Asp #1

Introduction to ASPIntroduction to ASP (Day 1)(Day 1) JoniJoni ATL - Bina NusantaraATL - Bina Nusantara

Agenda • ASP • Basic Control Flow – If Then Else – Select Case – For Loop – Do While Loop • Form Processing • Server Side Includes

ASP • Active Server Page • The default scripting language is VBScript, but you can use JScript also. • File extension: .asp

ASP • Syntax: – to execute some code <% code %> – to print a value <%= variable/expression %> • Variable • if then else, for, while • function / procedure

Variable <% option explicit %> <html> <head><title>hello</title></head> <body> <% dim name name = "Peter" dim n n = 18 %> <p>Hello <%= name %>!<br> Your age is <%= n %> </p> </body> </html> ‘option explicit’ enforces variable declaration. ‘option explicit’ enforces variable declaration. By default, you don’t need to declare variables. But for easier debugging, declare every variables. Variables can be string, integer and some other type. By default, you don’t need to declare variables. But for easier debugging, declare every variables. Variables can be string, integer and some other type.

ASP using JScript <%@ Language=Jscript %> <html> <head><title>hello</title></head> <body> <% var name = "Peter"; var n = 18; %> <p>Hello <%= name %>!<br> Your age is <%= n %> </p> </body> </html>

ASP-Generated HTML <html> <head><title>hello</title></head> <body> <p>Hello Peter!<br> Your age is 18 </p> </body> </html> This is what the browser receives. The browser doesn’t care whether this page is generated by ASP or not. And, it cannot see the ASP source code. This is what the browser receives. The browser doesn’t care whether this page is generated by ASP or not. And, it cannot see the ASP source code.

If Then Else <% if strName = “Peter” then %> How are you Peter! <% else if strName = “Mary” then %> Dear Mary! <% else %> How do you do! <%= strName %> <% end if %>

Select Case <% select case strName case “Peter” Response.Write(“…”) case “Mary” Response.Write(“…”) case else Response.Write(“…”) end select %>

For Loop <table border=“1”> <% for i = 1 to 7 %> <tr> <td><%=i%></td> <td><font size=“<%=i%>”>hello</font> </td> </tr> <% next %> </table>

Do While Loop <% dim sum, I i = 1 sum = 0 do while i < 8 sum = sum + I i = i + 1 if sum > 10 then exit do loop %> Exit the do loop immediately Exit the do loop immediately

Array <% dim i dim A() redim A(9) for i = 0 to 9 A(i) = i*i next redim preserve A(20) redim A(15) dim B(10,10) %> Array in VBScript is zero-based, i.e. it starts at 0. Dim A(n) wil give an array of size n+1. Array in VBScript is zero-based, i.e. it starts at 0. Dim A(n) wil give an array of size n+1. Resize an array (and preserve the data) Resize an array (and preserve the data) 2D array2D array

Form Processing • Use tag <form> … </form> • FORM allows the user to submit data to web server for processing • A FORM contains one or more input fields • After filling the FORM, the user can submit the data usually by pressing a submit button

Form Sample <body> <p>Please fill in the form:</p> <form action=“process.asp”>  <input type=“submit” name=“btnSubmit”> </form> </body> URL of an ASP page to process the submitted data URL of an ASP page to process the submitted data

Form Components • <input type=“text”> • <input type=“password”> • <input type=“hidden”> • <input type=“radio”> • <input type=“checkbox”> • <input type=“submit”> • <select> <option>…</option> </select> • <textarea> … </textarea>

Post Method <body> <p>Please fill in the form:</p> <form action=“process.asp” method=“post”>  <input type=“submit” name=“btnSubmit”> </form> </body> The default method of form is “get”. The data in the form are encoded and transmitted in the body of the HTTP request. They are invisible to the user. The default method of form is “get”. The data in the form are encoded and transmitted in the body of the HTTP request. They are invisible to the user. If we use method “GET”, the form data are attached to the URL submitted to the server. e.g. http://www.test.com/process.asp?name=tom&id=123 If we use method “GET”, the form data are attached to the URL submitted to the server. e.g. http://www.test.com/process.asp?name=tom&id=123

GET vs. POST • Encoded form data are attached to the end of the URL in GET method – visible to the end user – can be saved as bookmark – we can use such URL to store pre-filled request • Encoded form data are attached as the request body in POST method – necessary for large amount of form data, e.g. file upload

Server Side Includes •  •

Built-in ASP Objects (1/2) • Application – Share information among all users of an application • Request – Get information passed in HTTP request, e.g. user input in FORM and file upload • Response – Send information to browser, set cookies, and redirect to another URL

Built-in ASP Objects (2/2) • Server – Provides access to methods and properties on the server • Session – Stores information in a session • ObjectContext – Transaction management

Request Object • We use these two collections to retrieve data submitted in a form – Request.QueryString - query string in URL, sent by the GET method – Request.Form - form elements in the request body, sent by the POST method • Request.Cookies is a collection of cookies sent in the HTTP request

Response Object • Send output to the browser • Response.Write “Hello” • Response.Buffer = true - enable buffering of the response output • Response.Flush - flush the buffered input immediately

Response Object • Response.Redirect URL - redirect the browser to another URL • Response.Expires = n - expires in n minutes • Response.End - stop processing of the ASP file and returns

ASP Session • Originally, HTTP is stateless – the browser and the server do not remember information between web pages – difficult to write nontrivial web application • Cookies in browser and session variables in ASP provide a solution

Typical usage of session • The session starts when a user logs in. • The session stores the user’s login information: user name, preferences, etc and intermediate data in a transaction (e.g shopping cart) • The session ends when the user logs out.

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