--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Loaders/LoaderStateMachine.h	Tue May 28 21:59:20 2019 +0200
@@ -0,0 +1,119 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero 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
+ * Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#pragma once
+
+#include "../Messages/IObservable.h"
+#include "../Messages/IObserver.h"
+#include "../Oracle/GetOrthancImageCommand.h"
+#include "../Oracle/GetOrthancWebViewerJpegCommand.h"
+#include "../Oracle/IOracle.h"
+#include "../Oracle/OracleCommandExceptionMessage.h"
+#include "../Oracle/OrthancRestApiCommand.h"
+
+#include <Core/IDynamicObject.h>
+
+#include <list>
+
+namespace OrthancStone
+{
+  /**
+     This class is supplied with Oracle commands and will schedule up to 
+     simultaneousDownloads_ of them at the same time, then will schedule the 
+     rest once slots become available. It is used, a.o., by the 
+     OrtancMultiframeVolumeLoader class.
+  */
+  class LoaderStateMachine : public IObserver
+  {
+  protected:
+    class State : public Orthanc::IDynamicObject
+    {
+    private:
+      LoaderStateMachine&  that_;
+
+    public:
+      State(LoaderStateMachine& that) :
+      that_(that)
+      {
+      }
+
+      State(const State& currentState) :
+      that_(currentState.that_)
+      {
+      }
+
+      void Schedule(OracleCommandWithPayload* command) const
+      {
+        that_.Schedule(command);
+      }
+
+      template <typename T>
+      T& GetLoader() const
+      {
+        return dynamic_cast<T&>(that_);
+      }
+      
+      virtual void Handle(const OrthancRestApiCommand::SuccessMessage& message);
+      
+      virtual void Handle(const GetOrthancImageCommand::SuccessMessage& message);
+      
+      virtual void Handle(const GetOrthancWebViewerJpegCommand::SuccessMessage& message);
+    };
+
+    void Schedule(OracleCommandWithPayload* command);
+
+    void Start();
+
+  private:
+    void Step();
+
+    void Clear();
+
+    void HandleExceptionMessage(const OracleCommandExceptionMessage& message);
+
+    template <typename T>
+    void HandleSuccessMessage(const T& message);
+
+    typedef std::list<IOracleCommand*>  PendingCommands;
+
+    IOracle&         oracle_;
+    bool             active_;
+    unsigned int     simultaneousDownloads_;
+    PendingCommands  pendingCommands_;
+    unsigned int     activeCommands_;
+
+  public:
+    LoaderStateMachine(IOracle& oracle,
+                       IObservable& oracleObservable);
+
+    virtual ~LoaderStateMachine()
+    {
+      Clear();
+    }
+
+    bool IsActive() const
+    {
+      return active_;
+    }
+
+    void SetSimultaneousDownloads(unsigned int count);  
+  };
+}