I am facing an issue with two different endpoints in my single asp.net app. Basically, the issue is that one of the endpoints does not allow asynchronous methods in the page and the other endpoint does. If I run the app one endpoint will ask me to have an asynchronous asp.net page, but the other one crashes and vice versa.
public async Task<AirtableListRecordsResponse> RetrieveRecord()
{
string MyProductID = ProductID;
string baseId = "00000000000xxxx";
string appKey = "00000000000xxxx";
var records = new List<AirtableRecord>();
using (AirtableBase airtableBase = new AirtableBase(appKey, baseId))
{
Task<AirtableListRecordsResponse> task = airtableBase.ListRecords(tableName: "efls", filterByFormula: ProductID);
AirtableListRecordsResponse response = await task;
if (!response.Success)
{
string errorMessage = null;
if (response.AirtableApiError is AirtableApiException)
{
errorMessage = response.AirtableApiError.ErrorMessage;
}
else
{
errorMessage = "Unknown error";
}
// Report errorMessage
}
else
{
records.AddRange(response.Records.ToList());
var record = response.Records;
//offset = response.Offset;
//var record = response.Record;
foreach (var item in record)
{
foreach (var Fields in item.Fields)
{
if (Fields.Key == "pdfUrl")
{
string link = Fields.Value.ToString();
MyLink = Fields.Value.ToString();
}
}
}
// Do something with your retrieved record.
// Such as getting the attachmentList of the record if you
// know the Attachment field name
//var attachmentList = response.Record.GetAttachmentField(YOUR_ATTACHMENT_FIELD_NAME);
}
return response;
}
}
This is the asynchronous method which asks for an asynchronous page, the other contains a strong structure and it cannot be changed for any reason. Is there any way to make them work together?
I am using airtable.com api by the way.
Thanks in advance.
I solved by my own,
The solution I found is the following:
When a page works with two different endpoints and one of them obligates the page to be asynchronous the best solution is to split the procedures into two different sections and/or pages, one of them will call the asynchronous methods and retrieves the info and other works without being asynchronous.
How can I pass the information between the sites?
Using session variables, there are endpoints which only needs to display simple data as in this case, so the session variables will be called in the page #2 which is the non-asynchronous page.
It is a simple solution but effective.
Thank you very much to all for you answers.
Using Wait on Task, you can use synchronous method
Task<AirtableListRecordsResponse> task = Task.Run(() => airtableBase.ListRecords(tableName: "efls", filterByFormula: ProductID));
task.Wait();
AirtableListRecordsResponse response = task.Result;
Use it only when you cannot use async method.
This method is completely deadlock free as mentioned on msdn blog-
https://blogs.msdn.microsoft.com/jpsanders/2017/08/28/asp-net-do-not-use-task-result-in-main-context/
Related
I've never attempted to use WaitAll() or WhenAll() when running async functionality. After looking at many documentations, SO posts, and tutorials, I haven't found enough information for this, so here I am.
I'm trying to figure out the best/proper way(s) to do the following:
Using EF6, get data as List<Entity>.
Iterate through each Entity and call an external API to perform some action.
External API returns data per Entity which I need to store on the same Entity.
Currently I have built (not tested) the following (without the error handling code):
public IEnumerable<Entity> Process() {
bool hasChanged = false;
var data = _db.Entity.Where(x => !x.IsRegistered);
foreach (var entity in data) {
var result = await CallExternalApi(entity.Id, entity.Name);
entity.RegistrationId = result.RegistrationId;
entity.IsRegistered = true;
_db.Entry(entity).State = EntityState.Modified;
hasChanges = true;
}
if (hasChanges) {
uow.Commit();
}
return data;
}
I feel like I may be able to take advantage of some other functionality/feature in async, but if I can I'm not sure how to implement it here.
Any guidance is really appreciated.
Update
The API I'm calling is the Zoom Api to add Registrants. While they do have an route to batch add Registrants, it does not return the RegistrantId and the Join Url I need.
First, figure out if your external API might have a way to get all the items you want in a batch. If it does, use that instead of sending a whole bunch of requests.
If you need to send a separate request for each item, but want to do it concurrently, you could do this:
public async Task<IReadOnlyCollection<Entity>> Process() {
var data = _db.Entity.Where(x => !x.IsRegistered).ToList();
if(!data.Any()) { return data; }
var entityResultTasks = data
.Select(async entity => new { entity, result = await CallExternalApi(entity.Id, entity.Name) })
.ToList();
var entityResults = await Task.WhenAll(entityResultTasks);
foreach (var entityResult in entityResults) {
var entity = entityResult.entity;
var result = entityResult.result;
entity.RegistrationId = result.RegistrationId;
entity.IsRegistered = true;
_db.Entry(entity).State = EntityState.Modified;
}
uow.Commit();
return data;
}
You will want to watch out for possible concurrency limits on the target source. Consider using Chunk to break your work into batches of acceptable sizes, or leveraging a semaphore or something to throttle the number of calls you're making.
