ASP.NET C# Search Engine (Highlighting, JSON, jQuery & Silverlight)

using System;
using System.IO;
using System.Xml;
using ionic.utils.zip;

namespace Searcharoo.Common
{
    /// <summary>
    /// Load a Microsoft PowerPoint 2007 Xml file format
    /// </summary>
    /// <remarks>
    /// <see cref="DocxDocument" />
    /// </remarks>
    public class PptxDocument : DownloadDocument
    {
        private string _WordsOnly;

        public PptxDocument(Uri location)
            : base(location)
        {
            Extension = "pptx";
        }
        
        public override void Parse()
        {
            // no parsing (for now). perhaps in future we can regex look for urls (www.xxx.com) and try to link to them...
        }

        public override string WordsOnly
        {
            get { return _WordsOnly; }
        }

        /// <remarks>
        /// .NET System.IO.Compression and zip files
        /// http://blogs.msdn.com/dotnetinterop/archive/2006/04/05/.NET-System.IO.Compression-and-zip-files.aspx
        /// </remarks>
        public override bool GetResponse(System.Net.HttpWebResponse webresponse)
        {
            string filename = System.IO.Path.Combine(
                          Preferences.DownloadedTempFilePath
                        , (System.IO.Path.GetFileName(this.Uri.LocalPath)) );
            this.Title = System.IO.Path.GetFileNameWithoutExtension(filename);

            SaveDownloadedFile(webresponse, filename);
            try
            {   // Will be accessing this data in the pptx file
                //  ppt/presentation.xml      p:presentation/sldIdLst
                //  ppt/slides/slide{0}.xml   a:t
                try
                {
                    using (ZipFile zip = ZipFile.Read(filename))
                    {
                        int slideCount = 0;
                        using (MemoryStream streamroot = new MemoryStream())
                        {   // open the presentation 'root' file to see how many slides there are
                            zip.Extract("ppt/presentation.xml", streamroot);
                            streamroot.Seek(0, SeekOrigin.Begin);
                            XmlDocument xmldocroot = new XmlDocument();
                            xmldocroot.Load(streamroot);
                            XmlNodeList objXML = xmldocroot.GetElementsByTagName("p:sldId");
                            slideCount = objXML.Count;
                        }
                        XmlDocument xmlSlide;
                        string entryToExtractPattern = @"ppt/slides/slide{0}.xml";
                        for (int slideId = 1; slideId <= slideCount; slideId++)
                        {   // now open each slide file to extract text
                            using (MemoryStream stream = new MemoryStream())
                            {
                                string entryToExtract = String.Format(entryToExtractPattern, slideId);
                                zip.Extract(entryToExtract, stream);
                                stream.Seek(0, SeekOrigin.Begin);
                                xmlSlide = new XmlDocument();
                                xmlSlide.Load(stream);
                            }
                            string slideWords = "";
                            foreach (XmlElement x in xmlSlide.GetElementsByTagName("a:t"))
                            {
                                slideWords = slideWords + " " + x.InnerText;
                            }
                            _WordsOnly = _WordsOnly + " " + slideWords + Environment.NewLine + Environment.NewLine;
                            this.All = _WordsOnly;
                        }
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
                System.IO.File.Delete(filename);    // clean up
            }
            catch (Exception)
            {
                //                ProgressEvent(this, new ProgressEventArgs(2, "IFilter failed on " + this.Uri + " " + e.Message + ""));
            }
            if (this.All != string.Empty)
            {
                this.Description = base.GetDescriptionFromWordsOnly(WordsOnly);
                return true;
            }
            else
            {
                return false;
            }
        }

       
    }
}