#include "webcc/http_response.h"
+
+namespace webcc {
+
+class HttpClientSession {
+public:
+  HttpClientSession();
+
+  ~HttpClientSession() = default;
+
+  void AddHeader(const std::string& key, const std::string& value) {
+    headers_.Add(key, value);
+  }
+
+  HttpResponsePtr Request(HttpRequestArgs&& args);
+
+  HttpResponsePtr Get(const std::string& url,
+                      std::vector<std::string>&& parameters = {},
+                      std::vector<std::string>&& headers = {},
+                      HttpRequestArgs&& args = HttpRequestArgs());
+
+  HttpResponsePtr Post(const std::string& url,
+                       std::string&& data, bool json,
+                       std::vector<std::string>&& headers = {},
+                       HttpRequestArgs&& args = HttpRequestArgs());
+
+private:
+  void InitHeaders();
+
+  // Headers to be sent on each request sent from this session.
+  HttpHeaderDict headers_;
+};
+
+}  // namespace webcc
+
+#endif  // WEBCC_HTTP_CLIENT_SESSION_H_
diff --git a/webcc/http_session.cc b/webcc/http_connection.cc
similarity index 74%
rename from webcc/http_session.cc
rename to webcc/http_connection.cc
index e1add89..580a75e 100644
--- a/webcc/http_session.cc
+++ b/webcc/http_connection.cc
@@ -1,4 +1,4 @@
-#include "webcc/http_session.h"
+#include "webcc/http_connection.h"
 
 #include <utility>  // for move()
 
@@ -11,18 +11,18 @@ using boost::asio::ip::tcp;
 
 namespace webcc {
 
-HttpSession::HttpSession(tcp::socket socket, HttpRequestHandler* handler)
+HttpConnection::HttpConnection(tcp::socket socket, HttpRequestHandler* handler)
     : socket_(std::move(socket)),
       buffer_(kBufferSize),
       request_handler_(handler),
       request_parser_(&request_) {
 }
 
-void HttpSession::Start() {
+void HttpConnection::Start() {
   DoRead();
 }
 
-void HttpSession::Close() {
+void HttpConnection::Close() {
   LOG_INFO("Close socket...");
 
   boost::system::error_code ec;
@@ -32,27 +32,27 @@ void HttpSession::Close() {
   }
 }
 
-void HttpSession::SetResponseContent(std::string&& content,
-                                     const std::string& media_type,
-                                     const std::string& charset) {
+void HttpConnection::SetResponseContent(std::string&& content,
+                                        const std::string& media_type,
+                                        const std::string& charset) {
   response_.SetContent(std::move(content), true);
   response_.SetContentType(media_type, charset);
 }
 
-void HttpSession::SendResponse(http::Status status) {
+void HttpConnection::SendResponse(http::Status status) {
   response_.set_status(status);
   response_.Prepare();
   DoWrite();
 }
 
-void HttpSession::DoRead() {
+void HttpConnection::DoRead() {
   socket_.async_read_some(boost::asio::buffer(buffer_),
-                          std::bind(&HttpSession::OnRead, shared_from_this(),
+                          std::bind(&HttpConnection::OnRead, shared_from_this(),
                                     std::placeholders::_1,
                                     std::placeholders::_2));
 }
 
-void HttpSession::OnRead(boost::system::error_code ec, std::size_t length) {
+void HttpConnection::OnRead(boost::system::error_code ec, std::size_t length) {
   if (ec) {
     LOG_ERRO("Socket read error (%s).", ec.message().c_str());
     if (ec != boost::asio::error::operation_aborted) {
@@ -77,16 +77,16 @@ void HttpSession::OnRead(boost::system::error_code ec, std::size_t length) {
 
   LOG_VERB("HTTP request:\n%s", request_.Dump(4, "> ").c_str());
 
-  // Enqueue this session.
+  // Enqueue this connection.
   // Some worker thread will handle it later.
   request_handler_->Enqueue(shared_from_this());
 }
 
-void HttpSession::DoWrite() {
+void HttpConnection::DoWrite() {
   LOG_VERB("HTTP response:\n%s", response_.Dump(4, "> ").c_str());
 
   boost::asio::async_write(socket_, response_.ToBuffers(),
-                           std::bind(&HttpSession::OnWrite, shared_from_this(),
+                           std::bind(&HttpConnection::OnWrite, shared_from_this(),
                                      std::placeholders::_1,
                                      std::placeholders::_2));
 }
@@ -95,7 +95,7 @@ void HttpSession::DoWrite() {
 // This write handler will be called from main thread (the thread calling
 // io_context.run), even though AsyncWrite() is invoked by worker threads.
 // This is ensured by Asio.
-void HttpSession::OnWrite(boost::system::error_code ec, std::size_t length) {
+void HttpConnection::OnWrite(boost::system::error_code ec, std::size_t length) {
   if (ec) {
     LOG_ERRO("Socket write error (%s).", ec.message().c_str());
 
@@ -112,7 +112,7 @@ void HttpSession::OnWrite(boost::system::error_code ec, std::size_t length) {
 
 // Socket close VS. shutdown:
 //   https://stackoverflow.com/questions/4160347/close-vs-shutdown-socket
-void HttpSession::Shutdown() {
+void HttpConnection::Shutdown() {
   LOG_INFO("Shutdown socket...");
 
   // Initiate graceful connection closure.
diff --git a/webcc/http_session.h b/webcc/http_connection.h
similarity index 72%
rename from webcc/http_session.h
rename to webcc/http_connection.h
index 9675969..497150a 100644
--- a/webcc/http_session.h
+++ b/webcc/http_connection.h
@@ -1,5 +1,5 @@
-#ifndef WEBCC_HTTP_SESSION_H_
-#define WEBCC_HTTP_SESSION_H_
+#ifndef WEBCC_HTTP_CONNECTION_H_
+#define WEBCC_HTTP_CONNECTION_H_
 
 #include <memory>
 #include <string>
@@ -14,18 +14,23 @@
 
 namespace webcc {
 
+class HttpConnection;
 class HttpRequestHandler;
 
-class HttpSession : public std::enable_shared_from_this<HttpSession> {
- public:
-  HttpSession(boost::asio::ip::tcp::socket socket,
-              HttpRequestHandler* handler);
+typedef std::shared_ptr<HttpConnection> HttpConnectionPtr;
 
