Ok the Salesforce class "SForceService" is generated when you create a reference to the Enterprise WSDL.

 

from there you do this ...

 

    /// <summary>

    /// Wrapper to enable compression on the Salesforce service.

    /// </summary>

    public class GZipSforceService : SforceService

    {

        public GZipSforceService()

        {

            this.EnableDecompression = true;

        }

 

        protected override System.Net.WebRequest GetWebRequest(Uri uri)

        {

            return new GzipWebRequest(base.GetWebRequest(uri));

        }

    }

 

 

That gives you the base service class that you can use.

You then one of these to handle the compression ...

 

       /// <summary>

       /// This class wraps an existing WebRequest, and will handle compressing the request. The framework provided

    /// code will handle uncompressing the response.

       ///

       /// To use this with a Soap Client, create a new class that derives from the WSDL generated class and override GetWebRequest,

       /// its implementation should simply be

       ///           return new GzipWebRequest(base.GetWebRequest(uri));

       ///

       /// Then when using the web service, remember to create instances of the derived class, rather than the generated class

    /// This approach allows you to add compression support without having to change any generated code.

       /// </summary>

       public class GzipWebRequest : WebRequest

       {

        private WebRequest wr;

        private Stream request_stream = null;

 

              /// <summary>

              /// Construct an WebRequest wrapper that gzip compresses the request stream.

              /// </summary>

              /// <param>The WebRequest we're wrapping.</param>

              public GzipWebRequest(WebRequest wrappedRequest)

              {

                     this.wr = wrappedRequest;

                     wr.Headers["Content-Encoding"] = "gzip";

              }

 

        // most of these just delegate to the contained WebRequest

              public override string Method

              {

                     get { return wr.Method; }

                     set { wr.Method = value; }

              }

      

              public override Uri RequestUri

              {

                     get { return wr.RequestUri; }

              }

      

              public override WebHeaderCollection Headers

              {

                     get { return wr.Headers; }

                     set { wr.Headers = value; }

              }

      

              public override long ContentLength

              {

                     get { return wr.ContentLength; }

                     set { wr.ContentLength = value; }

              }

      

              public override string ContentType

              {

                     get { return wr.ContentType; }

                     set { wr.ContentType = value; }

              }

      

              public override ICredentials Credentials

              {

                     get { return wr.Credentials; }

                     set { wr.Credentials = value; }

              }

      

              public override bool PreAuthenticate

              {

                     get { return wr.PreAuthenticate; }

                     set { wr.PreAuthenticate = value; }

              }

      

              public override System.IO.Stream GetRequestStream()

              {

                     return WrappedRequestStream(wr.GetRequestStream());

              }

      

              public override IAsyncResult BeginGetRequestStream(AsyncCallback callback, object state)

              {

                     return wr.BeginGetRequestStream (callback, state);

              }

      

              public override System.IO.Stream EndGetRequestStream(IAsyncResult asyncResult)

              {

                     return WrappedRequestStream(wr.EndGetRequestStream(asyncResult));

              }

      

              /// <summary>

              /// helper function that wraps the request stream in a GZipStream

              /// </summary>

              /// <param>The Stream we're compressing</param>

              /// <returns></returns>

              private Stream WrappedRequestStream(Stream requestStream)

              {

                     if ( request_stream == null )

                           request_stream = new GZipStream(requestStream, CompressionMode.Compress);

                     return request_stream;

              }

 

        public override WebResponse GetResponse()

        {

            try

            {

                return wr.GetResponse();

            }

            catch (Exception e)

            {

                throw e;

            }

        }

      

              public override IAsyncResult BeginGetResponse(AsyncCallback callback, object state)

              {

                     return wr.BeginGetResponse (callback, state);

              }

      

              public override WebResponse EndGetResponse(IAsyncResult asyncResult)

              {

                     return wr.EndGetResponse(asyncResult);

              }

       }

}