public async Task<string> NextPageBlock(string sourceId, string set, string qexpr, string prevlast)
 {
     JavaScriptSerializer jser = new JavaScriptSerializer();
     dynamic sobj = jser.DeserializeObject(set) as dynamic;
     EntitySetType type;
     if (Enum.TryParse<EntitySetType>(sobj["set"], out type))
     {
         switch (type)
         {
             case EntitySetType.User:
                 {
                     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
                     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(User));
                     DataContractJsonSerializer ser3 = new DataContractJsonSerializer(typeof(UserPageBlock));
                     System.IO.MemoryStream strm = new System.IO.MemoryStream();
                     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
                     strm.Write(sbf, 0, sbf.Length);
                     strm.Position = 0;
                     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
                     UserServiceProxy svc = new UserServiceProxy();
                     UserSet _set = new UserSet();
                     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
                     _set.PageSize_ = int.Parse(sobj["pageSize"]);
                     if (sobj.ContainsKey("setFilter"))
                         _set.SetFilter = sobj["setFilter"];
                     User _prevlast = null;
                     if (!string.IsNullOrEmpty(prevlast))
                     {
                         strm = new System.IO.MemoryStream();
                         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
                         strm.Write(sbf, 0, sbf.Length);
                         strm.Position = 0;
                         _prevlast = ser2.ReadObject(strm) as User;
                     }
                     var result = await svc.NextPageBlockAsync(ApplicationContext.ClientContext, _set, _qexpr, _prevlast);
                     strm = new System.IO.MemoryStream();
                     ser3.WriteObject(strm, result);
                     string json = System.Text.Encoding.UTF8.GetString(strm.ToArray());
                     return json;
                 }
             case EntitySetType.Role:
                 {
                     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
                     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(Role));
                     DataContractJsonSerializer ser3 = new DataContractJsonSerializer(typeof(RolePageBlock));
                     System.IO.MemoryStream strm = new System.IO.MemoryStream();
                     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
                     strm.Write(sbf, 0, sbf.Length);
                     strm.Position = 0;
                     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
                     RoleServiceProxy svc = new RoleServiceProxy();
                     RoleSet _set = new RoleSet();
                     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
                     _set.PageSize_ = int.Parse(sobj["pageSize"]);
                     if (sobj.ContainsKey("setFilter"))
                         _set.SetFilter = sobj["setFilter"];
                     Role _prevlast = null;
                     if (!string.IsNullOrEmpty(prevlast))
                     {
                         strm = new System.IO.MemoryStream();
                         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
                         strm.Write(sbf, 0, sbf.Length);
                         strm.Position = 0;
                         _prevlast = ser2.ReadObject(strm) as Role;
                     }
                     var result = await svc.NextPageBlockAsync(ApplicationContext.ClientContext, _set, _qexpr, _prevlast);
                     strm = new System.IO.MemoryStream();
                     ser3.WriteObject(strm, result);
                     string json = System.Text.Encoding.UTF8.GetString(strm.ToArray());
                     return json;
                 }
             case EntitySetType.MemberNotification:
                 {
                     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
                     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(MemberNotification));
                     DataContractJsonSerializer ser3 = new DataContractJsonSerializer(typeof(MemberNotificationPageBlock));
                     System.IO.MemoryStream strm = new System.IO.MemoryStream();
                     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
                     strm.Write(sbf, 0, sbf.Length);
                     strm.Position = 0;
                     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
                     MemberNotificationServiceProxy svc = new MemberNotificationServiceProxy();
                     MemberNotificationSet _set = new MemberNotificationSet();
                     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
                     _set.PageSize_ = int.Parse(sobj["pageSize"]);
                     if (sobj.ContainsKey("setFilter"))
                         _set.SetFilter = sobj["setFilter"];
                     MemberNotification _prevlast = null;
                     if (!string.IsNullOrEmpty(prevlast))
                     {
                         strm = new System.IO.MemoryStream();
                         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
                         strm.Write(sbf, 0, sbf.Length);
                         strm.Position = 0;
                         _prevlast = ser2.ReadObject(strm) as MemberNotification;
                     }
                     var result = await svc.NextPageBlockAsync(ApplicationContext.ClientContext, _set, _qexpr, _prevlast);
                     strm = new System.IO.MemoryStream();
                     ser3.WriteObject(strm, result);
                     string json = System.Text.Encoding.UTF8.GetString(strm.ToArray());
                     return json;
                 }
             case EntitySetType.ShortMessage:
                 {
                     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
