1. Anatomy of an ASP.NET Page

2. Slide 2 Compiling an ASP.NET Page An ASP.NET page is compiled when it is rendered for the first time A page is compiled to a class that derives from Page Parse the.aspx file and create a class that derives from Page The preceding class is then compiled to an assembly This process is transparent

3. Slide 3 Compiling an ASP page (Illustration)

4. Slide 4 IIS File Mappings.asax –application files.ascx – ASP user controls.asmx – Web services.aspx – ASP.NET Web pages

5. Slide 5 Processing Directives Processing directives are used to configure the runtime environment Directives can appear anywhere on a page but best practices dictate that they appear at the beginning of the page Directives begin with Make sure you don’t forget the %>

6. Slide 6 Processing Directives Processing directive are used to configure the runtime environment Processing directives have the following format:

7. Slide 7 Processing Directives ( @ Page ) It can appear only in.aspx pages Attributes are divided into roughly three categories Compilation Page behavior Page output There are other tools to configure the same options beyond processing directives

8. Slide 8 Processing Directives Page Compilation See Table 3-5 on page 104 for a complete list CodeFile lists the file containing the VB or C# code for the.aspx page Language describes the programming language for the CodeFile ClassName explicitly sets the name of the class created upon compilation

9. Slide 9 Processing Directives (Referenced Assemblies) Most assemblies are automatically provided by the compiler Assembly references can also be added using the @Assembly directive Assembly references can also be added in the web.config file

10. Slide 10 Introduction to the Page Class The Page class provides the basic behavior for an ASP Web page It’s objects allow you to reference The application itself ( Application ) The server itself ( Server ) The HTTP request ( HttpRequest ) The HTTP response ( HttpResponse ) The user’s session ( Session )

11. Slide 11 Page Class Properties (1) Controls returns a collection of controls on the page IsPostBack indicates whether the page is being loaded in response to a postback or is being loaded for the first time PreviousPage returns a reference to the caller page Only meaningful in case of a cross-page postback Check IsCrossPagePostback

12. Slide 12 Page Class Properties (2) ClientTarget allows you to specify the type of browser Note that automatic browser detection is disabled EnableTheming and Theme allows you to set page themes (more later) MaintainScrollPositionOnPostback allows the page position to be persisted from one postback to the next

13. Slide 13 Page Class Methods (1) DataBind binds all data bound controls to their data sources (more later) Validate causes validation controls to validate their data SetFocus sets input focus to the desired control instance There are methods to work with client script

14. Slide 14 Introduction to Page Events First, this topic is very important to getting your ASP applications to work ASP uses the eventing model to Persist state from one postback to the next Create static and dynamic controls Bind control instances to data sources And much more As your book says “state is an illusion of continuity”

15. Slide 15 Page Life Cycle (1) When a page is requested The runtime figures out why the page is being processed Normal request Postback Cross-page postback callback

16. Slide 16 Page Life Cycle (2) PreInit Event It’s the first event in the page life cycle Master page has not been associated Themes have not been associated It’s possible to change master page or theme association at this time IsCallback, IsCrossPagePostback and IsPostBack are set at this time Control instances have been created

17. Slide 17 Page Life Cycle (3) Init Event Master page and theme have been set and cannot be changed Child controls are initialized and the ID is set Child controls are initialized recursively Init event fires for all child controls before the event fires for the page itself

18. Slide 18 Page Life Cycle (4) InitComplete event Here, viewstate tracking is turn on The event fires only for the page PreLoad event System initialization is complete We don’t typically do much here

19. Slide 19 Page Life Cycle (5) Load event The event is raised first for the page and then recursively for all child controls You can access control properties and view state at this time Create dynamic controls in this event Use IsPostBack to check whether the page is being loaded in response to a postback or new page

20. Slide 20 Page Life Cycle (6) LoadComplete fires after Load At this point, the page begins its rendering phase

21. Slide 21 Page Life Cycle (7) PreRender event Fires for the page first and then recursively for all controls Use to update controls before the output is rendered PreRenderComplete event Raised only for the page after PreRender has fired for all child control instances

22. Slide 22 Page Life Cycle (8) SaveStateComplete event It fires for all constituent controls and then the page itself Next, the markup is generated Unload event After rendering, the event fires for all control instances and then the page itself Use this event to close files or database connections