Question

I have a function that takes a url to an Excel file, and then exports it as a pdf:

public static void ExportFromExcel(string url)
{
    // Create COM Objects
    Application excelApplication = new Application();
    Workbook excelWorkbook = 
        excelApplication.Workbooks.Open(HttpContext.Current.Server.MapPath(url));

    try
    {
        // Call Excel's native export function
        excelWorkbook.ExportAsFixedFormat(
            XlFixedFormatType.xlTypePDF, 
            HttpContext.Current.Server.MapPath(url.Replace(".xlsx", ".pdf")));
    }
    catch (Exception ex)
    {

    }
    finally
    {
        // Close the workbook, quit Excel, and clean up regardless of the results
        excelWorkbook.Close();    // HANGS AND FAILS HERE
        excelApplication.Quit();

        excelApplication = null;
        excelWorkbook = null;
    }
}

What I’m doing is creating an Excel file, and then immediately creating a pdf from that file:

using (FileStream fs = File.Create(HttpContext.Current.Server.MapPath(filePath)))
{
    byte[] data = pck.GetAsByteArray();
    fs.Write(data, 0, data.Length);
}

Pdf.ExportFromExcel(filePath);

It will create the Excel file just fine, and it will also create the pdf. But the page hangs for a long time, and then gives me the error at excelWorkbook.Close(); in my pdf code:

The remote procedure call failed. (Exception from HRESULT: 0x800706BE)

The files actually get created though. But if I go to the file directory, there is a temporary Excel file as well (my Excel filename with the ~$ in front of it).

If I try and delete my Excel file, I get an error saying the file is being used by another process, and I can’t delete my Excel file until I kill the EXCEL.EXE in the Task Manager.

So for some reason, my Excel file won’t close after it finishes creating the pdf. Am I doing something wrong in my code?

Answer 1

Using Interop on the server (including ASP.NET/IIS!) is NOT supported by MS – see http://support.microsoft.com/default.aspx?scid=kb;EN-US;q257757#kb2

Since Windows Vista MS introduced several security-related measures which prevent a Windows Service (like ASP.NET on IIS) from doing “desktop-like” things (accessing printers, accessing network shares etc.)… which means you would have to circumvent several security measures to get it to work (NOT recommended!).

To deal with Excel files without any need for Office etc. in a server-scenario there are several options (free and commercial) out there:

I can recommend Aspose.Cells and Flexcel – both come with PDF export functionality… didn’t try SpreadsheetGear but hear+read lots of good things about it…

Free options (though for the newer xlsx format only, not sure whether they support PDF export!) are for example OpenXML 2 from MS and EPPlus.