Engine Object をロードするさまざまな方法

public class EngineLoader : IDisposable
{
    public EngineLoader()
    {
        // これらの変数を、FREngine.dll へのフル パス、Customer Project ID、
        // および該当する場合は、オンライン ライセンス トークン ファイルへのパスとオンライン ライセンスのパスワードで初期化します
        string enginePath = "";
        string customerProjectId = "";
        string licensePath = "";
        string licensePassword = "";
        // FREngine.dll ライブラリをロードします
        dllHandle = LoadLibraryEx(enginePath, IntPtr.Zero, LOAD_WITH_ALTERED_SEARCH_PATH);
           
        try
        {
            if (dllHandle == IntPtr.Zero)
            {
                throw new Exception("Can't load " + enginePath);
            }
            IntPtr initializeEnginePtr = GetProcAddress(dllHandle, "InitializeEngine");
            if (initializeEnginePtr == IntPtr.Zero)
            {
                throw new Exception("Can't find InitializeEngine function");
            }
            IntPtr deinitializeEnginePtr = GetProcAddress(dllHandle, "DeinitializeEngine");
            if (deinitializeEnginePtr == IntPtr.Zero)
            {
                throw new Exception("Can't find DeinitializeEngine function");
            }
            IntPtr dllCanUnloadNowPtr = GetProcAddress(dllHandle, "DllCanUnloadNow");
            if (dllCanUnloadNowPtr == IntPtr.Zero)
            {
                throw new Exception("Can't find DllCanUnloadNow function");
            }
            // ポインターをデリゲートに変換します
            initializeEngine = (InitializeEngine)Marshal.GetDelegateForFunctionPointer(
                initializeEnginePtr, typeof(InitializeEngine));
            deinitializeEngine = (DeinitializeEngine)Marshal.GetDelegateForFunctionPointer(
                deinitializeEnginePtr, typeof(DeinitializeEngine));
            dllCanUnloadNow = (DllCanUnloadNow)Marshal.GetDelegateForFunctionPointer(
                dllCanUnloadNowPtr, typeof(DllCanUnloadNow));
            // オンライン ライセンス ファイルへのパスとオンライン ライセンスのパスワードを渡して
            // InitializeEngine 関数を呼び出します
            int hresult = initializeEngine(customerProjectId, licensePath, licensePassword, 
                "", "", false, ref engine);
            Marshal.ThrowExceptionForHR(hresult);
        }
        catch (Exception)
        {
            // FREngine.dll ライブラリを解放します
            engine = null;
            // FreeLibrary の呼び出し前にすべてのオブジェクトを削除します
            GC.Collect();
            GC.WaitForPendingFinalizers();
            GC.Collect();
            FreeLibrary(dllHandle);
            dllHandle = IntPtr.Zero;
            initializeEngine = null;
            deinitializeEngine = null;
            dllCanUnloadNow = null;
            throw;
        }
    }
    // Kernel32.dll の関数
    [DllImport("kernel32.dll")]
    private static extern IntPtr LoadLibraryEx(string dllToLoad, IntPtr reserved, uint flags);
    private const uint LOAD_WITH_ALTERED_SEARCH_PATH = 0x00000008;
    [DllImport("kernel32.dll")]
    private static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName);
    [DllImport("kernel32.dll")]
    private static extern bool FreeLibrary(IntPtr hModule);
    // FREngine.dll の関数
    [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Unicode)]
    private delegate int InitializeEngine(string customerProjectId, string licensePath, 
        string licensePassword, string tempFolder, string dataFolder, bool isSharedCPUCoresMode, 
        ref FREngine.IEngine engine);
    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
    private delegate int DeinitializeEngine();
    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
    private delegate int DllCanUnloadNow();
    // 非公開変数
    private FREngine.IEngine engine = null;
    // FREngine.dll へのハンドル
    private IntPtr dllHandle = IntPtr.Zero;
    private InitializeEngine initializeEngine = null;
    private DeinitializeEngine deinitializeEngine = null;
    private DllCanUnloadNow dllCanUnloadNow = null;
}

IEngineLoader engineLoader = new FREngine.InprocLoader();
IEngine engine = engineLoader.InitializeEngine( customerProjectId, licensePath, licensePassword, "", "", false );
try {
 ...
} finally {
 engineLoader.ExplicitlyUnload();
}

IEngineLoader engineLoader = new FREngine.OutprocLoader();
IEngine engine = engineLoader.InitializeEngine( customerProjectId, licensePath, licensePassword, "", "", false);
try {
 ...
} finally {
 engineLoader.ExplicitlyUnload();
}