ASP.NET Page Life Cycle

Presented By : Abhishek Surhttp://www.abhisheksur.com/

Table of ContentIntroductionApplication Life Cycle

IIS Request ProcessApplication PoolWorker ProcessHTTP Handler/Module

ASP.NET Page Life CyclePage Life Cycle StepsPage Life Cycle Events

Life Cycle for Master Page and User ControlQA

IntroductionWhen Clients request for an aspx page from

browser and lot of stuffs happens in background to produce the output or sending response to client. This evolves ASP.NET Page Lifecycle.

ASP.NET Page Life Cycle is very much important to know for each and every developer to developed an ASP.NET Web Application.

All events, data processing, dynamic control creation, view state, postback, rendering etc. are depends with Page Life Cycle.

Application Life Cycle1. Client Request For

Information2. Request comes to Server3. Server Process the request4. Send the response back to

Client

Application Life Cycle - Contd.Key terms to remember

HTTP.SYS WAS Application Pool Worker Process

http://blogs.thesitedoctor.co.uk/tim/2006/06/30/Complete+Lifecycle+Of+An+ASPNet+Page+And+Controls.aspx

Application Life Cycle – Contd.Key Terms To Remember

Http ModuleHttp HandlerHttp Pipeline

End Of Application Life Cycle – Start Page Life CycleRequest Passes Through HTTP Pipe LineThis Start Page Life Cycle

ASP.NET Page Life Cycle BeginsStartInitializationLoadValidationEventsRender

S I

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V E

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Page Life Cycle - StartClient Request For ResourceRequest Comes To Server (IIS)IIS Process the Initial ProcessingRequest Passed through HTTP- Pipe LineASP.NET Page Life Cycle Starts

Page Life Cycle - InitializationSet Postback propertiesUnique ID for Each Control in the PageThemes needs to be initializedDynamic control need to be created

Page Life Cycle - LoadIf the Request is the post back request then it

loads data from View States and Control State

Page Life Cycle - ValidationValidate the pages ControlUpdates the IsValid property

Page Life Cycle - EventsThis will only fired if the request is an

postback event.Like, if the post back is happened for an

Button Click. Button Click event will fired.

Page Life Cycle - RenderBefore Rendering All View State data has

been set.Render() method for all control has been

called and write the out put on output stream.

Page Life Cycle - Events

http://msdn.microsoft.com/en-us/library/ms178472.aspx

ASP.NET Page Life Cycle EventsPreInit Init PreLoad LoadControl EventsPreRender SaveViewStateRender Unload

Page Life Cycle – EventsPreInit()

This is the first event which raised in asp.net page lifecycle

Check for Request is for Post Back or not. All dynamic control need to be created Theme Change, Master Page Set at runtime

Init() Raised after all controls have been initialized Build up a tree of controls from the ASPX file Turn on view state monitoring – any changes in

control will be tracked by View State for future.

Page Life Cycle - EventsPreLoad()

Load view state data for page and controls Load Postback data if needed We can process any kind operation that need to

perform before page load

Load() OnLoad methods control called for each and every

control We can create the connection initialization for any

kind of external source like database connection We can also set the control properties

Page Life Cycle - EventsControl Events

If this is an postback request , Corresponding events will triggered. Like, if the post back is happing for button click, then Button_Click Event will fired.

PreRender Each control of the page has a PreRender event which is

being invoked. EnsureChildControls is also being called during this events DataBind method for all control has also been called If we want to change any thing to any control this is the last

event where we can do because after the pageRender starts

Page Life Cycle - EventsSaveViewState

ViewState Monitoring is turned off as here all the ViewState Data need to be saved.

View State data saved in hidden filed called _VIEWSTATE

Render Pages calls the Render method for each and every

control. Text writer that writes the output to the as output

stream Output steam set to the page's Response property.

Page Life Cycle - EventsUnload

This is the last event of asp.net page life cycle This ensure the Request and Response has been

set to null. This is called only after the content of the page fully

rendered and response sent to client

Page Life Cycle - Master Page and User ControlsMasterPage gets initialized from the Page class in the

init phaze of page. The content of Masterpage gets loaded side by side as the page gets loaded.

User control will be initialized and added to the page and before page gets initialized

After page Onload, MasterPage_OnLoad gets called and UserControl_Onload gets called sequentially.

Followed by each of Page events, masterPage events gets called and next Usercontrol events are called.

During the unload phaze, Usercontrol gets unloaded first and then masterpage and Page in sequence.

For further reference refer to : http://blogs.thesitedoctor.co.uk/tim/2006/06/30/Complete+Lifecycle+Of+An+ASPNet+Page+And+Controls.aspx

Q/A

Thank you