Im working on a website that integrates with Dynamics 365 with the Dynamics SDK. We have seen errors in the logs such as “Cannot access a disposed object”. Upon further investigation we found out that the SDK methods are not thread safe so needed to refactor the code to take this into account.
We had a method such as follows that would create or update a Contact entity depending on whether it already exists:
public Guid? SetProfile(IProfile profile)
{
using (var xrm = new XrmServiceContext(_organizationService))
{
//check whether account already exists
var crmProfile = GetContact(xrm, profile.UserId);
if (crmProfile == null)
{
//create new account if required
{
crmProfile = new Contact
{
EMailAddress1 = profile.Username,
//lots of properties hidden to make for easier code example
};
}
xrm.AddObject(crmProfile);
}
else
{
//update existing account
crmProfile.new_Title = profile.Title.HasValue ? new OptionSetValue(profile.Title.Value) : null;
//lots of properties hidden to make for easier code example
xrm.UpdateObject(crmProfile);
}
var response = xrm.SaveChanges();
return crmProfile.Id;
}
}
When this method was executed concurrently by 2 or more users the error "Cannot access a disposed object" would be thrown, referring to the XrmServiceContext object.
I therefore knew that I needed to make this method thread-safe, but also it needs to be Synchronous as our UI depends on having the return value of the method. I played around with different threading methods:
Task.Factory.StartNew(() => delegate
new Thread()
However, with both of these methods I wasn't able to get the method to execute synchronously, so I ended up with:
public Guid? SetProfile(IProfile profile)
{
var task = new Task<Guid?>(() =>
{
using (var xrm = new XrmServiceContext(_organizationService))
{
//check whether account already exists
var crmProfile = GetContact(xrm, profile.UserId);
if (crmProfile == null)
{
//create new account if required
{
crmProfile = new Contact
{
EMailAddress1 = profile.Username,
//lots of properties hidden to make for easier code example
};
}
xrm.AddObject(crmProfile);
}
else
{
//update existing account
crmProfile.new_Title = profile.Title.HasValue ? new OptionSetValue(profile.Title.Value) : null;
//lots of properties hidden to make for easier code example
xrm.UpdateObject(crmProfile);
}
var response = xrm.SaveChanges();
return crmProfile.Id;
}
});
task.RunSynchronously();
return task.Result;
}
Everything I seemed to read online suggested I should use the StartNew method, however this is geared towards Asynchronous calls with I could not allow, and it also seemed that it doesnt guarantee a new thread - from what I've read I understand it is clever enough to know when it needs to create a new thread - however in my instance I have to be certain a new thread is used for the call to Dynamics.
Questions:
Anything wrong with the approach I've taken for a Web application?
If I can't use Asynchronous calls, is there any advantage whatsoever to using the StartNew method?
Many thanks for your time in advance
Kind regards
dotdev
I was trying to figure out some performance values of two scenarios. I thought I was only going to declare the obvious at first. But when I got the results I got a little confused. And now I am looking for a justification for the case.
I have a library which makes couple of queries through a MongoDb database and Active Directory services, then returns the results to client, which are:
GetUserType - to MongoDb - there is a collection which has username and type fields in its all documents. In the query I give the username and ask for the type field.
LoginCheck - to Active Directory - given the username and the password from the client, I create a PrincipalContext object to access to AD server and call ValidateCredentials upon it.
This job is performing on an existing MVC application at the moment. And we are going to create a new desktop application and employ it with the same job.
We were curios about how different can these two scenarios perform? We thought that a direct call to a library without any http connection would perform better than a service request without an hesitation. But we still wondered how much difference is there, and if it was acceptable we are going to make it work through the rest MVC service - because of reasons :)
Hence we tested out the following architectures:
Scenario 1:
Scenario 2:
Basically, what I do for performance test is this:
For scenario 1:
for(var i = 0; i<10000; i++)
{
new Class1().HeavyMethod();
}
For scenario 2:
// client side
for(var i = 0; i<10000; i++)
{
using ( var client = new HttpClient() )
{
var values = new Dictionary<string, string>();
var content = new FormUrlEncodedContent(values);
var response = client.PostAsync("http://localhost:654/Home/HeavyLift", content).Result;
var responseString = response.Content.ReadAsStringAsync().Result;
}
}
// MVC rest service
public class HomeController : Controller
{
public JsonResult HeavyLift()
{
return Json(new Class1().HeavyMethod(), JsonRequestBehavior.AllowGet);
}
}
Common Class:
public class Class1
{
public string HeavyMethod ()
{
var userName = "asdfasdfasd";
var password = "asdfasdfasdf";
try
{
// this call is to MongoDB
var userType = Personnel.GetPersonnelsType(userName).Result;
// this call is to Active Directory
var user = new ADUser(new Session
{
UserType = userType.Type,
UserName = userName,
Password = password
});
return userType.Type + "-" + user.Auth();
}
catch ( Exception e )
{
return e.Message;
}
}
}
The results for 10000 consecutive calls are confusingly shocking:
Scenario 1: 159181 ms
Scenario 2: 13952 ms
Scenario 1 starts off pretty quicly for the first few dosens of calls, then it starts to slow down.