-  ~HttpSession() = default;
+class HttpConnection : public std::enable_shared_from_this<HttpConnection> {
+public:
+  HttpConnection(boost::asio::ip::tcp::socket socket,
+                 HttpRequestHandler* handler);
 
-  WEBCC_DELETE_COPY_ASSIGN(HttpSession);
+  ~HttpConnection() = default;
 
-  const HttpRequest& request() const { return request_; }
+  WEBCC_DELETE_COPY_ASSIGN(HttpConnection);
+
+  const HttpRequest& request() const {
+    return request_;
+  }
 
   // Start to read and process the client request.
   void Start();
@@ -40,7 +45,7 @@ class HttpSession : public std::enable_shared_from_this<HttpSession> {
   // Send response to client with the given status.
   void SendResponse(http::Status status);
 
- private:
+private:
   void DoRead();
   void OnRead(boost::system::error_code ec, std::size_t length);
 
@@ -69,8 +74,6 @@ class HttpSession : public std::enable_shared_from_this<HttpSession> {
   HttpResponse response_;
 };
 
-typedef std::shared_ptr<HttpSession> HttpSessionPtr;
-
 }  // namespace webcc
 
-#endif  // WEBCC_HTTP_SESSION_H_
+#endif  // WEBCC_HTTP_CONNECTION_H_
diff --git a/webcc/http_message.cc b/webcc/http_message.cc
index 26d25a5..6e51409 100644
--- a/webcc/http_message.cc
+++ b/webcc/http_message.cc
@@ -17,38 +17,53 @@ const char CRLF[] = { '\r', '\n' };
 
 // -----------------------------------------------------------------------------
 
-void HttpMessage::SetHeader(const std::string& name, const std::string& value) {
+std::ostream& operator<<(std::ostream& os, const HttpMessage& message) {
+  message.Dump(os);
+  return os;
+}
+
+// -----------------------------------------------------------------------------
+
+void HttpHeaderDict::Add(const std::string& key, const std::string& value) {
   for (HttpHeader& h : headers_) {
-    if (boost::iequals(h.name, name)) {
-      h.value = value;
+    if (boost::iequals(h.first, key)) {
+      h.second = value;
       return;
     }
   }
-  headers_.push_back({ name, value });
+  headers_.push_back({ key, value });
 }
 
-void HttpMessage::SetHeader(std::string&& name, std::string&& value) {
+void HttpHeaderDict::Add(std::string&& key, std::string&& value) {
   for (HttpHeader& h : headers_) {
-    if (boost::iequals(h.name, name)) {
-      h.value = std::move(value);
+    if (boost::iequals(h.first, key)) {
+      h.second = std::move(value);
       return;
     }
   }
-  headers_.push_back({ std::move(name), std::move(value) });
+  headers_.push_back({ std::move(key), std::move(value) });
+}
+
+bool HttpHeaderDict::Has(const std::string& key) const {
+  for (const HttpHeader& h : headers_) {
+    if (boost::iequals(h.first, key)) {
+      return true;
+    }
+  }
+  return false;
 }
 
-// NOTE:
-// According to HTTP 1.1 RFC7231, the following examples are all equivalent,
-// but the first is preferred for consistency:
-//    text/html;charset=utf-8
-//    text/html;charset=UTF-8
-//    Text/HTML;Charset="utf-8"
-//    text/html; charset="utf-8"
+// -----------------------------------------------------------------------------
+
 // See: https://tools.ietf.org/html/rfc7231#section-3.1.1.1
 void HttpMessage::SetContentType(const std::string& media_type,
                                  const std::string& charset) {
-  SetHeader(http::headers::kContentType,
-            media_type + ";charset=" + charset);
+  if (charset.empty()) {
+    SetHeader(http::headers::kContentType, media_type);
+  } else {
+    SetHeader(http::headers::kContentType,
+              media_type + ";charset=" + charset);
+  }
 }
 
 void HttpMessage::SetContent(std::string&& content, bool set_length) {
@@ -72,10 +87,10 @@ std::vector<boost::asio::const_buffer> HttpMessage::ToBuffers() const {
 
   buffers.push_back(boost::asio::buffer(start_line_));
 
-  for (const HttpHeader& h : headers_) {
-    buffers.push_back(boost::asio::buffer(h.name));
+  for (const HttpHeader& h : headers_.data()) {
+    buffers.push_back(boost::asio::buffer(h.first));
     buffers.push_back(boost::asio::buffer(misc_strings::NAME_VALUE_SEPARATOR));
-    buffers.push_back(boost::asio::buffer(h.value));
+    buffers.push_back(boost::asio::buffer(h.second));
     buffers.push_back(boost::asio::buffer(misc_strings::CRLF));
   }
 
@@ -98,8 +113,8 @@ void HttpMessage::Dump(std::ostream& os, std::size_t indent,
 
   os << indent_str << start_line_;
 
-  for (const HttpHeader& h : headers_) {
-    os << indent_str << h.name << ": " << h.value << std::endl;
+  for (const HttpHeader& h : headers_.data()) {
+    os << indent_str << h.first << ": " << h.second << std::endl;
   }
 
   os << indent_str << std::endl;
@@ -144,9 +159,4 @@ std::string HttpMessage::Dump(std::size_t indent,
   return ss.str();
 }
 
-std::ostream& operator<<(std::ostream& os, const HttpMessage& message) {
-  message.Dump(os);
-  return os;
-}
-
 }  // namespace webcc
diff --git a/webcc/http_message.h b/webcc/http_message.h
index 5a2d918..7ebecdc 100644
--- a/webcc/http_message.h
+++ b/webcc/http_message.h
@@ -12,35 +12,76 @@
 
 namespace webcc {
 
-struct HttpHeader {
-  std::string name;
-  std::string value;
+// -----------------------------------------------------------------------------
+
+typedef std::pair<std::string, std::string> HttpHeader;
+
+class HttpMessage;
+
+std::ostream& operator<<(std::ostream& os, const HttpMessage& message);
+
+// -----------------------------------------------------------------------------
+
+class HttpHeaderDict {
+public:
+  std::size_t size() const {
+    return headers_.size();
+  }
+
+  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];
+  }
+
+  const std::vector<HttpHeader>& data() const {
+    return headers_;
+  }
+
+private:
+  std::vector<HttpHeader> headers_;
 };
 
