While (!stoppingToken.IsCancellationRequested) Var nextrun = _schedule.GetNextOccurrence(now) Īwait Task.Delay(5000, stoppingToken) //5 seconds delay Protected override async Task ExecuteAsync(CancellationToken stoppingToken) _nextRun = _schedule.GetNextOccurrence(DateTime.Now) _schedule = CrontabSchedule.Parse(Schedule) Public ScheduledProcessor(IServiceScopeFactory serviceScopeFactory) : base(serviceScopeFactory) Public abstract class ScheduledProcessor : ScopedProcessor This package can parse the Cron expression and determine the next run. For parsing the Cron expression we use a standard library ( nuget package NCrontab). You have to override the ExecuteAsync to start processing based on the Cron expression. When creating a base class for scheduled tasks, the ScopedProcessor is a good base class for the ScheduledProcessor. │ │ │ │ │ 7 is also Sunday on some systems) A Cron expression enables you to precisely specify when to start a task. For example 1 0 * * * will trigger 1 minute past midnight every day. Scheduling the background task with Cron expressionĪ Cron expression is a format that let you specify when to trigger the next execution of your task. In the basic implementation, the ScopedProcessor class adds a 5-second delay between the processing of the task. The implementation of the ProcessInScope method will run your logic. Using (var scope = _serviceScopeFactory.CreateScope())Īwait ProcessInScope(scope.ServiceProvider) The important part of the dependency injection is the Process method: The ScopedProcessor class from this article is a good starting point for implementing a scheduled task. How to do this can you read in ASP.NET Core background processing. When starting a scheduled task, the task has to be given an independent dependency injection scope. The IHostedService runs as a singleton for your task processing. When using the hosted service, you do need to keep in mind to handle the dependency injection correctly. When running a background task in ASP.NET Core, the IHostedService gives you a good skeleton to build the scheduler logic. You will have a good starting point to do your implementation. In this blog post, we will give you some pointers on some pitfalls. Let’s assume you are building the scheduling yourself because you can. NET technologies, Azure, VSTS, Testing, delivering great software. Focus on ALM, DevOps, APIs, Azure and everything around it. An out of the box solution you can a look at Hangfire,, or an external service that does an http call every x seconds to trigger the task (something like Pingdom). When building repeating or scheduled tasks there are many options on how to approach the scheduling and this approach can be influenced by a number of technical choices.īuilding the scheduling yourself is an option when you do not want to add extra dependencies to your project, have full control or just want an extra technical challenge. In many software projects, there are repetitive tasks some do just repeat every x seconds after the last instance is finished but you might also have to run a task on a schedule like every 10 minutes. In this post, we continue on this subject and add some pointers on how to perform scheduled background tasks. In the previous blog post called background tasks with ASP.NET Core using the IHostedService Peter described how to use the IHostedInterface for background tasks.
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