ASP.NET global.asax usage

Question

When to use and not to use global.asax file in asp.net application? I heard that you should use that file only at a pinch.

Answer 1

The Global.asax file is used to implement application and session level events, such as:

Application_Init - fired when an application first initializes

Application_Start - fired when the application first starts

Application_End - the final event fired when the application ends or times out

Session_Start - fired the first time a user’s session is started

Application_BeginRequest - fired with each new request

Application_EndRequest - fired when the application ends

Application_AuthenticateRequest - the event indicates that a request is ready to be authenticated.

Application_Error - fired when an unhandled error occurs within the application

Session_End - fired whenever a single user Session ends or times out.

Implementing these handlers can all be legitimate uses of the global.asax. For example, the Application_Error event handler typically logs any global errors, and the Application_End event handler typically contains application cleanup logic. These are good uses of the Global.asax. Use them whenever necessary, and don't be afraid if the file grows.

However, I have seen cases where developers have added all sorts of global methods to the global.asax that are indeed un-justified. For example, keep business logic related to a particular domain object inside the object itself rather than in the global.asax. If you find methods in the Global.asax that shouldn't be there refactor the work into the right location.