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Page life cycle of ASP.net page



The stsges of Page life cycle are as follows :
Methods Description
Page_Init Page Initialization
LoadViewState View State Loading
LoadPostData Postback Data Processing
Page_Load Page Loading
RaisePostDataChangedEvent PostBack Change Notification
RaisePostBackEvent PostBack Event Handling
Page_PreRender Page Pre Rendering Phase
SaveViewState View State Saving
Page_Render Page Rendering
Page_Unload Page Unloading

Page_Init :

The Page_Init event is the first event to be triggered in the page life cycle. In this the control tree has been created, the controls declared in the .aspx file are initialized. The viewstate is not available at this stage. We can create or re-create the controls that need to be created or re-created dynamically.

LoadViewState :

The Viewstate contains stored information that is set by the page and controls of the page. But the load view state event only occurs when the page has been posted back. Due to viewstate control's and page itself store information that is persistent among web requests. It contains the state of the controls the last time the page was processed on the server.

LoadPostData :

After viewstate is loaded the control are updated with posted values or values that are entered or changed by user.

Page_Load :

After Loadpostdata the page_load event is fired. In this event code written inside page load is executed once at the beginning of the page.

RaisePostDataChangedEvent :

In this event when user clicks submit button or any other button then it changes state of the page and the event related to that button is raised.

RaisePostBackEvent :

This methods knows which event has occurred and which related method you need to call like btnsubmit is clicked then it will call method related to it like “btnsubmit_click” to perform its functionality.

Page_PreRender :

At this stage page is prepared for Rendering and if user wants to chage anything he can change it here only as in this event viewstate is not saved and output is not rendered.

SaveViewState :

In this event values of viewstate is saved to control own viewstate collection. The resultant viewstate is serialized, hashed, base24 encoded and associated with the _viewstate hidden field.

Page_Render :

This method takes the HtmlWriter object and uses it to accumulate all HTML text to be generated for the control. For each control the page calls the render method and caches the HTML output.

Page_unload :

During this method, data can be released to free up resources on the server for other processes. Once this method is completed, the HTML is sent to the browser for client side processing.

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