Scenario 2 though offers a constant response time through 10k calls.
What is actually happening here?
Note: I checked the memory and cpu usages of the server that this scenarios runs on(everything runs on the same server) but there is nothing interesting actually, they are behaving just the same in terms of memory and cpu resources.
I've found a bug in my code that I'd love a good a explanation on.
I'm using the ThreadPool.QueueUserWorkItem to perform a task in a new thread.
Originally my code looked like this :-
var url = string.Format("{0}{1}", ConfigManager.SiteUrl, CanonicalUrl);
ThreadPool.QueueUserWorkItem(state => vice.WebsiteMessageService.SendSharePropertyMessage(url, txtEmailAddress.Text));
The bug, was that when the new thread fired my method, it lost the txtEmailAddress.Text's value, and therefore the email was never sent.
To correct this I made a simple change :-
var url = string.Format("{0}{1}", ConfigManager.SiteUrl, CanonicalUrl);
string emailAddress = txtEmailAddress.Text;
ThreadPool.QueueUserWorkItem(state => Service.WebsiteMessageService.SendSharePropertyMessage(url, emailAddress));
Now, the Thread hasthe value of my local variable fine, and the email is sent.
My Question is, Why cant my thread pass the value of the text box value directly?
That might very well be because the implementation of the Text property uses the view state (which, in turn, is lazily loaded) and by the time your work item is scheduled for an execution, there might be no view state to decode (as there's not HTTP context available to your work item by default).
Here's the relevant code (with the help from JustDecompile):
public virtual string Text
{
get
{
string item = (string)this.ViewState["Text"];
if (item != null)
{
return item;
}
return string.Empty;
}
set
{
this.ViewState["Text"] = value;
}
}
Hope this helps.
I am not sure what to use in this scenario.
I have an asp.net web api method that basically does this
Finds points of interests from foursquare near user.
Uses the foursquare locations to do queries in my database to find unique data about point of interest near user.
However since I need to store some of the foursquare information to link to my unique data to that location I decided to store all the information in my database and have my database act as my caching system.
This means anything new point of interest that comes in I have to insert into my database, check if it exists and if so then skip it or if it exists check the last refresh date(foursquare policy states all data must be refreshed after 30 day) and if it out past the refresh date I have to update the data.
I want to slow the user down and have to wait for the above to happen. I want my code to do step 1 and then do what I just mentioned while at the same time doing step 2.
Once step 2 finishes I want to return the data and let the user get on their way. If my caching system is not finished then it should keep going but not bog down the user.
I won't use any of these new results in step 2 as if I am inserting it then I won't have any data on that location at this time.
Not sure if I need to make a thread or use the async/await to achieve this.
Edit
Here is what I am trying to do
public HttpResponseMessage Get()
{
// this will do a foursquare lookup to find all stores near the user
// I want to insert them into my database and link it to my unquie data.
// stores pulled from foursquare will
// a) Be new and not in my database
// b) exist in my database but have been refreshed lately
// c) have not been refreshed in timeframe of foursquare policy
// THIS SHOULD WORK IN THE BACKGROUND
storeService.PointsOfInterestNearUser(80, -130); //As you can see it is
//void. Not sure where to put the async/await stuff
// find this product. Should be happening at the same time as above line.
var product = productService.FindProduct("Noodles");
//This will get returned to the user.
// the new stores taht are being added in StoreNearUser
//won't effect this search as I will have not data on this new store
// if existing store is being refreshed it is possible old
//address might be picked up...
//I can live with that as I doubt the address will change much.
// this should happen after product
var allStores = storeService.FindStoresThatHaveItem(product);
// this should be returned as soon as above line is finished.
//If StoreNearUser is not done, it should keep going but not hold up user.
return allStores;
}
public void StoresNearUser(double latitude, double longitude)
{
// get all categories I can about in foursquare.
