How to clear the cache of HttpWebRequest

I am developing against a proprietary library and I'm experiencing some issues with the cache of the HttpWebRequest. The library is using code equivalent to the one below to make the requests:

var request = WebRequest.Create("http://example.com/") as HttpWebRequest;

request.CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.CacheIfAvailable);

The external resource doesn't disallow caching although each response differs. Thus I am ending up getting the same response each time.

Is there any way to clear the contents of the HttpWebRequest cache? The right solution would be to fix the external source or perhaps change the cache policy, but neither is possible - hence the question.

Clearing the cache could have various impacts, so preferably the solution would be to invalidate the cache on a per resource basis.

.net caching httpwebrequest

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HttpWebRequest uses System.Net.Cache.RequestCache for caching. This is an abstract class; the actual implementation in the Microsoft CLR is Microsoft.Win32.WinInetCache which, as the name implies, uses the WinInet functions for caching.

This is the same cache used by Internet Explorer, so you can manually clear the cache by using IE's Delete Browsing History dialog. (Do this first as a test, to make sure clearing the WinInet cache solves your problem.)

Assuming that clearing the WinInet cache solves the problem, you can delete files programmatically by P/Invoking to the DeleteUrlCacheEntry WinInet API:

public static class NativeMethods
{
    [DllImport("WinInet.dll", PreserveSig = true, SetLastError = true)]
    public static extern void DeleteUrlCacheEntry(string url);
}

answered 2012-06-16T05:41:24.690

How to clear the cache of HttpWebRequest

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