+// -----------------------------------------------------------------------------
+
 // Base class for HTTP request and response messages.
 class HttpMessage {
- public:
-  HttpMessage() : content_length_(kInvalidLength) {}
+public:
+  HttpMessage() : content_length_(kInvalidLength) {
+  }
 
   virtual ~HttpMessage() = default;
 
-  const std::string& start_line() const { return start_line_; }
+  const std::string& start_line() const {
+    return start_line_;
+  }
 
   void set_start_line(const std::string& start_line) {
     start_line_ = start_line;
   }
 
-  std::size_t content_length() const { return content_length_; }
+  std::size_t content_length() const {
+    return content_length_;
+  }
 
-  const std::string& content() const { return content_; }
+  const std::string& content() const {
+    return content_;
+  }
 
-  // TODO: Rename to AddHeader.
-  void SetHeader(const std::string& name, const std::string& value);
+  void SetHeader(const std::string& key, const std::string& value) {
+    headers_.Add(key, value);
+  }
 
-  // TODO: Remove
-  void SetHeader(std::string&& name, std::string&& value);
+  void SetHeader(std::string&& key, std::string&& value) {
+    headers_.Add(std::move(key), std::move(value));
+  }
 
-  // E.g., "application/json; charset=utf-8"
+  // E.g., "text/html", "application/json; charset=utf-8", etc.
   void SetContentType(const std::string& media_type,
                       const std::string& charset);
 
@@ -51,7 +92,7 @@ class HttpMessage {
 
   // Make the message (e.g., update start line).
   // Must be called before ToBuffers()!
-  virtual void Prepare() = 0;
+  virtual bool Prepare() = 0;
 
   // Convert the message into a vector of buffers. The buffers do not own the
   // underlying memory blocks, therefore the message object must remain valid
@@ -66,7 +107,7 @@ class HttpMessage {
   std::string Dump(std::size_t indent = 0,
                    const std::string& prefix = "") const;
 
- protected:
+protected:
   void SetContentLength(std::size_t content_length) {
     content_length_ = content_length;
     SetHeader(http::headers::kContentLength, std::to_string(content_length));
@@ -77,13 +118,11 @@ class HttpMessage {
 
   std::size_t content_length_;
 
-  std::vector<HttpHeader> headers_;
+  HttpHeaderDict headers_;
 
   std::string content_;
 };
 
-std::ostream& operator<<(std::ostream& os, const HttpMessage& message);
-
 }  // namespace webcc
 
 #endif  // WEBCC_HTTP_MESSAGE_H_
diff --git a/webcc/http_request.cc b/webcc/http_request.cc
index 396f97c..a6f2cb5 100644
--- a/webcc/http_request.cc
+++ b/webcc/http_request.cc
@@ -1,46 +1,51 @@
 #include "webcc/http_request.h"
 
+#include "webcc/logger.h"
+
 namespace webcc {
 
 HttpRequest::HttpRequest(const std::string& method,
                          const std::string& url,
-                         const std::string& host,
-                         const std::string& port)
-    : method_(method), url_(url), host_(host), port_(port) {
+                         const std::vector<std::string>& parameters)
+    : method_(method), url_(url) {
+  assert(parameters.size() % 2 == 0);
+  for (std::size_t i = 1; i < parameters.size(); i += 2) {
+    url_.AddParameter(parameters[i - 1], parameters[i]);
+  }
 }
 
-void HttpRequest::Prepare() {
+bool HttpRequest::Prepare() {
+  if (url_.host().empty()) {
+    LOG_ERRO("Invalid request: host is missing.");
+    return false;
+  }
+
+  std::string target = "/" + url_.path();
+  if (!url_.query().empty()) {
+    target += "?";
+    target += url_.query();
+  }
+
   start_line_ = method_;
   start_line_ += " ";
-  start_line_ += url_;
+  start_line_ += target;
   start_line_ += " HTTP/1.1";
   start_line_ += CRLF;
 
-  if (port_.empty()) {
-    SetHeader(http::headers::kHost, host_);
+  if (url_.port().empty()) {
+    SetHeader(http::headers::kHost, url_.host());
   } else {
-    SetHeader(http::headers::kHost, host_ + ":" + port_);
+    SetHeader(http::headers::kHost, url_.host() + ":" + url_.port());
   }
 
-  // TODO: Support Keep-Alive connection.
-  //SetHeader(http::headers::kConnection, "close");
-
-  // TODO: Support gzip, deflate
-  SetHeader(http::headers::kAcceptEncoding, "identity");
-
-  // NOTE: C++11 requires a space between literal and string macro.
-  SetHeader(http::headers::kUserAgent, "Webcc/" WEBCC_VERSION);
+  return true;
 }
 
-// static
 HttpRequestPtr HttpRequest::New(const std::string& method,
                                 const std::string& url,
-                                const std::string& host,
-                                const std::string& port,
+                                const std::vector<std::string>& parameters,
                                 bool prepare) {
-  HttpRequestPtr request{
-    new HttpRequest{ method, url, host, port }
-  };
+  HttpRequestPtr request{ new HttpRequest{ method, url, parameters } };
 
   if (prepare) {
     request->Prepare();
diff --git a/webcc/http_request.h b/webcc/http_request.h
index d0224fd..ed26010 100644
--- a/webcc/http_request.h
+++ b/webcc/http_request.h
@@ -3,8 +3,10 @@
 
 #include <memory>
 #include <string>
+#include <vector>
 
 #include "webcc/http_message.h"
+#include "webcc/url.h"
 
 namespace webcc {
 
@@ -14,29 +16,34 @@ class HttpRequestParser;
 typedef std::shared_ptr<HttpRequest> HttpRequestPtr;
 
 class HttpRequest : public HttpMessage {
- public:
+public:
   HttpRequest() = default;
 
