diff --git a/ChangeLog b/ChangeLog
index 8993df88..12bdce80 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,33 @@
+2010-06-09  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
+
+	Made protected member variable private. Added accessor funcs.
+	* src/AbstractCommand.cc
+	* src/AbstractCommand.h
+	* src/AbstractProxyRequestCommand.cc
+	* src/AbstractProxyRequestCommand.h
+	* src/AbstractProxyResponseCommand.cc
+	* src/AbstractProxyResponseCommand.h
+	* src/CreateRequestCommand.cc
+	* src/DownloadCommand.cc
+	* src/DownloadCommand.h
+	* src/FtpDownloadCommand.cc
+	* src/FtpDownloadCommand.h
+	* src/FtpFinishDownloadCommand.cc
+	* src/FtpInitiateConnectionCommand.cc
+	* src/FtpNegotiationCommand.cc
+	* src/FtpNegotiationCommand.h
+	* src/FtpTunnelRequestCommand.cc
+	* src/FtpTunnelResponseCommand.cc
+	* src/HttpDownloadCommand.cc
+	* src/HttpInitiateConnectionCommand.cc
+	* src/HttpProxyRequestCommand.cc
+	* src/HttpProxyResponseCommand.cc
+	* src/HttpRequestCommand.cc
+	* src/HttpResponseCommand.cc
+	* src/HttpResponseCommand.h
+	* src/HttpSkipResponseCommand.cc
+	* src/InitiateConnectionCommand.cc
+
 2010-06-09  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
 
 	Made protected member variables of Command private. Added accessor
diff --git a/src/AbstractCommand.cc b/src/AbstractCommand.cc
index 1973020d..038780ef 100644
--- a/src/AbstractCommand.cc
+++ b/src/AbstractCommand.cc
@@ -77,15 +77,16 @@ AbstractCommand::AbstractCommand(cuid_t cuid,
                                  RequestGroup* requestGroup,
                                  DownloadEngine* e,
                                  const SocketHandle& s):
-  Command(cuid), checkPoint(global::wallclock), _requestGroup(requestGroup),
-  req(req), _fileEntry(fileEntry), e(e), socket(s),
-  checkSocketIsReadable(false), checkSocketIsWritable(false),
-  nameResolverCheck(false)
+  Command(cuid), _checkPoint(global::wallclock),
+  _timeout(requestGroup->getTimeout()),
+  _requestGroup(requestGroup),
+  _req(req), _fileEntry(fileEntry), _e(e), _socket(s),
+  _checkSocketIsReadable(false), _checkSocketIsWritable(false),
+  _nameResolverCheck(false)
 {
-  if(!socket.isNull() && socket->isOpen()) {
-    setReadCheckSocket(socket);
+  if(!_socket.isNull() && _socket->isOpen()) {
+    setReadCheckSocket(_socket);
   }
-  timeout = _requestGroup->getTimeout();
   _requestGroup->increaseStreamConnection();
   _requestGroup->increaseNumCommand();
 }
@@ -113,19 +114,19 @@ bool AbstractCommand::execute() {
     if(_requestGroup->downloadFinished() || _requestGroup->isHaltRequested()) {
       return true;
     }
-    if(!req.isNull() && req->removalRequested()) {
+    if(!_req.isNull() && _req->removalRequested()) {
       if(getLogger()->debug()) {
         getLogger()->debug
           ("CUID#%s - Discard original URI=%s because it is requested.",
-           util::itos(getCuid()).c_str(), req->getUri().c_str());
+           util::itos(getCuid()).c_str(), _req->getUri().c_str());
       }
       return prepareForRetry(0);
     }
     // TODO it is not needed to check other PeerStats every time.
     // Find faster Request when no segment is available.
-    if(!req.isNull() && _fileEntry->countPooledRequest() > 0 &&
-       !_requestGroup->getPieceStorage()->hasMissingUnusedPiece()) {
-      SharedHandle<Request> fasterRequest = _fileEntry->findFasterRequest(req);
+    if(!_req.isNull() && _fileEntry->countPooledRequest() > 0 &&
+       !getPieceStorage()->hasMissingUnusedPiece()) {
+      SharedHandle<Request> fasterRequest = _fileEntry->findFasterRequest(_req);
       if(!fasterRequest.isNull()) {
         if(getLogger()->info()) {
           getLogger()->info("CUID#%s - Use faster Request hostname=%s, port=%u",
@@ -134,29 +135,28 @@ bool AbstractCommand::execute() {
                             fasterRequest->getPort());
         }
         // Cancel current Request object and use faster one.
-        _fileEntry->removeRequest(req);
+        _fileEntry->removeRequest(_req);
         Command* command =
           InitiateConnectionCommandFactory::createInitiateConnectionCommand
-          (getCuid(), fasterRequest, _fileEntry, _requestGroup, e);
-        e->setNoWait(true);
-        e->addCommand(command);
+          (getCuid(), fasterRequest, _fileEntry, _requestGroup, _e);
+        _e->setNoWait(true);
+        _e->addCommand(command);
         return true;
       }
     }
-    if((checkSocketIsReadable && readEventEnabled()) ||
-       (checkSocketIsWritable && writeEventEnabled()) ||
+    if((_checkSocketIsReadable && readEventEnabled()) ||
+       (_checkSocketIsWritable && writeEventEnabled()) ||
        hupEventEnabled() ||
 #ifdef ENABLE_ASYNC_DNS
-       (nameResolverCheck && nameResolveFinished()) ||
+       (_nameResolverCheck && nameResolveFinished()) ||
 #endif // ENABLE_ASYNC_DNS
-       (!checkSocketIsReadable && !checkSocketIsWritable &&
-        !nameResolverCheck)) {
-      checkPoint = global::wallclock;
-      if(!_requestGroup->getPieceStorage().isNull()) {
+       (!_checkSocketIsReadable && !_checkSocketIsWritable &&
+        !_nameResolverCheck)) {
+      _checkPoint = global::wallclock;
+      if(!getPieceStorage().isNull()) {
         _segments.clear();
-        _requestGroup->getSegmentMan()->getInFlightSegment
-          (_segments, getCuid());
-        if(!req.isNull() && _segments.empty()) {
+        getSegmentMan()->getInFlightSegment(_segments, getCuid());
+        if(!_req.isNull() && _segments.empty()) {
           // This command previously has assigned segments, but it is
           // canceled. So discard current request chain.
           if(getLogger()->debug()) {
@@ -166,11 +166,11 @@ bool AbstractCommand::execute() {
           }
           return prepareForRetry(0);
         }
-        if(req.isNull() || req->getMaxPipelinedRequest() == 1 ||
+        if(_req.isNull() || _req->getMaxPipelinedRequest() == 1 ||
            _requestGroup->getDownloadContext()->getFileEntries().size() == 1) {
           if(_segments.empty()) {
             SharedHandle<Segment> segment =
-              _requestGroup->getSegmentMan()->getSegment(getCuid());
+              getSegmentMan()->getSegment(getCuid());
             if(!segment.isNull()) {
               _segments.push_back(segment);
             }
@@ -183,7 +183,7 @@ bool AbstractCommand::execute() {
             }
             // When all segments are ignored in SegmentMan, there are
             // no URIs available, so don't retry.
-            if(_requestGroup->getSegmentMan()->allSegmentsIgnored()) {
+            if(getSegmentMan()->allSegmentsIgnored()) {
               if(getLogger()->debug()) {
                 getLogger()->debug("All segments are ignored.");
               }
@@ -193,9 +193,9 @@ bool AbstractCommand::execute() {
             }
           }
         } else {
-          size_t maxSegments = req->getMaxPipelinedRequest();
+          size_t maxSegments = _req->getMaxPipelinedRequest();
           if(_segments.size() < maxSegments) {
-            _requestGroup->getSegmentMan()->getSegment
+            getSegmentMan()->getSegment
               (_segments, getCuid(), _fileEntry, maxSegments);
           }
           if(_segments.empty()) {
@@ -207,23 +207,23 @@ bool AbstractCommand::execute() {
     } else if(errorEventEnabled()) {
       throw DL_RETRY_EX
         (StringFormat(MSG_NETWORK_PROBLEM,
-                      socket->getSocketError().c_str()).str());
+                      _socket->getSocketError().c_str()).str());
     } else {
-      if(checkPoint.difference(global::wallclock) >= timeout) {
+      if(_checkPoint.difference(global::wallclock) >= _timeout) {
         // timeout triggers ServerStat error state.
 
         SharedHandle<ServerStat> ss =
-          e->getRequestGroupMan()->getOrCreateServerStat(req->getHost(),
-                                                         req->getProtocol());
+          _e->getRequestGroupMan()->getOrCreateServerStat(_req->getHost(),
+                                                          _req->getProtocol());
         ss->setError();
 
         throw DL_RETRY_EX2(EX_TIME_OUT, downloadresultcode::TIME_OUT);
       }
-      e->addCommand(this);
+      _e->addCommand(this);
       return false;
     }
   } catch(DlAbortEx& err) {
-    if(req.isNull()) {
+    if(_req.isNull()) {
       if(getLogger()->debug()) {
         getLogger()->debug(EX_EXCEPTION_CAUGHT, err);
       }
@@ -231,10 +231,10 @@ bool AbstractCommand::execute() {
       getLogger()->error
         (MSG_DOWNLOAD_ABORTED,
          DL_ABORT_EX2(StringFormat
-                      ("URI=%s", req->getCurrentUri().c_str()).str(),err),
-         util::itos(getCuid()).c_str(), req->getUri().c_str());
-      _fileEntry->addURIResult(req->getUri(), err.getCode());
-      _requestGroup->setLastUriResult(req->getUri(), err.getCode());
+                      ("URI=%s", _req->getCurrentUri().c_str()).str(),err),
+         util::itos(getCuid()).c_str(), _req->getUri().c_str());
+      _fileEntry->addURIResult(_req->getUri(), err.getCode());
+      _requestGroup->setLastUriResult(_req->getUri(), err.getCode());
       if(err.getCode() == downloadresultcode::CANNOT_RESUME) {
         _requestGroup->increaseResumeFailureCount();
       }
@@ -243,29 +243,29 @@ bool AbstractCommand::execute() {
     tryReserved();
     return true;
   } catch(DlRetryEx& err) {
-    assert(!req.isNull());
+    assert(!_req.isNull());
     if(getLogger()->info()) {
       getLogger()->info
         (MSG_RESTARTING_DOWNLOAD,
          DL_RETRY_EX2(StringFormat
-                      ("URI=%s", req->getCurrentUri().c_str()).str(),
+                      ("URI=%s", _req->getCurrentUri().c_str()).str(),
                       err),
-         util::itos(getCuid()).c_str(), req->getUri().c_str());
+         util::itos(getCuid()).c_str(), _req->getUri().c_str());
     }
-    req->addTryCount();
-    req->resetRedirectCount();
+    _req->addTryCount();
+    _req->resetRedirectCount();
     const unsigned int maxTries = getOption()->getAsInt(PREF_MAX_TRIES);
-    bool isAbort = maxTries != 0 && req->getTryCount() >= maxTries;
+    bool isAbort = maxTries != 0 && _req->getTryCount() >= maxTries;
     if(isAbort) {
       if(getLogger()->info()) {
         getLogger()->info(MSG_MAX_TRY,
-                          util::itos(getCuid()).c_str(), req->getTryCount());
+                          util::itos(getCuid()).c_str(), _req->getTryCount());
       }
       getLogger()->error(MSG_DOWNLOAD_ABORTED, err,
                          util::itos(getCuid()).c_str(),
-                         req->getUri().c_str());
-      _fileEntry->addURIResult(req->getUri(), err.getCode());
-      _requestGroup->setLastUriResult(req->getUri(), err.getCode());
+                         _req->getUri().c_str());
+      _fileEntry->addURIResult(_req->getUri(), err.getCode());
+      _requestGroup->setLastUriResult(_req->getUri(), err.getCode());
       if(err.getCode() == downloadresultcode::CANNOT_RESUME) {
         _requestGroup->increaseResumeFailureCount();
       }
@@ -277,9 +277,9 @@ bool AbstractCommand::execute() {
     }
   } catch(DownloadFailureException& err) {
     getLogger()->error(EX_EXCEPTION_CAUGHT, err);
-    if(!req.isNull()) {
-      _fileEntry->addURIResult(req->getUri(), err.getCode());
-      _requestGroup->setLastUriResult(req->getUri(), err.getCode());
+    if(!_req.isNull()) {
+      _fileEntry->addURIResult(_req->getUri(), err.getCode());
+      _requestGroup->setLastUriResult(_req->getUri(), err.getCode());
     }
     _requestGroup->setHaltRequested(true);
     return true;
@@ -308,59 +308,58 @@ void AbstractCommand::tryReserved() {
                        util::itos(getCuid()).c_str());
   }
   std::vector<Command*> commands;
-  _requestGroup->createNextCommand(commands, e, 1);
-  e->setNoWait(true);
-  e->addCommand(commands);
+  _requestGroup->createNextCommand(commands, _e, 1);
+  _e->setNoWait(true);
+  _e->addCommand(commands);
 }
 
 bool AbstractCommand::prepareForRetry(time_t wait) {
-  if(!_requestGroup->getPieceStorage().isNull()) {
-    _requestGroup->getSegmentMan()->cancelSegment(getCuid());
+  if(!getPieceStorage().isNull()) {
+    getSegmentMan()->cancelSegment(getCuid());
   }
-  if(!req.isNull()) {
-    _fileEntry->poolRequest(req);
+  if(!_req.isNull()) {
+    _fileEntry->poolRequest(_req);
     if(getLogger()->debug()) {
       getLogger()->debug("CUID#%s - Pooling request URI=%s",
-                         util::itos(getCuid()).c_str(), req->getUri().c_str());
+                         util::itos(getCuid()).c_str(), _req->getUri().c_str());
     }
-    if(!_requestGroup->getSegmentMan().isNull()) {
-      _requestGroup->getSegmentMan()->recognizeSegmentFor(_fileEntry);
+    if(!getSegmentMan().isNull()) {
+      getSegmentMan()->recognizeSegmentFor(_fileEntry);
     }
   }
 
-  Command* command = new CreateRequestCommand(getCuid(), _requestGroup, e);
+  Command* command = new CreateRequestCommand(getCuid(), _requestGroup, _e);
   if(wait == 0) {
-    e->setNoWait(true);
-    e->addCommand(command);
+    _e->setNoWait(true);
+    _e->addCommand(command);
   } else {
-    SleepCommand* scom = new SleepCommand(getCuid(), e, _requestGroup,
+    SleepCommand* scom = new SleepCommand(getCuid(), _e, _requestGroup,
                                           command, wait);
-    e->addCommand(scom);
+    _e->addCommand(scom);
   }
   return true;
 }
 
 void AbstractCommand::onAbort() {
-  if(!req.isNull()) {
+  if(!_req.isNull()) {
     // TODO This might be a problem if the failure is caused by proxy.
-    e->getRequestGroupMan()->getOrCreateServerStat
-      (req->getHost(), req->getProtocol())->setError();
-    _fileEntry->removeIdenticalURI(req->getUri());
-    _fileEntry->removeRequest(req);
+    _e->getRequestGroupMan()->getOrCreateServerStat
+      (_req->getHost(), _req->getProtocol())->setError();
+    _fileEntry->removeIdenticalURI(_req->getUri());
+    _fileEntry->removeRequest(_req);
   }
   if(getLogger()->debug()) {
     getLogger()->debug("CUID#%s - Aborting download",
                        util::itos(getCuid()).c_str());
   }
-  if(!_requestGroup->getPieceStorage().isNull()) {
-    SharedHandle<SegmentMan> segmentMan = _requestGroup->getSegmentMan();
-    segmentMan->cancelSegment(getCuid());
+  if(!getPieceStorage().isNull()) {
+    getSegmentMan()->cancelSegment(getCuid());
     // Don't do following process if BitTorrent is involved or files
     // in DownloadContext is more than 1. The latter condition is
     // limitation of current implementation.
     if(!getOption()->getAsBool(PREF_ALWAYS_RESUME) &&
        !_fileEntry.isNull() &&
-       segmentMan->calculateSessionDownloadLength() == 0 &&
+       getSegmentMan()->calculateSessionDownloadLength() == 0 &&
        !_requestGroup->p2pInvolved() &&
        _requestGroup->getDownloadContext()->getFileEntries().size() == 1) {
       const int maxTries = getOption()->getAsInt(PREF_MAX_RESUME_FAILURE_TRIES);
@@ -383,9 +382,9 @@ void AbstractCommand::onAbort() {
         std::deque<URIResult> res;
         _fileEntry->extractURIResult(res, downloadresultcode::CANNOT_RESUME);
         if(!res.empty()) {
-          segmentMan->cancelAllSegments();
-          segmentMan->eraseSegmentWrittenLengthMemo();
-          _requestGroup->getPieceStorage()->markPiecesDone(0);
+          getSegmentMan()->cancelAllSegments();
+          getSegmentMan()->eraseSegmentWrittenLengthMemo();
+          getPieceStorage()->markPiecesDone(0);
           std::vector<std::string> uris;
           uris.reserve(res.size());
           std::transform(res.begin(), res.end(), std::back_inserter(uris),
@@ -396,7 +395,7 @@ void AbstractCommand::onAbort() {
                                static_cast<unsigned long int>(uris.size()));
           }
           _fileEntry->addUris(uris.begin(), uris.end());
-          segmentMan->recognizeSegmentFor(_fileEntry);
+          getSegmentMan()->recognizeSegmentFor(_fileEntry);
         }
       }
     }
@@ -404,10 +403,10 @@ void AbstractCommand::onAbort() {
 }
 
 void AbstractCommand::disableReadCheckSocket() {
-  if(checkSocketIsReadable) {
-    e->deleteSocketForReadCheck(readCheckTarget, this);
-    checkSocketIsReadable = false;
-    readCheckTarget = SocketHandle();
+  if(_checkSocketIsReadable) {
+    _e->deleteSocketForReadCheck(_readCheckTarget, this);
+    _checkSocketIsReadable = false;
+    _readCheckTarget.reset();
   }  
 }
 
