OOP Class9

Private instance data members - accessors

Microsoft has stared calling private variables with accessors Properties

Private class memebers the use get and set keyword to set and retrieve data. Get and set are known as accessor methods private members are helpful when you want to also do other things when a data member is changed or change the rutern value under certain conditions. C# Programmer's Reference - Accessors http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csref/html/vclrfaccessorspg.asp. Lastly accessor also make read only and write only variables possible

<csharp>//private string color read/write private string color;

public string Color {

 get
 {
  return color;
 }
 set
 {
  color = value;
 }

}

//private string color read only private string color;

public string Color {

 get
 {
  return color;
 }

}</csharp>

Another property that is a good candidate for a private instance data member is the dogs age

<csharp> private string age;

public int Age {

 //age can only be accessed with get there is no set accessor
 //age must be set with HappyBirthday()
 get
 {
  return age;
 }

}

public int HappyBirthday() {

 age++;
 return age;

}

</csharp>

About aspx

VS Web Projects

Anatomy of an aspx page

Page Directive The page directive must be on the first line of an aspx page. It consists of Name/Value Pairs and sets parameters that will be used throughout the execution of the page ie. the language.

<%@ Page language="c#" debug="True" trace="False"%>

C# Code may be embedded in the page using script tags similar to javascript

<script language="c#" runat="server"> </script>

Notice the runat attribute is set to 'server'. This is what makes the code execute on the server rather than be parsed by the client.

Console applications start executing in the main method

<csharp>public static void Main() {}</csharp>

The .Net Framework can also execute on the web. Rather than having a Main method a web page starts it's execution with a method called Page_Load

<csharp>public Page_Load { }</csharp>

There are actually several method that are executed in an aspx page.

http://samples.gotdotnet.com/quickstart/aspplus/

Simple Aspx Page

http://iam.colum.edu/oop/classsource/class8/Aspx/hello.aspx hello.aspx

http://iam.colum.edu/oop/classsource/class8/Aspx/hello2.aspx hello2.aspx

http://iam.colum.edu/oop/classsource/class8/Aspx/Label.aspx Label.aspx

In class
Build three hello aspx pages similar to the ones above

Dogs on the web

DogWeb

HTML and HTTP

Http is a stateless protocol. There is mo mechanism built in to the protocol that allows the server to remeber clients or requests. An http simply responds to http verbs GET, POST, PUT, DEL, TRACE etc. contained in RFC 2068 HTTP/1.1

regular html forms post information using forms in 2 ways with a get or a post http request.

Get

Get send information to the server using the URI. Limited to 1024 character in some browsers and servers.

Example http://iam.colum.edu/oop/classsource/class9/simpleGet.html simpleGet.html - source

The simpleGet.html pages form has the action of 'simpleGet.aspx' this mean that when the form is submitted the browser will request the 'simpleGet.aspx' with whatever parameters are in the form. Since the method = get these pararmeters will show up are query string parameters

URI and querystring parameters

URI - Universal Resource Identifier http://src.doc.ic.ac.uk/computing/internet/rfc/rfc1630.txt RFC1630

Http URI

Protcol	Host	Port	Path	File	Fragment identifier	Querystring
http://	info.cern.ch	:8000	/imaginary/test/	file.html	#link	?test=yes

Post

Post posts the variables in the HTTP Header.

Example http://iam.colum.edu/oop/classsource/class9/simplePost.html simplePost.html - source

FirstName:
LastName:
Header Name 	Value HttpMethod 	GET
Connection 	keep-alive
Keep-Alive 	300
Accept 	text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Charset 	ISO-8859-1,utf-8;q=0.7,*;q=0.7
Accept-Encoding 	gzip,deflate
Accept-Language 	en-us,en;q=0.5
Cookie 	ASP.NET_SessionId=ezfgw255ix0zd5yogj3eawej
Host 	imdev
Referer 	http://imdev/infod/jeff/
User-Agent 	Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.1) Gecko/20060111 Firefox/1.5.0.1

REST

Representational state transfer

https://www.ibm.com/developerworks/webservices/library/ws-restful/

http://www.infoq.com/articles/rest-introduction

http://iam.colum.edu/oop/classsource/class9/htmlForms.html htmlForms.html - source

Courses on the Web

Student Web

Response Object

Response.Write()

http://iam.colum.edu/oop/classsource/class10/Response/Response1.aspx Response1.aspx - source

Response.End()

http://iam.colum.edu/oop/classsource/class10/Response/Response2.aspx Response2.aspx - source

Response.Clear()

http://iam.colum.edu/oop/classsource/class10/Response/ResponseClear.aspx ResponseClear.aspx - source

Response.Flush()

http://iam.colum.edu/oop/classsource/class10/Response/ResponseFlush.aspx ResponseFlush.aspx - source

Debugging with response object

Using the response buffer can be extreemely usefull for debugging. Sometime you may have to setup a small debug system to help catch errors in object that do not inherit from System.UI.Page.