-  // The |host| is a descriptive name (e.g., www.google.com) or a numeric IP
-  // address (127.0.0.1).
-  // The |port| is a numeric number (e.g., 9000). The default value (80 for HTTP
-  // or 443 for HTTPS) will be used to connect to server if it's empty.
+  // TODO: Move parameters
   HttpRequest(const std::string& method,
               const std::string& url,
-              const std::string& host,
-              const std::string& port = "");
+              const std::vector<std::string>& parameters = {});
 
   ~HttpRequest() override = default;
 
-  const std::string& method() const { return method_; }
+  const std::string& method() const {
+    return method_;
+  }
 
-  const std::string& url() const { return url_; }
+  const Url& url() const {
+    return url_;
+  }
 
-  const std::string& host() const { return host_; }
-  const std::string& port() const { return port_; }
+  const std::string& host() const {
+    return url_.host();
+  }
+
+  const std::string& port() const {
+    return url_.port();
+  }
 
   std::string port(const std::string& default_port) const {
-    return port_.empty() ? default_port : port_;
+    return port().empty() ? default_port : port();
   }
 
   // Shortcut to set `Accept` header.
@@ -51,30 +58,26 @@ class HttpRequest : public HttpMessage {
 
   // Prepare payload.
   // Compose start line, set Host header, etc.
-  void Prepare() override;
+  bool Prepare() override;
 
+  // TODO: Re-place
   static HttpRequestPtr New(const std::string& method,
                             const std::string& url,
-                            const std::string& host,
-                            const std::string& port = "",
+                            const std::vector<std::string>& parameters = {},
                             bool prepare = true);
 
- private:
+private:
   friend class HttpRequestParser;
 
-  void set_method(const std::string& method) { method_ = method; }
-  void set_url(const std::string& url) { url_ = url; }
+  void set_method(const std::string& method) {
+    method_ = method;
+  }
+  void set_url(const std::string& url) {
+    url_.Init(url);
+  }
 
-  // HTTP method.
   std::string method_;
-
-  // Request URL.
-  // A complete URL naming the requested resource, or the path component of
-  // the URL.
-  std::string url_;
-
-  std::string host_;
-  std::string port_;
+  Url url_;
 };
 
 }  // namespace webcc
diff --git a/webcc/http_request_args.h b/webcc/http_request_args.h
new file mode 100644
index 0000000..e53434f
--- /dev/null
+++ b/webcc/http_request_args.h
@@ -0,0 +1,140 @@
+#ifndef WEBCC_HTTP_REQUEST_ARGS_H_
+#define WEBCC_HTTP_REQUEST_ARGS_H_
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "webcc/globals.h"
+#include "webcc/logger.h"
+
+namespace webcc {
+
+class HttpClientSession;
+
+// Args maker for HttpClientSession.
+// Use method chaining to simulate Named Parameters.
+class HttpRequestArgs {
+public:
+  explicit HttpRequestArgs(const std::string& method = "")
+      : method_(method), json_(false), buffer_size_(0) {
+    LOG_VERB("HttpRequestArgs()");
+  }
+
+  HttpRequestArgs(const HttpRequestArgs&) = default;
+  HttpRequestArgs& operator=(const HttpRequestArgs&) = default;
+
+#if WEBCC_DEFAULT_MOVE_COPY_ASSIGN
+
+  HttpRequestArgs(HttpRequestArgs&&) = default;
+  HttpRequestArgs& operator=(HttpRequestArgs&&) = default;
+
+#else
+
+  HttpRequestArgs(HttpRequestArgs&& rhs)
+      : method_(std::move(rhs.method_)),
+        url_(std::move(rhs.url_)),
+        parameters_(std::move(rhs.parameters_)),
+        data_(std::move(rhs.data_)),
+        json_(rhs.json_),
+        headers_(std::move(rhs.headers_)),
+        buffer_size_(rhs.buffer_size_) {
+    LOG_VERB("HttpRequestArgs(&&)");
+  }
+
+  HttpRequestArgs& operator=(HttpRequestArgs&& rhs) {
+    if (&rhs != this) {
+      method_ = std::move(rhs.method_);
+      url_ = std::move(rhs.url_);
+      parameters_ = std::move(rhs.parameters_);
+      data_ = std::move(rhs.data_);
+      json_ = rhs.json_;
+      headers_ = std::move(rhs.headers_);
+      buffer_size_ = buffer_size_;
+    }
+    LOG_VERB("HttpRequestArgs& operator=(&&)");
+    return *this;
+  }
+
+#endif  // WEBCC_DEFAULT_MOVE_COPY_ASSIGN
+
+  HttpRequestArgs&& method(const std::string& method) {
+    method_ = method;
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& url(const std::string& url) {
+    url_ = url;
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& url(std::string&& url) {
+    url_ = std::move(url);
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& parameters(const std::vector<std::string>& parameters) {
+    parameters_ = parameters;
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& parameters(std::vector<std::string>&& parameters) {
+    parameters_ = std::move(parameters);
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& data(const std::string& data) {
+    data_ = data;
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& data(std::string&& data) {
+    data_ = std::move(data);
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& json(bool json = true) {
+    json_ = json;
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& headers(const std::vector<std::string>& headers) {
+    headers_ = headers;
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& headers(std::vector<std::string>&& headers) {
+    headers_ = std::move(headers);
+    return std::move(*this);
+  }
+
+  HttpRequestArgs&& buffer_size(std::size_t buffer_size) {
+    buffer_size_ = buffer_size;
+    return std::move(*this);
+  }
+
+private:
+  friend class HttpClientSession;
+
+  std::string method_;
+
+  std::string url_;
+
+  std::vector<std::string> parameters_;
+
+  // Data to send in the body of the request.
+  std::string data_;
+
+  // Is the data to send a JSON string?
+  bool json_;
+
+  std::vector<std::string> headers_;
+
+  // Size of the buffer to read response.
+  // Leave it to 0 for using default value.
+  std::size_t buffer_size_;
+};
+
+}  // namespace webcc
+
+#endif  // WEBCC_HTTP_REQUEST_ARGS_H_
diff --git a/webcc/http_request_handler.cc b/webcc/http_request_handler.cc
index 3e019f2..6d3cf7e 100644
--- a/webcc/http_request_handler.cc
+++ b/webcc/http_request_handler.cc
@@ -9,8 +9,8 @@
 
 namespace webcc {
 
-void HttpRequestHandler::Enqueue(HttpSessionPtr session) {
-  queue_.Push(session);
+void HttpRequestHandler::Enqueue(HttpConnectionPtr connection) {
+  queue_.Push(connection);
 }
 
 void HttpRequestHandler::Start(std::size_t count) {
@@ -24,14 +24,14 @@ void HttpRequestHandler::Start(std::size_t count) {
 void HttpRequestHandler::Stop() {
   LOG_INFO("Stopping workers...");
 
