Last few days I thinkin about output cache in asp.net. In my task I need to implement output cache for the very big project. After hours of searching I did not find any examples.
Most popular way to use output cache is declarative, in this case you need to write something like this on the page which you want to cache.
But if you need to cache whole site you must write this on all pages or master pages on project. It is madness. In this case you cant store all configuration in one place. All page have his own configurations..
Global.asax could help me, but my site contains about 20 web progects and ~20 global.asax files. And i don't want copy same code to each project.
For these reasons, i made decision to create HTTPModule. In Init method i subscribe to two events :
public void Init(HttpApplication app)
{
app.PreRequestHandlerExecute += new EventHandler(OnApplicationPreRequestHandlerExecute);
app.PostRequestHandlerExecute += new EventHandler(OnPostRequestHandlerExecute);
}
In method "OnPostRequestHandlerExecute" I set up output caching parameters for each new request :
public void OnPostRequestHandlerExecute(object sender, EventArgs e)
{
HttpApplication app = (HttpApplication)sender;
HttpCachePolicy policy = app.Response.Cache;
policy.SetCacheability(HttpCacheability.Server);
policy.SetExpires(app.Context.Timestamp.AddSeconds((double)600));
policy.SetMaxAge(new TimeSpan(0, 0, 600));
policy.SetValidUntilExpires(true);
policy.SetLastModified(app.Context.Timestamp);
policy.VaryByParams.IgnoreParams = true;
}
In "OnApplicationPreRequestHandlerExecute" method I set calback method to cache validation:
public void OnApplicationPreRequestHandlerExecute(object sender, EventArgs e)
{
HttpApplication app = (HttpApplication)sender;
app.Context.Response.Cache.AddValidationCallback(new HttpCacheValidateHandler(Validate), app);
}
And last part - callback validation method :
public void Validate(HttpContext context, Object data, ref HttpValidationStatus status)
{
if (context.Request.QueryString["id"] == "5")
{
status = HttpValidationStatus.IgnoreThisRequest;
context.Response.Cache.AddValidationCallback(new HttpCacheValidateHandler(Validate), "somecustomdata");
}
else
{
status = HttpValidationStatus.Valid;
}
}
To attach my HttpModule I use programmatically attach method :
[assembly: PreApplicationStartMethod(typeof(OutputCacheModule), "RegisterModule")]
This method works perfectly, but I want to know is there other ways to do this. Thanks.
