When making multiple requests in quick succession, I am sometimes hit with an InvalidOperationException which is marked as the operation is not valid due to the state of the object. I'm not entirely sure what's wrong with the following code:
this.Abort();
this.request = (HttpWebRequest)WebRequest.Create(uri);
this.result = new WebClientAsyncResult(this.request);
if (data != null)
{
this.request.ContentType = "application/x-www-form-urlencoded";
this.request.Method = "POST";
}
// BeginGetResponse does have a synchronous component
// See: http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.begingetresponse.aspx
Action asyncAction = () =>
{
try
{
if (this.request == null)
{
Debug.WriteLine("Request is null");
return;
}
if (request.Method == "POST")
{
GetRequest(result, data, responseAction, errorAction);
}
else
{
GetResponse(result, responseAction, errorAction);
}
}
catch (InvalidOperationException ex)
{
Debug.WriteLine("Invalid");
if (this.request == null)
{
errorAction(new Error(ex.InnerException) {WasAborted = true});
}
}
};
Dispatcher.BeginInvoke(asyncAction, null, null);
return this.result;
This was solve by using a local variable outside of the lambda as it wasn't capturing the value of the field until execution which was causing issues.
Related
I am new with Async and await using C# Programming. In WebAPI, we have created two API Controllers one with Async and await Programming and other is without that. We have done load testing using JMeter and we have got following results.
Users Sync Async
100 No Errors No Errors
500 No Errors No Errors
750 No Errors Errors - (59.0 %) - 502 Bad Gateway
763 No Errors Errors
764 No Errors Errors
765 Errors - (0.13 %) - 502 Bad Gateway Errors
1000 Errors Errors
Can you any please explain/suggest which approach is best or how can we proceed ?
API Code :
GetPersonalDetailsController - Async and await Used
public async Task<IHttpActionResult> GET([FromUri] RequestQueryListDTO objAPIRequest)
{
DateTime startResponseTime = DateTime.Now;
Response objResponse = null;
string strResponse = string.Empty;
var HeaderType = Request.Content.Headers.ContentType;
ProductBAL objProductBAL = null;
try
{
if (objAPIRequest != null)
{
Task<Response> tskGetProductDetails = Task<Response>.Run(() =>
{
objProductBAL = new ProductBAL();
return objProductBAL.GetProductDetails(objAPIRequest);
//Business Access Layer Logic calling
});
objResponse = await tskGetProductDetails;
}
else
{
objResponse = new Response();
objResponse.ReturnCode = -1;
objResponse.ReturnMessage = "Missing Parameters.";
}
}
catch (Exception ex)
{
\\ Exception Logging
}
finally
{
objProductBAL = null;
}
objResponse.ResponseTime = Math.Round((DateTime.Now - startResponseTime).TotalMilliseconds).ToString();
if (objResponse.ReturnCode == Convert.ToInt32(General.ReturnCode))
{
return Content<Response>(HttpStatusCode.BadRequest, objResponse);
}
else
{
return Ok(objResponse);
}
}
========================================================================
GetPDPController - Without using Async and await
public IHttpActionResult GET([FromUri] RequestQueryListDTO objAPIRequest)
{
DateTime startResponseTime = DateTime.Now;
Response objResponse = null;
string strResponse = string.Empty;
var HeaderType = Request.Content.Headers.ContentType;
try
{
if (objAPIRequest != null)
{
//Business Access Layer Logic calling
}
else
{
objResponse = new Response();
objResponse.ReturnCode = -1;
objResponse.ReturnMessage = "Missing Parameters.";
}
}
catch (Exception ex)
{
// Exception Logging Code
}
finally
{
objProductBAL = null;
}
objResponse.ResponseTime = Math.Round((DateTime.Now - startResponseTime).TotalMilliseconds).ToString();
if (objResponse.ReturnCode == Convert.ToInt32(General.ReturnCode))
{
return Content<Response>(HttpStatusCode.BadRequest, objResponse);
}
else
{
return Ok(objResponse);
}
}
My suggestion is have two methods, one Async and one not. That way you can test more.