-  // Close pending sessions.
-  for (HttpSessionPtr s = queue_.Pop(); s; s = queue_.Pop()) {
-    LOG_INFO("Closing pending session...");
+  // Close pending connections.
+  for (HttpConnectionPtr s = queue_.Pop(); s; s = queue_.Pop()) {
+    LOG_INFO("Closing pending connection...");
     s->Close();
   }
 
-  // Enqueue a null session to trigger the first worker to stop.
-  queue_.Push(HttpSessionPtr());
+  // Enqueue a null connection to trigger the first worker to stop.
+  queue_.Push(HttpConnectionPtr());
 
   for (auto& worker : workers_) {
     if (worker.joinable()) {
@@ -46,19 +46,19 @@ void HttpRequestHandler::WorkerRoutine() {
   LOG_INFO("Worker is running.");
 
   for (;;) {
-    HttpSessionPtr session = queue_.PopOrWait();
+    HttpConnectionPtr connection = queue_.PopOrWait();
 
-    if (!session) {
+    if (!connection) {
       LOG_INFO("Worker is going to stop.");
 
       // For stopping next worker.
-      queue_.Push(HttpSessionPtr());
+      queue_.Push(HttpConnectionPtr());
 
       // Stop the worker.
       break;
     }
 
-    HandleSession(session);
+    HandleConnection(connection);
   }
 }
 
diff --git a/webcc/http_request_handler.h b/webcc/http_request_handler.h
index 4cbd582..ac7c2cb 100644
--- a/webcc/http_request_handler.h
+++ b/webcc/http_request_handler.h
@@ -5,7 +5,7 @@
 #include <thread>
 #include <vector>
 
-#include "webcc/http_session.h"
+#include "webcc/http_connection.h"
 #include "webcc/queue.h"
 #include "webcc/soap_service.h"
 
@@ -16,28 +16,30 @@ class HttpResponse;
 
 // The common handler for all incoming requests.
 class HttpRequestHandler {
- public:
+public:
   HttpRequestHandler() = default;
   virtual ~HttpRequestHandler() = default;
 
   WEBCC_DELETE_COPY_ASSIGN(HttpRequestHandler);
 
-  // Put the session into the queue.
-  void Enqueue(HttpSessionPtr session);
+  // Put the connection into the queue.
+  void Enqueue(HttpConnectionPtr connection);
 
   // Start worker threads.
   void Start(std::size_t count);
 
-  // Close pending sessions and stop worker threads.
+  // Close pending connections and stop worker threads.
   void Stop();
 
- private:
+private:
   void WorkerRoutine();
 
   // Called by the worker routine.
-  virtual void HandleSession(HttpSessionPtr session) = 0;
+  virtual void HandleConnection(HttpConnectionPtr connection) = 0;
+
+private:
+  Queue<HttpConnectionPtr> queue_;
 
-  Queue<HttpSessionPtr> queue_;
   std::vector<std::thread> workers_;
 };
 
diff --git a/webcc/http_response.cc b/webcc/http_response.cc
index 324c047..97294a6 100644
--- a/webcc/http_response.cc
+++ b/webcc/http_response.cc
@@ -57,13 +57,13 @@ const std::string& ToString(int status) {
 
 }  // namespace status_strings
 
-void HttpResponse::Prepare() {
+bool HttpResponse::Prepare() {
   start_line_ = status_strings::ToString(status_);
 
-  // NOTE: C++11 requires a space between literal and string macro.
-  SetHeader("Server", "Webcc/" WEBCC_VERSION);
-
+  SetHeader("Server", USER_AGENT);
   SetHeader("Date", GetHttpDateTimestamp());
+
+  return true;
 }
 
 HttpResponse HttpResponse::Fault(http::Status status) {
diff --git a/webcc/http_response.h b/webcc/http_response.h
index f43f999..bedc717 100644
--- a/webcc/http_response.h
+++ b/webcc/http_response.h
@@ -19,7 +19,7 @@ class HttpResponse : public HttpMessage {
   void set_status(int status) { status_ = status; }
 
   // Set start line according to status code.
-  void Prepare() override;
+  bool Prepare() override;
 
   // Get a fault response when HTTP status is not OK.
   // TODO: Avoid copy.
diff --git a/webcc/http_response_parser.cc b/webcc/http_response_parser.cc
index 1e95ceb..6d6a2c8 100644
--- a/webcc/http_response_parser.cc
+++ b/webcc/http_response_parser.cc
@@ -12,15 +12,15 @@ HttpResponseParser::HttpResponseParser(HttpResponse* response)
 }
 
 bool HttpResponseParser::ParseStartLine(const std::string& line) {
-  std::vector<std::string> splitted;
-  boost::split(splitted, line, boost::is_any_of(" "), boost::token_compress_on);
+  std::vector<std::string> parts;
+  boost::split(parts, line, boost::is_any_of(" "), boost::token_compress_on);
 
-  if (splitted.size() < 3) {
+  if (parts.size() < 3) {
     LOG_ERRO("Invalid HTTP response status line: %s", line.c_str());
     return false;
   }
 
-  std::string& status_str = splitted[1];
+  std::string& status_str = parts[1];
 
   try {
     response_->set_status(std::stoi(status_str));
diff --git a/webcc/http_server.cc b/webcc/http_server.cc
index 16a5ad8..039430c 100644
--- a/webcc/http_server.cc
+++ b/webcc/http_server.cc
@@ -96,8 +96,8 @@ void HttpServer::DoAccept() {
         if (!ec) {
           LOG_INFO("Accepted a connection.");
 
-          std::make_shared<HttpSession>(std::move(socket),
-                                        GetRequestHandler())->Start();
+          std::make_shared<HttpConnection>(std::move(socket),
+                                           GetRequestHandler())->Start();
         }
 