@@ -415,16 +414,16 @@ void AbstractCommand::setReadCheckSocket(const SocketHandle& socket) {
   if(!socket->isOpen()) {
     disableReadCheckSocket();
   } else {
-    if(checkSocketIsReadable) {
-      if(readCheckTarget != socket) {
-        e->deleteSocketForReadCheck(readCheckTarget, this);
-        e->addSocketForReadCheck(socket, this);
-        readCheckTarget = socket;
+    if(_checkSocketIsReadable) {
+      if(_readCheckTarget != socket) {
+        _e->deleteSocketForReadCheck(_readCheckTarget, this);
+        _e->addSocketForReadCheck(socket, this);
+        _readCheckTarget = socket;
       }
     } else {
-      e->addSocketForReadCheck(socket, this);
-      checkSocketIsReadable = true;
-      readCheckTarget = socket;
+      _e->addSocketForReadCheck(socket, this);
+      _checkSocketIsReadable = true;
+      _readCheckTarget = socket;
     }
   }
 }
@@ -440,10 +439,10 @@ void AbstractCommand::setReadCheckSocketIf
 }
 
 void AbstractCommand::disableWriteCheckSocket() {
-  if(checkSocketIsWritable) {
-    e->deleteSocketForWriteCheck(writeCheckTarget, this);
-    checkSocketIsWritable = false;
-    writeCheckTarget = SocketHandle();
+  if(_checkSocketIsWritable) {
+    _e->deleteSocketForWriteCheck(_writeCheckTarget, this);
+    _checkSocketIsWritable = false;
+    _writeCheckTarget.reset();
   }
 }
 
@@ -451,16 +450,16 @@ void AbstractCommand::setWriteCheckSocket(const SocketHandle& socket) {
   if(!socket->isOpen()) {
     disableWriteCheckSocket();
   } else {
-    if(checkSocketIsWritable) {
-      if(writeCheckTarget != socket) {
-        e->deleteSocketForWriteCheck(writeCheckTarget, this);
-        e->addSocketForWriteCheck(socket, this);
-        writeCheckTarget = socket;
+    if(_checkSocketIsWritable) {
+      if(_writeCheckTarget != socket) {
+        _e->deleteSocketForWriteCheck(_writeCheckTarget, this);
+        _e->addSocketForWriteCheck(socket, this);
+        _writeCheckTarget = socket;
       }
     } else {
-      e->addSocketForWriteCheck(socket, this);
-      checkSocketIsWritable = true;
-      writeCheckTarget = socket;
+      _e->addSocketForWriteCheck(socket, this);
+      _checkSocketIsWritable = true;
+      _writeCheckTarget = socket;
     }
   }
 }
@@ -570,17 +569,17 @@ static bool inNoProxy(const SharedHandle<Request>& req,
 
 bool AbstractCommand::isProxyDefined() const
 {
-  return isProxyRequest(req->getProtocol(), getOption()) &&
-    !inNoProxy(req, getOption()->get(PREF_NO_PROXY));
+  return isProxyRequest(_req->getProtocol(), getOption()) &&
+    !inNoProxy(_req, getOption()->get(PREF_NO_PROXY));
 }
 
 SharedHandle<Request> AbstractCommand::createProxyRequest() const
 {
   SharedHandle<Request> proxyRequest;
-  if(inNoProxy(req, getOption()->get(PREF_NO_PROXY))) {
+  if(inNoProxy(_req, getOption()->get(PREF_NO_PROXY))) {
     return proxyRequest;
   }
-  std::string proxy = getProxyUri(req->getProtocol(), getOption());
+  std::string proxy = getProxyUri(_req->getProtocol(), getOption());
   if(!proxy.empty()) {
     proxyRequest.reset(new Request());
     if(proxyRequest->setUri(proxy)) {
@@ -625,9 +624,9 @@ bool AbstractCommand::asyncResolveHostname()
     return true;
   case AsyncNameResolver::STATUS_ERROR:
     disableNameResolverCheck(_asyncNameResolver);
-    if(!isProxyRequest(req->getProtocol(), getOption())) {
-      e->getRequestGroupMan()->getOrCreateServerStat
-        (req->getHost(), req->getProtocol())->setError();
+    if(!isProxyRequest(_req->getProtocol(), getOption())) {
+      _e->getRequestGroupMan()->getOrCreateServerStat
+        (_req->getHost(), _req->getProtocol())->setError();
     }
     throw DL_ABORT_EX
       (StringFormat(MSG_NAME_RESOLUTION_FAILED,
@@ -647,16 +646,16 @@ const std::vector<std::string>& AbstractCommand::getResolvedAddresses()
 void AbstractCommand::setNameResolverCheck
 (const SharedHandle<AsyncNameResolver>& resolver) {
   if(!resolver.isNull()) {
-    nameResolverCheck = true;
-    e->addNameResolverCheck(resolver, this);
+    _nameResolverCheck = true;
+    _e->addNameResolverCheck(resolver, this);
   }
 }
 
 void AbstractCommand::disableNameResolverCheck
 (const SharedHandle<AsyncNameResolver>& resolver) {
   if(!resolver.isNull()) {
-    nameResolverCheck = false;
-    e->deleteNameResolverCheck(resolver, this);
+    _nameResolverCheck = false;
+    _e->deleteNameResolverCheck(resolver, this);
   }
 }
 
@@ -670,7 +669,7 @@ bool AbstractCommand::nameResolveFinished() const {
 std::string AbstractCommand::resolveHostname
 (std::vector<std::string>& addrs, const std::string& hostname, uint16_t port)
 {
-  e->findAllCachedIPAddresses(std::back_inserter(addrs), hostname, port);
+  _e->findAllCachedIPAddresses(std::back_inserter(addrs), hostname, port);
   std::string ipaddr;
   if(addrs.empty()) {
 #ifdef ENABLE_ASYNC_DNS
@@ -688,7 +687,7 @@ std::string AbstractCommand::resolveHostname
       {
         NameResolver res;
         res.setSocktype(SOCK_STREAM);
-        if(e->getOption()->getAsBool(PREF_DISABLE_IPV6)) {
+        if(_e->getOption()->getAsBool(PREF_DISABLE_IPV6)) {
           res.setFamily(AF_INET);
         }
         res.resolve(addrs, hostname);
@@ -701,9 +700,9 @@ std::string AbstractCommand::resolveHostname
     }
     for(std::vector<std::string>::const_iterator i = addrs.begin(),
           eoi = addrs.end(); i != eoi; ++i) {
-      e->cacheIPAddress(hostname, *i, port);
+      _e->cacheIPAddress(hostname, *i, port);
     }
-    ipaddr = e->findCachedIPAddress(hostname, port);
+    ipaddr = _e->findCachedIPAddress(hostname, port);
   } else {
     ipaddr = addrs.front();
     if(getLogger()->info()) {
@@ -725,13 +724,13 @@ void AbstractCommand::prepareForNextAction(Command* nextCommand)
 
   std::vector<Command*> commands;
   try {
-    _requestGroup->processCheckIntegrityEntry(commands, entry, e);
+    _requestGroup->processCheckIntegrityEntry(commands, entry, _e);
   } catch(RecoverableException& e) {
     std::for_each(commands.begin(), commands.end(), Deleter());
     throw;
   }
-  e->addCommand(commands);
-  e->setNoWait(true);
+  _e->addCommand(commands);
+  _e->setNoWait(true);
 }
 
 bool AbstractCommand::checkIfConnectionEstablished
@@ -744,8 +743,8 @@ bool AbstractCommand::checkIfConnectionEstablished
     std::string error = socket->getSocketError();
     if(!error.empty()) {
       // See also InitiateConnectionCommand::executeInternal()
-      e->markBadIPAddress(connectedHostname, connectedAddr, connectedPort);
-      if(!e->findCachedIPAddress(connectedHostname, connectedPort).empty()) {
+      _e->markBadIPAddress(connectedHostname, connectedAddr, connectedPort);
+      if(!_e->findCachedIPAddress(connectedHostname, connectedPort).empty()) {
         if(getLogger()->info()) {
           getLogger()->info(MSG_CONNECT_FAILED_AND_RETRY,
                             util::itos(getCuid()).c_str(),
@@ -753,17 +752,17 @@ bool AbstractCommand::checkIfConnectionEstablished
         }
         Command* command =
           InitiateConnectionCommandFactory::createInitiateConnectionCommand
-          (getCuid(), req, _fileEntry, _requestGroup, e);
-        e->setNoWait(true);
-        e->addCommand(command);
+          (getCuid(), _req, _fileEntry, _requestGroup, _e);
+        _e->setNoWait(true);
+        _e->addCommand(command);
         return false;
       }
-      e->removeCachedIPAddress(connectedHostname, connectedPort);
+      _e->removeCachedIPAddress(connectedHostname, connectedPort);
       // Don't set error if proxy server is used and its method is GET.
-      if(resolveProxyMethod(req->getProtocol()) != V_GET ||
-         !isProxyRequest(req->getProtocol(), getOption())) {
-        e->getRequestGroupMan()->getOrCreateServerStat
-          (req->getHost(), req->getProtocol())->setError();
+      if(resolveProxyMethod(_req->getProtocol()) != V_GET ||
+         !isProxyRequest(_req->getProtocol(), getOption())) {
+        _e->getRequestGroupMan()->getOrCreateServerStat
+          (_req->getHost(), _req->getProtocol())->setError();
       }
       throw DL_RETRY_EX
         (StringFormat(MSG_ESTABLISHING_CONNECTION_FAILED, error.c_str()).str());
@@ -788,4 +787,9 @@ const SharedHandle<Option>& AbstractCommand::getOption() const
   return _requestGroup->getOption();
 }
 
+void AbstractCommand::createSocket()
+{
+  _socket.reset(new SocketCore());
+}
+
 } // namespace aria2
diff --git a/src/AbstractCommand.h b/src/AbstractCommand.h
index fc793cee..577eeedc 100644
--- a/src/AbstractCommand.h
+++ b/src/AbstractCommand.h
@@ -55,19 +55,83 @@ class AsyncNameResolver;
 
 class AbstractCommand : public Command {
 private:
-  Timer checkPoint;
-  time_t timeout;
-protected:
+  Timer _checkPoint;
+  time_t _timeout;
+
   RequestGroup* _requestGroup;
-  SharedHandle<Request> req;
+  SharedHandle<Request> _req;
   SharedHandle<FileEntry> _fileEntry;
-  DownloadEngine* e;
-  SharedHandle<SocketCore> socket;
+  DownloadEngine* _e;
+  SharedHandle<SocketCore> _socket;
   std::vector<SharedHandle<Segment> > _segments;
 
 #ifdef ENABLE_ASYNC_DNS
   SharedHandle<AsyncNameResolver> _asyncNameResolver;
+#endif // ENABLE_ASYNC_DNS
 
+  bool _checkSocketIsReadable;
+  bool _checkSocketIsWritable;
+  SharedHandle<SocketCore> _readCheckTarget;
+  SharedHandle<SocketCore> _writeCheckTarget;
+  bool _nameResolverCheck;
+
+#ifdef ENABLE_ASYNC_DNS
+  void setNameResolverCheck(const SharedHandle<AsyncNameResolver>& resolver);
+
+  void disableNameResolverCheck
+  (const SharedHandle<AsyncNameResolver>& resolver);
+
+  bool nameResolveFinished() const;
+#endif // ENABLE_ASYNC_DNS
+protected:
+  RequestGroup* getRequestGroup() const
+  {
+    return _requestGroup;
+  }
+
+  const SharedHandle<Request>& getRequest() const
+  {
+    return _req;
+  }
+
+  void setRequest(const SharedHandle<Request>& request)
+  {
+    _req = request;
+  }
+
+  const SharedHandle<FileEntry>& getFileEntry() const
+  {
+    return _fileEntry;
+  }
+
+  void setFileEntry(const SharedHandle<FileEntry>& fileEntry)
+  {
+    _fileEntry = fileEntry;
+  }
+
+  DownloadEngine* getDownloadEngine() const
+  {
+    return _e;
+  }
+
+  const SharedHandle<SocketCore>& getSocket() const
+  {
+    return _socket;
+  }
+
+  void setSocket(const SharedHandle<SocketCore>& s)
+  {
+    _socket = s;
+  }
+
+  void createSocket();
+
+  const std::vector<SharedHandle<Segment> >& getSegments() const
+  {
+    return _segments;
+  }
+
+#ifdef ENABLE_ASYNC_DNS
   bool isAsyncNameResolverInitialized() const;
 
   void initAsyncNameResolver(const std::string& hostname);
@@ -106,7 +170,7 @@ protected:
    */
   void setWriteCheckSocketIf(const SharedHandle<SocketCore>& socket, bool pred);
 
-  void setTimeout(time_t timeout) { this->timeout = timeout; }
+  void setTimeout(time_t timeout) { _timeout = timeout; }
 
   void prepareForNextAction(Command* nextCommand = 0);
 
@@ -143,20 +207,16 @@ protected:
   {
     return _requestGroup->getDownloadContext();
   }
-private:
-  bool checkSocketIsReadable;
-  bool checkSocketIsWritable;
-  SharedHandle<SocketCore> readCheckTarget;
-  SharedHandle<SocketCore> writeCheckTarget;
-  bool nameResolverCheck;
 
-#ifdef ENABLE_ASYNC_DNS
+  const SharedHandle<SegmentMan>& getSegmentMan() const
+  {
+    return _requestGroup->getSegmentMan();
+  }
 
-  void setNameResolverCheck(const SharedHandle<AsyncNameResolver>& resolver);
-
-  void disableNameResolverCheck(const SharedHandle<AsyncNameResolver>& resolver);
-  bool nameResolveFinished() const;
-#endif // ENABLE_ASYNC_DNS
+  const SharedHandle<PieceStorage>& getPieceStorage() const
+  {
+    return _requestGroup->getPieceStorage();
+  }
 public:
   AbstractCommand(cuid_t cuid, const SharedHandle<Request>& req,
                   const SharedHandle<FileEntry>& fileEntry,
diff --git a/src/AbstractProxyRequestCommand.cc b/src/AbstractProxyRequestCommand.cc
index d15d9dfc..02b1850f 100644
--- a/src/AbstractProxyRequestCommand.cc
+++ b/src/AbstractProxyRequestCommand.cc
@@ -64,37 +64,37 @@ AbstractProxyRequestCommand::AbstractProxyRequestCommand
   :
   AbstractCommand(cuid, req, fileEntry, requestGroup, e, s),
   _proxyRequest(proxyRequest),
-  httpConnection(new HttpConnection(cuid, s, getOption().get()))
+  _httpConnection(new HttpConnection(cuid, s, getOption().get()))
 {
   setTimeout(getOption()->getAsInt(PREF_CONNECT_TIMEOUT));
   disableReadCheckSocket();
-  setWriteCheckSocket(socket);
+  setWriteCheckSocket(getSocket());
 }
 
 AbstractProxyRequestCommand::~AbstractProxyRequestCommand() {}
 
 bool AbstractProxyRequestCommand::executeInternal() {
   //socket->setBlockingMode();
-  if(httpConnection->sendBufferIsEmpty()) {
+  if(_httpConnection->sendBufferIsEmpty()) {
     if(!checkIfConnectionEstablished
-       (socket, _connectedHostname, _connectedAddr, _connectedPort)) {
+       (getSocket(), _connectedHostname, _connectedAddr, _connectedPort)) {
       return true;
     }
     SharedHandle<HttpRequest> httpRequest(new HttpRequest());
     httpRequest->setUserAgent(getOption()->get(PREF_USER_AGENT));
-    httpRequest->setRequest(req);
+    httpRequest->setRequest(getRequest());
     httpRequest->setProxyRequest(_proxyRequest);
 
-    httpConnection->sendProxyRequest(httpRequest);
+    _httpConnection->sendProxyRequest(httpRequest);
   } else {
-    httpConnection->sendPendingData();
+    _httpConnection->sendPendingData();
   }
-  if(httpConnection->sendBufferIsEmpty()) {
-    e->addCommand(getNextCommand());
+  if(_httpConnection->sendBufferIsEmpty()) {
+    getDownloadEngine()->addCommand(getNextCommand());
     return true;
   } else {
-    setWriteCheckSocket(socket);
-    e->addCommand(this);
+    setWriteCheckSocket(getSocket());
+    getDownloadEngine()->addCommand(this);
     return false;
   }
 }
diff --git a/src/AbstractProxyRequestCommand.h b/src/AbstractProxyRequestCommand.h
index 4ffad746..0dfabbd3 100644
--- a/src/AbstractProxyRequestCommand.h
+++ b/src/AbstractProxyRequestCommand.h
@@ -43,16 +43,21 @@ class HttpConnection;
 class SocketCore;
 
 class AbstractProxyRequestCommand : public AbstractCommand {
-protected:
+private:
   SharedHandle<Request> _proxyRequest;
 