GetProductDetails
GetProductDetailsAsync
you would then need to change the signature of the calling method aka GET
public IHttpActionResult GET([FromUri] RequestQueryListDTO objAPIRequest)
{
var objResponse = new Response();
//check the properties of objAPIRequest
if(bad)
{
//add stuff if you want
return Content<Response>(HttpStatusCode.BadRequest, objResponse);
}
//Business Access Layer Logic calling
//-----------------------
ProductBAL objProductBAL = new ProductBAL();
//you need to change this to async
var productDetails = objProductBAL.GetProductDetails(objAPIRequest);
//-----------------------
return Ok(objResponse);
}
I have a function which checks and authenticates the User and on that basis the data is displayed to the respective User. And the function name is Get_AuthenticateUser_Ums(strUserName);
I call this function on Page_load. This function contains a web service. Now what I want is whenever the service is not working or has some issue, I want that the site should not be displayed to the user and message should prompt as The service is down, so couldnt load the site.
Below is my code
if (!IsPostBack)
{
Get_AuthenticateUser_Ums(strUserName); }
And function
private void Get_AuthenticateUser_Ums(string strUserName)
{
try
{
strReturnMessage = string.Empty;
Boolean bolReturn = ObjUMS.AuthenticateApplicationAccess(strUserName, strAppUrl, out strReturnMessage);
if (bolReturn)
{
DataSet dsUserGroups = new DataSet();
dsUserGroups = ObjUMS.GetUserAppDetailsbyUserNameApplicationUrl(strUserName, strAppUrl, out strReturnMessage);
if (dsUserGroups.Tables[1] != null && dsUserGroups.Tables[1].Rows.Count > 0)
{
string strSubGroupName = dsUserGroups.Tables[1].Rows[0]["SUBGROUP_NAME"].ToString();
if (strSubGroupName == "UBR Requester")
{
if (dsUserGroups.Tables[2] != null && dsUserGroups.Tables[2].Rows.Count > 0)
{
string[] allStates = dsUserGroups.Tables[2].AsEnumerable().Select(r => r.Field<string>("BOUNDARY_VALUE")).ToArray();
ViewState["States"] = string.Join(",", allStates);
}
}
else
{
Response.Redirect("~/NotAuthorize.aspx", false);
}
}
else
{
Response.Redirect("~/NotAuthorize.aspx", false);
}
}
else
{
Response.Redirect("~/NotAuthorize.aspx", false);
}
}
catch (Exception ex)
{
throw ex;
}
}
you can create a Method to check connection using the url to svc , and which returns a boolean based on that you can able to see whether the Service is up or not
public bool checkConnection(){
var url = "http://nvmbd1bkh150v02/UMSService/UserProvider.svc";
bool tosend = false;
try
{
var myRequest = (HttpWebRequest)WebRequest.Create(url);
var response = (HttpWebResponse)myRequest.GetResponse();
if (response.StatusCode == HttpStatusCode.OK)
{
tosend = true ;
// it's at least in some way responsive
// but may be internally broken
// as you could find out if you called one of the methods for real
Debug.Write(string.Format("{0} Available", url));
}
else
{
tosend = false;
// well, at least it returned...
Debug.Write(string.Format("{0} Returned, but with status: {1}",
url, response.StatusDescription));
}
}
catch (Exception ex)
{
// not available at all, for some reason
Debug.Write(string.Format("{0} unavailable: {1}", url, ex.Message));
}
return tosend;
}
I have three different databases that I need to check that I am connected to. This is what I originally have, which works perfectly fine.
public async Task<ServiceAvailabilityDTO> ServiceAvailabilityStatus()
{
return new ServiceAvailabilityDTO
{
IsDb1Online = await IsDb1Available(),
IsDb2Online = IsDb2Available(),
IsDb3Online = await IsDb3Available()
};
}
private async Task<bool> IsDb1Available()
{
var count = await _db1Service.GetDbCount();
if (count > 0)
return true;
return false;
}
private bool IsDb2Available()
{
if (_db2Service.GetDbCount() > 0)
return true;
return false;
}
private async Task<bool> IsDb3Available()
{
var pong = await _db3Provider.PingDb();
if(pong.Success == true && pong.Version != null)
return true;
return false;
}
Now however, I need to log exception messages in my DTO for each DB check.