         DoAccept();
diff --git a/webcc/http_server.h b/webcc/http_server.h
index 20e5e9e..2285d72 100644
--- a/webcc/http_server.h
+++ b/webcc/http_server.h
@@ -8,7 +8,7 @@
 #include "boost/asio/signal_set.hpp"
 
 #include "webcc/globals.h"
-#include "webcc/http_session.h"
+#include "webcc/http_connection.h"
 
 namespace webcc {
 
diff --git a/webcc/http_ssl_client.cc b/webcc/http_ssl_client.cc
index 295d49a..f567138 100644
--- a/webcc/http_ssl_client.cc
+++ b/webcc/http_ssl_client.cc
@@ -20,7 +20,7 @@ HttpSslClient::HttpSslClient(bool ssl_verify, std::size_t buffer_size)
 }
 
 Error HttpSslClient::Connect(const HttpRequest& request) {
-  Error error = DoConnect(request, kHttpSslPort);
+  Error error = DoConnect(request, kPort443);
   
   if (error != kNoError) {
     return error;
diff --git a/webcc/rest_client.h b/webcc/rest_client.h
index 172d3e8..f06128c 100644
--- a/webcc/rest_client.h
+++ b/webcc/rest_client.h
@@ -35,22 +35,22 @@ class RestClient {
   // instead for the HTTP status code.
 
   inline bool Get(const std::string& url, std::size_t buffer_size = 0) {
-    return Request(kHttpGet, url, "", buffer_size);
+    return Request("GET", url, "", buffer_size);
   }
 
   inline bool Post(const std::string& url, std::string&& content,
                    std::size_t buffer_size = 0) {
-    return Request(kHttpPost, url, std::move(content), buffer_size);
+    return Request("POST", url, std::move(content), buffer_size);
   }
 
   inline bool Put(const std::string& url, std::string&& content,
                   std::size_t buffer_size = 0) {
-    return Request(kHttpPut, url, std::move(content), buffer_size);
+    return Request("PUT", url, std::move(content), buffer_size);
   }
 
   inline bool Patch(const std::string& url, std::string&& content,
                     std::size_t buffer_size = 0) {
-    return Request(kHttpPatch, url, std::move(content), buffer_size);
+    return Request("PATCH", url, std::move(content), buffer_size);
   }
 
   inline bool Delete(const std::string& url, std::size_t buffer_size = 0) {
diff --git a/webcc/rest_request_handler.cc b/webcc/rest_request_handler.cc
index d556109..354875f 100644
--- a/webcc/rest_request_handler.cc
+++ b/webcc/rest_request_handler.cc
@@ -13,13 +13,14 @@ bool RestRequestHandler::Bind(RestServicePtr service, const std::string& url,
   return service_manager_.AddService(service, url, is_regex);
 }
 
-void RestRequestHandler::HandleSession(HttpSessionPtr session) {
-  const HttpRequest& http_request = session->request();
+void RestRequestHandler::HandleConnection(HttpConnectionPtr connection) {
+  const HttpRequest& http_request = connection->request();
 
-  Url url(http_request.url(), /*decode*/true);
+  // TODO
+  const Url& url = http_request.url();
 
-  if (!url.IsPathValid()) {
-    session->SendResponse(http::Status::kBadRequest);
+  if (url.path().empty()) {
+    connection->SendResponse(http::Status::kBadRequest);
     return;
   }
 
@@ -33,7 +34,7 @@ void RestRequestHandler::HandleSession(HttpSessionPtr session) {
 
   if (!service) {
     LOG_WARN("No service matches the URL path: %s", url.path().c_str());
-    session->SendResponse(http::Status::kNotFound);
+    connection->SendResponse(http::Status::kNotFound);
     return;
   }
 
@@ -42,13 +43,13 @@ void RestRequestHandler::HandleSession(HttpSessionPtr session) {
   service->Handle(rest_request, &rest_response);
 
   if (!rest_response.content.empty()) {
-    session->SetResponseContent(std::move(rest_response.content),
-                                http::media_types::kApplicationJson,
-                                http::charsets::kUtf8);
+    connection->SetResponseContent(std::move(rest_response.content),
+                                   http::media_types::kApplicationJson,
+                                   http::charsets::kUtf8);
   }
 
   // Send response back to client.
-  session->SendResponse(rest_response.status);
+  connection->SendResponse(rest_response.status);
 }
 
 }  // namespace webcc
diff --git a/webcc/rest_request_handler.h b/webcc/rest_request_handler.h
index 8f0a411..a7d421f 100644
--- a/webcc/rest_request_handler.h
+++ b/webcc/rest_request_handler.h
@@ -11,14 +11,15 @@
 namespace webcc {
 
 class RestRequestHandler : public HttpRequestHandler {
- public:
+public:
   RestRequestHandler() = default;
+
   ~RestRequestHandler() override = default;
 
   bool Bind(RestServicePtr service, const std::string& url, bool is_regex);
 
- private:
-  void HandleSession(HttpSessionPtr session) override;
+private:
+  void HandleConnection(HttpConnectionPtr connection) override;
 
   RestServiceManager service_manager_;
 };
diff --git a/webcc/rest_service.cc b/webcc/rest_service.cc
index 3109ed6..a191cec 100644
--- a/webcc/rest_service.cc
+++ b/webcc/rest_service.cc
@@ -8,9 +8,9 @@ namespace webcc {
 
 void RestListService::Handle(const RestRequest& request,
                              RestResponse* response) {
-  if (request.method == kHttpGet) {
+  if (request.method == http::kGet) {
     Get(UrlQuery(request.url_query_str), response);
-  } else if (request.method == kHttpPost) {
+  } else if (request.method == http::kPost) {
     Post(request.content, response);
   } else {
     LOG_ERRO("RestListService doesn't support '%s' method.",
@@ -22,13 +22,13 @@ void RestListService::Handle(const RestRequest& request,
 
 void RestDetailService::Handle(const RestRequest& request,
                                RestResponse* response) {
-  if (request.method == kHttpGet) {
+  if (request.method == http::kGet) {
     Get(request.url_sub_matches, UrlQuery(request.url_query_str), response);
-  } else if (request.method == kHttpPut) {
+  } else if (request.method == http::kPut) {
     Put(request.url_sub_matches, request.content, response);
-  } else if (request.method == kHttpPatch) {
+  } else if (request.method == http::kPatch) {
     Patch(request.url_sub_matches, request.content, response);
-  } else if (request.method == kHttpDelete) {
+  } else if (request.method == http::kDelete) {
     Delete(request.url_sub_matches, response);
   } else {
     LOG_ERRO("RestDetailService doesn't support '%s' method.",
diff --git a/webcc/rest_ssl_client.h b/webcc/rest_ssl_client.h
index 9c61666..f03a3cd 100644
--- a/webcc/rest_ssl_client.h
+++ b/webcc/rest_ssl_client.h
@@ -63,7 +63,7 @@ protected:
   // Default: "utf-8".
   std::string content_charset_;
 
