In an ASP.NET application, the lifecycle events within the Global.asax file occur in a specific sequence from the beginning to the end of the application and request lifecycles. Here is the sorted order of events based on their typical execution timeline:
Application_Start: Triggered when the application starts, once per application lifecycle.
Session_Start: Occurs when a new session is created for a user.
Application_BeginRequest: Fired at the beginning of each request.
Application_AuthenticateRequest: Occurs when the application attempts to identify the user.
Application_AuthorizeRequest: Triggered to determine if the identified user is authorized to proceed.
Application_ResolveRequestCache: Fired when the application tries to serve the request from the cache.
Application_AcquireRequestState: Occurs when the application acquires the current state associated with the request.
Application_PreRequestHandlerExecute: Triggered before the ASP.NET page framework begins executing the event handler for the request.
Application_PostRequestHandlerExecute: Fired after the event handler has been executed but before the result is sent to the client.
Application_ReleaseRequestState: Occurs when the application completes execution of all event handlers, allowing state modules to save their state data.
Application_UpdateRequestCache: Fired to update the cache with the response, if applicable.
Application_PreSendRequestHeaders: Triggered just before the HTTP headers are sent to the client.
Application_PreSendContent: Occurs just before the content is sent to the client.
Application_EndRequest: The last event fired for each request, used for cleanup tasks.
Session_End: Triggered when a session ends, either due to timeout or the user leaving the application.
Application_Error: Can occur at any point during the application lifecycle when an unhandled exception happens.
Application_Disposed: Occurs just before the application instance is destroyed. Typically not used in most applications but available for cleanup logic.
Application_End: Fired once when the application is ending, typically during a shutdown or restart.
This sequence provides a comprehensive framework for understanding the flow of events in an ASP.NET application from start to finish.
1