/// <include file='doc\DiscoveryRequestHandler.uex' path='docs/doc[@for="DiscoveryRequestHandler.ProcessRequest"]/*' />
        /// <devdoc>
        ///    <para>[To be supplied.]</para>
        /// </devdoc>
        public void ProcessRequest(HttpContext context)
        {
            TraceMethod method = Tracing.On ? new TraceMethod(this, "ProcessRequest") : null;

            if (Tracing.On)
            {
                Tracing.Enter("IHttpHandler.ProcessRequest", method, Tracing.Details(context.Request));
            }

            new PermissionSet(PermissionState.Unrestricted).Demand();
            // string cacheKey;

            string physicalPath = context.Request.PhysicalPath;

            if (CompModSwitches.DynamicDiscoverySearcher.TraceVerbose)
            {
                Debug.WriteLine("DiscoveryRequestHandle: handling " + physicalPath);
            }

            // Check to see if file exists locally.
            if (File.Exists(physicalPath))
            {
                DynamicDiscoveryDocument dynDisco = null;
                FileStream stream = null;
                try {
                    stream = new FileStream(physicalPath, FileMode.Open, FileAccess.Read);
                    XmlTextReader xmlReader = new XmlTextReader(stream);
                    xmlReader.WhitespaceHandling = WhitespaceHandling.Significant;
                    xmlReader.XmlResolver        = null;
                    xmlReader.DtdProcessing      = DtdProcessing.Prohibit;
                    if (xmlReader.IsStartElement("dynamicDiscovery", DynamicDiscoveryDocument.Namespace))
                    {
                        stream.Position = 0;
                        dynDisco        = DynamicDiscoveryDocument.Load(stream);
                    }
                }
                finally {
                    if (stream != null)
                    {
                        stream.Close();
                    }
                }

                if (dynDisco != null)
                {
                    string[] excludeList        = new string[dynDisco.ExcludePaths.Length];
                    string   discoFileDirectory = Path.GetDirectoryName(physicalPath);
                    string   discoFileName      = Path.GetFileName(physicalPath);

                    for (int i = 0; i < excludeList.Length; i++)
                    {
                        // Exclude list now consists of relative paths, so this transformation not needed.
                        // excludeList[i] = Path.Combine(discoFileDirectory, dynDisco.ExcludePaths[i].Path);
                        excludeList[i] = dynDisco.ExcludePaths[i].Path;
                    }

                    // Determine start url path for search
                    DynamicDiscoSearcher searcher;
                    Uri    searchStartUrl    = context.Request.Url;
                    string escapedUri        = RuntimeUtils.EscapeUri(searchStartUrl);
                    string searchStartUrlDir = GetDirPartOfPath(escapedUri);    // URL path without file name
                    string strLocalPath      = GetDirPartOfPath(searchStartUrl.LocalPath);

                    if (strLocalPath.Length == 0 ||                           // no subdir present, host only
                        CompModSwitches.DynamicDiscoveryVirtualSearch.Enabled // virtual search forced (for test suites).
                        )
                    {
                        discoFileName = GetFilePartOfPath(escapedUri);
                        searcher      = new DynamicVirtualDiscoSearcher(discoFileDirectory, excludeList, searchStartUrlDir);
                    }
                    else
                    {
                        searcher = new DynamicPhysicalDiscoSearcher(discoFileDirectory, excludeList, searchStartUrlDir);
                    }

                    if (CompModSwitches.DynamicDiscoverySearcher.TraceVerbose)
                    {
                        Debug.WriteLine("*** DiscoveryRequestHandler.ProcessRequest() - startDir: " + searchStartUrlDir + " discoFileName :" + discoFileName);
                    }
                    searcher.Search(discoFileName);

                    DiscoveryDocument discoFile = searcher.DiscoveryDocument;

                    MemoryStream memStream = new MemoryStream(1024);
                    StreamWriter writer    = new StreamWriter(memStream, new UTF8Encoding(false));
                    discoFile.Write(writer);
                    memStream.Position = 0;
                    byte[] data      = new byte[(int)memStream.Length];
                    int    bytesRead = memStream.Read(data, 0, data.Length);
                    context.Response.ContentType = ContentType.Compose("text/xml", Encoding.UTF8);
                    context.Response.OutputStream.Write(data, 0, bytesRead);
                }
                else
                {
                    // Else, just return the disco file
                    context.Response.ContentType = "text/xml";
                    context.Response.WriteFile(physicalPath);
                }
                if (Tracing.On)
                {
                    Tracing.Exit("IHttpHandler.ProcessRequest", method);
                }
                return;
            }
            if (Tracing.On)
            {
                Tracing.Exit("IHttpHandler.ProcessRequest", method);
            }

            // Else, file is not found
            throw new HttpException(404, Res.GetString(Res.WebPathNotFound, context.Request.Path));
        }