Simplified instantiation logic of MediaChangerFacade

mediachanger/AcsProxy.hpp

@@ -48,8 +48,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  virtual void mountTapeReadOnly(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot) = 0;
+  virtual void mountTapeReadOnly(const std::string &vid, const AcsLibrarySlot &librarySlot) = 0;
   
   /**
    * Request the CASTOR ACS daemon to mount the specifed tape for read/write
@@ -58,8 +57,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  virtual void mountTapeReadWrite(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot) = 0;
+  virtual void mountTapeReadWrite(const std::string &vid, const AcsLibrarySlot &librarySlot) = 0;
   
   /**
    * Request the CASTOR ACS daemon to dismount the specifed tape from the tape
@@ -68,8 +66,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  virtual void dismountTape(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot) = 0;
+  virtual void dismountTape(const std::string &vid, const AcsLibrarySlot &librarySlot) = 0;
 
   /**
    * Request the CASTOR ACS daemon to forcefully dismount the specifed tape
@@ -82,8 +79,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  virtual void forceDismountTape(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot) = 0;
+  virtual void forceDismountTape(const std::string &vid, const AcsLibrarySlot &librarySlot) = 0;
 
 }; // class AcsProxy
 

mediachanger/AcsProxyDummy.cpp

-/*
- * The CERN Tape Archive(CTA) project
- * Copyright(C) 2015  CERN
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- *(at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "mediachanger/AcsProxyDummy.hpp"
-
-//------------------------------------------------------------------------------
-// mountTapeReadOnly
-//------------------------------------------------------------------------------
-void cta::mediachanger::AcsProxyDummy::mountTapeReadOnly(const std::string &vid,
-  const cta::mediachanger::AcsLibrarySlot &librarySlot) {
-}
-
-//------------------------------------------------------------------------------
-// mountTapeForMigration
-//------------------------------------------------------------------------------
-void cta::mediachanger::AcsProxyDummy::mountTapeReadWrite(const std::string &vid,
-  const cta::mediachanger::AcsLibrarySlot &librarySlot) {
-}
-
-//------------------------------------------------------------------------------
-// dismountTape
-//------------------------------------------------------------------------------
-void cta::mediachanger::AcsProxyDummy::dismountTape(const std::string &vid,
-  const cta::mediachanger::AcsLibrarySlot &librarySlot) {
-}
-
-//------------------------------------------------------------------------------
-// dismountTape
-//------------------------------------------------------------------------------
-void cta::mediachanger::AcsProxyDummy::forceDismountTape(const std::string &vid,
-  const cta::mediachanger::AcsLibrarySlot &librarySlot) {
-}

mediachanger/AcsProxyDummy.hpp

-/*
- * The CERN Tape Archive(CTA) project
- * Copyright(C) 2015  CERN
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- *(at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#pragma once
-
-#include "mediachanger/AcsProxy.hpp"
-
-namespace cta {
-namespace mediachanger {
-
-/**
- * Concrete class implementimg a dummy AcsProxy.
- */
-class AcsProxyDummy: public AcsProxy {
-public:
-
-  /**
-   * Request the CASTOR ACS daemon to mount the specified tape for read-only
-   * access into the tape drive in the specified library slot.
-   *
-   * @param vid The volume identifier of the tape to be mounted.
-   * @param librarySlot The slot in the library that contains the tape drive.
-   */ 
-  void mountTapeReadOnly(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
-    
-  /** 
-   * Request the CASTOR ACS daemon to mount the specifed tape for read/write
-   * access into the tape drive in the specified library slot.
-   *    
-   * @param vid The volume identifier of the tape to be mounted.
-   * @param librarySlot The slot in the library that contains the tape drive.
-   */
-  void mountTapeReadWrite(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
-    
-  /** 
-   * Request the CASTOR ACS daemon to dismount the specifed tape from the tape
-   * drive in the specified library slot.
-   *
-   * @param vid The volume identifier of the tape to be mounted.
-   * @param librarySlot The slot in the library that contains the tape drive.
-   */
-  void dismountTape(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
-
-  /**
-   * Request the CASTOR ACS daemon to forcefully dismount the specifed tape
-   * from the tape drive in the specified library slot.  Forcefully means
-   * rewinding and ejecting the tape if necessary.
-   *
-   * @param vid The volume identifier of the tape to be mounted.
-   * @param librarySlot The slot in the library that contains the tape drive.
-   */
-  void forceDismountTape(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
-
-}; // class AcsProxyDummy
-
-} // namespace mediachanger
-} // namespace cta
-

