9/11/2023 0 Comments Office background task handlerCancellation tokens are useful mainly for long running calls that consume significant resources, when stopping the request will not have any side effects.įinally, for the purposes of this article, we used Task.Delay to simulate a long running operation. If the request modifies the state, you will not want such a request to be cancelled. Using cancellation tokens is a good practice, but it is not always recommended in your controller action methods. while(!cancellationToken.IsCancellationRequested) You can listen for cancellation requests by polling the value of the CancellationToken.IsCancellationRequested property as shown in the code snippet given below. Listening for cancellation requests in ASP.NET Core It should be noted that all long running operations must respect the cancellation request and cancel the long running operations so that resources can be released. Cancellation tokens should also be passed to other internal operations.Įventually, the object that created the long running operations may - after a time deadline is reached, or when a user stops a request - propagate a cancellation notification to these cancellation tokens. When an object creates one or more long running operations, it should pass cancellation tokens to all of those operations. When working on web applications, you might often make use of long running tasks, i.e., database calls, file handling, etc. If so, the current operation should cease immediately. An async task receives a cancellation token and examines it to see if a cancellation is requested. In an async task, cancellation indicates that the task should cease performing its current activity. You can use CancellationTokens to stop async tasks as well. In other words, using a CancellationToken can help you stop long running requests from using resources when the user has stopped or refreshed the web page. You can use a CancellationToken to stop a long running operation when the user cancels a request in the web browser. Additionally, the IsCancellationRequested property of the cancellation token instance is set to true, indicating that the CancellationTokenSource has been canceled and cancellation of the task has been requested. When a CancellationTokenSource is canceled, all consumers of CancellationTokens are notified accordingly. What are cancellation tokens? When should we use them?Ī CancellationToken is a lightweight object created by a CancellationTokenSource instance. We’ll use this ASP.NET Core 7 Web API project to create minimal API endpoints and work with cancellation tokens. Ensure that the check boxes “Enable Docker,” “Configure for HTTPS,” and “Enable Open API Support” are unchecked as we won’t be using any of those features here.Leave the “Authentication Type” as “None” (default). In the “Additional Information” window shown next, uncheck the check box that says “Use controllers…” since we’ll be using minimal APIs in this example.Optionally check the “Place solution and project in the same directory” check box, depending on your preferences.In the “Configure your new project” window, specify the name and location for the new project.In the “Create new project” window, select “ASP.NET Core Web API” from the list of templates displayed.Launch the Visual Studio 2022 Preview IDE.Following these steps will create a new ASP.NET Core 7 Web API project in Visual Studio 2022 Preview: Create an ASP.NET Core 7 minimal Web API project in Visual Studio 2022įirst off, let’s create an ASP.NET Core minimal API project in Visual Studio.
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