C# ASP.NET HttpModules: HttpApplication Events

asp.netchttpapplicationhttpmodule

I have an HttpApplication (Global.asax) in my web application, I use this to catch and log unhandled Exceptions and to setup WebFormURLRouting. This all works, however I want to move this code into my Application Framework, (ie not in Global.asax.cs)

I have just tried to create an HttpApplication class in the framework but it seems I cant override the Events? Anyway I believe I can use an HttpModule instead to use consume these events, does this:

1) Eliminate the need for the Global.asax completely?

2) How does this effect scaling up, ie eventually running the application on a web farm

3) I have HttpHandlers to handle other things like File Uploading and File downloading, is there a limit to how many HttpModule/HttpHandlers should be used or should these be combined somehow to reduce overhead?

Any comments appreciated

Best Answer

Listening to the events you know from Global.asax, in an HTTP module, is as simple as hooking up to the events of the HttpApplication instance in the module's Init method. You cannot override the methods of the HttpApplication, you should listen to it's events.

As for your other questions: 1) Yes, in many of my web projects, we do not use a Global.asax

2) This does not really affect up-scaling. For each web server in the farm, you would need to have your HTTPModule hooked up correctly. But since this is done in web.config, it should be there already.

3) Short answer: No. For httphandlers, they are selected and run based on the incoming http request file extension and/or path and HTTP method. You would really need a lot of these before the selection of a specific handler becomes a performance issue. For HttpModules, you have the option of running some code at each request, and obviously, if that code takes time to run, it will affect performance. But it will be your code that takes the time, not the fact that it is being run via a http module.

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common

.net – ASP.NET Web Site or ASP.NET Web Application

Website:

The Web Site project is compiled on the fly. You end up with a lot more DLL files, which can be a pain. It also gives problems when you have pages or controls in one directory that need to reference pages and controls in another directory since the other directory may not be compiled into the code yet. Another problem can be in publishing.

If Visual Studio isn't told to re-use the same names constantly, it will come up with new names for the DLL files generated by pages all the time. That can lead to having several close copies of DLL files containing the same class name, which will generate plenty of errors. The Web Site project was introduced with Visual Studio 2005, but it has turned out not to be popular.

Web Application:

The Web Application Project was created as an add-in and now exists as part of SP 1 for Visual Studio 2005. The main differences are the Web Application Project was designed to work similarly to the Web projects that shipped with Visual Studio 2003. It will compile the application into a single DLL file at build time. To update the project, it must be recompiled and the DLL file published for changes to occur.

Another nice feature of the Web Application project is it's much easier to exclude files from the project view. In the Web Site project, each file that you exclude is renamed with an excluded keyword in the filename. In the Web Application Project, the project just keeps track of which files to include/exclude from the project view without renaming them, making things much tidier.

Reference

The article ASP.NET 2.0 - Web Site vs Web Application project also gives reasons on why to use one and not the other. Here is an excerpt of it:

You need to migrate large Visual Studio .NET 2003 applications to VS 2005? use the Web Application project.

You want to open and edit any directory as a Web project without creating a project file? use Web Site project.

You need to add pre-build and post-build steps during compilation? use Web Application project.

You need to build a Web application using multiple Web projects? use the Web Application project.

You want to generate one assembly for each page? use the Web Site project.

You prefer dynamic compilation and working on pages without building entire site on each page view? use Web Site project.

You prefer single-page code model to code-behind model? use Web Site project.

Web Application Projects versus Web Site Projects (MSDN) explains the differences between the web site and web application projects. Also, it discusses the configuration to be made in Visual Studio.