public async Task<ServiceAvailabilityDTO> ServiceAvailabilityStatus()
{
return new ServiceAvailabilityDTO
{
IsDb1Online = await IsDb1Available(),
IsDb2Online = IsDb2Available(),
IsDb3Online = await IsDb3Available(this) // This is an example. I want to pass the reference of **ServiceAvailabilityDTO** to **IsDb3Available**
};
}
private async Task<bool> IsDb3Available(ServiceAvailabilityDTO availability)
{
try
{
var pong = await _db3Provider.PingDb();
if(pong.Success == true && pong.Version != null)
return true;
return false;
}
catch (Exception e)
{
var exceptionMessage = e.Message;
if (e.InnerException != null)
{
// This is what I hope to put into the object reference
exceptionMessage = String.Join("\n", exceptionMessage, e.InnerException.Message);
availability.db3Exception = exceptionMessage ;
}
return false;
}
}
My question is;
Can I keep my return method the same as in the first example, and pass the object reference to each method to store the exception and still return my bool value.
Or does the object not get created until all of the method calls have happened, and then create the object with the returned values?
I know I could just create the object normally and pass it in each
method call, but it is specifically this way of doing it that has
inspired me to ask this question, purely to be informed and learn
from.
Thanks.
No, you cannot do it like this because in the context of what you're doing this does not refer to the object you're populating, it refers to the object containing the method you're calling.
public async Task<ServiceAvailabilityDTO> ServiceAvailabilityStatus()
{
return new ServiceAvailabilityDTO
{
IsDb1Online = await IsDb1Available(),
IsDb2Online = IsDb2Available(),
IsDb3Online = await IsDb3Available(this) // here 'this' does NOT ref to ServiceAvailabilityDTO
};
}
There is no keyword which does refer to ServiceAvailabilityDTO either, so you're left with creating the object, and passing it to each method. At this point, I dont think there is much point you returning the boolean either - you may as well set the boolean property in line
public async Task<ServiceAvailabilityDTO> ServiceAvailabilityStatus()
{
var sa = new ServiceAvailabilityDTO();
await CheckDb1Available(sa);
CheckDb2Available(sa);
await CheckDb3Available(sa);
return sa;
}
(Note I've renamed the methods from Is* to Check* as the former implies a return boolean, the latter implies something going on inline.)
y query is something like
this.ProcessRequestSync(() => this.Client.CreateDocumentQuery<Model>(this.DocumentDBCollectionLink).Where(d => d.name.Equals(name) && d.code.Equals(code) && d.Type.Equals(this.documentType) && d.CreatedBy.Equals(myName).ToList<Model>());
public dynamic ProcessRequestSync(Func<dynamic> getRequest)
{
var delay = TimeSpan.Zero;
var minDelayTime = new TimeSpan(0, 0, 1);
for (;;)
{
try
{
Thread.Sleep(delay);
return getRequest();
}
catch (DocumentClientException documentClientException)
{
var statusCode = (int)documentClientException.StatusCode;
if (statusCode == 429 || statusCode == 503)
{
string errorMessage = string.Format("failed at DocumentDB with {0} status and {1} retry time", statusCode, documentClientException.RetryAfter);
this.Logger.Log(errorMessage );
// Back off if the request rate is too large or the service is temporarily unavailable
delay = TimeSpan.Compare(documentClientException.RetryAfter, minDelayTime) >= 0 ? documentClientException.RetryAfter: minDelayTime;
}
else
{
throw;
}
}
}
}
This is the method for retry logic when requestRateTooLarge exception raise.
I am not sure, whether it is working fine or not,
I am getting Exception: Microsoft.Azure.Documents.RequestRateTooLargeException while querying and inserting around 4000 records at a time,
I used the same retry logic for inserting, its working fine.
I am not getting any error and also successfully inserted all records but unable to get query data.