-  SharedHandle<HttpConnection> httpConnection;
+  SharedHandle<HttpConnection> _httpConnection;
 
   std::string _connectedHostname;
   std::string _connectedAddr;
   uint16_t _connectedPort;
-
+protected:
   virtual bool executeInternal();
+
+  const SharedHandle<HttpConnection>& getHttpConnection() const
+  {
+    return _httpConnection;
+  }
 public:
   AbstractProxyRequestCommand(cuid_t cuid,
                               const SharedHandle<Request>& req,
diff --git a/src/AbstractProxyResponseCommand.cc b/src/AbstractProxyResponseCommand.cc
index e0e5b16a..3806507c 100644
--- a/src/AbstractProxyResponseCommand.cc
+++ b/src/AbstractProxyResponseCommand.cc
@@ -62,21 +62,21 @@ AbstractProxyResponseCommand::AbstractProxyResponseCommand
  DownloadEngine* e,
  const SocketHandle& s)
   :AbstractCommand(cuid, req, fileEntry, requestGroup, e, s),
-   httpConnection(httpConnection) {}
+   _httpConnection(httpConnection) {}
 
 AbstractProxyResponseCommand::~AbstractProxyResponseCommand() {}
 
 bool AbstractProxyResponseCommand::executeInternal() {
-  SharedHandle<HttpResponse> httpResponse = httpConnection->receiveResponse();
+  SharedHandle<HttpResponse> httpResponse = _httpConnection->receiveResponse();
   if(httpResponse.isNull()) {
     // the server has not responded our request yet.
-    e->addCommand(this);
+    getDownloadEngine()->addCommand(this);
     return false;
   }
   if(httpResponse->getResponseStatus() != HttpHeader::S200) {
     throw DL_RETRY_EX(EX_PROXY_CONNECTION_FAILED);
   }
-  e->addCommand(getNextCommand());
+  getDownloadEngine()->addCommand(getNextCommand());
   return true;
 }
 
diff --git a/src/AbstractProxyResponseCommand.h b/src/AbstractProxyResponseCommand.h
index e0b06a8f..8e391574 100644
--- a/src/AbstractProxyResponseCommand.h
+++ b/src/AbstractProxyResponseCommand.h
@@ -43,10 +43,15 @@ class HttpConnection;
 class SocketCore;
 
 class AbstractProxyResponseCommand : public AbstractCommand {
+private:
+  SharedHandle<HttpConnection> _httpConnection;
 protected:
-  SharedHandle<HttpConnection> httpConnection;
-
   virtual bool executeInternal();
+
+  const SharedHandle<HttpConnection>& getHttpConnection() const
+  {
+    return _httpConnection;
+  }
 public:
   AbstractProxyResponseCommand
   (cuid_t cuid,
diff --git a/src/CreateRequestCommand.cc b/src/CreateRequestCommand.cc
index 40a6c6f6..e519c017 100644
--- a/src/CreateRequestCommand.cc
+++ b/src/CreateRequestCommand.cc
@@ -67,39 +67,41 @@ CreateRequestCommand::CreateRequestCommand(cuid_t cuid,
 
 bool CreateRequestCommand::executeInternal()
 {
-  if(_segments.empty()) {
-    _fileEntry = _requestGroup->getDownloadContext()->findFileEntryByOffset(0);
+  if(getSegments().empty()) {
+    setFileEntry(getDownloadContext()->findFileEntryByOffset(0));
   } else {
     // We assume all segments belongs to same file.
-    _fileEntry = _requestGroup->getDownloadContext()->findFileEntryByOffset
-      (_segments.front()->getPositionToWrite());
+    setFileEntry(getDownloadContext()->findFileEntryByOffset
+                 (getSegments().front()->getPositionToWrite()));
   }
-  if(_fileEntry->getRemainingUris().empty() &&
+  if(getFileEntry()->getRemainingUris().empty() &&
      getOption()->getAsBool(PREF_REUSE_URI) &&
-     _fileEntry->countPooledRequest() == 0) {
-    _fileEntry->reuseUri(_requestGroup->getNumConcurrentCommand());
+     getFileEntry()->countPooledRequest() == 0) {
+    getFileEntry()->reuseUri(getRequestGroup()->getNumConcurrentCommand());
   }
-  req = _fileEntry->getRequest(_requestGroup->getURISelector(),
-                               getOption()->get(PREF_REFERER),
-                               // Don't use HEAD request when file
-                               // size is known.
-                               // Use HEAD for dry-run mode.
-                               (_fileEntry->getLength() == 0 &&
-                                getOption()->getAsBool(PREF_USE_HEAD)) ||
-                               getOption()->getAsBool(PREF_DRY_RUN)?
-                               Request::METHOD_HEAD:Request::METHOD_GET);
-  if(req.isNull()) {
-    if(!_requestGroup->getSegmentMan().isNull()) {
-      _requestGroup->getSegmentMan()->ignoreSegmentFor(_fileEntry);
+  setRequest
+    (getFileEntry()->getRequest(getRequestGroup()->getURISelector(),
+                                getOption()->get(PREF_REFERER),
+                                // Don't use HEAD request when file
+                                // size is known.
+                                // Use HEAD for dry-run mode.
+                                (getFileEntry()->getLength() == 0 &&
+                                 getOption()->getAsBool(PREF_USE_HEAD)) ||
+                                getOption()->getAsBool(PREF_DRY_RUN)?
+                                Request::METHOD_HEAD:Request::METHOD_GET));
+  if(getRequest().isNull()) {
+    if(!getSegmentMan().isNull()) {
+      getSegmentMan()->ignoreSegmentFor(getFileEntry());
     }
     throw DL_ABORT_EX("No URI available.");
   }
 
   Command* command =
     InitiateConnectionCommandFactory::createInitiateConnectionCommand
-    (getCuid(), req, _fileEntry, _requestGroup, e);
-  e->setNoWait(true);
-  e->addCommand(command);
+    (getCuid(), getRequest(), getFileEntry(), getRequestGroup(),
+     getDownloadEngine());
+  getDownloadEngine()->setNoWait(true);
+  getDownloadEngine()->addCommand(command);
   return true;
 }
 
@@ -113,16 +115,16 @@ bool CreateRequestCommand::prepareForRetry(time_t wait)
   // called repeatedly. This means that newly created
   // CreateRequestCommand is deleted one second later: This is not
   // efficient. For this reason, reuse current CreateRequestCommand.
-  if(!_requestGroup->getPieceStorage().isNull()) {
-    _requestGroup->getSegmentMan()->cancelSegment(getCuid());
+  if(!getPieceStorage().isNull()) {
+    getSegmentMan()->cancelSegment(getCuid());
   }
   if(getLogger()->debug()) {
     getLogger()->debug("CUID#%s - Reusing CreateRequestCommand",
                        util::itos(getCuid()).c_str());
   }
   SleepCommand* scom = new SleepCommand
-    (getCuid(), e, _requestGroup, this, wait);
-  e->addCommand(scom);
+    (getCuid(), getDownloadEngine(), getRequestGroup(), this, wait);
+  getDownloadEngine()->addCommand(scom);
   return false;
 }
 
diff --git a/src/DownloadCommand.cc b/src/DownloadCommand.cc
index 96b12d97..a9cfd24a 100644
--- a/src/DownloadCommand.cc
+++ b/src/DownloadCommand.cc
@@ -76,7 +76,9 @@ DownloadCommand::DownloadCommand(cuid_t cuid,
                                  DownloadEngine* e,
                                  const SocketHandle& s):
   AbstractCommand(cuid, req, fileEntry, requestGroup, e, s),
-  _buf(new unsigned char[BUFSIZE])
+  _buf(new unsigned char[BUFSIZE]),
+  _startupIdleTime(10),
+  _lowestDownloadSpeedLimit(0)
 #ifdef ENABLE_MESSAGE_DIGEST
   , _pieceHashValidationEnabled(false)
 #endif // ENABLE_MESSAGE_DIGEST
@@ -84,8 +86,7 @@ DownloadCommand::DownloadCommand(cuid_t cuid,
 #ifdef ENABLE_MESSAGE_DIGEST
   {
     if(getOption()->getAsBool(PREF_REALTIME_CHUNK_CHECKSUM)) {
-      std::string algo =
-        _requestGroup->getDownloadContext()->getPieceHashAlgo();
+      const std::string& algo = getDownloadContext()->getPieceHashAlgo();
       if(MessageDigestContext::supports(algo)) {
         _messageDigestContext.reset(new MessageDigestContext());
         _messageDigestContext->trySetAlgo(algo);
@@ -97,46 +98,47 @@ DownloadCommand::DownloadCommand(cuid_t cuid,
   }
 #endif // ENABLE_MESSAGE_DIGEST
 
-  peerStat = req->initPeerStat();
-  peerStat->downloadStart();
-  _requestGroup->getSegmentMan()->registerPeerStat(peerStat);
+  _peerStat = req->initPeerStat();
+  _peerStat->downloadStart();
+  getSegmentMan()->registerPeerStat(_peerStat);
 }
 
 DownloadCommand::~DownloadCommand() {
-  peerStat->downloadStop();
-  _requestGroup->getSegmentMan()->updateFastestPeerStat(peerStat);
+  _peerStat->downloadStop();
+  getSegmentMan()->updateFastestPeerStat(_peerStat);
   delete [] _buf;
 }
 
 bool DownloadCommand::executeInternal() {
-  if(e->getRequestGroupMan()->doesOverallDownloadSpeedExceed() ||
-     _requestGroup->doesDownloadSpeedExceed()) {
-    e->addCommand(this);
+  if(getDownloadEngine()->getRequestGroupMan()->doesOverallDownloadSpeedExceed()
+     || getRequestGroup()->doesDownloadSpeedExceed()) {
+    getDownloadEngine()->addCommand(this);
     disableReadCheckSocket();
     return false;
   }
-  setReadCheckSocket(socket);
-  SharedHandle<Segment> segment = _segments.front();
+  setReadCheckSocket(getSocket());
+  SharedHandle<Segment> segment = getSegments().front();
 
   size_t bufSize;
   if(segment->getLength() > 0) {
     if(static_cast<uint64_t>(segment->getPosition()+segment->getLength()) <=
-       static_cast<uint64_t>(_fileEntry->getLastOffset())) {
+       static_cast<uint64_t>(getFileEntry()->getLastOffset())) {
       bufSize = std::min(segment->getLength()-segment->getWrittenLength(),
                          BUFSIZE);
     } else {
       bufSize =
-        std::min(static_cast<size_t>
-                 (_fileEntry->getLastOffset()-segment->getPositionToWrite()),
-                 BUFSIZE);
+        std::min
+        (static_cast<size_t>
+         (getFileEntry()->getLastOffset()-segment->getPositionToWrite()),
+         BUFSIZE);
     }
   } else {
     bufSize = BUFSIZE;
   }
-  socket->readData(_buf, bufSize);
+  getSocket()->readData(_buf, bufSize);
 
   const SharedHandle<DiskAdaptor>& diskAdaptor =
-    _requestGroup->getPieceStorage()->getDiskAdaptor();
+    getPieceStorage()->getDiskAdaptor();
 
   const unsigned char* bufFinal;
   size_t bufSizeFinal;
@@ -173,24 +175,21 @@ bool DownloadCommand::executeInternal() {
   if(bufSizeFinal > 0) {
     segment->updateWrittenLength(bufSizeFinal);
   }
-
-  peerStat->updateDownloadLength(bufSize);
-
-  _requestGroup->getSegmentMan()->updateDownloadSpeedFor(peerStat);
-
+  _peerStat->updateDownloadLength(bufSize);
+  getSegmentMan()->updateDownloadSpeedFor(_peerStat);
   bool segmentPartComplete = false;
   // Note that GrowSegment::complete() always returns false.
   if(_transferEncodingDecoder.isNull() && _contentEncodingDecoder.isNull()) {
     if(segment->complete() ||
-       segment->getPositionToWrite() == _fileEntry->getLastOffset()) {
+       segment->getPositionToWrite() == getFileEntry()->getLastOffset()) {
       segmentPartComplete = true;
     } else if(segment->getLength() == 0 && bufSize == 0 &&
-              !socket->wantRead() && !socket->wantWrite()) {
+              !getSocket()->wantRead() && !getSocket()->wantWrite()) {
       segmentPartComplete = true;
     }
   } else if(!_transferEncodingDecoder.isNull() &&
             (segment->complete() ||
-             segment->getPositionToWrite() == _fileEntry->getLastOffset())) {
+             segment->getPositionToWrite() == getFileEntry()->getLastOffset())){
     // In this case, transferEncodingDecoder is used and
     // Content-Length is known.
     segmentPartComplete = true;
@@ -202,7 +201,7 @@ bool DownloadCommand::executeInternal() {
   }
 
   if(!segmentPartComplete && bufSize == 0 &&
-     !socket->wantRead() && !socket->wantWrite()) {
+     !getSocket()->wantRead() && !getSocket()->wantWrite()) {
     throw DL_RETRY_EX(EX_GOT_EOF);
   }
 
@@ -219,8 +218,7 @@ bool DownloadCommand::executeInternal() {
 
       {
         const std::string& expectedPieceHash =
-          _requestGroup->getDownloadContext()->getPieceHash
-          (segment->getIndex());
+          getDownloadContext()->getPieceHash(segment->getIndex());
         if(_pieceHashValidationEnabled && !expectedPieceHash.empty()) {
           if(segment->isHashCalculated()) {
             if(getLogger()->debug()) {
@@ -236,31 +234,31 @@ bool DownloadCommand::executeInternal() {
               (segment, expectedPieceHash,
                MessageDigestHelper::digest
                (_messageDigestContext.get(),
-                _requestGroup->getPieceStorage()->getDiskAdaptor(),
+                getPieceStorage()->getDiskAdaptor(),
                 segment->getPosition(),
                 segment->getLength()));
           }
         } else {
-          _requestGroup->getSegmentMan()->completeSegment(getCuid(), segment);
+          getSegmentMan()->completeSegment(getCuid(), segment);
         }
       }
 
 #else // !ENABLE_MESSAGE_DIGEST
-      _requestGroup->getSegmentMan()->completeSegment(getCuid(), segment);
+      getSegmentMan()->completeSegment(getCuid(), segment);
 #endif // !ENABLE_MESSAGE_DIGEST
     } else {
       // If segment is not canceled here, in the next pipelining
       // request, aria2 requests bad range
       // [FileEntry->getLastOffset(), FileEntry->getLastOffset())
-      _requestGroup->getSegmentMan()->cancelSegment(getCuid(), segment);
+      getSegmentMan()->cancelSegment(getCuid(), segment);
     }
     checkLowestDownloadSpeed();
     // this unit is going to download another segment.
     return prepareForNextSegment();
   } else {
     checkLowestDownloadSpeed();
-    setWriteCheckSocketIf(socket, socket->wantWrite());
-    e->addCommand(this);
+    setWriteCheckSocketIf(getSocket(), getSocket()->wantWrite());
+    getDownloadEngine()->addCommand(this);
     return false;
   }
 }
@@ -268,67 +266,62 @@ bool DownloadCommand::executeInternal() {
 void DownloadCommand::checkLowestDownloadSpeed() const
 {
   // calculate downloading speed
-  if(peerStat->getDownloadStartTime().difference(global::wallclock) >=
-     startupIdleTime) {
-    unsigned int nowSpeed = peerStat->calculateDownloadSpeed();
-    if(lowestDownloadSpeedLimit > 0 &&  nowSpeed <= lowestDownloadSpeedLimit) {
+  if(_peerStat->getDownloadStartTime().difference(global::wallclock) >=
+     _startupIdleTime) {
+    unsigned int nowSpeed = _peerStat->calculateDownloadSpeed();
+    if(_lowestDownloadSpeedLimit > 0 && nowSpeed <= _lowestDownloadSpeedLimit) {
       throw DL_ABORT_EX2(StringFormat(EX_TOO_SLOW_DOWNLOAD_SPEED,
                                       nowSpeed,
-                                      lowestDownloadSpeedLimit,
-                                      req->getHost().c_str()).str(),
+                                      _lowestDownloadSpeedLimit,
+                                      getRequest()->getHost().c_str()).str(),
                          downloadresultcode::TOO_SLOW_DOWNLOAD_SPEED);
     }
   }
 }
 
