Considerations for threading in web environment

Question

Hello, I am getting started with ASP.NET web development and was wondering what the differences are when multi-threading a standard winforms application versus a web-based application written in asp.net that will run in IIS. Is there any difference and if so, what are the limitations (and conversely any positives) of threading a web application, Thank you in advance

Answer 1

Threading isn't really an issue in the web world. There isn't any state and each request is a new instance of the web page. There are ways to track state between requests such as cookies, sessionstate, viewstate.

Answer 2

In the Windows GUI world, you always have the "UI thread" which you can use to communicate with the user. For example, you can start a BackgroundWorker in the UI thread, which will raise an event in the UI thread after completing its work: In a Windows UI application, you can be pretty sure that the UI thread is still there, unless the user has closed the application.

In the web world, you have no equivalent main thread. There are just web requests: Sometimes there are none and sometimes there are many at the same time; it is even possible that one single request will be handled by multiple threads without you knowing it. If you start a background thread with a lengthy operation, you need to either

• delay finishing the web request until the background thread has completed -- which means a slow response time for the user and somehow defeats the purpose of a background thread or
• regularly (during future requests) check the state of the thread and inform the user when it has finished.

Of course, that's only a problem if you want some user interaction after the thread has finished. If you don't, just start it and it will eventually finish (unless someone restarts IIS).