Common Steps in an ASP.NET Page's Life Cycle

I’ve been sifting through code written in Whidbey lately, and noticed that there have been a lot of new events added to the page life cycle of an ASP.NET 2.0 webpage, as opposed to the page life cycle of an ASP.NET v1.1 page. Since Whidbey is still in Beta (and therefore always subject to change), and since I am somewhat apprehensive about learning new functionality that may never get released, I drew up a basic diagram as well as a list of common tasks that occur during the lifecycles of both ASP.NET v1.1 and v2.0 pages, to use as an easy reference. Being the technical simpleton that I am, I chose to keep the diagram and list… uh… simple :).

Below the diagram is the list of common tasks that are performed during a page’s life cycle in ASP.NET 1.1 and 2.0:

1. Start

HTTPRuntime

Global.asax is parsed and compiled.

PreInit

Check for IsPostback.
Create or recreate dynamic controls.
Set the Master page dynamically.
Set the StyleSheetTheme property.
Set the Culture property.
Read or set the Profile property values.

2. Page Initialization

Page_Init

Read or change Control properties.
Setup handlers for events.
Load external template files.

LoadViewState()

Load application persistent information to controls.
Specify how ViewState is stored.
Specify how ViewState is mapped to the internal state.

3. Load

Page_Load

If this is the page’s first time being processed, then perform initial databinding.
Read and update control properties.

4. Validation

Validate()

Validate information assigned to validation controls.

5. Event Handling

Page_DataBinding()

Bind data sources to controls.

Page_PreRender

Make final modifications to the page
Change the control tree structure.

SaveViewState()

6. Rendering

Page_Render

Make changes to the HTML of a page.
Write text for controls on a page.

7. Unload

Page_Dispose

Discard objects used in the page, including the Page object.

Page_Unload

Close open files.

Close open database connections.

Finish logging or other request-specific tasks.

I thought I'd add a few handy links for ASP.NET 2.0 Page Life Cycle events in case anyone is interested: An ASP.NET 2.0 Life Cycle diagram to put on your wall, and a fairly comprehensive list of ASP.NET 2.0 Page Life Cycle events that get fired during page execution.

Shannon Frick

Common Steps in an ASP.NET Page's Life Cycle