wint100
asked on
Task Async Await Silverlight 5 Cross-Thread Violation
Hi,
I'm trying to use the TPL in my SL5 application to simplify the Async Service calls.
I'm calling the following from my MainPage code behind, with the method being called being an async void that does the work with the service proxy. An Cross-Thread access exception always gets thrown for this code, and none of the asyn void code is reached, even though I'm not trying to interact with the UI:
Am I missing something, or is there a better way to perform this. Basically I need to use this static method (WCFServiceQueryHelper.Sto reData), wait for it to complete, without blocking the UI thread, then continue to the next method after handling any exception caught.
This is to replace all the direct service calls, and callback events in the mainpage code, as it gets very messy. The static method (WCFServiceHelper) will use async/await and interact with the ServiceProxy, meaning the MainPage code can simply call this static method, and when complete, move onto the next method.
Thanks
I'm trying to use the TPL in my SL5 application to simplify the Async Service calls.
I'm calling the following from my MainPage code behind, with the method being called being an async void that does the work with the service proxy. An Cross-Thread access exception always gets thrown for this code, and none of the asyn void code is reached, even though I'm not trying to interact with the UI:
var result = Task.Factory.StartNew(WCFServiceQueryHelper.StoreData);
await result;
Am I missing something, or is there a better way to perform this. Basically I need to use this static method (WCFServiceQueryHelper.Sto
This is to replace all the direct service calls, and callback events in the mainpage code, as it gets very messy. The static method (WCFServiceHelper) will use async/await and interact with the ServiceProxy, meaning the MainPage code can simply call this static method, and when complete, move onto the next method.
Thanks
ASKER
Hi,
Thanks for your feedback. Methods called are below. changing the method to return gives the same exception:
{System.UnauthorizedAccess Exception: Invalid cross-thread access.
at MS.Internal.XcpImports.Che ckThread()
at System.Windows.Application .get_Host( )
at EnergyViewerV2.Helpers.Ele cWCFServic eQueryHelp er..cctor( )}
With the ServiceProxy class as follows:
Thanks for your feedback. Methods called are below. changing the method to return gives the same exception:
{System.UnauthorizedAccess
at MS.Internal.XcpImports.Che
at System.Windows.Application
at EnergyViewerV2.Helpers.Ele
public static async void StoreElecAnnualData()
{
//Annual Electric Data Collection
if (!NetworkInterface.GetIsNetworkAvailable())
{
if (app.ElecAnnualData == null)
{
if (DeserializeAnnualDataFromXML("ElecAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName) != null) app.ElecAnnualData = DeserializeAnnualDataFromXML("ElecAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName);
}
if (app.ElecPrevAnnualData == null)
{
if (DeserializeAnnualDataFromXML("ElecPrevAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName) != null) app.ElecPrevAnnualData = DeserializeAnnualDataFromXML("ElecPrevAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName);
}
}
else
{
try
{
sDate = app.isRollingAnnual?RollingDatesHelper.AnnualCurrentPeriodStart().ToLongDateString(): DateTime.Now.ToLongDateString();
app.ElecAnnualData = await ServiceProxy.GetAnnualData(sDate,
app.isRollingAnnual
? RollingDatesHelper.
AnnualCurrentPeriodEnd().
ToLongDateString()
: null,
app.ObjRefs[app.CurrentBuilding].elecMeter,
app.isRollingAnnual ? 7000 : 3000, false,
false);
//Store the data to IS
if (app.ElecAnnualData != null) SerializeAnnualDataListToXML(app.ElecAnnualData, "ElecAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName);
sDate2 = app.isRollingAnnual ? RollingDatesHelper.AnnualPreviousPeriodStart().ToShortDateString() : DateTime.Now.AddMonths(-12).ToShortDateString();
app.ElecPrevAnnualData =
await
ServiceProxy.GetAnnualData(sDate2,
app.isRollingAnnual
? RollingDatesHelper.AnnualPreviousPeriodEnd().ToShortDateString()
: null, app.ObjRefs[app.CurrentBuilding].elecMeter,
app.isRollingAnnual ? 8000 : 4000, false, false);
//Store the data to IS
if (app.ElecPrevAnnualData != null) SerializeAnnualDataListToXML(app.ElecPrevAnnualData, "ElecPrevAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName);
}
catch (Exception ex)
{
errorHandling.Error("The following error occurred trying to gather Annual Elec Data from Database: " + ex.Message, "Annual Elec Error", app.isDebugging);
if (app.ElecAnnualData == null)
{
if (DeserializeAnnualDataFromXML("ElecAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName) != null) app.ElecAnnualData = DeserializeAnnualDataFromXML("ElecAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName);
}
if (app.ElecPrevAnnualData == null)
{
if (DeserializeAnnualDataFromXML("ElecPrevAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName) != null) app.ElecPrevAnnualData = DeserializeAnnualDataFromXML("ElecPrevAnnual" + app.ObjRefs[app.CurrentBuilding].BuildingNo + app.ObjRefs[app.CurrentBuilding].BuildingName);
}
}
}
}
With the ServiceProxy class as follows:
public class ServiceProxy
{
static Uri address = new Uri(Application.Current.Host.Source, "../Services/SilverlightService.svc");
public static Task<ObservableCollection<EnergyData>> GetAnnualData(string sDate, string eDate, string MeterID, int index,
bool occupancyRequired, bool tempRequired)
{
var tcs = new TaskCompletionSource<ObservableCollection<EnergyData>>();
var client = new SilverlightServiceClient("CustomBinding_SilverlightService", address.AbsoluteUri);
client.getAnnualDataCompleted += (s, e) =>
{
if (e.Error != null)
tcs.TrySetException(e.Error);
else if (e.Cancelled)
tcs.TrySetCanceled();
else
tcs.TrySetResult(e.Result);
};
client.getAnnualDataAsync(sDate,eDate,MeterID,index,occupancyRequired,tempRequired);
return tcs.Task;
}
}
ASKER
Checking though my code, it looks like I'm calling the first method within a new Threadpool.QueueUserWorkIt em:
ThreadPool.QueueUserWorkIt em(delegat e
{
CallMethod();
};
ThreadPool.QueueUserWorkIt
{
CallMethod();
};
From the code, it doesn't looks like accessing any UI element. Did you tried to call debug and fine which line the error is thrown? Maybe a test method which call just the above method.
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ASKER
Found the solution
Just to test, if you just have "return statement" in above method, does your code works fine ?