mediachanger/AcsProxyZmq.cpp

@@ -167,8 +167,7 @@ Frame createAcsForceDismountTapeFrame(const std::string &vid, const AcsLibrarySl
 //------------------------------------------------------------------------------
 // constructor
 //------------------------------------------------------------------------------
-AcsProxyZmq::AcsProxyZmq(const unsigned short serverPort,
-  void *const zmqContext) throw():
+AcsProxyZmq::AcsProxyZmq(void *const zmqContext, const unsigned short serverPort) throw():
   m_serverPort(serverPort),
   m_serverSocket(zmqContext, ZMQ_REQ) {
   connectZmqSocketToLocalhost(m_serverSocket, serverPort);

mediachanger/AcsProxyZmq.hpp

@@ -19,6 +19,7 @@
 #pragma once
 
 #include "mediachanger/AcsProxy.hpp"
+#include "mediachanger/Constants.hpp"
 #include "mediachanger/ZmqSocketMT.hpp"
 
 #include <mutex>
@@ -35,11 +36,11 @@ public:
   /**
    * Constructor.
    *
+   * @param zmqContext The ZMQ context.
    * @param serverPort The TCP/IP port on which the CASTOR ACS daemon is
    * listening for ZMQ messages.
-   * @param zmqContext The ZMQ context.
    */
-  AcsProxyZmq(const unsigned short serverPort, void *const zmqContext) throw();
+  AcsProxyZmq(void *const zmqContext, const unsigned short serverPort = ACS_PORT) throw();
 
   /**
    * Request the CASTOR ACS daemon to mount the specified tape for read-only
@@ -48,8 +49,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  void mountTapeReadOnly(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
+  void mountTapeReadOnly(const std::string &vid, const AcsLibrarySlot &librarySlot);
 
   /** 
    * Request the CASTOR ACS daemon to mount the specifed tape for read/write
@@ -58,8 +58,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  void mountTapeReadWrite(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
+  void mountTapeReadWrite(const std::string &vid, const AcsLibrarySlot &librarySlot);
 
   /** 
    * Request the CASTOR ACS daemon to dismount the specifed tape from the tape
@@ -68,8 +67,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  void dismountTape(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
+  void dismountTape(const std::string &vid, const AcsLibrarySlot &librarySlot);
 
   /**
    * Request the CASTOR ACS daemon to forcefully dismount the specifed tape
@@ -79,8 +77,7 @@ public:
    * @param vid The volume identifier of the tape to be mounted.
    * @param librarySlot The slot in the library that contains the tape drive.
    */
-  void forceDismountTape(const std::string &vid,
-    const cta::mediachanger::AcsLibrarySlot &librarySlot);
+  void forceDismountTape(const std::string &vid, const AcsLibrarySlot &librarySlot);
 
 private:
   

