Web Service Compression with .NET CF We'll look at how to use standard web server compression with XML Web Services to make Pocket PC applications use less bandwidth, and thereby save communication costs. This is extra interesting as mobile devices tend to use bandwidth that is more expensive (GPRS, etc). Most enterprise Pocket PC solutions involve communication with a back-end server. With the introduction of the SOAP standard (or the more commonly used term "XML Web Services"), the industry had an option of accessing back-end resources in a standard way. Further, as Pocket PCs got the powerful (and nicely wrapped) support for calling those XML Web Service, the mobile solutions could benefit from easier integration and faster solution implementation. However, as SOAP is based on XML, and XML is a text-based format with extensive meta-data, the network traffic can be quite heavy. For a normal network connection (one that you normally have to your desktop), this is normally to a problem. But for most mobile solutions, that use network connection with lower bandwidth, this can create performance problems. Even worse, as those mobile network connections are more expensive to use, this can also create high communication costs.

WSCompress Anyplace Sample

  cscript.exe C:\Inetpub\AdminScripts\adsutil.vbs
    set W3Svc/Filters/Compression/gzip/HcScriptFileExtensions "asp" "dll" "exe" "aspx" "asmx"

  cscript.exe C:\Inetpub\AdminScripts\adsutil.vbs
    set W3Svc/Filters/Compression/deflate/HcScriptFileExtensions "asp" "dll" "exe" "aspx" "asmx"

  cscript.exe C:\Inetpub\AdminScripts\adsutil.vbs
    set W3SVC/Filters/Compression/gzip/HcDynamicCompressionLevel "9"

  cscript.exe C:\Inetpub\AdminScripts\adsutil.vbs
    set W3SVC/Filters/Compression/deflate/HcDynamicCompressionLevel "9"

  iisreset /restart

  <IIsCompressionScheme Location ="/LM/W3SVC/Filters/Compression/deflate"
    HcCompressionDll="C:\WINNT\system32\inetsrv\gzip.dll"
    HcCreateFlags="0"
    HcDoDynamicCompression="TRUE"
    HcDoOnDemandCompression="TRUE"
    HcDoStaticCompression="TRUE"
    HcDynamicCompressionLevel="9"
    HcFileExtensions="htm
      html
      txt"
    HcMimeType=""
    HcOnDemandCompLevel="10"
    HcPriority="1"
    HcScriptFileExtensions="asp
      dll
      exe
      aspx
      asmx"
  >
  </IIsCompressionScheme>
  <IIsCompressionScheme Location ="/LM/W3SVC/Filters/Compression/gzip"
    HcCompressionDll="C:\WINNT\system32\inetsrv\gzip.dll"
    HcCreateFlags="1"
    HcDoDynamicCompression="TRUE"
    HcDoOnDemandCompression="TRUE"
    HcDoStaticCompression="TRUE"
    HcDynamicCompressionLevel="9"
    HcFileExtensions="htm
      html
      txt"
    HcMimeType=""
    HcOnDemandCompLevel="10"
    HcPriority="1"
    HcScriptFileExtensions="asp
      dll
      exe
      aspx
      asmx"
  >
  </IIsCompressionScheme>

1. In IIS Manager, expand the local computer, click to select, then right-click the Web Sites folder, and then click Properties.
2. Click the Service tab, select the Compress application files check box, and click OK.

  cscript.exe C:\Inetpub\AdminScripts\adsutil.vbs
    set W3SVC/1/Root/WSCompression/DoDynamicCompression True

1. Download the .NET CF 1.0 SP2 Developer Redistributable.
2. Unpack the netcf.core.ppc3.x86.cab from the distribution (with a tool like WinRAR).
3. Rename the SYC6B2~1.014 file to System.Web.Services.dll.
4. Copy it to the C:\Program Files\Microsoft Visual Studio .NET 2003\CompactFrameworkSDK\v1.0.5000\Windows CE folder (could be located elsewhere depending on chosen installation location).

  [WebMethod]
  public DataSet GetDataSet(string table)
  {
    SqlConnection cn = new SqlConnection("Data Source=(local);" +
      "Initial Catalog=Northwind;Integrated Security=SSPI;");
    cn.Open();
    SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM " + table, cn);
    DataSet ds = new DataSet();
    da.Fill(ds, table);
    return ds;
  }

  private WebServices.DataService ws = new WebServices.DataService();

  Stopwatch sw = Stopwatch.StartNew();
  DataSet ds = ws.GetDataSet(tableTextBox.Text);
  sw.Stop();
  xmlTextBox.Text = ds.GetXml();
  MessageBox.Show(sw.ElapsedMilliseconds.ToString() + " ms");

  protected override System.Net.WebRequest GetWebRequest(Uri uri)
  {
    System.Net.WebRequest request = base.GetWebRequest(uri);
    request.Headers.Add("Accept-Encoding", "gzip, deflate");
    return request;
  }
  protected override System.Net.WebResponse
    GetWebResponse(System.Net.WebRequest request)
  {
    HttpWebResponseDecompressed response = new
      HttpWebResponseDecompressed(request);
    return response;
  }

  internal class HttpWebResponseDecompressed : WebResponse 
  {
    private HttpWebResponse response;

    public HttpWebResponseDecompressed(WebRequest request) 
    {
      response = (HttpWebResponse)request.GetResponse();
    }
    public override void Close() 
    {
      response.Close();
    }
    public override Stream GetResponseStream()
    {
      Stream compressedStream = null;
      if(response.ContentEncoding == "gzip")
      {
        compressedStream = new
          GZipInputStream(response.GetResponseStream());
      }
      else if(response.ContentEncoding == "deflate")
      {
        compressedStream = new
          ZipInputStream(response.GetResponseStream());
      }
      if(compressedStream != null)
      {
        // Decompress
        MemoryStream decompressedStream = new MemoryStream();
        int totalSize = 0;
        int size = 2048;
        byte[] writeData = new byte[2048];
        while(true) 
        {
          size = compressedStream.Read(writeData, 0, size);
          totalSize += size;
          if(size > 0) 
            decompressedStream.Write(writeData, 0, size);
          else 
            break;
        }
        decompressedStream.Seek(0, SeekOrigin.Begin);
        return decompressedStream;
      }
      else
        return response.GetResponseStream();
    }
    public override long ContentLength 
    {
      get { return response.ContentLength; }
    }
    public override string ContentType 
    {
      get { return response.ContentType; }
    }
    public override System.Net.WebHeaderCollection Headers
    {
      get { return response.Headers; }
    }
    public override System.Uri ResponseUri
    {
      get { return response.ResponseUri; }
    }
  }

  request.Headers.Add("Accept-Encoding", "gzip");

  request.Headers.Add("Accept-Encoding", "deflate");

		©2001-2009 Christian Forsberg & Andreas Sjöström