Asp.Net Control Architecture

1. Asp.Net Control Architecture Sundararajan Subramanian Software Development Engineer | Microsoft Sundararajan.Subramanian@microsoft.com

2. Agenda • Introduction • What is a Custom Control? • Custom Controls • User Controls • Server Controls • User Controls – Demo • Server Controls – Rendering – Demo • Properties & State Management • Control Life Cycle. • Server Controls – Composite Controls • Event Handling • Summary

3. What is a Server Control? • .Net component that is used to generate the user interface of an ASP.NET Web application. • Eg: Label, GridView, etc.,

4. Types of Controls • Declarative Markup in .Aspx Page • Common functionalities Refactored into a User Control - .ascx • Reusable behavior built /compiled and packaged as Server Control

5. Ways to Author Custom controls • User Controls • Simple, declarative authoring model (.ascx file) • Scoped to a single application • Well suited to static content and layout • “Custom” or Compiled Controls • Code-based authoring model (.cs or .vb class file) • Easily shared across applications • Well suited to dynamic or programmatic generation of content and layout • More complex, but also more capabilities

6. DEMO User Controls

7. DEMO Custom Server control – Rendering Sample

8. Which Base Class To Choose? • System.Web.UI.control • System.Web.UI.WebControls.WebControl • Derive from Existing Controls

9. Properties • Getters And Setters • Allows the Client to set the properties at design time or runtime. • String _Text; • Public String Text{ • get { • return _Text; • } • Set { • _Text=Value; • } • }

10. State Management • View State • Session State • Application State • Control state • Override Savecontrolstate and Loadcontrolstate • Custom State management • Override LoadViewstate and SaveviewState

11. State Management - Sample [ Bindable(true), Category("Appearance"), DefaultValue(""), Description(“...") ] public string Text { get { object o = ViewState[“Text"]; if (o == null) return String.Empty; else return (string)o; } set { ViewState[“Text"] = value; } }

12. Control Life Cycle Post Back Only

13. Control Life Cycle …. Post Back Only

14. Raising an Event • Define the EventArgs • Define the Event Delegate • Define a method that invokes the event Delegate public class LogOutEventArgs : EventArgs {...} public delegate void LogOutEventHandler(object sender,LogOutEventArgs e); protected virtual void OnLogOut(LogOutEventArgs e) { if (LogOut != null) { LogOut(this, e); } }

15. DEMO Raising Events

16. Composite controls • Based on object composition • Combining the existing controls and delegating the responsibility to the existing controls. • Reuses the feature of existing controls

17. DEMO Composite Control Event Handling

18. Performance Considerations • Use Event Properties for handling Events • Store only necessary information in State • Store very minimal information in Control state

19. Summary • Controls provide ways to reuse functionality in web apps • Use User controls for within application usage • Create Specialized derived controls to make Incremental changes to existing controls • Use Composition to leverage existing controls to build more complex controls

20. Contact • Contact me @ • http://blogs.msdn.com/sundararajan • Sundararajan.subramanian@microsoft.com