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POASP.NET Caching - Programatically Invalidating Server Cache...confusion on example
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  1. POASP.NET Caching - Programatically Invalidating Server Cache...confusion on example
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    copied!<p>I'm reading how to programmatically invalidate cached pages on the server in ASP.NET, and the book ("MCTS Self-Paced Traing Kit (Exam 70-515)") says:</p> <blockquote> <p>To directly control whether a cached version of a page is used or whether the page is dynamically generated, response to the ValidateCacheOutput event and set a valid value for the HttpValidationStatus attribute.</p> </blockquote> <p>The code segments look like the following:</p> <pre><code>public static void ValidateCacheOutput(HttpContext context, Object data, ref HttpValidationStatus status) { if (context.Request.QueryString["Status"] != null) { string pageStatus = context.Request.QueryString["Status"]; if (pageStatus == "invalid") status = HttpValidationStatus.Invalid; else if (pageStatus == "ignore") status = HttpValidationStatus.IgnoreThisRequest; else status = HttpValidationStatus.Valid; } else status = HttpValidationStatus.Valid; } protected void Page_Load(object sender, EventArgs e) { Response.Cache.AddValidationCallback( new HttpCacheValidateHandler(ValidateCacheOutput), null); } </code></pre> <p>Could someone please explain to me what this code is doing? Also, the main question I have is that I thought Cached pages were simply returned from the server, but the code below indicates that the page life-cycle is being invoked (Page_Load event); I'm confused because the page life-cycle isn't invoked if a cached page is returned, so how would the code in the Page_Load event even fire?</p> <p>Note: Here's the <a href="http://msdn.microsoft.com/en-us/library/a5e5hdyz.aspx" rel="nofollow">same example</a> that the book has</p>
 

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