How to use the PDF viewer control in ASP.NET(Classic) platform?

public class PdfViewerAPIController : ApiController

{

    public object PostViewerAction(Dictionary<string, string> jsonResult)

    {

        PdfViewerHelper helper = new PdfViewerHelper();

        helper.Load(Helper.GetFilePath("Barcode.pdf"));

        object output = helper.ProcessPdf(jsonResult);

        string response = JsonConvert.SerializeObject(output);

        return response;

    }

}

public class Helper

{

    public static string GetFilePath(string path)

    {

        string _dataPath = GetCommonFolder(new DirectoryInfo(HttpContext.Current.Request.PhysicalApplicationPath));

        _dataPath += @"\" + path;

        return _dataPath;

    }

    static string GetCommonFolder(DirectoryInfo dtInfo)

    {

        var _folderNames = dtInfo.GetDirectories("Data");

        if (_folderNames.Length > 0)

        {

            return _folderNames[0].FullName;

        }

        return dtInfo.Parent != null ? GetCommonFolder(dtInfo.Parent) : string.Empty;

    }

}