mediachanger/CMakeLists.txt

@@ -25,7 +25,6 @@ PROTOBUF_GENERATE_CPP(ProtoSources ProtoHeaders ${ProtoFiles})
 set (MEDIACHANGER_LIB_SRC_FILES
   AcsLibrarySlot.cpp
   AcsProxy.cpp
-  AcsProxyDummy.cpp
   AcsProxyZmq.cpp
   CmdLine.cpp
   CmdLineTool.cpp
@@ -41,7 +40,6 @@ set (MEDIACHANGER_LIB_SRC_FILES
   MessageHeader.cpp
   messages.cpp
   MmcProxy.cpp
-  MmcProxyDummy.cpp
   MmcProxyLog.cpp
   MmcProxyNotSupported.cpp
   ${ProtoSources}
@@ -49,12 +47,12 @@ set (MEDIACHANGER_LIB_SRC_FILES
   RmcMarshal.hpp
   RmcMountMsgBody.cpp
   RmcProxy.cpp
-  RmcProxyDummy.cpp
   RmcProxyTcpIp.cpp
   RmcUnmountMsgBody.cpp
   ScsiLibrarySlot.cpp
   SmartZmqContext.cpp
   TapeLibraryType.cpp
+  ZmqContextSingleton.cpp
   ZmqMsg.cpp
   ZmqSocket.cpp
   ZmqSocketMT.cpp
@@ -78,7 +76,6 @@ set (MEDIACHANGER_UNIT_TESTS_LIB_SRC_FILES
   IoTest.cpp
   LibrarySlotParserTest.cpp
   ManualLibrarySlotTest.cpp
-  MediaChangerFacadeTest.cpp
   MountCmdLine.cpp
   MountCmdLineTest.cpp
   ScsiLibrarySlotTest.cpp)

mediachanger/Constants.hpp

@@ -98,10 +98,16 @@ const unsigned short ACS_PORT = 54521;
  */
 const unsigned short RMC_PORT = 5014;
 
+/**
+ * The network timeout of rmc communications should be several minutes due
+ * to the time it takes to mount and unmount tapes.
+ */
+const int RMC_NET_TIMEOUT = 600; // Timeout in seconds
+
 /**
  * The maximum number of attempts a retriable RMC request should be issued.
  */
-const int RMC_MAXRQSTATTEMPTS = 10;
+const int RMC_MAX_RQST_ATTEMPTS = 10;
 
 /**
  * The magic number to identify taped messages.

mediachanger/DismountCmdLine.cpp

@@ -133,6 +133,13 @@ bool cta::mediachanger::DismountCmdLine::getForce() const throw() {
   return m_force;
 }
 
+//------------------------------------------------------------------------------
+// getProgramName
+//------------------------------------------------------------------------------
+std::string cta::mediachanger::DismountCmdLine::getProgramName() {
+  return "cta-mediachanger-dismount";
+}
+
 //------------------------------------------------------------------------------
 // processOption
 //------------------------------------------------------------------------------
@@ -166,10 +173,10 @@ void cta::mediachanger::DismountCmdLine::processOption(const int opt) {
 // getUsage
 //------------------------------------------------------------------------------
 std::string cta::mediachanger::DismountCmdLine::getUsage() throw() {
-  return
+  return std::string() +
   "Usage:\n"
   "\n"
-  "  cta-mediachanger-dismount [options] VID DRIVE_SLOT\n"
+  "  " + getProgramName() + " [options] VID DRIVE_SLOT\n"
   "\n"
   "Where:\n"
   "\n"

mediachanger/DismountCmdLine.hpp

@@ -109,6 +109,13 @@ public:
    */
   bool getForce() const throw();
 
+  /**
+   * Return sthe program name.
+   *
+   * @return sthe program name.
+   */
+  static std::string getProgramName();
+
 private:
 
   /**

mediachanger/DismountCmdMain.cpp

@@ -17,13 +17,10 @@
  */
 
 #include "common/exception/Exception.hpp"
+#include "common/log/StdoutLogger.hpp"
 #include "common/utils/utils.hpp"
-#include "mediachanger/AcsProxyZmq.hpp"
 #include "mediachanger/DismountCmd.hpp"
 #include "mediachanger/DismountCmdLine.hpp"
-#include "mediachanger/RmcProxyTcpIp.hpp"
-#include "mediachanger/MmcProxyNotSupported.hpp"
-#include "mediachanger/SmartZmqContext.hpp"
 