-  // Default headers for all session requests.
+  // Default headers for each request sent from this session.
   std::map<std::string, std::string> headers_;
 
 private:
@@ -96,7 +96,7 @@ public:
 
   inline bool Post(const std::string& url, std::string&& content,
                    const SSMap& headers = {}, std::size_t buffer_size = 0) {
-    return Request(kHttpPost, url, std::move(content), headers, buffer_size);
+    return Request(Post, url, std::move(content), headers, buffer_size);
   }
 
   inline bool Put(const std::string& url, std::string&& content,
diff --git a/webcc/soap_client.cc b/webcc/soap_client.cc
index 4888b02..c0f42f7 100644
--- a/webcc/soap_client.cc
+++ b/webcc/soap_client.cc
@@ -48,7 +48,14 @@ bool SoapClient::Request(const std::string& operation,
   std::string http_content;
   soap_request.ToXml(format_raw_, indent_str_, &http_content);
 
-  HttpRequest http_request(kHttpPost, url_, host_, port_);
+  // TODO
+  std::string url = host_;
+  url += url_;
+  if (!port_.empty()) {
+    url += ":" + port_;
+  }
+
+  HttpRequest http_request(http::kPost, url);
 
   http_request.SetContent(std::move(http_content), true);
 
diff --git a/webcc/soap_parameter.h b/webcc/soap_parameter.h
index 720827b..ccdda20 100644
--- a/webcc/soap_parameter.h
+++ b/webcc/soap_parameter.h
@@ -53,13 +53,11 @@ class SoapParameter {
 
 #else
 
-  // Use "= default" if drop the support of VS 2013.
   SoapParameter(SoapParameter&& rhs)
       : key_(std::move(rhs.key_)), value_(std::move(rhs.value_)),
     as_cdata_(rhs.as_cdata_) {
   }
 
-  // Use "= default" if drop the support of VS 2013.
   SoapParameter& operator=(SoapParameter&& rhs) {
     if (&rhs != this) {
       key_ = std::move(rhs.key_);
diff --git a/webcc/soap_request_handler.cc b/webcc/soap_request_handler.cc
index e4898a0..9dbe579 100644
--- a/webcc/soap_request_handler.cc
+++ b/webcc/soap_request_handler.cc
@@ -15,17 +15,17 @@ bool SoapRequestHandler::Bind(SoapServicePtr service, const std::string& url) {
   return true;
 }
 
-void SoapRequestHandler::HandleSession(HttpSessionPtr session) {
-  SoapServicePtr service = GetServiceByUrl(session->request().url());
+void SoapRequestHandler::HandleConnection(HttpConnectionPtr connection) {
+  SoapServicePtr service = GetServiceByUrl(connection->request().url().path());
   if (!service) {
-    session->SendResponse(http::Status::kBadRequest);
+    connection->SendResponse(http::Status::kBadRequest);
     return;
   }
 
   // Parse the SOAP request XML.
   SoapRequest soap_request;
-  if (!soap_request.FromXml(session->request().content())) {
-    session->SendResponse(http::Status::kBadRequest);
+  if (!soap_request.FromXml(connection->request().content())) {
+    connection->SendResponse(http::Status::kBadRequest);
     return;
   }
 
@@ -40,7 +40,7 @@ void SoapRequestHandler::HandleSession(HttpSessionPtr session) {
   }
 
   if (!service->Handle(soap_request, &soap_response)) {
-    session->SendResponse(http::Status::kBadRequest);
+    connection->SendResponse(http::Status::kBadRequest);
     return;
   }
 
@@ -48,16 +48,16 @@ void SoapRequestHandler::HandleSession(HttpSessionPtr session) {
   soap_response.ToXml(format_raw_, indent_str_, &content);
 
   if (soap_version_ == kSoapV11) {
-    session->SetResponseContent(std::move(content),
+    connection->SetResponseContent(std::move(content),
                                 http::media_types::kTextXml,
                                 http::charsets::kUtf8);
   } else {
-    session->SetResponseContent(std::move(content),
+    connection->SetResponseContent(std::move(content),
                                 http::media_types::kApplicationSoapXml,
                                 http::charsets::kUtf8);
   }
 
-  session->SendResponse(http::Status::kOK);
+  connection->SendResponse(http::Status::kOK);
 }
 
 SoapServicePtr SoapRequestHandler::GetServiceByUrl(const std::string& url) {
diff --git a/webcc/soap_request_handler.h b/webcc/soap_request_handler.h
index 7ef8dc4..6a3c367 100644
--- a/webcc/soap_request_handler.h
+++ b/webcc/soap_request_handler.h
@@ -10,15 +10,16 @@
 namespace webcc {
 
 class SoapRequestHandler : public HttpRequestHandler {
- public:
+public:
   explicit SoapRequestHandler(SoapVersion soap_version)
-      : soap_version_(soap_version),
-        format_raw_(true) {
+      : soap_version_(soap_version), format_raw_(true) {
   }
 
   ~SoapRequestHandler() override = default;
 
-  void set_format_raw(bool format_raw) { format_raw_ = format_raw; }
+  void set_format_raw(bool format_raw) {
+    format_raw_ = format_raw;
+  }
 
   void set_indent_str(const std::string& indent_str) {
     indent_str_ = indent_str;
@@ -26,8 +27,8 @@ class SoapRequestHandler : public HttpRequestHandler {
 
   bool Bind(SoapServicePtr service, const std::string& url);
 