//First time from db otherwise cached.
List<StoreCategory> storeCategories = GetStoreCategories();
// do a request and get everything in near the user
//(provided it is also in a category I care about)
var request = CreateFoursquareStoreRequest
(latitude, longitude, storeCategories);
// do the actual call.
var response = client.Execute<VenueSearch>(request);
if (response.StatusCode == System.Net.HttpStatusCode.OK)
{
// start going through the results, add or update or skip of entry will happen
AddUpdateStores(storeCategories, response);
}
else
{
ErrorSignal.FromCurrentContext().Raise(response.ErrorException);
}
}
Edit 2
public async Task StoresNearUser(double latitude, double longitude)
{
// get all categories I can about in foursquare. First time from db otherwise cached.
List<StoreCategory> storeCategories = GetStoreCategories();
// do a request and get everything in near the user(provided it is also in a category I care about)
var request = CreateFoursquareStoreRequest(latitude, longitude, storeCategories);
await client.ExecuteAsync<VenueSearch>
( request
, response =>
{
if (response.StatusCode == System.Net.HttpStatusCode.OK)
{
AddUpdateStores(storeCategories, response);
}
else
{
ErrorSignal.FromCurrentContext()
.Raise(response.ErrorException);
}
}
);
}
gives me this error
Cannot await 'RestSharp.RestRequestAsyncHandle'
I also don't get the difference between Task and void. From what I read if you just use Task it means you are sending nothing back of meaning, then why not just use void?
Edit 2
I found this post to show me how to make the wrapper for Restsharp. It is not 100% what I want but that is a separate issue.
public async Task StoresNearUser(double latitude, double longitude)
{
List<StoreCategory> storeCategories = GetStoreCategories();
var request = CreateFoursquareStoreRequest
(latitude, longitude, maxRadius, returnLimit, storeCategories);
var response = await client.GetResponseAsync(request);
if (response.StatusCode == HttpStatusCode.OK)
{
// had to use json.net right now as the wrapper does not expose restsharps deserilizer
var venue = JsonConvert
.DeserializeObject<VenueSearch>(response.Content);
AddUpdateStores(storeCategories, venue);
}
else
{
ErrorSignal.FromCurrentContext()
.Raise(response.ErrorException);
}
}
public async Task<HttpResponseMessage>Get()
{
await storeService.PointsOfInterestNearUser(80, -130);
var product = productService.FindProduct("Noodles");
var allStores = storeService.FindStoresThatHaveItem(product);
return allStores;
}
When I watch from the debugger it looks like it is still all going in order. I think product and allStores need to be since I need the product before I can find the stores but PointsOfInterestNearUser should be going at the same time as FindProduct.
Edit 3
Here is my FindProduct Method. Not sure what to make async to me it looks like everything needs to wait.
public ResponseResult<Product> FindProduct(string barcode)
{
ResponseResult<Product> responseResult = new ResponseResult<Product>();
Product product = null;
try
{
var findBarCode = context.Barcodes.Where(x => x.Code == barcode).Select(x => x.Product).FirstOrDefault();
responseResult.Response = product;
if (product == null)
{
responseResult.Status.Code = HttpStatusCode.NotFound;
}
else
{
responseResult.Status.Code = HttpStatusCode.OK;
}
}
catch (SqlException ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
responseResult.Status.Code = HttpStatusCode.InternalServerError;
responseResult.Status.Message = GenericErrors.InternalError;
}
return responseResult;
}
Edit 4
Still not sure how to do the Task.WhenAll()
public async Task<HttpResponseMessage>Get()
{
Task[] tasks = new Task[2];
tasks[0] = storeService.PointsOfInterestNearUser(80, -130);
tasks[1] = productService.FindProduct("Noodles");
await Task.WhenAll(tasks);
// not sure how to get product back out. I looked in the debugger and saw a "Result" that has it but when I do tasks[1].Result inetllisene cannot find .Result
var allStores = storeService.FindStoresThatHaveItem(product);
return allStores;
}
I would recommend using async/await for this. Updating a cache is one of the rare situations where returning early from an ASP.NET request is acceptable. You can see my blog post on the subject for some helpful code.
So, something like this (simplified to just look up one "interesting place" per location):
public async Task<PlaceWithData> FindPlaceAsync(Location myLocation)
{
Place place = await GetPlaceFromFoursquareAsync(myLocation);
PlaceWithData ret = await GetExtraDataFromDatabaseAsync(place);
if (ret.NeedsRefresh)
BackgroundTaskManager.Run(() => UpdateDatabaseAsync(place, ret));
return ret;
}
You may also want to consider extending the ASP.NET caching system rather than doing a "roll your own" cache.