 #include <exception>
 #include <google/protobuf/stubs/common.h>
@@ -73,24 +70,8 @@ int main(const int argc, char *const *const argv) {
 static int exceptionThrowingMain(const int argc, char *const *const argv) {
   using namespace cta;
 
-  const int sizeOfIOThreadPoolForZMQ = 1;
-  mediachanger::SmartZmqContext
-    zmqContext(mediachanger::SmartZmqContext::instantiateZmqContext(sizeOfIOThreadPoolForZMQ));
-  mediachanger::AcsProxyZmq acs(mediachanger::ACS_PORT, zmqContext.get());
-
-  mediachanger::MmcProxyNotSupported mmc;
-
-  const unsigned short rmcPort = mediachanger::RMC_PORT;
-
-  const unsigned int rmcMaxRqstAttempts = mediachanger::RMC_MAXRQSTATTEMPTS;
-
-  // The network timeout of rmc communications should be several minutes due
-  // to the time it takes to mount and unmount tapes
-  const int rmcNetTimeout = 600; // Timeout in seconds
-
-  mediachanger::RmcProxyTcpIp rmc(rmcPort, rmcNetTimeout, rmcMaxRqstAttempts);
-
-  mediachanger::MediaChangerFacade mc(acs, mmc, rmc);
+  log::StdoutLogger log(mediachanger::DismountCmdLine::getProgramName());
+  mediachanger::MediaChangerFacade mc(log);
   
   mediachanger::DismountCmd cmd(std::cin, std::cout, std::cerr, mc);
 

mediachanger/MediaChangerFacade.cpp

@@ -16,7 +16,12 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "mediachanger/AcsProxyZmq.hpp"
+#include "mediachanger/Constants.hpp"
 #include "mediachanger/MediaChangerFacade.hpp"
+#include "mediachanger/MmcProxyLog.hpp"
+#include "mediachanger/RmcProxyTcpIp.hpp"
+#include "mediachanger/ZmqContextSingleton.hpp"
 #include "common/exception/Exception.hpp"
 
 namespace cta {
@@ -25,46 +30,37 @@ namespace mediachanger {
 //------------------------------------------------------------------------------
 // constructor
 //------------------------------------------------------------------------------
-MediaChangerFacade::MediaChangerFacade(
-  AcsProxy &acs,
-  MmcProxy &mmc,
-  RmcProxy &rmc) throw():
-  m_acs(acs),
-  m_mmc(mmc),
-  m_rmc(rmc) {
-}
-
-//------------------------------------------------------------------------------
-// constructor
-//------------------------------------------------------------------------------
-MediaChangerFacade::MediaChangerFacade(
-  AcsProxy &acs,
-  RmcProxy &rmc) throw():
-  m_acs(acs),
-  m_mmc(m_mmcNotSupported),
-  m_rmc(rmc) {
+MediaChangerFacade::MediaChangerFacade(log::Logger &log, void *const zmqContext) throw():
+  m_log(log),
+  m_zmqContext(zmqContext) {
 }
 
 //------------------------------------------------------------------------------
 // mountTapeReadOnly
 //------------------------------------------------------------------------------
-void MediaChangerFacade::mountTapeReadOnly(
-  const std::string &vid, const LibrarySlot &slot) {
+void MediaChangerFacade::mountTapeReadOnly(const std::string &vid, const LibrarySlot &slot) {
   try {
     const TapeLibraryType libraryType = slot.getLibraryType();
 
