How to maintain user session using mysql/php in windows phone ?

   using (var store = IsolatedStorageFile.GetUserStoreForApplication())
    using (var stream = new IsolatedStorageFileStream("data.txt",
                                                    FileMode.Create,
                                                    FileAccess.Write,
                                                    store))
    {
      var serializer = new XmlSerializer(typeof(FeedViewModel));
      serializer.Serialize(stream, ViewModel);
    }