What is HTTP Handler and HTTP Module in asp.net? Co-Relation and Differences

I have little bit confusion about HTTP Handler and HTTP Module. Then I move to community and get a huge response. After studying for a while now I get a clear idea. Now sharing with you hope that it will also help other guys.


What is HTTP handler?


An ASP.NET HTTP handler is the process (frequently referred to as the "endpoint") that runs in response to a request made to an ASP.NET Web application. The most common handler is an ASP.NET page handler that processes .aspx files. When users request an .aspx file, the request is processed by the page through the page handler. You can create your own HTTP handlers that render custom output to the browser.(msdn)

HTTP handlers process the request and are generally responsible for initiating necessary business logic tied to the request. Custom handlers must implement the System.Web.IHttpHandler interface. Additionally, a handler factory can be created which will analyze a request to determine what HTTP handler is appropriate. Custom handler factories implement the System.Web.IHttpHandlerFactory interface.

ASP.net execution process(Image source:MSDN)

What is HTTP Module?

An HTTP module is an assembly that is called on every request that is made to your application. HTTP modules are called as part of the ASP.NET request pipeline and have access to life-cycle events throughout the request. HTTP modules let you examine incoming and outgoing requests and take action based on the request.(msdn)

HTTP modules are executed before and after the handler and provide a method for interacting with the request.
Custom modules must implement the System.Web.IHttpModule interface. Modules are typically synchronized with events of the System.Web.IHttpModule class (implemented within the Global.asax.cs or .vb file).

The following consists of a list of events that should be considered when implementing your module:

1.BeginRequest
2.AuthenticateRequest
3.AuthorizeRequest
4.ResolveRequestCache
5.AcquireRequestState
6.PreRequestHandlerExecute
7.PostRequestHandlerExecute
8.ReleaseRequestState
9.UpdateRequestCache
10.EndRequest
11.PreSendRequestHeaders
12.PreSendRequestContent
13.Error

Co-Relation
The co-relation between HTTP handler and HTTP module is both are an integral part of the ASP.NET application.
Every request flows through a number of HTTP modules, which cover various areas of the application (i.e. authentication and session information). After passing through each module, the request is assigned to a single HTTP handler, which determines how the system will respond to the request. Upon completion of the request handler, the response flows back through the HTTP modules to the user.


Differences


HTTP Module
1.It represents more something like an modulare peace of code that's similar to another Global.asax.
2.It represent code that is in play for all page requests.
3.These are objects which also participate the pipeline.

HTTP Handler
1.Its a handler for one request.
2.It is more like a single page.
3.These are the end point objects in ASP.NET pipeline.
4.These are essentially processes the request and produces the response

Comments

Ashu said…
Blog was helpful in clearing the differences. Saved my lot of time.
Dinesh Gupta said…
Good one, Its helpful!!!
Dinesh Gupta said…
Good one, Its helpfull!!! :)

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