- private:
-  void HandleSession(HttpSessionPtr session) override;
+private:
+  void HandleConnection(HttpConnectionPtr connection) override;
 
   SoapServicePtr GetServiceByUrl(const std::string& url);
 
diff --git a/webcc/url.cc b/webcc/url.cc
index 63e85bc..76782ae 100644
--- a/webcc/url.cc
+++ b/webcc/url.cc
@@ -4,6 +4,8 @@
 #include <functional>
 #include <sstream>
 
+#include "boost/algorithm/string.hpp"
+
 namespace webcc {
 
 // -----------------------------------------------------------------------------
@@ -244,48 +246,86 @@ UrlQuery::ConstIterator UrlQuery::Find(const std::string& key) const {
 // -----------------------------------------------------------------------------
 
 Url::Url(const std::string& str, bool decode) {
+  Init(str, decode);
+}
+
+void Url::Init(const std::string& str, bool decode, bool clear) {
+  if (clear) {
+    Clear();
+  }
+
   if (!decode || str.find('%') == std::string::npos) {
-    Init(str);
+    Parse(str);
     return;
   }
 
   std::string decoded;
   if (Decode(str, &decoded)) {
-    Init(decoded);
+    Parse(decoded);
   } else {
-    // TODO(Adam): Exception?
-    Init(str);
+    // TODO: Exception?
+    Parse(str);
   }
 }
 
-bool Url::IsPathValid() const {
-  // URL path must be absolute.
-  if (path_.empty() || path_[0] != '/') {
-    return false;
+void Url::AddParameter(const std::string& key, const std::string& value) {
+  if (!query_.empty()) {
+    query_ += "&";
   }
-  return true;
+  query_ += key + "=" + value;
 }
 
-std::vector<std::string> Url::SplitPath(const std::string& path) {
-  std::vector<std::string> results;
-  std::stringstream iss(path);
-  std::string s;
-  while (std::getline(iss, s, '/')) {
-    if (!s.empty()) {
-      results.push_back(s);
-    }
+void Url::Parse(const std::string& str) {
+  std::string tmp = boost::trim_left_copy(str);
+
+  std::size_t pos = std::string::npos;
+
+  pos = tmp.find("://");
+  if (pos != std::string::npos) {
+    scheme_ = tmp.substr(0, pos);
+    tmp = tmp.substr(pos + 3);
   }
-  return results;
-}
 
-void Url::Init(const std::string& str) {
-  std::size_t pos = str.find('?');
-  if (pos == std::string::npos) {
-    path_ = str;
+  pos = tmp.find('/');
+  if (pos != std::string::npos) {
+    host_ = tmp.substr(0, pos);
+
+    tmp = tmp.substr(pos + 1);
+
+    pos = tmp.find('?');
+    if (pos != std::string::npos) {
+      path_ = tmp.substr(0, pos);
+      query_ = tmp.substr(pos + 1);
+    } else {
+      path_ = tmp;
+    }
   } else {
-    path_ = str.substr(0, pos);
-    query_ = str.substr(pos + 1);
+    path_ = "";
+
+    pos = tmp.find('?');
+    if (pos != std::string::npos) {
+      host_ = tmp.substr(0, pos);
+      query_ = tmp.substr(pos + 1);
+    } else {
+      host_ = tmp;
+    }
   }
+
+  if (!host_.empty()) {
+    pos = host_.find(':');
+    if (pos != std::string::npos) {
+      port_ = host_.substr(pos + 1);
+      host_ = host_.substr(0, pos);
+    }
+  }
+}
+
+void Url::Clear() {
+  scheme_.clear();
+  host_.clear();
+  port_.clear();
+  path_.clear();
+  query_.clear();
 }
 
 }  // namespace webcc
diff --git a/webcc/url.h b/webcc/url.h
index a0dc5f5..7b3ba71 100644
--- a/webcc/url.h
+++ b/webcc/url.h
@@ -2,10 +2,6 @@
 #define WEBCC_URL_H_
 
 // A simplified implementation of URL (or URI).
-// The URL should start with "/".
-// The parameters (separated by ";") are not supported.
-// Example:
-//   /inventory-check.cgi?item=12731&color=blue&size=large
 
 #include <string>
 #include <utility>
@@ -17,7 +13,7 @@ namespace webcc {
 
 // URL query parameters.
 class UrlQuery {
- public:
+public:
   typedef std::pair<std::string, std::string> Parameter;
   typedef std::vector<Parameter> Parameters;
 
@@ -48,7 +44,7 @@ class UrlQuery {
   // E.g., "item=12731&color=blue&size=large".
   std::string ToString() const;
 
- private:
+private:
   typedef Parameters::const_iterator ConstIterator;
   ConstIterator Find(const std::string& key) const;
 
@@ -58,34 +54,46 @@ class UrlQuery {
 // -----------------------------------------------------------------------------
 
 class Url {
- public:
+public:
   Url() = default;
-  Url(const std::string& str, bool decode);
 
-  bool IsPathValid() const;
+  // TODO: decode/encode/encoded?
+  explicit Url(const std::string& str, bool decode = true);
 
-  const std::string& path() const {
-    return path_;
+  void Init(const std::string& str, bool decode = true, bool clear = true);
+
+  const std::string& scheme() const {
+    return scheme_;
+  }
+
+  const std::string& host() const {
+    return host_;
   }
 
-  void set_path(const std::string& path) {
-    path_ = path;
+  const std::string& port() const {
+    return port_;
+  }
+
+  const std::string& path() const {
+    return path_;
   }
 
   const std::string& query() const {
     return query_;
   }
 
-  void set_query(const std::string& query) {
-    query_ = query;
-  }
+  // Add a parameter to the query string.
+  void AddParameter(const std::string& key, const std::string& value);
 
-  // Split a path into its hierarchical components.
-  static std::vector<std::string> SplitPath(const std::string& path);
+private:
+  void Parse(const std::string& str);
 
- private:
-  void Init(const std::string& str);
+  void Clear();
 
+  // TODO: Support auth & fragment.
+  std::string scheme_;
+  std::string host_;
+  std::string port_;
   std::string path_;
   std::string query_;
 };