Phase

What a control needs to do

Method or event to override

Initialize

Initialize settings needed during the lifetime of the incoming Web request.

Init event (OnInit method)

Load view state

At the end of this phase, the ViewState property of a control is automatically populated as described in MaintainingState in a Control. A control can override the default implementation of the LoadViewState method to customize state restoration.

LoadViewState method

Process postback data

Process incoming form data and update properties accordingly.

LoadPostData method (if IPostBackDataHandler is implemented)

Load

Perform actions common to all requests, such as setting up a database query. At this point, server controls in the tree are created and initialized, the state is restored, and form controls reflect client-side data.

Load event

(OnLoad method)

Send postback change notifications

Raise change events in response to state changes between the current and previous postbacks.

RaisePostDataChangedEvent method (if IPostBackDataHandler is implemented)

Handle postback events

Handle the client-side event that caused the postback and raise appropriate events on the server.

RaisePostBackEvent method(if IPostBackEventHandler is implemented)

Prerender

Perform any updates before the output is rendered. Any changes made to the state of the control in the prerender phase can be saved, while changes made in the rendering phase are lost.

PreRender event
(OnPreRender method)

Save state

The ViewState property of a control is automatically persisted to a string object after this stage. This string object is sent to the client and back as a hidden variable. For improving efficiency, a control can override the SaveViewState method to modify the ViewState property.

SaveViewState method

Render

Generate output to be rendered to the client.

Render method

Dispose

Perform any final cleanup before the control is torn down. References to expensive resources such as database connections must be released in this phase.

Dispose method

Unload

Perform any final cleanup before the control is torn down. Control authors generally perform cleanup in Dispose and do not handle this event.

UnLoad event (On UnLoad method)