                     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(ShortMessage));
                     DataContractJsonSerializer ser3 = new DataContractJsonSerializer(typeof(ShortMessagePageBlock));
                     System.IO.MemoryStream strm = new System.IO.MemoryStream();
                     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
                     strm.Write(sbf, 0, sbf.Length);
                     strm.Position = 0;
                     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
                     var svc = new ShortMessageServiceProxy();
                     var _set = new ShortMessageSet();
                     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
                     _set.PageSize_ = int.Parse(sobj["pageSize"]);
                     if (!sobj.ContainsKey("setFilter"))
                         throw new Exception("The page is not properly parameterized!");
                     else
                     {
                         Func<string, string, int> count = (s, p) =>
                         {
                             int _cnt = 0;
                             int i = 0;
                             while ((i = s.IndexOf(p, i)) != -1)
                             {
                                 _cnt++;
                                 i += p.Length;
                             }
                             return _cnt;
                         };
                         string filter = sobj["setFilter"];
                         if (filter.Contains("ToID is null") && filter.Contains("___usergroups___") && count(filter, "||") == 0)
                         {
                             string[] mbgrpIds = await GroupChatViewContext.UserGroupChatMembers(System.Web.HttpContext.Current.User.Identity.GetUserId());
                             if (mbgrpIds == null || mbgrpIds.Length == 0)
                                 throw new Exception(ResourceUtils.GetString("234038e6185f013e25d0213c06f5a0e9", "You are not a member of any chat group."));
                             string groupexpr = "";
                             foreach (var gid in mbgrpIds)
                                 groupexpr += (groupexpr != "" ? " || " : "") + "GroupID == \"" + gid + "\"";
                             _set.SetFilter = filter.Replace("___usergroups___", groupexpr);
                         }
                         else if (filter.EndsWith("&& ToID is not null && GroupID is null && ( ToID == \"{0}\" || FromID == \"{0}\" )") && count(filter, "||") == 1)
                         {
                             filter = string.Format(filter, System.Web.HttpContext.Current.User.Identity.GetUserId());
                             _set.SetFilter = filter;
                         }
                         else
                             throw new Exception("The page is not properly parameterized!");
                     }
                     ShortMessage _prevlast = null;
                     if (!string.IsNullOrEmpty(prevlast))
                     {
                         strm = new System.IO.MemoryStream();
                         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
                         strm.Write(sbf, 0, sbf.Length);
                         strm.Position = 0;
                         _prevlast = ser2.ReadObject(strm) as ShortMessage;
                     }
                     var result = await svc.NextPageBlockAsync(ApplicationContext.ClientContext, _set, _qexpr, _prevlast);
                     strm = new System.IO.MemoryStream();
                     ser3.WriteObject(strm, result);
                     string json = System.Text.Encoding.UTF8.GetString(strm.ToArray());
                     return json;
                 }
         }
     }
     return null;
 }
 public async Task<string> GetPageItems(string sourceId, string set, string qexpr, string prevlast)
 {
     JavaScriptSerializer jser = new JavaScriptSerializer();
     dynamic sobj = jser.DeserializeObject(set) as dynamic;
     EntitySetType type;
     if (Enum.TryParse<EntitySetType>(sobj["set"], out type))
     {
         switch (type)
         {
             case EntitySetType.User:
                 {
                     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
                     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(User));
                     var ser3 = new JavaScriptSerializer();
                     System.IO.MemoryStream strm = new System.IO.MemoryStream();
                     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
                     strm.Write(sbf, 0, sbf.Length);
                     strm.Position = 0;
                     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
                     UserServiceProxy svc = new UserServiceProxy();
                     UserSet _set = new UserSet();
                     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
                     _set.PageSize_ = int.Parse(sobj["pageSize"]);
                     if (sobj.ContainsKey("setFilter"))
                         _set.SetFilter = sobj["setFilter"];
                     User _prevlast = null;
                     if (!string.IsNullOrEmpty(prevlast))
                     {
                         strm = new System.IO.MemoryStream();
                         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
                         strm.Write(sbf, 0, sbf.Length);
                         strm.Position = 0;
                         _prevlast = ser2.ReadObject(strm) as User;
                     }
                     var result = await svc.GetPageItemsAsync(ApplicationContext.ClientContext, _set, _qexpr, _prevlast);
                     var ar = new List<dynamic>();
                     foreach (var e in result)
                     {
                         ar.Add(new { Id = e.ID.ToString(), DistinctString = e.DistinctString });
                     }
                     string json = ser3.Serialize(ar);
                     return json;
                 }
             case EntitySetType.Role:
                 {
                     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