Based on #aravind Ramachandra and #Ryan CrawCour answers above/below, this is what I am using to get round the issue.
public async Task SaveToDocDb(dynamic jsonDocToSave)
{
using (var client = new DocumentClient(endpoint, authKey))
{
var queryDone = false;
while (!queryDone)
{
try
{
await client.CreateDocumentAsync(docCollectionlink, jsonDocToSave);
queryDone = true;
}
catch (DocumentClientException documentClientException)
{
var statusCode = (int)documentClientException.StatusCode;
if (statusCode == 429 || statusCode == 503)
Thread.Sleep(documentClientException.RetryAfter);
else
throw;
}
catch (AggregateException aggregateException)
{
if(aggregateException.InnerException.GetType() == typeof(DocumentClientException)){
var docExcep = aggregateException.InnerException as DocumentClientException;
var statusCode = (int)docExcep.StatusCode;
if (statusCode == 429 || statusCode == 503)
Thread.Sleep(docExcep.RetryAfter);
else
throw;
}
else
throw;
}
}
}
}
You also need a catch block for AggregateException, and check if the AggregateException.InnerException is a DocumentClientException and performs the same check for StatusCode == 429. Since the query execution is asynchronous, you might be getting the throttle exception wrapped inside an AggregateException.
If you could post a full repro, we might able to definitively identify the problem.
I am developing a web api using WCF Web Api preview 5. At the moment I have a resource class fully functional, how ever I noticed my methods inside this resouce are getting complex.
For example:
[WebInvoke(UriTemplate = "{EhrID}/PhysicalTest",Method="POST")]
public HttpResponseMessage<DTO.PhysicalTest> PostPhysicalTest(int EhrID, DTO.PhysicalTest PhysicalTestDTO)
{
var EHR = repository.FindById(EhrID);
var PhysicalTest = Mapper.Map<DTO.PhysicalTest, PhysicalTest>(PhysicalTestDTO);
if (PhysicalTest == null)
{
var response = CreateResponseForException("No object to store", HttpStatusCode.BadRequest);
throw new HttpResponseException(response);
}
try
{
if (EHR.PhysicalTests == null)
{
EHR.PhysicalTests = new List<PhysicalTest>();
}
PhysicalTest.CreationDate = DateTime.Now;
EHR.PhysicalTests.Add(PhysicalTest);
_unitOfWork.Commit();
return new HttpResponseMessage<DTO.PhysicalTest>(PhysicalTestDTO, HttpStatusCode.Created);
}
catch (Exception ex) {
var response = CreateResponseForException("Cannot create Physical Test", HttpStatusCode.InternalServerError);
throw new HttpResponseException(response);
}
}
As you may notice this method has the task of posting a new Physical Test, but it's actually validating my model too (I'm missing lots of validations still, property validations), which should not be this class concern. If there any approachable way to reduce the complexity of the methods inside de resource?
I would split it up into smaller more focused methods. I might also start using instance variables instead of passing all these arguments around, but for the sake of this post I've rewritten it without pushing stuff to instance variables.
[WebInvoke(UriTemplate = "{EhrID}/PhysicalTest",Method="POST")]
public HttpResponseMessage<DTO.PhysicalTest> PostPhysicalTest(int EhrID, DTO.PhysicalTest PhysicalTestDTO)
{
var EHR = repository.FindById(EhrID);
var PhysicalTest = Mapper.Map<DTO.PhysicalTest, PhysicalTest>(PhysicalTestDTO);
if (PhysicalTest == null)
{
var response = CreateResponseForException("No object to store", HttpStatusCode.BadRequest);
throw new HttpResponseException(response);
}
PostPhysicalTest(EHR, PhysicalTest);
return new HttpResponseMessage<DTO.PhysicalTest>(PhysicalTestDTO, HttpStatusCode.Created);
}
private void PostPhysicalTest(EHR ehr, PhysicalTest physicalTest)
{
try
{
CreatePhysicalTest(ehr, physicalTest);
}
catch (Exception ex) {
var response = CreateResponseForException("Cannot create Physical Test", HttpStatusCode.InternalServerError);
throw new HttpResponseException(response);
}
}
private void CreatePhysicalTest(EHR ehr, PhysicalTest physicalTest)
{
if (ehr.PhysicalTests == null)
{
ehr.PhysicalTests = new List<PhysicalTest>();
}
physicalTest.CreationDate = DateTime.Now;
ehr.PhysicalTests.Add(physicalTest);
_unitOfWork.Commit();
}