 bool DownloadCommand::prepareForNextSegment() {
-  if(_requestGroup->downloadFinished()) {
-    const SharedHandle<DownloadContext>& dctx =
-      _requestGroup->getDownloadContext();
+  if(getRequestGroup()->downloadFinished()) {
     // Remove in-flight request here.
-    _fileEntry->poolRequest(req);
+    getFileEntry()->poolRequest(getRequest());
     // If this is a single file download, and file size becomes known
     // just after downloading, set total length to FileEntry object
     // here.
-    if(dctx->getFileEntries().size() == 1) {
-      const SharedHandle<FileEntry>& fileEntry = dctx->getFirstFileEntry();
-      if(fileEntry->getLength() == 0) {
-        fileEntry->setLength
-          (_requestGroup->getPieceStorage()->getCompletedLength());
+    if(getDownloadContext()->getFileEntries().size() == 1) {
+      if(getFileEntry()->getLength() == 0) {
+        getFileEntry()->setLength(getPieceStorage()->getCompletedLength());
       }
     }
 #ifdef ENABLE_MESSAGE_DIGEST
-    if(dctx->getPieceHashAlgo().empty()) {
+    if(getDownloadContext()->getPieceHashAlgo().empty()) {
       SharedHandle<CheckIntegrityEntry> entry
-        (new ChecksumCheckIntegrityEntry(_requestGroup));
+        (new ChecksumCheckIntegrityEntry(getRequestGroup()));
       if(entry->isValidationReady()) {
         entry->initValidator();
         // TODO do we need cuttrailinggarbage here?
-        e->getCheckIntegrityMan()->pushEntry(entry);
+        getDownloadEngine()->getCheckIntegrityMan()->pushEntry(entry);
       }
     }
     // Following 2lines are needed for DownloadEngine to detect
     // completed RequestGroups without 1sec delay.
-    e->setNoWait(true);
-    e->setRefreshInterval(0);
+    getDownloadEngine()->setNoWait(true);
+    getDownloadEngine()->setRefreshInterval(0);
 #endif // ENABLE_MESSAGE_DIGEST
     return true;
   } else {
     // The number of segments should be 1 in order to pass through the next
     // segment.
-    if(_segments.size() == 1) {
-      SharedHandle<Segment> tempSegment = _segments.front();
+    if(getSegments().size() == 1) {
+      SharedHandle<Segment> tempSegment = getSegments().front();
       if(!tempSegment->complete()) {
         return prepareForRetry(0);
       }
-      SharedHandle<SegmentMan> segmentMan = _requestGroup->getSegmentMan();
       SharedHandle<Segment> nextSegment =
-        segmentMan->getCleanSegmentIfOwnerIsIdle
+        getSegmentMan()->getCleanSegmentIfOwnerIsIdle
         (getCuid(), tempSegment->getIndex()+1);
       if(nextSegment.isNull()) {
         return prepareForRetry(0);
       } else {
-        e->addCommand(this);
+        getDownloadEngine()->addCommand(this);
         return false;
       }
     } else {
@@ -345,7 +338,7 @@ void DownloadCommand::validatePieceHash(const SharedHandle<Segment>& segment,
 {
   if(actualPieceHash == expectedPieceHash) {
     getLogger()->info(MSG_GOOD_CHUNK_CHECKSUM, actualPieceHash.c_str());
-    _requestGroup->getSegmentMan()->completeSegment(getCuid(), segment);
+    getSegmentMan()->completeSegment(getCuid(), segment);
   } else {
     getLogger()->info(EX_INVALID_CHUNK_CHECKSUM,
                       segment->getIndex(),
@@ -353,7 +346,7 @@ void DownloadCommand::validatePieceHash(const SharedHandle<Segment>& segment,
                       expectedPieceHash.c_str(),
                       actualPieceHash.c_str());
     segment->clear();
-    _requestGroup->getSegmentMan()->cancelSegment(getCuid());
+    getSegmentMan()->cancelSegment(getCuid());
     throw DL_RETRY_EX
       (StringFormat("Invalid checksum index=%d", segment->getIndex()).str());
   }
diff --git a/src/DownloadCommand.h b/src/DownloadCommand.h
index af63c093..1abe4b58 100644
--- a/src/DownloadCommand.h
+++ b/src/DownloadCommand.h
@@ -49,9 +49,9 @@ class DownloadCommand : public AbstractCommand {
 private:
   unsigned char* _buf;
 
-  time_t startupIdleTime;
-  unsigned int lowestDownloadSpeedLimit;
-  SharedHandle<PeerStat> peerStat;
+  time_t _startupIdleTime;
+  unsigned int _lowestDownloadSpeedLimit;
+  SharedHandle<PeerStat> _peerStat;
 
 #ifdef ENABLE_MESSAGE_DIGEST
 
@@ -66,15 +66,14 @@ private:
                          const std::string& actualPieceHash);
 
   void checkLowestDownloadSpeed() const;
-protected:
+
   SharedHandle<Decoder> _transferEncodingDecoder;
 
   SharedHandle<Decoder> _contentEncodingDecoder;
-
+protected:
   virtual bool executeInternal();
 
   virtual bool prepareForNextSegment();
-
 public:
   DownloadCommand(cuid_t cuid,
                   const SharedHandle<Request>& req,
@@ -84,16 +83,28 @@ public:
                   const SharedHandle<SocketCore>& s);
   virtual ~DownloadCommand();
 
+  const SharedHandle<Decoder>& getTransferEncodingDecoder() const
+  {
+    return _transferEncodingDecoder;
+  }
+
   void setTransferEncodingDecoder(const SharedHandle<Decoder>& decoder);
 
+  const SharedHandle<Decoder>& getContentEncodingDecoder() const
+  {
+    return _contentEncodingDecoder;
+  }
+
   void setContentEncodingDecoder(const SharedHandle<Decoder>& decoder);
 
-  void setStartupIdleTime(time_t startupIdleTime) {
-    this->startupIdleTime = startupIdleTime;
+  void setStartupIdleTime(time_t startupIdleTime)
+  {
+    _startupIdleTime = startupIdleTime;
   }
 
-  void setLowestDownloadSpeedLimit(unsigned int lowestDownloadSpeedLimit) {
-    this->lowestDownloadSpeedLimit = lowestDownloadSpeedLimit;
+  void setLowestDownloadSpeedLimit(unsigned int lowestDownloadSpeedLimit)
+  {
+    _lowestDownloadSpeedLimit = lowestDownloadSpeedLimit;
   }
 };
 
diff --git a/src/FtpDownloadCommand.cc b/src/FtpDownloadCommand.cc
index cb735f3a..02023277 100644
--- a/src/FtpDownloadCommand.cc
+++ b/src/FtpDownloadCommand.cc
@@ -62,7 +62,7 @@ FtpDownloadCommand::FtpDownloadCommand
  const SocketHandle& ctrlSocket)
   :DownloadCommand(cuid, req, fileEntry, requestGroup, e, dataSocket),
    _ftpConnection(ftpConnection),
-   ctrlSocket(ctrlSocket) {}
+   _ctrlSocket(ctrlSocket) {}
 
 FtpDownloadCommand::~FtpDownloadCommand() {}
 
@@ -71,14 +71,14 @@ bool FtpDownloadCommand::prepareForNextSegment()
 {
   if(getOption()->getAsBool(PREF_FTP_REUSE_CONNECTION) &&
      static_cast<uint64_t>
-     (_fileEntry->gtoloff(_segments.front()->getPositionToWrite())) ==
-     _fileEntry->getLength()) {
+     (getFileEntry()->gtoloff(getSegments().front()->getPositionToWrite())) ==
+     getFileEntry()->getLength()) {
     Command* command = new FtpFinishDownloadCommand
-      (getCuid(), req, _fileEntry, _requestGroup, _ftpConnection, e,
-       ctrlSocket);
-    e->addCommand(command);
+      (getCuid(), getRequest(), getFileEntry(), getRequestGroup(),
+       _ftpConnection, getDownloadEngine(), _ctrlSocket);
+    getDownloadEngine()->addCommand(command);
 
-    if(_requestGroup->downloadFinished()) {
+    if(getRequestGroup()->downloadFinished()) {
       // To run checksum checking, we had to call following function here.
       DownloadCommand::prepareForNextSegment();
     }
diff --git a/src/FtpDownloadCommand.h b/src/FtpDownloadCommand.h
index 194b0345..bd5b4d0a 100644
--- a/src/FtpDownloadCommand.h
+++ b/src/FtpDownloadCommand.h
@@ -45,7 +45,7 @@ class FtpDownloadCommand : public DownloadCommand {
 private:
   SharedHandle<FtpConnection> _ftpConnection;
 
-  SharedHandle<SocketCore> ctrlSocket;
+  SharedHandle<SocketCore> _ctrlSocket;
 protected:
   virtual bool prepareForNextSegment();
 public:
diff --git a/src/FtpFinishDownloadCommand.cc b/src/FtpFinishDownloadCommand.cc
index e143743a..f3090eec 100644
--- a/src/FtpFinishDownloadCommand.cc
+++ b/src/FtpFinishDownloadCommand.cc
@@ -71,13 +71,13 @@ FtpFinishDownloadCommand::FtpFinishDownloadCommand
 // AbstractCommand::_segments is empty.
 bool FtpFinishDownloadCommand::execute()
 {
-  if(_requestGroup->isHaltRequested()) {
+  if(getRequestGroup()->isHaltRequested()) {
     return true;
   }
   try {
     unsigned int status = _ftpConnection->receiveResponse();
     if(status == 0) {
-      e->addCommand(this);
+      getDownloadEngine()->addCommand(this);
       return false;
     }
     if(status != 226) {
@@ -86,13 +86,14 @@ bool FtpFinishDownloadCommand::execute()
     if(getOption()->getAsBool(PREF_FTP_REUSE_CONNECTION)) {
       std::map<std::string, std::string> options;
       options["baseWorkingDir"] = _ftpConnection->getBaseWorkingDir();
-      e->poolSocket(req, _ftpConnection->getUser(), createProxyRequest(),
-                    socket, options);
+      getDownloadEngine()->poolSocket
+        (getRequest(), _ftpConnection->getUser(), createProxyRequest(),
+         getSocket(), options);
     }
   } catch(RecoverableException& e) {
     getLogger()->info(EX_EXCEPTION_CAUGHT, e);
   }
-  if(_requestGroup->downloadFinished()) {
+  if(getRequestGroup()->downloadFinished()) {
     return true;
   } else {
     return prepareForRetry(0);
diff --git a/src/FtpInitiateConnectionCommand.cc b/src/FtpInitiateConnectionCommand.cc
index 3fd52954..bbd6503d 100644
--- a/src/FtpInitiateConnectionCommand.cc
+++ b/src/FtpInitiateConnectionCommand.cc
@@ -80,16 +80,16 @@ Command* FtpInitiateConnectionCommand::createNextCommand
   if(!proxyRequest.isNull()) {
     std::map<std::string, std::string> options;
     SharedHandle<SocketCore> pooledSocket;
-    std::string proxyMethod = resolveProxyMethod(req->getProtocol());
+    std::string proxyMethod = resolveProxyMethod(getRequest()->getProtocol());
     if(proxyMethod == V_GET) {
-      pooledSocket = e->popPooledSocket
-        (req->getHost(), req->getPort(),
+      pooledSocket = getDownloadEngine()->popPooledSocket
+        (getRequest()->getHost(), getRequest()->getPort(),
          proxyRequest->getHost(), proxyRequest->getPort());
     } else {
-      pooledSocket = e->popPooledSocket
-        (options, req->getHost(), req->getPort(),
-         e->getAuthConfigFactory()->createAuthConfig
-         (req, getOption().get())->getUser(),
+      pooledSocket = getDownloadEngine()->popPooledSocket
+        (options, getRequest()->getHost(), getRequest()->getPort(),
+         getDownloadEngine()->getAuthConfigFactory()->createAuthConfig
+         (getRequest(), getOption().get())->getUser(),
          proxyRequest->getHost(), proxyRequest->getPort());
     }
     if(pooledSocket.isNull()) {
@@ -97,26 +97,27 @@ Command* FtpInitiateConnectionCommand::createNextCommand
         getLogger()->info(MSG_CONNECTING_TO_SERVER,
                           util::itos(getCuid()).c_str(), addr.c_str(), port);
       }
-      socket.reset(new SocketCore());
-      socket->establishConnection(addr, port);
+      createSocket();
+      getSocket()->establishConnection(addr, port);
       
       if(proxyMethod == V_GET) {
         // Use GET for FTP via HTTP proxy.
-        req->setMethod(Request::METHOD_GET);
+        getRequest()->setMethod(Request::METHOD_GET);
         SharedHandle<HttpConnection> hc
-          (new HttpConnection(getCuid(), socket, getOption().get()));
+          (new HttpConnection(getCuid(), getSocket(), getOption().get()));
         
         HttpRequestCommand* c =
-          new HttpRequestCommand(getCuid(), req, _fileEntry,
-                                 _requestGroup, hc, e, socket);
+          new HttpRequestCommand(getCuid(), getRequest(), getFileEntry(),
+                                 getRequestGroup(), hc, getDownloadEngine(),
+                                 getSocket());
         c->setConnectedAddr(hostname, addr, port);
         c->setProxyRequest(proxyRequest);
         command = c;
       } else if(proxyMethod == V_TUNNEL) {
         FtpTunnelRequestCommand* c =
-          new FtpTunnelRequestCommand(getCuid(), req, _fileEntry,
-                                      _requestGroup, e,
-                                      proxyRequest, socket);
+          new FtpTunnelRequestCommand(getCuid(), getRequest(), getFileEntry(),
+                                      getRequestGroup(), getDownloadEngine(),
+                                      proxyRequest, getSocket());
         c->setConnectedAddr(hostname, addr, port);
         command = c;
       } else {
@@ -126,19 +127,21 @@ Command* FtpInitiateConnectionCommand::createNextCommand
     } else {
       if(proxyMethod == V_TUNNEL) {
         command =
-          new FtpNegotiationCommand(getCuid(), req, _fileEntry,
-                                    _requestGroup, e, pooledSocket,
+          new FtpNegotiationCommand(getCuid(), getRequest(), getFileEntry(),
+                                    getRequestGroup(), getDownloadEngine(),
+                                    pooledSocket,
                                     FtpNegotiationCommand::SEQ_SEND_CWD,
                                     options["baseWorkingDir"]);
       } else if(proxyMethod == V_GET) {
         // Use GET for FTP via HTTP proxy.
-        req->setMethod(Request::METHOD_GET);
+        getRequest()->setMethod(Request::METHOD_GET);
         SharedHandle<HttpConnection> hc
           (new HttpConnection(getCuid(), pooledSocket, getOption().get()));
         
         HttpRequestCommand* c =
-          new HttpRequestCommand(getCuid(), req, _fileEntry,
-                                 _requestGroup, hc, e, pooledSocket);
+          new HttpRequestCommand(getCuid(), getRequest(), getFileEntry(),
+                                 getRequestGroup(), hc, getDownloadEngine(),
+                                 pooledSocket);
         c->setProxyRequest(proxyRequest);
         command = c;
       } else {
@@ -149,25 +152,29 @@ Command* FtpInitiateConnectionCommand::createNextCommand
   } else {
     std::map<std::string, std::string> options;
     SharedHandle<SocketCore> pooledSocket =
-      e->popPooledSocket(options, resolvedAddresses, req->getPort(),
-                         e->getAuthConfigFactory()->createAuthConfig
-                         (req, getOption().get())->getUser());
+      getDownloadEngine()->popPooledSocket
+      (options, resolvedAddresses,
+       getRequest()->getPort(),
+       getDownloadEngine()->getAuthConfigFactory()->createAuthConfig
+       (getRequest(), getOption().get())->getUser());
     if(pooledSocket.isNull()) {
       if(getLogger()->info()) {
         getLogger()->info(MSG_CONNECTING_TO_SERVER,
                           util::itos(getCuid()).c_str(), addr.c_str(), port);
       }
-      socket.reset(new SocketCore());
-      socket->establishConnection(addr, port);
+      createSocket();
+      getSocket()->establishConnection(addr, port);
       FtpNegotiationCommand* c =
-        new FtpNegotiationCommand(getCuid(), req, _fileEntry,
-                                  _requestGroup, e, socket);
+        new FtpNegotiationCommand(getCuid(), getRequest(), getFileEntry(),
+                                  getRequestGroup(), getDownloadEngine(),
+                                  getSocket());
       c->setConnectedAddr(hostname, addr, port);
       command = c;
     } else {
       command =
-        new FtpNegotiationCommand(getCuid(), req, _fileEntry,
-                                  _requestGroup, e, pooledSocket,
+        new FtpNegotiationCommand(getCuid(), getRequest(), getFileEntry(),
+                                  getRequestGroup(), getDownloadEngine(),
+                                  pooledSocket,
                                   FtpNegotiationCommand::SEQ_SEND_CWD,
                                   options["baseWorkingDir"]);
     }
diff --git a/src/FtpNegotiationCommand.cc b/src/FtpNegotiationCommand.cc
index 303de573..aecd0e1e 100644
--- a/src/FtpNegotiationCommand.cc
+++ b/src/FtpNegotiationCommand.cc
@@ -83,104 +83,105 @@ FtpNegotiationCommand::FtpNegotiationCommand
  const SharedHandle<FileEntry>& fileEntry,
  RequestGroup* requestGroup,
  DownloadEngine* e,
- const SocketHandle& s,
+ const SocketHandle& socket,
  Seq seq,
  const std::string& baseWorkingDir):
-  AbstractCommand(cuid, req, fileEntry, requestGroup, e, s), sequence(seq),
-  ftp(new FtpConnection(cuid, socket, req,
+  AbstractCommand(cuid, req, fileEntry, requestGroup, e, socket), _sequence(seq),
+  _ftp(new FtpConnection(cuid, socket, req,
                         e->getAuthConfigFactory()->createAuthConfig
                         (req, requestGroup->getOption().get()),
                         getOption().get()))
 {
-  ftp->setBaseWorkingDir(baseWorkingDir);
+  _ftp->setBaseWorkingDir(baseWorkingDir);
   if(seq == SEQ_RECV_GREETING) {
     setTimeout(getOption()->getAsInt(PREF_CONNECT_TIMEOUT));
   }
   disableReadCheckSocket();
-  setWriteCheckSocket(socket);
+  setWriteCheckSocket(getSocket());
 }
 