     // Dispatch the appropriate helper method depending on library slot type
     switch(libraryType) {
     case TAPE_LIBRARY_TYPE_ACS:
-      return m_acs.mountTapeReadOnly(vid,
-        dynamic_cast<const AcsLibrarySlot&>(slot));
+      {
+        AcsProxyZmq acs(m_zmqContext);
+        return acs.mountTapeReadOnly(vid, dynamic_cast<const AcsLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_MANUAL:
-      return m_mmc.mountTapeReadOnly(vid,
-        dynamic_cast<const ManualLibrarySlot&>(slot));
+      {
+        MmcProxyLog mmc(m_log);
+        return mmc.mountTapeReadOnly(vid, dynamic_cast<const ManualLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_SCSI:
-      // SCSI media-changers to not support read-only mounts
-      return m_rmc.mountTapeReadWrite(vid,
-         dynamic_cast<const ScsiLibrarySlot&>(slot));
+      {
+        RmcProxyTcpIp rmc;
+
+        // SCSI media-changers to not support read-only mounts
+        return rmc.mountTapeReadWrite(vid, dynamic_cast<const ScsiLibrarySlot&>(slot));
+      }
     default:
       {
         // Should never get here
@@ -85,22 +81,27 @@ void MediaChangerFacade::mountTapeReadOnly(
 //------------------------------------------------------------------------------
 // mountTapeReadWrite
 //------------------------------------------------------------------------------
-void MediaChangerFacade::mountTapeReadWrite(
-  const std::string &vid, const LibrarySlot &slot) {
+void MediaChangerFacade::mountTapeReadWrite(const std::string &vid, const LibrarySlot &slot) {
   try {
     const TapeLibraryType libraryType = slot.getLibraryType();
 
     // Dispatch the appropriate helper method depending on library slot type
     switch(libraryType) {
     case TAPE_LIBRARY_TYPE_ACS: 
-      return m_acs.mountTapeReadWrite(vid,
-        dynamic_cast<const AcsLibrarySlot&>(slot));
+      {
+        AcsProxyZmq acs(m_zmqContext);
+        return acs.mountTapeReadWrite(vid, dynamic_cast<const AcsLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_MANUAL: 
-      return m_mmc.mountTapeReadWrite(vid,
-        dynamic_cast<const ManualLibrarySlot&>(slot));
+      {
+        MmcProxyLog mmc(m_log);
+        return mmc.mountTapeReadWrite(vid, dynamic_cast<const ManualLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_SCSI:
-      return m_rmc.mountTapeReadWrite(vid,
-        dynamic_cast<const ScsiLibrarySlot&>(slot));
+      {
+        RmcProxyTcpIp rmc;
+        return rmc.mountTapeReadWrite(vid, dynamic_cast<const ScsiLibrarySlot&>(slot));
+      }
     default:
       {
         // Should never get here
@@ -121,22 +122,27 @@ void MediaChangerFacade::mountTapeReadWrite(
 //------------------------------------------------------------------------------
 // dismountTape
 //------------------------------------------------------------------------------
-void MediaChangerFacade::dismountTape(
-  const std::string &vid, const LibrarySlot &slot) {
+void MediaChangerFacade::dismountTape(const std::string &vid, const LibrarySlot &slot) {
   try {
     const TapeLibraryType libraryType = slot.getLibraryType();
   
     // Dispatch the appropriate helper method depending on library slot type
     switch(libraryType) {
     case TAPE_LIBRARY_TYPE_ACS:
-      return m_acs.dismountTape(vid,
-        dynamic_cast<const AcsLibrarySlot&>(slot));
+      {
+        AcsProxyZmq acs(m_zmqContext);
+        return acs.dismountTape(vid, dynamic_cast<const AcsLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_MANUAL:
-      return m_mmc.dismountTape(vid,
-        dynamic_cast<const ManualLibrarySlot&>(slot));
+      {
+        MmcProxyLog mmc(m_log);
+        return mmc.dismountTape(vid, dynamic_cast<const ManualLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_SCSI:
-      return m_rmc.dismountTape(vid,
-        dynamic_cast<const ScsiLibrarySlot&>(slot));
+      {
+        RmcProxyTcpIp rmc;
+        return rmc.dismountTape(vid, dynamic_cast<const ScsiLibrarySlot&>(slot));
+      }
     default:
       {
         // Should never get here
@@ -157,22 +163,27 @@ void MediaChangerFacade::dismountTape(
 //------------------------------------------------------------------------------
 // forceDismountTape
 //------------------------------------------------------------------------------
-void MediaChangerFacade::forceDismountTape(
-  const std::string &vid, const LibrarySlot &slot) {
+void MediaChangerFacade::forceDismountTape(const std::string &vid, const LibrarySlot &slot) {
   try {
     const TapeLibraryType libraryType = slot.getLibraryType();
 
