Open XPS

    string output = System.IO.Path.GetTempPath() + Guid.NewGuid().ToString() + ".pdf";
    // create a stream for input XPS file
    using (var psStream = new System.IO.FileStream("template.xps", System.IO.FileMode.Create, System.IO.FileAccess.Read))
    {
        // create a stream for output PDF file
        using (var pdfStream = System.IO.File.Open(output, System.IO.FileMode.Open, System.IO.FileAccess.Write))
        {
            // load the XPS file from stream
            var document = new Aspose.Page.XPS.PsDocument(psStream);
            // create an instance of PdfSaveOptions
            var options = new Aspose.Page.XPS.Device.PdfSaveOptions();
            // create PDF rendering device for XPS
            var device = new Aspose.Page.XPS.Device.PdfDevice(pdfStream);
            // save XPS as PDF
            ocument.Save(device, options);
        }
    }
    // load resultant PDF in default application
    System.Diagnostics.Process.Start(output);