 FtpNegotiationCommand::~FtpNegotiationCommand() {}
 
 bool FtpNegotiationCommand::executeInternal() {
-  while(processSequence(_segments.front()));
-  if(sequence == SEQ_RETRY) {
+  while(processSequence(getSegments().front()));
+  if(_sequence == SEQ_RETRY) {
     return prepareForRetry(0);
-  } else if(sequence == SEQ_NEGOTIATION_COMPLETED) {
+  } else if(_sequence == SEQ_NEGOTIATION_COMPLETED) {
     FtpDownloadCommand* command =
       new FtpDownloadCommand
-      (getCuid(), req, _fileEntry, _requestGroup, ftp, e, dataSocket, socket);
+      (getCuid(), getRequest(), getFileEntry(), getRequestGroup(), _ftp,
+       getDownloadEngine(), _dataSocket, getSocket());
     command->setStartupIdleTime(getOption()->getAsInt(PREF_STARTUP_IDLE_TIME));
     command->setLowestDownloadSpeedLimit
       (getOption()->getAsInt(PREF_LOWEST_SPEED_LIMIT));
-    if(!_fileEntry->isSingleHostMultiConnectionEnabled()) {
-      _fileEntry->removeURIWhoseHostnameIs(req->getHost());
+    if(!getFileEntry()->isSingleHostMultiConnectionEnabled()) {
+      getFileEntry()->removeURIWhoseHostnameIs(getRequest()->getHost());
     }
-    _requestGroup->getURISelector()->tuneDownloadCommand
-      (_fileEntry->getRemainingUris(), command);
-    e->addCommand(command);
+    getRequestGroup()->getURISelector()->tuneDownloadCommand
+      (getFileEntry()->getRemainingUris(), command);
+    getDownloadEngine()->addCommand(command);
     return true;
-  } else if(sequence == SEQ_HEAD_OK ||
-            sequence == SEQ_DOWNLOAD_ALREADY_COMPLETED) {
+  } else if(_sequence == SEQ_HEAD_OK ||
+            _sequence == SEQ_DOWNLOAD_ALREADY_COMPLETED) {
     return true;
-  } else if(sequence == SEQ_FILE_PREPARATION) {
+  } else if(_sequence == SEQ_FILE_PREPARATION) {
     if(getOption()->getAsBool(PREF_FTP_PASV)) {
-      sequence = SEQ_SEND_PASV;
+      _sequence = SEQ_SEND_PASV;
     } else {
-      sequence = SEQ_PREPARE_SERVER_SOCKET;
+      _sequence = SEQ_PREPARE_SERVER_SOCKET;
     }
     return false;
-  } else if(sequence == SEQ_EXIT) {
+  } else if(_sequence == SEQ_EXIT) {
     return true;
   } else {
-    e->addCommand(this);
+    getDownloadEngine()->addCommand(this);
     return false;
   }
 }
 
 bool FtpNegotiationCommand::recvGreeting() {
   if(!checkIfConnectionEstablished
-     (socket, _connectedHostname, _connectedAddr, _connectedPort)) {
-    sequence = SEQ_EXIT;
+     (getSocket(), _connectedHostname, _connectedAddr, _connectedPort)) {
+    _sequence = SEQ_EXIT;
     return false;
   }
-  setTimeout(_requestGroup->getTimeout());
+  setTimeout(getRequestGroup()->getTimeout());
   //socket->setBlockingMode();
   disableWriteCheckSocket();
-  setReadCheckSocket(socket);
+  setReadCheckSocket(getSocket());
 
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   if(status == 0) {
     return false;
   }
   if(status != 220) {
     throw DL_ABORT_EX(EX_CONNECTION_FAILED);
   }
-  sequence = SEQ_SEND_USER;
+  _sequence = SEQ_SEND_USER;
 
   return true;
 }
 
 bool FtpNegotiationCommand::sendUser() {
-  if(ftp->sendUser()) {
+  if(_ftp->sendUser()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_USER;
+    _sequence = SEQ_RECV_USER;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvUser() {
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   switch(status) {
   case 0:
     return false;
   case 230:
-    sequence = SEQ_SEND_TYPE;
+    _sequence = SEQ_SEND_TYPE;
     break;
   case 331:
-    sequence = SEQ_SEND_PASS;
+    _sequence = SEQ_SEND_PASS;
     break;
   default:
     throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, status).str());
@@ -189,56 +190,56 @@ bool FtpNegotiationCommand::recvUser() {
 }
 
 bool FtpNegotiationCommand::sendPass() {
-  if(ftp->sendPass()) {
+  if(_ftp->sendPass()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_PASS;
+    _sequence = SEQ_RECV_PASS;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvPass() {
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   if(status == 0) {
     return false;
   }
   if(status != 230) {
     throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, status).str());
   }
-  sequence = SEQ_SEND_TYPE;
+  _sequence = SEQ_SEND_TYPE;
   return true;
 }
 
 bool FtpNegotiationCommand::sendType() {
-  if(ftp->sendType()) {
+  if(_ftp->sendType()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_TYPE;
+    _sequence = SEQ_RECV_TYPE;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvType() {
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   if(status == 0) {
     return false;
   }
   if(status != 200) {
     throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, status).str());
   }
-  sequence = SEQ_SEND_PWD;
+  _sequence = SEQ_SEND_PWD;
   return true;
 }
 
 bool FtpNegotiationCommand::sendPwd()
 {
-  if(ftp->sendPwd()) {
+  if(_ftp->sendPwd()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_PWD;
+    _sequence = SEQ_RECV_PWD;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
@@ -246,42 +247,42 @@ bool FtpNegotiationCommand::sendPwd()
 bool FtpNegotiationCommand::recvPwd()
 {
   std::string pwd;
-  unsigned int status = ftp->receivePwdResponse(pwd);
+  unsigned int status = _ftp->receivePwdResponse(pwd);
   if(status == 0) {
     return false;
   }
   if(status != 257) {
     throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, status).str());
   }
-  ftp->setBaseWorkingDir(pwd);
+  _ftp->setBaseWorkingDir(pwd);
   if(getLogger()->info()) {
     getLogger()->info("CUID#%s - base working directory is '%s'",
                       util::itos(getCuid()).c_str(), pwd.c_str());
   }
-  sequence = SEQ_SEND_CWD;
+  _sequence = SEQ_SEND_CWD;
   return true;
 }
 
 bool FtpNegotiationCommand::sendCwd() {
   // Calling setReadCheckSocket() is needed when the socket is reused, 
-  setReadCheckSocket(socket);
-  if(ftp->sendCwd()) {
+  setReadCheckSocket(getSocket());
+  if(_ftp->sendCwd()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_CWD;
+    _sequence = SEQ_RECV_CWD;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvCwd() {
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   if(status == 0) {
     return false;
   }
   if(status != 250) {
     poolConnection();
-    _requestGroup->increaseAndValidateFileNotFoundCount();
+    getRequestGroup()->increaseAndValidateFileNotFoundCount();
     if (status == 550)
       throw DL_ABORT_EX2(MSG_RESOURCE_NOT_FOUND,
                          downloadresultcode::RESOURCE_NOT_FOUND);
@@ -289,20 +290,20 @@ bool FtpNegotiationCommand::recvCwd() {
       throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, status).str());
   }
   if(getOption()->getAsBool(PREF_REMOTE_TIME)) {
-    sequence = SEQ_SEND_MDTM;
+    _sequence = SEQ_SEND_MDTM;
   } else {
-    sequence = SEQ_SEND_SIZE;
+    _sequence = SEQ_SEND_SIZE;
   }
   return true;
 }
 
 bool FtpNegotiationCommand::sendMdtm()
 {
-  if(ftp->sendMdtm()) {
+  if(_ftp->sendMdtm()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_MDTM;
+    _sequence = SEQ_RECV_MDTM;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
@@ -310,13 +311,13 @@ bool FtpNegotiationCommand::sendMdtm()
 bool FtpNegotiationCommand::recvMdtm()
 {
   Time lastModifiedTime = Time::null();
-  unsigned int status = ftp->receiveMdtmResponse(lastModifiedTime);
+  unsigned int status = _ftp->receiveMdtmResponse(lastModifiedTime);
   if(status == 0) {
     return false;
   }
   if(status == 213) {
     if(lastModifiedTime.good()) {
-      _requestGroup->updateLastModifiedTime(lastModifiedTime);
+      getRequestGroup()->updateLastModifiedTime(lastModifiedTime);
       time_t t = lastModifiedTime.getTime();
       struct tm* tms = gmtime(&t); // returned struct is statically allocated.
       if(tms) {
@@ -340,84 +341,87 @@ bool FtpNegotiationCommand::recvMdtm()
                         util::itos(getCuid()).c_str());
     }
   }
-  sequence = SEQ_SEND_SIZE;
+  _sequence = SEQ_SEND_SIZE;
   return true;  
 }
 
 bool FtpNegotiationCommand::sendSize() {
-  if(ftp->sendSize()) {
+  if(_ftp->sendSize()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_SIZE;
+    _sequence = SEQ_RECV_SIZE;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::onFileSizeDetermined(uint64_t totalLength)
 {
-  _fileEntry->setLength(totalLength);
-  if(_fileEntry->getPath().empty()) {
-    _fileEntry->setPath
+  getFileEntry()->setLength(totalLength);
+  if(getFileEntry()->getPath().empty()) {
+    getFileEntry()->setPath
       (util::applyDir
        (getDownloadContext()->getDir(),
-        util::fixTaintedBasename(util::percentDecode(req->getFile()))));
+        util::fixTaintedBasename
+        (util::percentDecode(getRequest()->getFile()))));
   }
-  _requestGroup->preDownloadProcessing();
-  if(e->getRequestGroupMan()->isSameFileBeingDownloaded(_requestGroup)) {
+  getRequestGroup()->preDownloadProcessing();
+  if(getDownloadEngine()->getRequestGroupMan()->
+     isSameFileBeingDownloaded(getRequestGroup())) {
     throw DOWNLOAD_FAILURE_EXCEPTION
       (StringFormat(EX_DUPLICATE_FILE_DOWNLOAD,
-                    _requestGroup->getFirstFilePath().c_str()).str());
+                    getRequestGroup()->getFirstFilePath().c_str()).str());
   }
   if(totalLength == 0) {
 
     if(getOption()->getAsBool(PREF_FTP_PASV)) {
-      sequence = SEQ_SEND_PASV;
+      _sequence = SEQ_SEND_PASV;
     } else {
-      sequence = SEQ_PREPARE_SERVER_SOCKET;
+      _sequence = SEQ_PREPARE_SERVER_SOCKET;
     }
 
     if(getOption()->getAsBool(PREF_DRY_RUN)) {
-      _requestGroup->initPieceStorage();
+      getRequestGroup()->initPieceStorage();
       onDryRunFileFound();
       return false;
     }
 
-    if(_requestGroup->downloadFinishedByFileLength()) {
-      _requestGroup->initPieceStorage();
-      _requestGroup->getPieceStorage()->markAllPiecesDone();
-      sequence = SEQ_DOWNLOAD_ALREADY_COMPLETED;
+    if(getRequestGroup()->downloadFinishedByFileLength()) {
+      getRequestGroup()->initPieceStorage();
+      getPieceStorage()->markAllPiecesDone();
+      _sequence = SEQ_DOWNLOAD_ALREADY_COMPLETED;
 
       getLogger()->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
-                          util::itos(_requestGroup->getGID()).c_str(),
-                          _requestGroup->getFirstFilePath().c_str());
+                          util::itos(getRequestGroup()->getGID()).c_str(),
+                          getRequestGroup()->getFirstFilePath().c_str());
 
       poolConnection();
 
       return false;
     }
 
-    _requestGroup->shouldCancelDownloadForSafety();
-    _requestGroup->initPieceStorage();
-    _requestGroup->getPieceStorage()->getDiskAdaptor()->initAndOpenFile();
+    getRequestGroup()->shouldCancelDownloadForSafety();
+    getRequestGroup()->initPieceStorage();
+    getPieceStorage()->getDiskAdaptor()->initAndOpenFile();
 
     if(getDownloadContext()->knowsTotalLength()) {
-      sequence = SEQ_DOWNLOAD_ALREADY_COMPLETED;
+      _sequence = SEQ_DOWNLOAD_ALREADY_COMPLETED;
       poolConnection();
       return false;
     }
     // We have to make sure that command that has Request object must
     // have segment after PieceStorage is initialized. See
     // AbstractCommand::execute()
-    _requestGroup->getSegmentMan()->getSegment(getCuid(), 0);
+    getSegmentMan()->getSegment(getCuid(), 0);
     return true;
   } else {
-    _requestGroup->adjustFilename
-      (SharedHandle<BtProgressInfoFile>(new DefaultBtProgressInfoFile
-                                        (_requestGroup->getDownloadContext(),
-                                         SharedHandle<PieceStorage>(),
-                                         getOption().get())));
-    _requestGroup->initPieceStorage();
+    getRequestGroup()->adjustFilename
+      (SharedHandle<BtProgressInfoFile>
+       (new DefaultBtProgressInfoFile
+        (getDownloadContext(),
+         SharedHandle<PieceStorage>(),
+         getOption().get())));
+    getRequestGroup()->initPieceStorage();
 
     if(getOption()->getAsBool(PREF_DRY_RUN)) {
       onDryRunFileFound();
@@ -425,27 +429,28 @@ bool FtpNegotiationCommand::onFileSizeDetermined(uint64_t totalLength)
     }
 
     BtProgressInfoFileHandle infoFile
-      (new DefaultBtProgressInfoFile(_requestGroup->getDownloadContext(),
-                                     _requestGroup->getPieceStorage(),
+      (new DefaultBtProgressInfoFile(getDownloadContext(),
+                                     getPieceStorage(),
                                      getOption().get()));
-    if(!infoFile->exists() && _requestGroup->downloadFinishedByFileLength()) {
-      _requestGroup->getPieceStorage()->markAllPiecesDone();
+    if(!infoFile->exists() &&
+       getRequestGroup()->downloadFinishedByFileLength()) {
+      getPieceStorage()->markAllPiecesDone();
 
-      sequence = SEQ_DOWNLOAD_ALREADY_COMPLETED;
+      _sequence = SEQ_DOWNLOAD_ALREADY_COMPLETED;
       
       getLogger()->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
-                          util::itos(_requestGroup->getGID()).c_str(),
-                          _requestGroup->getFirstFilePath().c_str());
+                          util::itos(getRequestGroup()->getGID()).c_str(),
+                          getRequestGroup()->getFirstFilePath().c_str());
 
       poolConnection();
       
       return false;
     }
-    _requestGroup->loadAndOpenFile(infoFile);
+    getRequestGroup()->loadAndOpenFile(infoFile);
     // We have to make sure that command that has Request object must
     // have segment after PieceStorage is initialized. See
     // AbstractCommand::execute()
-    _requestGroup->getSegmentMan()->getSegment(getCuid(), 0);
+    getSegmentMan()->getSegment(getCuid(), 0);
 
     prepareForNextAction(this);
 
@@ -456,7 +461,7 @@ bool FtpNegotiationCommand::onFileSizeDetermined(uint64_t totalLength)
 
 bool FtpNegotiationCommand::recvSize() {
   uint64_t size = 0;
-  unsigned int status = ftp->receiveSizeResponse(size);
+  unsigned int status = _ftp->receiveSizeResponse(size);
   if(status == 0) {
     return false;
   }
@@ -467,13 +472,13 @@ bool FtpNegotiationCommand::recvSize() {
         (StringFormat(EX_TOO_LARGE_FILE,
                       util::uitos(size, true).c_str()).str());
     }
-    if(_requestGroup->getPieceStorage().isNull()) {
+    if(getPieceStorage().isNull()) {
 
-      sequence = SEQ_FILE_PREPARATION;
+      _sequence = SEQ_FILE_PREPARATION;
       return onFileSizeDetermined(size);
 
     } else {
-      _requestGroup->validateTotalLength(_fileEntry->getLength(), size);
+      getRequestGroup()->validateTotalLength(getFileEntry()->getLength(), size);
     }
 
   } else {
@@ -484,7 +489,7 @@ bool FtpNegotiationCommand::recvSize() {
     // Even if one of the other servers waiting in the queue supports SIZE
     // command, resuming and segmented downloading are disabled when the first
     // contacted FTP server doesn't support it.
-    if(_requestGroup->getPieceStorage().isNull()) {
+    if(getPieceStorage().isNull()) {
       getDownloadContext()->markTotalLengthIsUnknown();
       return onFileSizeDetermined(0);
 