Response.Flush()

http://iam.colum.edu/oop/classsource/class10/Response/ResponseDebug.aspx ResponseDebug.aspx - source

Home Work

Convert one of your classes to work as an aspx page.

Have a nice break....

Web Forms

Examples of Web Forms

http://iam.colum.edu/oop/classsource/class9/aspForms.aspx aspForms.aspx - Source

todo examples of all the html elements and how they react to form submits

Persisting Data

POST and GET

http://iam.colum.edu/oop/browser/browser.aspx?f=/classsource/class9

an asps page posting to itself

GET

Simple get page http://iam.colum.edu/oop/classsource/class9/simpleGet.html source

http://iam.colum.edu/oop/classsource/class9/simpleGet.aspx source

POST

Simple post page http://iam.colum.edu/oop/classsource/class9/simplePost.html source

http://iam.colum.edu/oop/classsource/class9/simplePost.aspx source

Simple post page http://iam.colum.edu/oop/classsource/class9/simplePostValues.html source

http://iam.colum.edu/oop/classsource/class9/simplePostValues.aspx source

ASP POSTBACK

http://iam.colum.edu/oop/classsource/class9/postBack.aspx source

Events in c# and aspx

Event handlers

OnClick

http://iam.colum.edu/oop/classsource/class9/events/events1.aspx events1.aspx - source

OnCommand

http://iam.colum.edu/oop/classsource/class9/events/events2.aspx events2.aspx - source

http://iam.colum.edu/oop/classsource/class9/events/events3.aspx events3.aspx - source

<csharp>

<%@ Page language="c#" debug="True" trace="false"%>

<script language="c#" runat="server">

   Dog fido;
   
   public void Page_Load()
   {
       fido = new Dog();
       
       
   }

   public void Button1_OnClick(Object sender, EventArgs e)
   {
       Response.Write("Hello from Button1_OnClick");
       lblBark.Text = fido.Bark();
   }

   public class Dog 
   {
       public string Name;		// the dog's name
       public int Age;			// the dog's age
       public int Weight;			// the dog's weight
       public string BarkSound;	// the sound of the dog's bark

       public Dog()
       {
           BarkSound = "Woof!!!";
       }

       public string Bark()
       {
           return this.BarkSound;
       }
       public void Eat()
       {
           //put eat code here 
       }
   }	

</script>

test

Hello in div

</csharp>

Home Work

Create a web page with a button that uses your class.

Motorvehicle Diagram

Oop Motorvehicle Diagram

http://iam.colum.edu/oop/browser/browser.aspx?f=/classsource/class7/MotorvehicleRace

Windows forms

Events

events from a windows form or web page are handled by event handlers. Events are raised when a user interacts with interface elements and handled by the event handlers.

http://www.csharphelp.com/archives/archive253.html

Examaple of event handlers and classes

http://iam.colum.edu/oop/MotorvehicleRace.zip

<csharp> private void button1_Click(object sender, EventArgs e)

       {
           Console.WriteLine("button1 Clicked");
           MessageBox.Show("button1 Clicked");   
       }

</csharp>

Create a windows form with a button the uses your class.

<csharp> using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms;

namespace WindowsDog {

   public partial class Form1 : Form
   {
       Dog fido;
       
       public Form1()
       {
           InitializeComponent();
           fido = new Dog();
       }

       private void btnBark_Click(object sender, EventArgs e)
       {
           lblBark.Text = fido.Bark();
       }

       public class Dog 
       {
           public string Name;		// the dog's name
           public int Age;			// the dog's age
           public int Weight;			// the dog's weight
           public string BarkSound;	// the sound of the dog's bark

           public Dog()
           {
               BarkSound = "Woof!!!";
           }

           public string Bark()
           {
               return this.BarkSound;
           }
           public void Eat()
           {
               //put eat code here 
           }
       }	
   }

} </csharp>

Home Work

Put your class in a windows form. Use and event to call one of your methods.