WCF Service method Need to be consume in SharePoint Webpart using Jquery

Question

My Requirement is that in SharePoint Visual webpart if i click on the Likes Button for a photo it should increase the likes count in the List Column from client  side, here i am able to do when i use javascript, but coming to normal visitor, it is giving access denied error, so i tried to do impersonation in Javascript, and after some struggling i came to know that we cant impersonate in javascript, to do this we should go for creating a method in WCF which will be impersonated and trying to consume in JQuery, please help me with a sample example how to do this.

Here i am pasting the methods which i used in WCF

IGallery.cs

-----------------

[ServiceContract]

    public interface IGallery

    {

        [OperationContract]

        [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.Wrapped, ResponseFormat = WebMessageFormat.Json)]

        string UpdateListData(string ID, string columnData);

    }

Gallery.cs

------------------

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]

    public class Gallery : IGallery

    {

        public string UpdateListData(string listItemId, string columnData)

        {

            try

            {

                SPSite site = new SPSite(SPContext.Current.Site.Url);

                SPSecurity.RunWithElevatedPrivileges(delegate()

                {

                    using (SPSite osite = new SPSite(site.ID))

                    {

                        using (SPWeb web = osite.OpenWeb())

                        {

                            SPList list = web.Lists["PhotoGallery"];

                            if (Convert.ToInt32(listItemId.ToString()) != 0)

                            {

                                SPListItem item = list.Items.GetItemById(Convert.ToInt32(listItemId.ToString()));

                                if (item != null)

                                {

                                    item["LikesCount"] = columnData;

                                    item.Update();

                                }

                            }

                        }

                    }

                });

                return "Success";

            }

            catch (SPException)

            {

                return "Fail";

            }

        }

    }

Please help me ...

Thanks in Advanced

Gaja