                     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(Role));
                     var ser3 = new JavaScriptSerializer();
                     System.IO.MemoryStream strm = new System.IO.MemoryStream();
                     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
                     strm.Write(sbf, 0, sbf.Length);
                     strm.Position = 0;
                     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
                     RoleServiceProxy svc = new RoleServiceProxy();
                     RoleSet _set = new RoleSet();
                     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
                     _set.PageSize_ = int.Parse(sobj["pageSize"]);
                     if (sobj.ContainsKey("setFilter"))
                         _set.SetFilter = sobj["setFilter"];
                     Role _prevlast = null;
                     if (!string.IsNullOrEmpty(prevlast))
                     {
                         strm = new System.IO.MemoryStream();
                         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
                         strm.Write(sbf, 0, sbf.Length);
                         strm.Position = 0;
                         _prevlast = ser2.ReadObject(strm) as Role;
                     }
                     var result = await svc.GetPageItemsAsync(ApplicationContext.ClientContext, _set, _qexpr, _prevlast);
                     var ar = new List<dynamic>();
                     foreach (var e in result)
                     {
                         ar.Add(new { Id = e.ID.ToString(), DistinctString = e.DistinctString });
                     }
                     string json = ser3.Serialize(ar);
                     return json;
                 }
             case EntitySetType.MemberNotification:
                 {
                     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
                     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(MemberNotification));
                     var ser3 = new JavaScriptSerializer();
                     System.IO.MemoryStream strm = new System.IO.MemoryStream();
                     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
                     strm.Write(sbf, 0, sbf.Length);
                     strm.Position = 0;
                     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
                     MemberNotificationServiceProxy svc = new MemberNotificationServiceProxy();
                     MemberNotificationSet _set = new MemberNotificationSet();
                     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
                     _set.PageSize_ = int.Parse(sobj["pageSize"]);
                     if (sobj.ContainsKey("setFilter"))
                         _set.SetFilter = sobj["setFilter"];
                     MemberNotification _prevlast = null;
                     if (!string.IsNullOrEmpty(prevlast))
                     {
                         strm = new System.IO.MemoryStream();
                         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
                         strm.Write(sbf, 0, sbf.Length);
                         strm.Position = 0;
                         _prevlast = ser2.ReadObject(strm) as MemberNotification;
                     }
                     var result = await svc.GetPageItemsAsync(ApplicationContext.ClientContext, _set, _qexpr, _prevlast);
                     var ar = new List<dynamic>();
                     foreach (var e in result)
                     {
                         ar.Add(new { Id = e.ID.ToString(), DistinctString = e.DistinctString });
                     }
                     string json = ser3.Serialize(ar);
                     return json;
                 }
         }
     }
     return null;
 }
 public static async Task<string> GetNotifications(string set, string qexpr, string prevlast)
 {
     var cntx = Cntx;
     JavaScriptSerializer jser = new JavaScriptSerializer();
     dynamic sobj = jser.DeserializeObject(set) as dynamic;
     DataContractJsonSerializer ser1 = new DataContractJsonSerializer(typeof(QueryExpresion));
     DataContractJsonSerializer ser2 = new DataContractJsonSerializer(typeof(MemberNotification));
     var ser3 = new JavaScriptSerializer();
     System.IO.MemoryStream strm = new System.IO.MemoryStream();
     byte[] sbf = System.Text.Encoding.UTF8.GetBytes(qexpr);
     strm.Write(sbf, 0, sbf.Length);
     strm.Position = 0;
     var _qexpr = ser1.ReadObject(strm) as QueryExpresion;
     MemberNotificationServiceProxy svc = new MemberNotificationServiceProxy();
     MemberNotificationSet _set = new MemberNotificationSet();
     _set.PageBlockSize = int.Parse(sobj["pageBlockSize"]);
     _set.PageSize_ = int.Parse(sobj["pageSize"]);
      _set.SetFilter = sobj["setFilter"];
      string usrId = HttpContext.Current.User.Identity.GetUserId();
      if (_set.SetFilter.Contains(usrId))
      {
          // just in case the script was tempered with by clients.
          _set.SetFilter += " && UserRef.ID == \"" + usrId + "\"";
      }
     MemberNotification _prevlast = null;
     if (!string.IsNullOrEmpty(prevlast))
     {
         strm = new System.IO.MemoryStream();
         sbf = System.Text.Encoding.UTF8.GetBytes(prevlast);
         strm.Write(sbf, 0, sbf.Length);
         strm.Position = 0;
         _prevlast = ser2.ReadObject(strm) as MemberNotification;
     }
     var result = (await svc.GetPageItemsAsync(cntx, _set, _qexpr, _prevlast)).ToArray();
     List<dynamic> ar = new List<dynamic>();
     Dictionary<int, MemberNotificationType> dic = new Dictionary<int, MemberNotificationType>();
     foreach (var e in result)
     {
         MemberNotificationType c;
         if (!dic.TryGetValue(e.TypeID, out c))
         {
             c = await svc.MaterializeMemberNotificationTypeRefAsync(cntx, e);
             c.TypeName = MapCategoryName(c);
             dic.Add(e.TypeID, c);
         }
         ar.Add(new
         {
             categ = new { Id = c.ID, name = c.TypeName },
             data = e
         });
     }
     string json = ser3.Serialize(ar);
     return json;
 }