Get host name without using HttpRequest

问题:

I want to run a "background job" in my ASP.NET application (periodically, as separate thread). And I need host name (DNS name or IP) to do my tasks. The problem is that the HttpContext.Current may be not available here (it's NULL).

Is there any way to get a host name in not using HttpContext.Current.Request.Url.Host.

回答1:

When the host name is available in HttpContext.Request.Url.Host, it is a result of the host name being part of the request sent by the client. As an example, take a request to this page:

GET /questions/2164261/get-host-name-without-using-httprequest HTTP/1.1
Host: stackoverflow.com
...

When running in a background thread, no request context is available, and there really is no concept of a host name at all. Your only alternative is to store the hostname within the code or in configuration.

Slightly off topic: Running scheduled tasks within a web application is asking for trouble, and spawning threads only deals with a few of them. If at all possible, consider running your scheduled jobs from a Windows service, possibly built using a framework like NCron.

回答2:

probably you can add a class variable in your thread class, and set this variable with request.url.host before you run the thread class.

this method can also apply to the session object.

回答3:

Keep in mind that it's a bad idea to initiate that "background job" from a web application if you need that background process to run 24/7 independently. Even if you start it in a new thread. Your web app may have no requests for some time. In this case the run time will shut down the process and all its "child" threads. For continuous running you need to run it as a Windows service. Otherwise, the Darren is right, use the System.Net.Dns.GetHostName().

回答4:

I'm using the same approach as you for scheduling regular tasks and the way I worked around this is to store the machine name for later use when the application gets any kind of web request.

It's a rather dirty hack, but the only way to do this unless you want to hard-code it or retrieve it from an external configuration file, which was too dangerous (unreliable) for my purposes.