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Generic Handler Registration in Web.Config

Answer 1

+1 A:

A handler is just another type of file you can browse to. An HTTP Module has to be registered in a web.config, but not necessarily a handler.

Jonas 2009-10-12 22:51:30

But if I want to overwrite asp.net default httphandlers for whole project then I'll need to register it in web.config right ?

Braveyard 2009-10-12 22:55:54

I'm not 100% sure what you're asking...are you adding a handler that has the same name as a built-in handler?

Jonas 2009-10-12 22:56:48

Or are you adding a handler that's intended to map to a wildcard path? IE, any request to *.foo should be directed to your handler?

Jonas 2009-10-12 22:57:22

I mean there must be default httphandler which handles all requests before passing to httpmodules, right ? and it handles all the requests unless otherwise isn't specified, what if I want to write my own custom handler which handles everthing in my project ? Then should I register it as default httphandler ?

Braveyard 2009-10-12 22:59:49

That's where you're confusing an HTTP module with an HTTP handler. An HTTP handler is just a slimmed down page, really...a URL that you browse directly to. An HTTP module is code that runs during the request pipeline, and is run for every (managed) request. See here for an example: http://msdn.microsoft.com/en-us/library/aa719858(VS.71).aspx

Jonas 2009-10-12 23:04:37

Thanks a lot for helping me.

Braveyard 2009-10-13 08:15:05

Answer 2

+4 A:

Generally, the generic handler in Asp.net is designed for supporting some small task like creating some thumbnail pictures that doesn't require Asp.net process. So, you can call it like call a simple asp.net page like "www.somesite.com/Thumbnail.ashx?filename=abc.jpg".

By the way, if you want to map this handler with some URL like the following URL.

www.somesite.com/Thumbnail/abc.jpg
www.somesite.com/Thumbnail/dog.jpg
www.somesite.com/Thumbnail/cat.jpg

You need to use some URL routing like web form routing (based on System.Routing) for mapping it. So, you can use the following code for doing like the above example.

public static void RegisterRoutes(RouteCollection routes)
{
  routes.Map("Thumbnail", "Thumbnail/{filename}").To("~/Thumbnail.ashx");
}

For more information about Web Form mapping, please look at Using Routing With Web Forms by Phil Haack.

However, if you need to create some Http handler that can handler some specify file type for your application like JavaScript file handler. You must create class that inherits from IHttpHandler. After that, you must register it in web.config file for specify file type that is handled by this handler. Please look at HTTP Handlers and HTTP Modules in ASP.NET By Mansoor Ahmed Siddiqui

PS. If you use generic handler for registering in web.config file, you need to create 2 files that are SomeHandler.ashx and SomeHandler.ashx.cs. It's quite complicate for creating some simple file handler. In the other hand, you can create only one cs file that inherits from IHttpHandler class for doing the same thing.

Soul_Master 2009-10-12 23:14:40

Thanks, now that makes sense.

Braveyard 2009-10-12 23:33:23

Good explaination 1+.....

Muhammad Akhtar 2009-10-13 09:45:48

Answer 3

+1 A:

I believe you may be thinking of an HTTP module instead of an HTTP Handler

An HTTP Module intercepts every HTTP request to the site and can optionally do some operations in the HTTP pipeline or intercept the call entirely. Modules must be registered in the web.config

On the other hand, an HTTPHandler works almost exactly the same as an ASPX page, except it is a bit more lightweight and doesn't process all the page events you do not need for something such as an image handler.

Chris Ballance 2009-10-12 23:42:17

Thanks for the nice answer but actually I wasn't confusing Httphandler with httpModule I kinda know what they were. I was asking why I register httphandler :) well thanks tho.

Braveyard 2009-10-13 05:32:38

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