Question about EWS - The operation has timed out

Question

hi everyone,
I'm developing a solution which uses public folder database in Exchange Server to store tasks:
- We use 1 account to access to public folder database by using EWS.
- Currently, this public folder database contains 60000 tasks and they are being accessed by 700 users, they always have the following exception: 
04/23/2015 09:41:15:  - The request failed. The operation has timed out
Message :The request failed. The operation has timed out
Source :Microsoft.Exchange.WebServices
Stack Trace :   at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request)
   at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ValidateAndEmitRequest(IEwsHttpWebRequest& request)
   at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.Execute()
   at Microsoft.Exchange.WebServices.Data.ExchangeService.FindItems[TItem](IEnumerable`1 parentFolderIds, SearchFilter searchFilter, String queryString, ViewBase view, Grouping groupBy, ServiceErrorHandling errorHandlingMode)
   at Microsoft.Exchange.WebServices.Data.ExchangeService.FindItems(FolderId parentFolderId, SearchFilter searchFilter, ViewBase view, Grouping groupBy)
Please help.
Thanks a lot.
Phuc

Answer 1

Thanks Glen for your reply.
Here is a code block which retrieve the number of task of some groups
foreach (var bu in request.BusinessUnits)
SearchFilter businessUnitFilter = new SearchFilter.IsEqualTo(BusinessUnitAliasProp, bu);//, ContainmentMode.FullString, ComparisonMode.IgnoreCase);
SearchFilter[] filters = new SearchFilter[] { actualOwnerFilter, statusFilter, businessUnitFilter };
var filterCollection = new SearchFilter.SearchFilterCollection(LogicalOperator.And, filters);
GroupedFindItemsResults<Item> taskResults = this.exchangeService.FindItems(_publicFolderId, filterCollection, itemView, groupByApplication);
if (taskResults != null && taskResults.ItemGroups != null)
foreach (var groupItem in taskResults.ItemGroups)
if (!dict.ContainsKey(groupItem.GroupIndex))
dict.Add(groupItem.GroupIndex, new Dictionary<string, int>());
if (!dict[groupItem.GroupIndex].ContainsKey(bu))
dict[groupItem.GroupIndex].Add(bu, groupItem.Items.Count);
Please let me know if it's too complex and might affect to the performance of Exchange Server