in ancient ages..

• ...somewhere around year 2011...
• ...it was not easy to run task in background (for web app)

in ancient ages..

    public class JobHost : IRegisteredObject
    {
        public JobHost() {
            HostingEnvironment.RegisterObject(this);
        }
        public void Stop(bool immediate) {
            HostingEnvironment.UnregisterObject(this);
        }
        public void DoWork(Action work) {
            work();
        }
    }
    ...
    new JobHost().DoWork(() => { /* ... get the job done... */ });
    ...
    

code from http://haacked.com/archive/2011/10/16/the-dangers-of-implementing-recurring-background-tasks-in-asp-net.aspx/

QueueBackgroundWorkItem

• introduced in .NET 4.5.2
• to be used for simple long running tasks
• not very long :)
• its still in web server process
• ASP.NET runtime will try to delay AppDomain shutdown

QueueBackgroundWorkItem

DEMO

QBWI limitations

• only in ASP.NET
• better be ready in 30s :)
• no execution context, need to copy values from HttpContext
• no guarantee that it will be ever executed
• no guarantee that it will run to completion
• CancellationToken is only a suggestion to shutdown, if you not obey your job will be killed

Quartz.NET

• open source library
• works in any .net app, single or in cluster
• load balance & failover
• persistence (configurable)
• extensible by plugins

just...

    Install-Package Quartz

    public class MyJob : IJob
    {
        public void Execute(IJobExecutionContext context)
        {
            // ... just get the job done here
        }
    }
    

jobs

• simple class, public ctor, implements IJob interface
• allow to pass context (IJobExecutionContext)
• IStatefulJob, IInteruptableJob
• JJobExecutionContext & IJobDataMap

triggers

• simple triggers
• daily time triggers
• calendar interval triggers
• cron triggers

listeners

• allows to execute code when sth happened
• TriggerListener
• JobListener
• SchedulerListener

scheduler

• use helpers to build jobs & triggers
• remoting to schedule jobs from app
• handle with care!
• ...and remember about security!

Quartz.NET

DEMO

but why not
windows scheduler?

• simpler API
• no WMI required (full trust?)
• persistence & simpler backups
• custom monitoring & jobs management
• extensible by plugins & custom implemetation

and why use
windows scheduler?

• another service to deploy & maintain
• no code required :)
• integrated with admin management & monitoring tools

Azure WebJob

• various process types: node, php, cmd, bash, python
• continous (running all the time), scheduled & on demand runs
• windows scheduler scaled to the cloud :)
• still in preview (install nuget package with -pre option)

Azure WebJob

DEMO