@@ -493,62 +498,62 @@ bool FtpNegotiationCommand::recvSize() {
     // wrong file to be downloaded if user-specified URL is wrong.
   }
   if(getOption()->getAsBool(PREF_FTP_PASV)) {
-    sequence = SEQ_SEND_PASV;
+    _sequence = SEQ_SEND_PASV;
   } else {
-    sequence = SEQ_PREPARE_SERVER_SOCKET;
+    _sequence = SEQ_PREPARE_SERVER_SOCKET;
   }
   return true;
 }
 
 void FtpNegotiationCommand::afterFileAllocation()
 {
-  setReadCheckSocket(socket);
+  setReadCheckSocket(getSocket());
 }
 
 bool FtpNegotiationCommand::prepareServerSocket()
 {
-  serverSocket = ftp->createServerSocket();
-  sequence = SEQ_SEND_PORT;
+  _serverSocket = _ftp->createServerSocket();
+  _sequence = SEQ_SEND_PORT;
   return true;
 }
 
 bool FtpNegotiationCommand::sendPort() {
   afterFileAllocation();
-  if(ftp->sendPort(serverSocket)) {
+  if(_ftp->sendPort(_serverSocket)) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_PORT;
+    _sequence = SEQ_RECV_PORT;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvPort() {
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   if(status == 0) {
     return false;
   }
   if(status != 200) {
     throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, status).str());
   }
-  sequence = SEQ_SEND_REST;
+  _sequence = SEQ_SEND_REST;
   return true;
 }
 
 bool FtpNegotiationCommand::sendPasv() {
   afterFileAllocation();
-  if(ftp->sendPasv()) {
+  if(_ftp->sendPasv()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_PASV;
+    _sequence = SEQ_RECV_PASV;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvPasv() {
   std::pair<std::string, uint16_t> dest;
-  unsigned int status = ftp->receivePasvResponse(dest);
+  unsigned int status = _ftp->receivePasvResponse(dest);
   if(status == 0) {
     return false;
   }
@@ -558,7 +563,7 @@ bool FtpNegotiationCommand::recvPasv() {
   // TODO Should we check to see that dest.first is not in noProxy list?
   if(isProxyDefined()) {
     _dataConnAddr = dest;
-    sequence = SEQ_RESOLVE_PROXY;
+    _sequence = SEQ_RESOLVE_PROXY;
     return true;
   } else {
     // make a data connection to the server.
@@ -567,11 +572,11 @@ bool FtpNegotiationCommand::recvPasv() {
                         dest.first.c_str(),
                         dest.second);
     }
-    dataSocket.reset(new SocketCore());
-    dataSocket->establishConnection(dest.first, dest.second);
+    _dataSocket.reset(new SocketCore());
+    _dataSocket->establishConnection(dest.first, dest.second);
     disableReadCheckSocket();
-    setWriteCheckSocket(dataSocket);
-    sequence = SEQ_SEND_REST_PASV;
+    setWriteCheckSocket(_dataSocket);
+    _sequence = SEQ_SEND_REST_PASV;
     return false;
   }
 }
@@ -589,27 +594,29 @@ bool FtpNegotiationCommand::resolveProxy()
     getLogger()->info(MSG_CONNECTING_TO_SERVER, util::itos(getCuid()).c_str(),
                       _proxyAddr.c_str(), proxyReq->getPort());
   }
-  dataSocket.reset(new SocketCore());                  
-  dataSocket->establishConnection(_proxyAddr, proxyReq->getPort());
+  _dataSocket.reset(new SocketCore());                  
+  _dataSocket->establishConnection(_proxyAddr, proxyReq->getPort());
   disableReadCheckSocket();
-  setWriteCheckSocket(dataSocket);
-  _http.reset(new HttpConnection(getCuid(), dataSocket, getOption().get()));
-  sequence = SEQ_SEND_TUNNEL_REQUEST;
+  setWriteCheckSocket(_dataSocket);
+  _http.reset(new HttpConnection(getCuid(), _dataSocket, getOption().get()));
+  _sequence = SEQ_SEND_TUNNEL_REQUEST;
   return false;
 }
 
 bool FtpNegotiationCommand::sendTunnelRequest()
 {
   if(_http->sendBufferIsEmpty()) {
-    if(dataSocket->isReadable(0)) {
-      std::string error = socket->getSocketError();
+    if(_dataSocket->isReadable(0)) {
+      std::string error = getSocket()->getSocketError();
       if(!error.empty()) {
         SharedHandle<Request> proxyReq = createProxyRequest();
-        e->markBadIPAddress(proxyReq->getHost(),_proxyAddr,proxyReq->getPort());
-        std::string nextProxyAddr = e->findCachedIPAddress
+        getDownloadEngine()->markBadIPAddress(proxyReq->getHost(),
+                                              _proxyAddr,proxyReq->getPort());
+        std::string nextProxyAddr = getDownloadEngine()->findCachedIPAddress
           (proxyReq->getHost(), proxyReq->getPort());
         if(nextProxyAddr.empty()) {
-          e->removeCachedIPAddress(proxyReq->getHost(), proxyReq->getPort());
+          getDownloadEngine()->removeCachedIPAddress(proxyReq->getHost(),
+                                                     proxyReq->getPort());
           throw DL_RETRY_EX
             (StringFormat(MSG_ESTABLISHING_CONNECTION_FAILED,
                           error.c_str()).str());
@@ -625,7 +632,7 @@ bool FtpNegotiationCommand::sendTunnelRequest()
                               util::itos(getCuid()).c_str(),
                               _proxyAddr.c_str(), proxyReq->getPort());
           }
-          dataSocket->establishConnection(_proxyAddr, proxyReq->getPort());
+          _dataSocket->establishConnection(_proxyAddr, proxyReq->getPort());
           return false;
         }
       }
@@ -644,11 +651,11 @@ bool FtpNegotiationCommand::sendTunnelRequest()
   }
   if(_http->sendBufferIsEmpty()) {
     disableWriteCheckSocket();
-    setReadCheckSocket(dataSocket);
-    sequence = SEQ_RECV_TUNNEL_RESPONSE;
+    setReadCheckSocket(_dataSocket);
+    _sequence = SEQ_RECV_TUNNEL_RESPONSE;
     return false;
   } else {
-    setWriteCheckSocket(dataSocket);
+    setWriteCheckSocket(_dataSocket);
     return false;
   }
 }
@@ -662,29 +669,29 @@ bool FtpNegotiationCommand::recvTunnelResponse()
   if(httpResponse->getResponseStatus() != HttpHeader::S200) {
     throw DL_RETRY_EX(EX_PROXY_CONNECTION_FAILED);
   }
-  sequence = SEQ_SEND_REST_PASV;
+  _sequence = SEQ_SEND_REST_PASV;
   return true;
 }
 
 bool FtpNegotiationCommand::sendRestPasv(const SharedHandle<Segment>& segment) {
-  //dataSocket->setBlockingMode();
-  setReadCheckSocket(socket);
+  //_dataSocket->setBlockingMode();
+  setReadCheckSocket(getSocket());
   disableWriteCheckSocket();
   return sendRest(segment);
 }
 
 bool FtpNegotiationCommand::sendRest(const SharedHandle<Segment>& segment) {
-  if(ftp->sendRest(segment)) {
+  if(_ftp->sendRest(segment)) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_REST;
+    _sequence = SEQ_RECV_REST;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvRest(const SharedHandle<Segment>& segment) {
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   if(status == 0) {
     return false;
   }
@@ -696,27 +703,27 @@ bool FtpNegotiationCommand::recvRest(const SharedHandle<Segment>& segment) {
                          downloadresultcode::CANNOT_RESUME);
     }
   }
-  sequence = SEQ_SEND_RETR;
+  _sequence = SEQ_SEND_RETR;
   return true;
 }
 
 bool FtpNegotiationCommand::sendRetr() {
-  if(ftp->sendRetr()) {
+  if(_ftp->sendRetr()) {
     disableWriteCheckSocket();
-    sequence = SEQ_RECV_RETR;
+    _sequence = SEQ_RECV_RETR;
   } else {
-    setWriteCheckSocket(socket);
+    setWriteCheckSocket(getSocket());
   }
   return false;
 }
 
 bool FtpNegotiationCommand::recvRetr() {
-  unsigned int status = ftp->receiveResponse();
+  unsigned int status = _ftp->receiveResponse();
   if(status == 0) {
     return false;
   }
   if(status != 150 && status != 125) {
-    _requestGroup->increaseAndValidateFileNotFoundCount();
+    getRequestGroup()->increaseAndValidateFileNotFoundCount();
     if (status == 550)
       throw DL_ABORT_EX2(MSG_RESOURCE_NOT_FOUND,
                          downloadresultcode::RESOURCE_NOT_FOUND);
@@ -724,12 +731,12 @@ bool FtpNegotiationCommand::recvRetr() {
       throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, status).str());
   }
   if(getOption()->getAsBool(PREF_FTP_PASV)) {
-    sequence = SEQ_NEGOTIATION_COMPLETED;
+    _sequence = SEQ_NEGOTIATION_COMPLETED;
     return false;
   } else {
     disableReadCheckSocket();
-    setReadCheckSocket(serverSocket);
-    sequence = SEQ_WAIT_CONNECTION;
+    setReadCheckSocket(_serverSocket);
+    _sequence = SEQ_WAIT_CONNECTION;
     return false;
   }
 }
@@ -737,17 +744,17 @@ bool FtpNegotiationCommand::recvRetr() {
 bool FtpNegotiationCommand::waitConnection()
 {
   disableReadCheckSocket();
-  setReadCheckSocket(socket);
-  dataSocket.reset(serverSocket->acceptConnection());
-  dataSocket->setNonBlockingMode();
-  sequence = SEQ_NEGOTIATION_COMPLETED;
+  setReadCheckSocket(getSocket());
+  _dataSocket.reset(_serverSocket->acceptConnection());
+  _dataSocket->setNonBlockingMode();
+  _sequence = SEQ_NEGOTIATION_COMPLETED;
   return false;
 }
 
 bool FtpNegotiationCommand::processSequence
 (const SharedHandle<Segment>& segment) {
   bool doNextSequence = true;
-  switch(sequence) {
+  switch(_sequence) {
   case SEQ_RECV_GREETING:
     return recvGreeting();
   case SEQ_SEND_USER:
@@ -816,16 +823,17 @@ void FtpNegotiationCommand::poolConnection() const
 {
   if(getOption()->getAsBool(PREF_FTP_REUSE_CONNECTION)) {
     std::map<std::string, std::string> options;
-    options["baseWorkingDir"] = ftp->getBaseWorkingDir();
-    e->poolSocket(req, ftp->getUser(), createProxyRequest(), socket, options);
+    options["baseWorkingDir"] = _ftp->getBaseWorkingDir();
+    getDownloadEngine()->poolSocket(getRequest(), _ftp->getUser(),
+                                    createProxyRequest(), getSocket(), options);
   }
 }
 
 void FtpNegotiationCommand::onDryRunFileFound()
 {
-  _requestGroup->getPieceStorage()->markAllPiecesDone();
+  getPieceStorage()->markAllPiecesDone();
   poolConnection();
-  sequence = SEQ_HEAD_OK;
+  _sequence = SEQ_HEAD_OK;
 }
 
 } // namespace aria2
diff --git a/src/FtpNegotiationCommand.h b/src/FtpNegotiationCommand.h
index 7eb94795..3a9520ca 100644
--- a/src/FtpNegotiationCommand.h
+++ b/src/FtpNegotiationCommand.h
@@ -122,10 +122,10 @@ private:
 
   void onDryRunFileFound();
 
-  SharedHandle<SocketCore> dataSocket;
-  SharedHandle<SocketCore> serverSocket;
-  Seq sequence;
-  SharedHandle<FtpConnection> ftp;
+  SharedHandle<SocketCore> _dataSocket;
+  SharedHandle<SocketCore> _serverSocket;
+  Seq _sequence;
+  SharedHandle<FtpConnection> _ftp;
   // For tunneling
   SharedHandle<HttpConnection> _http;
   // IP, Port pair in pasv response
diff --git a/src/FtpTunnelRequestCommand.cc b/src/FtpTunnelRequestCommand.cc
index 2fcfbcd3..c6ff69fe 100644
--- a/src/FtpTunnelRequestCommand.cc
+++ b/src/FtpTunnelRequestCommand.cc
@@ -58,7 +58,8 @@ FtpTunnelRequestCommand::~FtpTunnelRequestCommand() {}
 Command* FtpTunnelRequestCommand::getNextCommand()
 {
   return new FtpTunnelResponseCommand
-    (getCuid(), req, _fileEntry, _requestGroup, httpConnection, e, socket);
+    (getCuid(), getRequest(), getFileEntry(), getRequestGroup(),
+     getHttpConnection(), getDownloadEngine(), getSocket());
 }
 
 } // namespace aria2
diff --git a/src/FtpTunnelResponseCommand.cc b/src/FtpTunnelResponseCommand.cc
index d1d1afb1..86084fe2 100644
--- a/src/FtpTunnelResponseCommand.cc
+++ b/src/FtpTunnelResponseCommand.cc
@@ -59,8 +59,9 @@ FtpTunnelResponseCommand::~FtpTunnelResponseCommand() {}
 
 Command* FtpTunnelResponseCommand::getNextCommand()
 {
-  return new FtpNegotiationCommand(getCuid(), req, _fileEntry,
-                                   _requestGroup, e, socket);
+  return new FtpNegotiationCommand(getCuid(), getRequest(), getFileEntry(),
+                                   getRequestGroup(), getDownloadEngine(),
+                                   getSocket());
 }
 
 } // namespace aria2
diff --git a/src/HttpDownloadCommand.cc b/src/HttpDownloadCommand.cc
index 3121da3f..7ff66769 100644
--- a/src/HttpDownloadCommand.cc
+++ b/src/HttpDownloadCommand.cc
@@ -71,29 +71,29 @@ HttpDownloadCommand::HttpDownloadCommand
 HttpDownloadCommand::~HttpDownloadCommand() {}
 
 bool HttpDownloadCommand::prepareForNextSegment() {
-  bool downloadFinished = _requestGroup->downloadFinished();
-  if(req->isPipeliningEnabled() && !downloadFinished) {
+  bool downloadFinished = getRequestGroup()->downloadFinished();
+  if(getRequest()->isPipeliningEnabled() && !downloadFinished) {
     HttpRequestCommand* command =
-      new HttpRequestCommand(getCuid(), req, _fileEntry,
-                             _requestGroup, _httpConnection, e,
-                             socket);
+      new HttpRequestCommand(getCuid(), getRequest(), getFileEntry(),
+                             getRequestGroup(), _httpConnection,
+                             getDownloadEngine(), getSocket());
     // Set proxy request here. aria2 sends the HTTP request specialized for
     // proxy.
-    if(resolveProxyMethod(req->getProtocol()) == V_GET) {
+    if(resolveProxyMethod(getRequest()->getProtocol()) == V_GET) {
       command->setProxyRequest(createProxyRequest());
     }
-    e->addCommand(command);
+    getDownloadEngine()->addCommand(command);
     return true;
   } else {
-    if(req->isPipeliningEnabled() ||
-       (req->isKeepAliveEnabled() &&
+    if(getRequest()->isPipeliningEnabled() ||
+       (getRequest()->isKeepAliveEnabled() &&
         (
-         ((!_transferEncodingDecoder.isNull() &&
-           _transferEncodingDecoder->finished()) ||
-          (!_contentEncodingDecoder.isNull() &&
-           _contentEncodingDecoder->finished())) ||
-         _fileEntry->getLastOffset() ==
-         _segments.front()->getPositionToWrite()
+         ((!getTransferEncodingDecoder().isNull() &&
+           getTransferEncodingDecoder()->finished()) ||
+          (!getContentEncodingDecoder().isNull() &&
+           getContentEncodingDecoder()->finished())) ||
+         getFileEntry()->getLastOffset() ==
+         getSegments().front()->getPositionToWrite()
          )
         )
        ) {
@@ -102,20 +102,23 @@ bool HttpDownloadCommand::prepareForNextSegment() {
       // pool terminated socket.  In HTTP/1.1, keep-alive is default,
       // so closing connection without Connection: close header means
       // that server is broken or not configured properly.
-      e->poolSocket(req, createProxyRequest(), socket);
+      getDownloadEngine()->poolSocket
+        (getRequest(), createProxyRequest(), getSocket());
     }
     // The request was sent assuming that server supported pipelining, but
     // it turned out that server didn't support it.
     // We detect this situation by comparing the end byte in range header
     // of the response with the end byte of segment.
     // If it is the same, HTTP negotiation is necessary for the next request.
-    if(!req->isPipeliningEnabled() && req->isPipeliningHint() &&
+    if(!getRequest()->isPipeliningEnabled() &&
+       getRequest()->isPipeliningHint() &&
        !downloadFinished) {
-      const SharedHandle<Segment>& segment = _segments.front();
+      const SharedHandle<Segment>& segment = getSegments().front();
 
