Dynamic Web Pages

Dynamic Web Pages Brad Polzar March 8, 2007

Outline • What are Dynamic Web Pages? • Server Side Dynamics • Active Server Pages • Hypertext Preprocessor • Client Side Dynamics • JavaScript • Java Applets • Flash

What is a dynamic Web Page? • General Definition: • A web page that changes based on the input of the user outside of navigating to another page. • A more specific definition: • A web page that dynamically decides what to display given the user’s actions and/or conditions that are currently met. • A really picky one: • A web page that is the result of a server dynamically deciding what html code to send based on user actions and currently met conditions.

Server Side • Premise • Server Side Scripting • Active Server Pages • Hypertext Preprocessor

Active Server Pages (ASP) • Microsoft’s version of dynamic web pages • Can use one of four scripting languages: • VBScript • JScript • PerlScript • Python • Server Requirements • Instant ASP (iASP) • Chili!ASP • Can also run on other platforms

An ASP Page • Embedded into an html page • Tags • <% and %> • <%@ Language= %> • <script> and </script> <%@ Language=VBScript %> <html> <body> <% Response.Write(“Hello World!”) %> </body> </html>

The Browser’s Code <%@ Language=VBScript %> <html> </body> <% Response.Write(“Hello World!”) %> </body> </html> <html> </body> Hello World! </body> </html>

ASP Collections • Similar to a sorted array • Name / Value pairs • Name: Brad • Class: CS4110 • Date: Mar 8, 2007

ASP Objects • Response Object • Request Object • Session Object • Application Object • Server Object • ObjectContext Object • ASPError Object

Response Object • Deals with the response to the client • Methods • Write • Redirect • Flush • End • Clear • Handles writing cookies

Request Object • Deals with the request to the server • Collections • Cookies • Query String • Form

QueryString and Form • Both pass information from client to server • QueryString • Passes through URL • http://www.mywebsite.com/asp?querystring • …?field1=value&field2=value2&… • Request.QueryString(field1) • Form • Passes through request • Request.Form(field1)

Getting QueryString and Form Info • Use html forms • To pass via QueryString • <form method=“get”> • To pass via Form • <form method=“post”>

Cookies • Stored on client’s computer • Automatically sent with request • Pros: • Keeps info off of server • Fairly small • Cons: • Doesn’t maintain account across multiple computers • Not all computers allow • Expiration • Only simple data types

Creating Cookies • Simple Cookie – one value • <% Response.Cookies(“varName”) = “value” %> • Will create if it doesn’t exist • Will overwrite if does • MUST DO THIS BEFORE THE <html> TAG! • Complex Cookie – A Cookie with Keys • Can set a cookie to have multiple values <% Response.Cookies(“cookieName”)(“field1”) = “value1” Response.Cookies(“cookieName”)(“field2”) = “value2” %>

Reading Cookies • Will automatically send with request • <% var = Request.Cookies(“varName”) %> • Will return “” if varName is not a cookie

Session Object • Holds information of client’s current session • Uses: Stores complex info • Objects • Arrays • Negatives: • Session ending time • Space on server • Server Performance • Used through cookies

Application Object • Keeps state of the server • Only one instance • Used for data that is global and changed often

Reading and Writing Files • Databases • Text Files

ASP.Net • Same Objects as ASP • Uses .Net Common Runtime Languages • Visual Basic • Visual C# • Visual J#

Hypertext Preprocessor (PHP) • Used to stand for Personal Home Page • Uses Apache Server • Is a scripting language • Is also a dynamic web technology • Current versions are PHP4 and PHP5

A PHP Page • Tags • <?php and ?> • <script language=“php”> and </script> • <% and %>

PHP syntax • Instruction separation - ; • Comments • Variables • Start with $ • Continue with name • Must start with _ or a letter • No type defined

PHP variables • Eight types • Four primitive • Integer • Floating point • String • Boolean • Two compound • Object • Array • Two special • Resource • NULL

PHP Variables Con’t • PHP4 – can assign by reference • Don’t have to initialize • Default values • Integer and Floating Point: 0 • String: empty string • Boolean: False • Array: empty array

PHP SuperGlobals • SuperGlobal • Def: predefined variables global in every scope • $GLOBALS • $_SERVER • $_GET • $_POST • $_COOKIES • $_FILE • $_ENV • $_REQUEST • $_SESSION

PHP Database Support • Formats supported • Access • SQL • MySQL • Oracle

Client-Side Scripting • Premise • JavaScript • VBScript

JavaScript • Not simple Java • Procedural Script • Object-Orientated Script • Objects created at run-time • Intrinsic Objects • Number • String • Boolean • Date

Client-side Scripting • Accessing Scripts • Include in HTML document • Reference another file • Access to client’s computer

Other Dynamic Utilities • Flash • Java Applets

Works Consulted • Mitchell, Scott and Atkinson, James. (2000) Sams Teach Yourself Active Server Pages 3.0 in 21 Days. Indiapolis, IN: Sams. • Achour, Mehdi, et al. (2007) PHP Manual. http://www.php.net/manual/en/. • w3schools.com “ASP Tutorial.” Retrieved March 5, 2007 from http://www.w3schools.com/asp/default.asp. • Wikipedia.org (2007) “ASP.Net.” Retrieved March 5, 2007 from http://en.wikipedia.org/wiki/ASP.NET. • Flanagan, David. (1998) JavaScript: The Definitive Guide. Sebastopol, CA: O’Reilly.

Dynamic Web Pages