ASP.NET Server Controls

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ASP.NET Server Controls

• Presented By
• Robin Lilly
• iLogbook

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Agenda

• Introduction
• Basic control authoring topicsImplementing
  properties
• Rendering
• Raising Events
• Extending existing controls
• Compositing existing controls

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Agenda

• Build some real world examples
• 2 ADA controls
• Label
• ltlabel forltClientIDgtNamelt/labelgt,
• Textbox
• Inherited textbox that implements onfocus
  onblur
• Inspect a Shopping Cart
• Composite Control
• Inspect code
• CreateChildControls()
• BackButton prevention via session state
• Properties
• UI Type Editor
• Events
• State Management View State and Session

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What Is A Server Control?

• A server control is a .NET component that is used
  to generate the user interface of an ASP.NET Web
  application.
• It is implemented as a managed class deriving
  directly or indirectly from the
  System.Web.UI.Control base class.

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What Is A Server Control?Speaking More
Practically

• A Web user interface element
• Renders into HTML, script or a different markup
  format
• Allows customization of rendering
• A Web user interface component
• Exposes properties, events and methods and is
  programmable
• Provides higher level abstractions
• Performs post-back processing
• Handles differences between browsers
• Consistent programming model
• A RAD component that offers adesign-time
  experience

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2 Ways To AuthorServer 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

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Setting up your Solution

• Use a WebControlLibrary project to create custom
  compiled controls
• Initialize the Version attribute
• Add a Web app to test controls
• Solution gt Add New gt Web Application
• Add a ToolBox reference
• Customize Toolbox gt Browse

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Rendering

• Override Render to representative markup
• Use HtmlTextWriter API to implement rendering
  logic
• public override void Render(HtmlTextWriter
  writer)
• writer.RenderBeginTag(HtmlTextWriterTag.Span)
• writer.Write(Text)
• writer.RenderEndTag()

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Custom Toolbox Glyph

• Bitmap file with same base name as control class
  in the same namespace
• TextBoxADA
• Build Action Embedded Resource
• Image properties
• File type supported is bitmap
• 16x16 pixels
• Lower-left pixel is used to determine
  transparency
• Adds an extra professional touch

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Building Controls In Visual Studio .NET

• Setting up your Solution
• Choosing a Tag Prefix
• Choosing a Toolbox Glyph
• Debugging your Control

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What is the ADA?

• Defines web accessibility
• American Disabilities Act or US Section 508
  compliance http//www.section508.gov/
  http//www.usdoj.gov/crt/ada/adahom1.htm
• Universities and Governments are required to
  implement.

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Some Requirements for ADA

• Input controls must have a description of the
  input item.

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Requirements for ADA

• Lets see it in action http//localhost/serverregis
  tration/registration2.aspx

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ADALabel

• Simple, minimal control
• Renders a ltlabel forclientidgtNamelt/labelgt
• Inherits from LiteralControl
• Metadata on properties
• Demonstrates state management
• Uses ViewState in property implementation
• Demonstrates basic rendering
• Render Method

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ADATextBox

• Simple, minimal control
• Renders in TextBox
• onfocus"if(this.value'Enter Serial
  Number')value''"
• onblur"if(this.value'')value'Enter Serial
  Number'
• Inherits from LiteralControl
• Inherits from TextBox
• Demonstrates state management
• Uses ViewState in property implementation
• Demonstrates basic rendering
• AddAttributesToRender method

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ADATextBox

• Metadata on properties
• Declarative way of specifying behavior
• Property editing in property browser
• Property persistence
• Conversion of types to/from strings
• Metadata can be applied to events, methods and
  types as well

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ADAInitialValue Property
Bindable(true), Category("Appearance"),
DefaultValue(""), Description(...") public
string InitialValue get object o
ViewStateInitialValue " if (o
null) return String.Empty
else return (string)o
set ViewStateInitialValue "
value this.Text value
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demo
ADATextBox ADALabel
State managed properties, Rendering
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Composite Control

• Contains Table, TableRows and TableCells,
  Textbox, Button
• Implements the standard composite control pattern
• Implements INamingContainer
• Overrides Controls property to ensure child
  controls
• Overrides CreateChildControls to implement logic
  of creating child controls

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Why Our own Shopping Cart at UTEP

• Needed to call our own credit card api TOUCHNET
  internally
• Needed to be reusable by all programmers
• Handle financial accounting transactions
  differently.
• Nothing existed that solved the problems

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Shopping Cart Composite
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CreateChildControls
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AddDataGrid
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AddDataGrid (cont)
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AddDataGrid (cont)
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Event Implementation

• Standard event pattern has two parts
• Event declaration
• OnltEventgt protected virtual method

Public Event FinishShopping as ShoppingEventHandle
r Protected Sub OnFinishShopping(E as
ShoppingEventArgs) RaiseEvent
FinishShopping(Me,E) End Sub
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Events Implemented

• SuccessShopping
• CancelShopping
• FinishShopping

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ShoppingEventArgs
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Shopping Session Table

• Exists to prevent Recharges
• Hitting the Back in Browser and then recharging
  the card for the same purchase

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Session State Table

• CreateSessionShoppingCart

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Shopping Session Table

• IsSessionShoppingCartExist

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Session State Procedures

• DeleteOldShoppingCartSessions
• delete SessionShoppingCart
• where CreateDate lt DateAdd(day,-7,GetDate())

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Add Item to Cart
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demo
Shopping Cart
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CartData
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MySession
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EmptyCart

• Used after Finish Shopping?

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AddCreditCard
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AddCreditCard
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AddCreditCard (cont)
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AddCreditCard
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AddCreditCard(cont)
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Successful Charge
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Charge Credit Card Button
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Some of Public Style Properties

• ItemHeaderText - get/set
• DescriptionHeaderText get/set
• QuantityHeaderText get/set
• PriceHeaderText get/set
• AmountHeaderText get/set
• DisplayQuantity get/set
• DisplayGrid get/set
• DataGridCSSClass get/set DataGrid Style
• ValidateCSSClass get/set Validator Styles
• RequireCSSClass get/set Required Validator
  Styles
• DisplayErrorStar get/set Bool
• DataGridBackColor get/set Color
• DataGridHeaderColor get/set Color
• DataGridForeColor get/set Color

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Debugging Your Control

1. Set a breakpoint in your control runtime
2. Set the Web App as Startup Project
3. Set a Startup Web page
4. F5
5. Use your control in the running page

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State Management

• Session vs. View State
• View State
• Override various methods to perform custom state
  management
• TrackViewState
• SaveViewState
• LoadViewState
• Required any time you have nested objects like
  Styles or collection properties
• Call on IStateManager implementation of these
  objects to include their state as part of
  Controls state

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Key Points

• Controls provide an abstraction and reusability
  mechanism for web apps
• ASP.NET provides a rich framework for creating
  server controls
• Create specialized derived controls to make
  incremental changes toexisting controls
• Use composition to leverage existing controls in
  more specialized scenarios
• Think about your Markup!!!!!

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Essential Resources

• Developing Microsoft ASP.NET Server Controls and
  Components

• ISBN 0-7356-1582-9
• Download
• Source Code
• Design Guidelines
• http//www.microsoft.com/mspress/books/5728.asp

• ASP.NET Forums at http//www.asp.net/forums
• MSDN and .NET Framework SDK Documentation

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Download
Samples

• http//www.ilogbook.com/

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Questions And Answers
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Server Control
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