-      off_t lastOffset =_fileEntry->gtoloff
-        (std::min(static_cast<off_t>(segment->getPosition()+segment->getLength()),
-                  _fileEntry->getLastOffset()));
+      off_t lastOffset =getFileEntry()->gtoloff
+        (std::min(static_cast<off_t>
+                  (segment->getPosition()+segment->getLength()),
+                  getFileEntry()->getLastOffset()));
       
       if(lastOffset ==
          _httpResponse->getHttpHeader()->getRange()->getEndByte()+1) {
diff --git a/src/HttpInitiateConnectionCommand.cc b/src/HttpInitiateConnectionCommand.cc
index c940a071..822e6c24 100644
--- a/src/HttpInitiateConnectionCommand.cc
+++ b/src/HttpInitiateConnectionCommand.cc
@@ -73,32 +73,39 @@ Command* HttpInitiateConnectionCommand::createNextCommand
   Command* command;
   if(!proxyRequest.isNull()) {
     SharedHandle<SocketCore> pooledSocket =
-      e->popPooledSocket(req->getHost(), req->getPort(),
-                         proxyRequest->getHost(), proxyRequest->getPort());
-    std::string proxyMethod = resolveProxyMethod(req->getProtocol());
+      getDownloadEngine()->popPooledSocket
+      (getRequest()->getHost(), getRequest()->getPort(),
+       proxyRequest->getHost(), proxyRequest->getPort());
+    std::string proxyMethod = resolveProxyMethod(getRequest()->getProtocol());
     if(pooledSocket.isNull()) {
       if(getLogger()->info()) {
         getLogger()->info(MSG_CONNECTING_TO_SERVER,
                           util::itos(getCuid()).c_str(), addr.c_str(), port);
       }
-      socket.reset(new SocketCore());
-      socket->establishConnection(addr, port);
+      createSocket();
+      getSocket()->establishConnection(addr, port);
 
       if(proxyMethod == V_TUNNEL) {
         HttpProxyRequestCommand* c =
-          new HttpProxyRequestCommand(getCuid(), req, _fileEntry,
-                                      _requestGroup, e,
-                                      proxyRequest, socket);
+          new HttpProxyRequestCommand(getCuid(),
+                                      getRequest(),
+                                      getFileEntry(),
+                                      getRequestGroup(),
+                                      getDownloadEngine(),
+                                      proxyRequest,
+                                      getSocket());
         c->setConnectedAddr(hostname, addr, port);
         command = c;
       } else if(proxyMethod == V_GET) {
         SharedHandle<HttpConnection> httpConnection
-          (new HttpConnection(getCuid(), socket, getOption().get()));
-        HttpRequestCommand* c = new HttpRequestCommand(getCuid(), req,
-                                                       _fileEntry,
-                                                       _requestGroup,
-                                                       httpConnection, e,
-                                                       socket);
+          (new HttpConnection(getCuid(), getSocket(), getOption().get()));
+        HttpRequestCommand* c = new HttpRequestCommand(getCuid(),
+                                                       getRequest(),
+                                                       getFileEntry(),
+                                                       getRequestGroup(),
+                                                       httpConnection,
+                                                       getDownloadEngine(),
+                                                       getSocket());
         c->setConnectedAddr(hostname, addr, port);
         c->setProxyRequest(proxyRequest);
         command = c;
@@ -109,10 +116,12 @@ Command* HttpInitiateConnectionCommand::createNextCommand
     } else {
       SharedHandle<HttpConnection> httpConnection
         (new HttpConnection(getCuid(), pooledSocket, getOption().get()));
-      HttpRequestCommand* c = new HttpRequestCommand(getCuid(), req,
-                                                     _fileEntry,
-                                                     _requestGroup,
-                                                     httpConnection, e,
+      HttpRequestCommand* c = new HttpRequestCommand(getCuid(),
+                                                     getRequest(),
+                                                     getFileEntry(),
+                                                     getRequestGroup(),
+                                                     httpConnection,
+                                                     getDownloadEngine(),
                                                      pooledSocket);
       if(proxyMethod == V_GET) {
         c->setProxyRequest(proxyRequest);
@@ -121,22 +130,26 @@ Command* HttpInitiateConnectionCommand::createNextCommand
     }
   } else {
     SharedHandle<SocketCore> pooledSocket =
-      e->popPooledSocket(resolvedAddresses, req->getPort());
+      getDownloadEngine()->popPooledSocket
+      (resolvedAddresses, getRequest()->getPort());
     if(pooledSocket.isNull()) {
       if(getLogger()->info()) {
         getLogger()->info(MSG_CONNECTING_TO_SERVER,
                           util::itos(getCuid()).c_str(), addr.c_str(), port);
       }
-      socket.reset(new SocketCore());
-      socket->establishConnection(addr, port);
+      createSocket();
+      getSocket()->establishConnection(addr, port);
     } else {
-      socket = pooledSocket;
+      setSocket(pooledSocket);
     }
     SharedHandle<HttpConnection> httpConnection
-      (new HttpConnection(getCuid(), socket, getOption().get()));
+      (new HttpConnection(getCuid(), getSocket(), getOption().get()));
     HttpRequestCommand* c =
-      new HttpRequestCommand(getCuid(), req, _fileEntry, _requestGroup,
-                             httpConnection, e, socket);
+      new HttpRequestCommand(getCuid(), getRequest(), getFileEntry(),
+                             getRequestGroup(),
+                             httpConnection,
+                             getDownloadEngine(),
+                             getSocket());
     if(pooledSocket.isNull()) {
       c->setConnectedAddr(hostname, addr, port);
     }
diff --git a/src/HttpProxyRequestCommand.cc b/src/HttpProxyRequestCommand.cc
index 7de74682..90cd0298 100644
--- a/src/HttpProxyRequestCommand.cc
+++ b/src/HttpProxyRequestCommand.cc
@@ -58,7 +58,8 @@ HttpProxyRequestCommand::~HttpProxyRequestCommand() {}
 Command* HttpProxyRequestCommand::getNextCommand()
 {
   return new HttpProxyResponseCommand
-    (getCuid(), req, _fileEntry, _requestGroup, httpConnection, e, socket);
+    (getCuid(), getRequest(), getFileEntry(), getRequestGroup(),
+     getHttpConnection(), getDownloadEngine(), getSocket());
 }
 
 } // namespace aria2
diff --git a/src/HttpProxyResponseCommand.cc b/src/HttpProxyResponseCommand.cc
index b577017f..e0a23c36 100644
--- a/src/HttpProxyResponseCommand.cc
+++ b/src/HttpProxyResponseCommand.cc
@@ -59,8 +59,9 @@ HttpProxyResponseCommand::~HttpProxyResponseCommand() {}
 
 Command* HttpProxyResponseCommand::getNextCommand()
 {
-  return new HttpRequestCommand(getCuid(), req, _fileEntry,
-                                _requestGroup, httpConnection, e, socket);
+  return new HttpRequestCommand(getCuid(), getRequest(), getFileEntry(),
+                                getRequestGroup(), getHttpConnection(),
+                                getDownloadEngine(), getSocket());
 }
 
 } // namespace aria2
diff --git a/src/HttpRequestCommand.cc b/src/HttpRequestCommand.cc
index 85b2a244..9e598adb 100644
--- a/src/HttpRequestCommand.cc
+++ b/src/HttpRequestCommand.cc
@@ -73,7 +73,7 @@ HttpRequestCommand::HttpRequestCommand
 {
   setTimeout(getOption()->getAsInt(PREF_CONNECT_TIMEOUT));
   disableReadCheckSocket();
-  setWriteCheckSocket(socket);
+  setWriteCheckSocket(getSocket());
 }
 
 HttpRequestCommand::~HttpRequestCommand() {}
@@ -115,47 +115,48 @@ createHttpRequest(const SharedHandle<Request>& req,
 
 bool HttpRequestCommand::executeInternal() {
   //socket->setBlockingMode();
-  if(req->getProtocol() == Request::PROTO_HTTPS) {
-    socket->prepareSecureConnection();
-    if(!socket->initiateSecureConnection(req->getHost())) {
-      setReadCheckSocketIf(socket, socket->wantRead());
-      setWriteCheckSocketIf(socket, socket->wantWrite());
-      e->addCommand(this);
+  if(getRequest()->getProtocol() == Request::PROTO_HTTPS) {
+    getSocket()->prepareSecureConnection();
+    if(!getSocket()->initiateSecureConnection(getRequest()->getHost())) {
+      setReadCheckSocketIf(getSocket(), getSocket()->wantRead());
+      setWriteCheckSocketIf(getSocket(), getSocket()->wantWrite());
+      getDownloadEngine()->addCommand(this);
       return false;
     }
   }
   if(_httpConnection->sendBufferIsEmpty()) {
     if(!checkIfConnectionEstablished
-       (socket, _connectedHostname, _connectedAddr, _connectedPort)) {
+       (getSocket(), _connectedHostname, _connectedAddr, _connectedPort)) {
       return true;
     }
 
-    if(_segments.empty()) {
+    if(getSegments().empty()) {
       SharedHandle<HttpRequest> httpRequest
-        (createHttpRequest(req,
-                           _fileEntry,
+        (createHttpRequest(getRequest(),
+                           getFileEntry(),
                            SharedHandle<Segment>(),
-                           _requestGroup->getTotalLength(),
+                           getRequestGroup()->getTotalLength(),
                            getOption(),
-                           _requestGroup,
-                           e->getCookieStorage(),
-                           e->getAuthConfigFactory(),
+                           getRequestGroup(),
+                           getDownloadEngine()->getCookieStorage(),
+                           getDownloadEngine()->getAuthConfigFactory(),
                            _proxyRequest));
       _httpConnection->sendRequest(httpRequest);
     } else {
       for(std::vector<SharedHandle<Segment> >::const_iterator itr =
-            _segments.begin(), eoi = _segments.end(); itr != eoi; ++itr) {
+            getSegments().begin(), eoi = getSegments().end();
+          itr != eoi; ++itr) {
         const SharedHandle<Segment>& segment = *itr;
         if(!_httpConnection->isIssued(segment)) {
           SharedHandle<HttpRequest> httpRequest
-            (createHttpRequest(req,
-                               _fileEntry,
+            (createHttpRequest(getRequest(),
+                               getFileEntry(),
                                segment,
-                               _requestGroup->getTotalLength(),
+                               getRequestGroup()->getTotalLength(),
                                getOption(),
-                               _requestGroup,
-                               e->getCookieStorage(),
-                               e->getAuthConfigFactory(),
+                               getRequestGroup(),
+                               getDownloadEngine()->getCookieStorage(),
+                               getDownloadEngine()->getAuthConfigFactory(),
                                _proxyRequest));
           _httpConnection->sendRequest(httpRequest);
         }
@@ -165,15 +166,19 @@ bool HttpRequestCommand::executeInternal() {
     _httpConnection->sendPendingData();
   }
   if(_httpConnection->sendBufferIsEmpty()) {
-    Command* command = new HttpResponseCommand(getCuid(), req, _fileEntry,
-                                               _requestGroup,
-                                               _httpConnection, e, socket);
-    e->addCommand(command);
+    Command* command = new HttpResponseCommand(getCuid(),
+                                               getRequest(),
+                                               getFileEntry(),
+                                               getRequestGroup(),
+                                               _httpConnection,
+                                               getDownloadEngine(),
+                                               getSocket());
+    getDownloadEngine()->addCommand(command);
     return true;
   } else {
-    setReadCheckSocketIf(socket, socket->wantRead());
-    setWriteCheckSocketIf(socket, socket->wantWrite());
-    e->addCommand(this);
+    setReadCheckSocketIf(getSocket(), getSocket()->wantRead());
+    setWriteCheckSocketIf(getSocket(), getSocket()->wantWrite());
+    getDownloadEngine()->addCommand(this);
     return false;
   }
 }
diff --git a/src/HttpResponseCommand.cc b/src/HttpResponseCommand.cc
index 02991f7d..30f7045a 100644
--- a/src/HttpResponseCommand.cc
+++ b/src/HttpResponseCommand.cc
@@ -87,21 +87,21 @@ HttpResponseCommand::HttpResponseCommand
  DownloadEngine* e,
  const SocketHandle& s)
   :AbstractCommand(cuid, req, fileEntry, requestGroup, e, s),
-   httpConnection(httpConnection)
+   _httpConnection(httpConnection)
 {}
 
 HttpResponseCommand::~HttpResponseCommand() {}
 
 bool HttpResponseCommand::executeInternal()
 {
-  SharedHandle<HttpRequest> httpRequest = httpConnection->getFirstHttpRequest();
-  SharedHandle<HttpResponse> httpResponse = httpConnection->receiveResponse();
+  SharedHandle<HttpRequest> httpRequest =_httpConnection->getFirstHttpRequest();
+  SharedHandle<HttpResponse> httpResponse = _httpConnection->receiveResponse();
   if(httpResponse.isNull()) {
     // The server has not responded to our request yet.
     // For socket->wantRead() == true, setReadCheckSocket(socket) is already
     // done in the constructor.
-    setWriteCheckSocketIf(socket, socket->wantWrite());
-    e->addCommand(this);
+    setWriteCheckSocketIf(getSocket(), getSocket()->wantWrite());
+    getDownloadEngine()->addCommand(this);
     return false;
   }
   // check HTTP status number
@@ -112,39 +112,40 @@ bool HttpResponseCommand::executeInternal()
   // Disable persistent connection if:
   //   Connection: close is received or the remote server is not HTTP/1.1.
   // We don't care whether non-HTTP/1.1 server returns Connection: keep-alive.
-  req->supportsPersistentConnection
+  getRequest()->supportsPersistentConnection
     (httpResponse->supportsPersistentConnection());
-  if(req->isPipeliningEnabled()) {
-    req->setMaxPipelinedRequest
+  if(getRequest()->isPipeliningEnabled()) {
+    getRequest()->setMaxPipelinedRequest
       (getOption()->getAsInt(PREF_MAX_HTTP_PIPELINING));
   }
 
   if(httpResponse->getResponseStatus() >= HttpHeader::S300) {
     if(httpResponse->getResponseStatus() == HttpHeader::S404) {
-      _requestGroup->increaseAndValidateFileNotFoundCount();
+      getRequestGroup()->increaseAndValidateFileNotFoundCount();
     }
     return skipResponseBody(httpResponse);
   }
-  if(!_fileEntry->isSingleHostMultiConnectionEnabled()) {
+  if(!getFileEntry()->isSingleHostMultiConnectionEnabled()) {
     // TODO redirection should be considered here. We need to parse
     // original URI to get hostname.
-    _fileEntry->removeURIWhoseHostnameIs(req->getHost());
+    getFileEntry()->removeURIWhoseHostnameIs(getRequest()->getHost());
   }
-  if(_requestGroup->getPieceStorage().isNull()) {
+  if(getPieceStorage().isNull()) {
     uint64_t totalLength = httpResponse->getEntityLength();
-    _fileEntry->setLength(totalLength);
-    if(_fileEntry->getPath().empty()) {
-      _fileEntry->setPath
+    getFileEntry()->setLength(totalLength);
+    if(getFileEntry()->getPath().empty()) {
+      getFileEntry()->setPath
         (util::applyDir
          (getDownloadContext()->getDir(),
           util::fixTaintedBasename(httpResponse->determinFilename())));
     }
-    _fileEntry->setContentType(httpResponse->getContentType());
-    _requestGroup->preDownloadProcessing();
-    if(e->getRequestGroupMan()->isSameFileBeingDownloaded(_requestGroup)) {
+    getFileEntry()->setContentType(httpResponse->getContentType());
+    getRequestGroup()->preDownloadProcessing();
+    if(getDownloadEngine()->getRequestGroupMan()->
+       isSameFileBeingDownloaded(getRequestGroup())) {
       throw DOWNLOAD_FAILURE_EXCEPTION
         (StringFormat(EX_DUPLICATE_FILE_DOWNLOAD,
-                      _requestGroup->getFirstFilePath().c_str()).str());
+                      getRequestGroup()->getFirstFilePath().c_str()).str());
     }
     // update last modified time
     updateLastModifiedTime(httpResponse->getLastModifiedTime());
@@ -153,8 +154,8 @@ bool HttpResponseCommand::executeInternal()
     // assume we can do segmented downloading
     if(totalLength == 0 || shouldInflateContentEncoding(httpResponse)) {
       // we ignore content-length when inflate is required
-      _fileEntry->setLength(0);
-      if(req->getMethod() == Request::METHOD_GET &&
+      getFileEntry()->setLength(0);
+      if(getRequest()->getMethod() == Request::METHOD_GET &&
          (totalLength != 0 ||
           !httpResponse->getHttpHeader()->defined(HttpHeader::CONTENT_LENGTH))){
         // DownloadContext::knowsTotalLength() == true only when
@@ -167,22 +168,22 @@ bool HttpResponseCommand::executeInternal()
     }
   } else {
     // validate totalsize
-    _requestGroup->validateTotalLength(_fileEntry->getLength(),
+    getRequestGroup()->validateTotalLength(getFileEntry()->getLength(),
                                        httpResponse->getEntityLength());
     // update last modified time
     updateLastModifiedTime(httpResponse->getLastModifiedTime());
-    if(_requestGroup->getTotalLength() == 0) {
+    if(getRequestGroup()->getTotalLength() == 0) {
       // Since total length is unknown, the file size in previously
       // failed download could be larger than the size this time.
       // Also we can't resume in this case too.  So truncate the file
       // anyway.
-      _requestGroup->getPieceStorage()->getDiskAdaptor()->truncate(0);
-      e->addCommand
+      getPieceStorage()->getDiskAdaptor()->truncate(0);
+      getDownloadEngine()->addCommand
         (createHttpDownloadCommand(httpResponse,
                                    getTransferEncodingDecoder(httpResponse),
                                    getContentEncodingDecoder(httpResponse)));
     } else {
-      e->addCommand(createHttpDownloadCommand
+      getDownloadEngine()->addCommand(createHttpDownloadCommand
                     (httpResponse, getTransferEncodingDecoder(httpResponse)));
     }
     return true;
@@ -192,7 +193,7 @@ bool HttpResponseCommand::executeInternal()
 void HttpResponseCommand::updateLastModifiedTime(const Time& lastModified)
 {
   if(getOption()->getAsBool(PREF_REMOTE_TIME)) {
-    _requestGroup->updateLastModifiedTime(lastModified);
+    getRequestGroup()->updateLastModifiedTime(lastModified);
   }
 }
 
