huoxudong125/webbackgrounder

Proof of concept of a web based background task manager that deals well with web farms/app shutdowns

Intro

WebBackgrounder is a proof-of-concept of a web-farm friendly background task manager meant to just work with a vanilla ASP.NET web application.

Problem Statement

Code that runs within ASP.NET does not own the App Domain. IIS and ASP.NET are free to shut down the app domain at any moment.

Typically, when that happens, ASP.NET flushes the requests giving them time to finish what they're doing before tearing down the App Domain.

But if you're doing work on background thread that ASP.NET doesn't know about, it could end up tearing down the app domain in the middle of the work, leaving your data in a potentially invalid state.

There are ways to notify ASP.NET that work is in progress. WebBackgrounder demonstrates the use of such facilities.

Likewise, if you have multiple web servers in a farm, you'd like some small amount of coordination between them without them having to explicitly know about each other so they don't duplicate each other's work.

Why not use Azure Queues or a Scheduled Task?

For an enterprise solution, using an Azure Queue, a Windows Service, or a system level scheduled task are much better solutions. The goal of this project would be to allow those to easily hook in and provide this functionality.

But for a small project, or for development environments, you still want these tasks to run without requiring a bunch of setup or a connection to Azure.

What this is not

This is not a general purpose scheduling framework. There are much better ones out there such as hangfire.io, FluentScheduler and Quartz.net. The goal of this project is to handle one task only, manage a recurring task on an interval in the background for a web app.

The needs I have are very simple. I didn't need a high fidelity scheduler. Maybe later, I'll look to integrate what I've done with one of the others. But for now, this scratches an itch.