In ASP.NET to process requests a pipeline model
is used which consists of HTTPModules and HTTPHnadler objects. This pipeline
model forms the low level framework which is used by web pages and web services.
Here we will see a high level overview of asp.net request processing.
When we request a URL from a Web browser, the request is sent to the web server. The web server maps the file extensions with the dll's that will handle the
request called as ISAPI extension mappings. We can also configure the mappings
in IIS.
For ASP.NET pages the extension is aspx. So when request for an ASP.NET page comes
to the web server, the web server passes the request to the asp.net dll which
passes the request to the worker process.The following diagram illustrates the
process. This diagram is based on the IIS 5 processing model.
![HttpHndlr1.jpg]()
Once the request reaches the worker process it is processed by the pipeline
which runs within asp.net worker process. The httpRequest is received by an
instance of HTTPRuntime class which creates an instance of HTTPApplication class
to process the request.
HTTPApplication class contains number of HTTPModules to which request and
response are passed on its way to the HTTPHandler.
HTTPModules are filters that can examine and modify the contents of request and
response.
The end of the pipeline is HTTPHandler which is an object of the class that
implements IHTTPHandler interface.Asp.net page and web services are examples of
HTTPHandlers.
![HttpHndlr2.jpg]()
We can create our own HTTPHandlers by following the following steps
- Implementing the IHTTPHandler
- Copying the compiled dlls to the bin
directory of the application
- Registering the handlers in the
web.config.
We can register the HTTPHandlers in the
web.config file by using the following web.config file element.
<httpHandlers>
<add verb="*" path="*.Test "
type="ClassName, AssemblyName" />
</httpHandlers>
Above verb is the method used Get Or Post .Type
is the className and assembly name and path is the URL .