     // Dispatch the appropriate helper method depending on library slot type
     switch(libraryType) {
     case TAPE_LIBRARY_TYPE_ACS:
-      return m_acs.forceDismountTape(vid,
-        dynamic_cast<const AcsLibrarySlot&>(slot));
+      {
+        AcsProxyZmq acs(m_zmqContext);
+        return acs.forceDismountTape(vid, dynamic_cast<const AcsLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_MANUAL:
-      return m_mmc.forceDismountTape(vid,
-        dynamic_cast<const ManualLibrarySlot&>(slot));
+      {
+        MmcProxyLog mmc(m_log);
+        return mmc.forceDismountTape(vid, dynamic_cast<const ManualLibrarySlot&>(slot));
+      }
     case TAPE_LIBRARY_TYPE_SCSI:
-      return m_rmc.forceDismountTape(vid,
-        dynamic_cast<const ScsiLibrarySlot&>(slot));
+      {
+        RmcProxyTcpIp rmc;
+        return rmc.forceDismountTape(vid, dynamic_cast<const ScsiLibrarySlot&>(slot));
+      }
     default:
       {
         // Should never get here

mediachanger/MediaChangerFacade.hpp

@@ -18,23 +18,17 @@
 
 #pragma once
 
+#include "common/log/Logger.hpp"
 #include "mediachanger/LibrarySlot.hpp"
-#include "mediachanger/MmcProxy.hpp"
-#include "mediachanger/MmcProxyNotSupported.hpp"
-#include "mediachanger/RmcProxy.hpp"
-#include "mediachanger/AcsProxy.hpp"
+#include "mediachanger/ZmqContextSingleton.hpp"
 
-#include <unistd.h>
-#include <sys/types.h>
+#include <string>
 
 namespace cta {
 namespace mediachanger {
 
 /**
- * Provides a facade to three communications proxies: acs, manual and rmc.
- *
- * This facade will forward requests to mount and dismount tapes to the
- * appropriate communications proxy based on the type of library slot.
+ * A facade to multiple types of tape media changer.
  */
 class MediaChangerFacade {
 public:
@@ -42,21 +36,12 @@ public:
   /**
    * Constructor.
    *
-   * @param acs Proxy object representing the CASTOR ACS daemon.
-   * @param mmc Proxy object representing the manual media-changer.
-   * @param rmc Proxy object representing the rmcd daemon.
-   */
-  MediaChangerFacade(AcsProxy &acs, MmcProxy &mmc, RmcProxy &rmc) throw();
-
-  /**
-   * Constructor.
-   *
-   * Use this constructor when manual media-changers are not to be supported.
-   *
-   * @param acs Proxy object representing the CASTOR ACS daemon.
-   * @param rmc Proxy object representing the rmcd daemon.
+   * @param log Object representing the API to the CTA logging system.
+   * @param zmqContext The ZMQ context.  There is usually one ZMQ context within
+   * a program.  Set this parameter in order for the MediaChangerFacade to share
+   * an already existing ZMQ context.
    */
-  MediaChangerFacade(AcsProxy &acs, RmcProxy &rmc) throw();
+  MediaChangerFacade(log::Logger &log, void *const zmqContext = ZmqContextSingleton::instance()) throw();
 
   /**
    * Requests the media changer to mount the specified tape for read-only
@@ -104,25 +89,14 @@ public:
 private:
 
   /**