@@ -215,12 +216,12 @@ bool HttpResponseCommand::handleDefaultEncoding
 (const SharedHandle<HttpResponse>& httpResponse)
 {
   SharedHandle<HttpRequest> httpRequest = httpResponse->getHttpRequest();
-  _requestGroup->adjustFilename
+  getRequestGroup()->adjustFilename
     (SharedHandle<BtProgressInfoFile>(new DefaultBtProgressInfoFile
-                                      (_requestGroup->getDownloadContext(),
+                                      (getDownloadContext(),
                                        SharedHandle<PieceStorage>(),
                                        getOption().get())));
-  _requestGroup->initPieceStorage();
+  getRequestGroup()->initPieceStorage();
 
   if(getOption()->getAsBool(PREF_DRY_RUN)) {
     onDryRunFileFound();
@@ -228,47 +229,44 @@ bool HttpResponseCommand::handleDefaultEncoding
   }
 
   BtProgressInfoFileHandle infoFile
-    (new DefaultBtProgressInfoFile(_requestGroup->getDownloadContext(),
-                                   _requestGroup->getPieceStorage(),
+    (new DefaultBtProgressInfoFile(getDownloadContext(),
+                                   getPieceStorage(),
                                    getOption().get()));
-  if(!infoFile->exists() && _requestGroup->downloadFinishedByFileLength()) {
-    _requestGroup->getPieceStorage()->markAllPiecesDone();
-
+  if(!infoFile->exists() && getRequestGroup()->downloadFinishedByFileLength()) {
+    getPieceStorage()->markAllPiecesDone();
     getLogger()->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
-                        util::itos(_requestGroup->getGID()).c_str(),
-                        _requestGroup->getFirstFilePath().c_str());
-
+                        util::itos(getRequestGroup()->getGID()).c_str(),
+                        getRequestGroup()->getFirstFilePath().c_str());
     return true;
   }
-  _requestGroup->loadAndOpenFile(infoFile);
-  File file(_requestGroup->getFirstFilePath());
+  getRequestGroup()->loadAndOpenFile(infoFile);
+  File file(getRequestGroup()->getFirstFilePath());
   // We have to make sure that command that has Request object must
   // have segment after PieceStorage is initialized. See
   // AbstractCommand::execute()
-  SharedHandle<Segment> segment =
-    _requestGroup->getSegmentMan()->getSegment(getCuid(), 0);
+  SharedHandle<Segment> segment = getSegmentMan()->getSegment(getCuid(), 0);
   // pipelining requires implicit range specified. But the request for
   // this response most likely dones't contains range header. This means
   // we can't continue to use this socket because server sends all entity
   // body instead of a segment.
   // Therefore, we shutdown the socket here if pipelining is enabled.
   DownloadCommand* command = 0;
-  if(req->getMethod() == Request::METHOD_GET &&
+  if(getRequest()->getMethod() == Request::METHOD_GET &&
      !segment.isNull() && segment->getPositionToWrite() == 0 &&
-     !req->isPipeliningEnabled()) {
+     !getRequest()->isPipeliningEnabled()) {
     command = createHttpDownloadCommand
       (httpResponse, getTransferEncodingDecoder(httpResponse));
   } else {
-    _requestGroup->getSegmentMan()->cancelSegment(getCuid());
-    _fileEntry->poolRequest(req);
+    getSegmentMan()->cancelSegment(getCuid());
+    getFileEntry()->poolRequest(getRequest());
   }
   // After command is passed to prepareForNextAction(), it is managed
   // by CheckIntegrityEntry.
   prepareForNextAction(command);
   command = 0;
-  if(req->getMethod() == Request::METHOD_HEAD) {
+  if(getRequest()->getMethod() == Request::METHOD_HEAD) {
     poolConnection();
-    req->setMethod(Request::METHOD_GET);
+    getRequest()->setMethod(Request::METHOD_GET);
   }
   return true;
 }
@@ -314,47 +312,43 @@ bool HttpResponseCommand::handleOtherEncoding
   SharedHandle<HttpRequest> httpRequest = httpResponse->getHttpRequest();
 
   if(getOption()->getAsBool(PREF_DRY_RUN)) {
-    _requestGroup->initPieceStorage();
+    getRequestGroup()->initPieceStorage();
     onDryRunFileFound();
     return true;
   }
 
-  if(req->getMethod() == Request::METHOD_HEAD) {
+  if(getRequest()->getMethod() == Request::METHOD_HEAD) {
     poolConnection();
-    req->setMethod(Request::METHOD_GET);
+    getRequest()->setMethod(Request::METHOD_GET);
     return prepareForRetry(0);
   }
 
   // For zero-length file, check existing file comparing its size
-  if(_requestGroup->downloadFinishedByFileLength()) {
-    _requestGroup->initPieceStorage();
-    _requestGroup->getPieceStorage()->markAllPiecesDone();
-
+  if(getRequestGroup()->downloadFinishedByFileLength()) {
+    getRequestGroup()->initPieceStorage();
+    getPieceStorage()->markAllPiecesDone();
     getLogger()->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
-                        util::itos(_requestGroup->getGID()).c_str(),
-                        _requestGroup->getFirstFilePath().c_str());
-
+                        util::itos(getRequestGroup()->getGID()).c_str(),
+                        getRequestGroup()->getFirstFilePath().c_str());
     poolConnection();
     return true;
   }
 
-  _requestGroup->shouldCancelDownloadForSafety();
-  _requestGroup->initPieceStorage();
-
-  _requestGroup->getPieceStorage()->getDiskAdaptor()->initAndOpenFile();
-
+  getRequestGroup()->shouldCancelDownloadForSafety();
+  getRequestGroup()->initPieceStorage();
+  getPieceStorage()->getDiskAdaptor()->initAndOpenFile();
   // In this context, knowsTotalLength() is true only when the file is
   // really zero-length.
-  if(_requestGroup->getDownloadContext()->knowsTotalLength()) {
+  if(getDownloadContext()->knowsTotalLength()) {
     poolConnection();
     return true;
   }
   // We have to make sure that command that has Request object must
   // have segment after PieceStorage is initialized. See
   // AbstractCommand::execute()
-  _requestGroup->getSegmentMan()->getSegment(getCuid(), 0);
+  getSegmentMan()->getSegment(getCuid(), 0);
 
-  e->addCommand
+  getDownloadEngine()->addCommand
     (createHttpDownloadCommand(httpResponse,
                                getTransferEncodingDecoder(httpResponse),
                                getContentEncodingDecoder(httpResponse)));
@@ -369,22 +363,23 @@ bool HttpResponseCommand::skipResponseBody
   // thrown away.
 
   HttpSkipResponseCommand* command = new HttpSkipResponseCommand
-    (getCuid(), req, _fileEntry, _requestGroup, httpConnection, httpResponse,
-     e, socket);
+    (getCuid(), getRequest(), getFileEntry(), getRequestGroup(),
+     _httpConnection, httpResponse,
+     getDownloadEngine(), getSocket());
   command->setTransferEncodingDecoder(decoder);
 
   // If request method is HEAD or the response body is zero-length,
   // set command's status to real time so that avoid read check blocking
-  if(req->getMethod() == Request::METHOD_HEAD ||
+  if(getRequest()->getMethod() == Request::METHOD_HEAD ||
      (httpResponse->getEntityLength() == 0 &&
       !httpResponse->isTransferEncodingSpecified())) {
     command->setStatusRealtime();
     // If entity length == 0, then socket read/write check must be disabled.
     command->disableSocketCheck();
-    e->setNoWait(true);
+    getDownloadEngine()->setNoWait(true);
   }
 
-  e->addCommand(command);
+  getDownloadEngine()->addCommand(command);
   return true;
 }
 
@@ -395,8 +390,10 @@ HttpDownloadCommand* HttpResponseCommand::createHttpDownloadCommand
 {
 
   HttpDownloadCommand* command =
-    new HttpDownloadCommand(getCuid(), req, _fileEntry, _requestGroup,
-                            httpResponse, httpConnection, e, socket);
+    new HttpDownloadCommand(getCuid(), getRequest(), getFileEntry(),
+                            getRequestGroup(),
+                            httpResponse, _httpConnection,
+                            getDownloadEngine(), getSocket());
   command->setStartupIdleTime(getOption()->getAsInt(PREF_STARTUP_IDLE_TIME));
   command->setLowestDownloadSpeedLimit
     (getOption()->getAsInt(PREF_LOWEST_SPEED_LIMIT));
@@ -407,25 +404,26 @@ HttpDownloadCommand* HttpResponseCommand::createHttpDownloadCommand
     // Since the compressed file's length are returned in the response header
     // and the decompressed file size is unknown at this point, disable file
     // allocation here.
-    _requestGroup->setFileAllocationEnabled(false);
+    getRequestGroup()->setFileAllocationEnabled(false);
   }
 
-  _requestGroup->getURISelector()->tuneDownloadCommand
-    (_fileEntry->getRemainingUris(), command);
+  getRequestGroup()->getURISelector()->tuneDownloadCommand
+    (getFileEntry()->getRemainingUris(), command);
 
   return command;
 }
 
 void HttpResponseCommand::poolConnection()
 {
-  if(req->supportsPersistentConnection()) {
-    e->poolSocket(req, createProxyRequest(), socket);
+  if(getRequest()->supportsPersistentConnection()) {
+    getDownloadEngine()->poolSocket(getRequest(), createProxyRequest(),
+                                    getSocket());
   }
 }
 
 void HttpResponseCommand::onDryRunFileFound()
 {
-  _requestGroup->getPieceStorage()->markAllPiecesDone();
+  getPieceStorage()->markAllPiecesDone();
   poolConnection();
 }
 
diff --git a/src/HttpResponseCommand.h b/src/HttpResponseCommand.h
index 20371905..a62a7331 100644
--- a/src/HttpResponseCommand.h
+++ b/src/HttpResponseCommand.h
@@ -48,7 +48,7 @@ class SocketCore;
 
 class HttpResponseCommand : public AbstractCommand {
 private:
-  SharedHandle<HttpConnection> httpConnection;
+  SharedHandle<HttpConnection> _httpConnection;
 
   bool handleDefaultEncoding(const SharedHandle<HttpResponse>& httpResponse);
   bool handleOtherEncoding(const SharedHandle<HttpResponse>& httpResponse);
diff --git a/src/HttpSkipResponseCommand.cc b/src/HttpSkipResponseCommand.cc
index 974b4a82..7818d5f0 100644
--- a/src/HttpSkipResponseCommand.cc
+++ b/src/HttpSkipResponseCommand.cc
@@ -87,13 +87,13 @@ void HttpSkipResponseCommand::setTransferEncodingDecoder
 
 bool HttpSkipResponseCommand::executeInternal()
 {
-  if(req->getMethod() == Request::METHOD_HEAD ||
+  if(getRequest()->getMethod() == Request::METHOD_HEAD ||
      (_totalLength == 0 && _transferEncodingDecoder.isNull())) {
     // If request method is HEAD or content-length header is present and
     // it's value is 0, then pool socket for reuse.
     // If content-length header is not present, then EOF is expected in the end.
     // In this case, the content is thrown away and socket cannot be pooled. 
-    if(req->getMethod() == Request::METHOD_HEAD ||
+    if(getRequest()->getMethod() == Request::METHOD_HEAD ||
        _httpResponse->getHttpHeader()->defined(HttpHeader::CONTENT_LENGTH)) {
       poolConnection();
     }
@@ -104,7 +104,7 @@ bool HttpSkipResponseCommand::executeInternal()
   size_t bufSize = BUFSIZE;
 
   try {
-    socket->readData(buf, bufSize);
+    getSocket()->readData(buf, bufSize);
 
     if(_transferEncodingDecoder.isNull()) {
       _receivedBytes += bufSize;
@@ -114,7 +114,7 @@ bool HttpSkipResponseCommand::executeInternal()
       _transferEncodingDecoder->decode(buf, bufSize);
     }
     if(_totalLength != 0 && bufSize == 0 &&
-       !socket->wantRead() && !socket->wantWrite()) {
+       !getSocket()->wantRead() && !getSocket()->wantWrite()) {
       throw DL_RETRY_EX(EX_GOT_EOF);
     }
   } catch(RecoverableException& e) {
@@ -127,7 +127,7 @@ bool HttpSkipResponseCommand::executeInternal()
   bool finished = false;
   if(_transferEncodingDecoder.isNull()) {
     if(bufSize == 0) {
-      if(!socket->wantRead() && !socket->wantWrite()) {
+      if(!getSocket()->wantRead() && !getSocket()->wantWrite()) {
         return processResponse();
       }
     } else {
@@ -140,16 +140,17 @@ bool HttpSkipResponseCommand::executeInternal()
     poolConnection();
     return processResponse();
   } else {
-    setWriteCheckSocketIf(socket, socket->wantWrite());
-    e->addCommand(this);
+    setWriteCheckSocketIf(getSocket(), getSocket()->wantWrite());
+    getDownloadEngine()->addCommand(this);
     return false;
   }
 }
 
 void HttpSkipResponseCommand::poolConnection() const
 {
-  if(req->supportsPersistentConnection()) {
-    e->poolSocket(req, createProxyRequest(), socket);
+  if(getRequest()->supportsPersistentConnection()) {
+    getDownloadEngine()->poolSocket
+      (getRequest(), createProxyRequest(), getSocket());
   }
 }
 
@@ -159,7 +160,8 @@ bool HttpSkipResponseCommand::processResponse()
     unsigned int rnum =
       _httpResponse->getHttpRequest()->getRequest()->getRedirectCount();
     if(rnum >= Request::MAX_REDIRECT) {
-      throw DL_ABORT_EX(StringFormat("Too many redirects: count=%u", rnum).str());
+      throw DL_ABORT_EX
+        (StringFormat("Too many redirects: count=%u", rnum).str());
     }
     _httpResponse->processRedirect();
     return prepareForRetry(0);
@@ -167,8 +169,8 @@ bool HttpSkipResponseCommand::processResponse()
     if(_httpResponse->getResponseStatus() == HttpHeader::S401) {
       if(getOption()->getAsBool(PREF_HTTP_AUTH_CHALLENGE) &&
          !_httpResponse->getHttpRequest()->authenticationUsed() &&
-         e->getAuthConfigFactory()->activateBasicCred
-         (req->getHost(), req->getDir(), getOption().get())) {
+         getDownloadEngine()->getAuthConfigFactory()->activateBasicCred
+         (getRequest()->getHost(), getRequest()->getDir(), getOption().get())) {
         return prepareForRetry(0);
       } else {
         throw DL_ABORT_EX(EX_AUTH_FAILED);
@@ -177,7 +179,10 @@ bool HttpSkipResponseCommand::processResponse()
       throw DL_ABORT_EX2(MSG_RESOURCE_NOT_FOUND,
                          downloadresultcode::RESOURCE_NOT_FOUND);
     } else {
-      throw DL_ABORT_EX(StringFormat(EX_BAD_STATUS, util::parseUInt(_httpResponse->getResponseStatus())).str());
+      throw DL_ABORT_EX
+        (StringFormat
+         (EX_BAD_STATUS,
+          util::parseUInt(_httpResponse->getResponseStatus())).str());
     }
   } else {
     return prepareForRetry(0);
diff --git a/src/InitiateConnectionCommand.cc b/src/InitiateConnectionCommand.cc
index 6ef9e9c2..8b57e18e 100644
--- a/src/InitiateConnectionCommand.cc
+++ b/src/InitiateConnectionCommand.cc
@@ -77,8 +77,8 @@ bool InitiateConnectionCommand::executeInternal() {
   uint16_t port;
   SharedHandle<Request> proxyRequest = createProxyRequest();
   if(proxyRequest.isNull()) {
-    hostname = req->getHost();
-    port = req->getPort();
+    hostname = getRequest()->getHost();
+    port = getRequest()->getPort();
   } else {
     hostname = proxyRequest->getHost();
     port = proxyRequest->getPort();
@@ -86,21 +86,21 @@ bool InitiateConnectionCommand::executeInternal() {
   std::vector<std::string> addrs;
   std::string ipaddr = resolveHostname(addrs, hostname, port);
   if(ipaddr.empty()) {
-    e->addCommand(this);
+    getDownloadEngine()->addCommand(this);
     return false;
   }
   try {
     Command* command = createNextCommand(hostname, ipaddr, port,
                                          addrs, proxyRequest);
-    e->addCommand(command);
+    getDownloadEngine()->addCommand(command);
     return true;
   } catch(RecoverableException& ex) {
     // Catch exception and retry another address.
     // See also AbstractCommand::checkIfConnectionEstablished
 
     // TODO ipaddr might not be used if pooled sockt was found.
-    e->markBadIPAddress(hostname, ipaddr, port);
-    if(!e->findCachedIPAddress(hostname, port).empty()) {
+    getDownloadEngine()->markBadIPAddress(hostname, ipaddr, port);
+    if(!getDownloadEngine()->findCachedIPAddress(hostname, port).empty()) {
       if(getLogger()->info()) {
         getLogger()->info(EX_EXCEPTION_CAUGHT, ex);
         getLogger()->info(MSG_CONNECT_FAILED_AND_RETRY,
@@ -108,12 +108,13 @@ bool InitiateConnectionCommand::executeInternal() {
       }
       Command* command =
         InitiateConnectionCommandFactory::createInitiateConnectionCommand
-        (getCuid(), req, _fileEntry, _requestGroup, e);
-      e->setNoWait(true);
-      e->addCommand(command);
+        (getCuid(), getRequest(), getFileEntry(), getRequestGroup(),
+         getDownloadEngine());
+      getDownloadEngine()->setNoWait(true);
+      getDownloadEngine()->addCommand(command);
       return true;
     }
-    e->removeCachedIPAddress(hostname, port);
+    getDownloadEngine()->removeCachedIPAddress(hostname, port);
     throw;
   }
 }