WCF fileupload using jquery

[DataContract]
   public class File
   {
       [DataMember]
       public string fileName { get; set; }
       [DataMember]
       public Stream stream { get; set; }
   }

[WebInvoke(Method = "*", UriTemplate = "UploadFile", BodyStyle = WebMessageBodyStyle.WrappedRequest, ResponseFormat = WebMessageFormat.Json)]
       [OperationContract]
       void UploadFile(File file);

public void UploadFile(File files)
       {
           try
           {
               string FilePath = "";
               string FileName = "";
               string[] file = files.fileName.Split('.');
               if (file[1].ToLower().Equals("png") || file[1].ToLower().Equals("jpg"))
               {
                    FileName = string.Format(@"{0}." + file[1], Guid.NewGuid());
                   FilePath = Path.Combine(HostingEnvironment.MapPath("~/Files/Image"), FileName);
               }
               else
               {
                    FileName = string.Format(@"{0}.pdf", Guid.NewGuid());
                   FilePath = Path.Combine(HostingEnvironment.MapPath("~/Files/Uploads"), FileName);

               }

               int length = 0;
               using (FileStream writer = new FileStream(FilePath, FileMode.Create))
               {
                   int readCount;
                   var buffer = new byte[8192];
                   while ((readCount = files.stream.Read(buffer, 0, buffer.Length)) != 0)
                   {
                       writer.Write(buffer, 0, readCount);
                       length += readCount;
                   }
               }
           }
           catch (Exception ex)
           {

           }
       }

$("#btnUpload").click(function () {
                var data = new FormData();
                fileData = document.getElementById("fileUpload").files[0];
                var param={fileName:fileData.name}
               
                $.ajax({
                    url: 'http://localhost:54594/Expense.svc/UploadFile', // Dynamically uploads the files which is chosen.
                    type: 'POST',
                    data: fileData, // This would pass the file object with data
                    cache: false,
                    processData: false, // Don't process the files
                    contentType: "application/octet-stream", // Setting content type to "application/octet-stream" as jQuery will tell the server its not query string.
                    success: function (data) {
                        alert('Successful..');
                    },
                    error: function (data) {
                        alert('Error Occurred');
                    }
                });
            });