UWEC Web Publishers Users Group

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UWECWeb PublishersUsers Group

• An Overview of Web Scripting

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Goals of this Talk

• Teach you how to program
• Define and categorize web scripting approaches to
  enable effective communication with web scripting
  professionals
• Use as many acronyms as possible!

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Why Script?

• Turns static pages into dynamic pages
• Enhanced graphical interface
• Customized responses to user input
• Update of pages from databases

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Which Scripting Technology?

• So you have decided that you want dynamic web
  pages, the next step is to pick a scripting
  technology
• To name a few major players
• ASP, JSP, PHP, Servlet, JavaScript, VBScript,
  Applet, SSI, ColdFusion, Perl(CGI/Mod), Flash

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Web Architecture Review
Web Server
Browser
HTTP
DB Server
Client
Server
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Client-side Scripting

• HTML and scripts are both downloaded to the
  browser
• Scripts run inside browser, interactively
  changing the web page
• Example www.uwec.edu

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Server-side Scripting

• Scripts are run on the server, producing plain
  HTML
• Dynamically generated HTML is downloaded to
  browser
• Example jonah.cs.uwec.edu/CS245/stevende/cdlist.h
  tm

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Comparison
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Client-side Technologies

• There are two main types of client scripting
• Scripts that are tightly integrated with the
  other HTML elements on the screen
• Scripts that run independently from the other
  HTML elements and tend to run as separate
  programs in a subsection of the browser window

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DHTML

• Stands for Dynamic HTML
• DHTML is not scripting language
• It is a term used when one makes a page that uses
  HTML, Stylesheets, and a scripting language
• Often JavaScript is used as the scripting language

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JavaScript

• JavaScript is a scripting language based on the
  syntax of Java (Sun Microsystems)
• But it is much simpler to code and learn than
  Java (not fully object-oriented)
• Functions (little scripts) are placed within
  tags near the top of the page
• These functions are then attached to various
  event that can occur to HTML elements on a web
  page (i.e. it is tightly integrated)
• Example when the mouse is placed over a
  particular HTML element, such as a link

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JavaScript
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JavaScript

• JavaScript is used mostly to
• Provide enhanced GUIs
• Button rollovers
• Dropdown menus
• Perform form field validation
• Making sure all required data is filled in a form
  before it is sent to the server for processing

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JavaScript

• JavaScript is restricted from accessing the local
  file system for security purposes
• Data can only be saved in cookies
• Cookies are small pieces of information that are
  stored in a special location dictated by the
  browser
• Enforces file system security
• Provides a place to store minimal data

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VBScript

• Stands for Visual Basic Script
• Based on the syntax of Visual Basic (Microsoft)
• Similar in many ways to JavaScript
• JavaScript is much more popular as a client-side
  scripting language
• Used more as a server-side scripting language in
  the ASP framework

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Applets

• Applets are actual Java programs that are run
  within the web browser
• The compiled Java Applet (machine readable, not
  human readable) is downloaded as a separate file
  from the HTML tags
• Pros
• Full power of Java
• Security
• Cons
• Large download size
• Browser plug-in required

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Applets

• Code is started with an tag in the HTML
  file
• Start the applet program in a section of the
  larger browser window
• Example http//www.sapello.com/slidepuzzle/
• Applets dont interact with other web page
  elements

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Flash / Shockwave

• More animation control technologies than pure
  scripting (Macromedia)
• Scripting is involved under the hood
• Similar in style to Applets in terms of running
  independently from other web page elements
• Becoming more popular
• Example nickjr.com

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Server-side Technologies

• Recall that for client-side scripting
• The HTML and script are both sent to the client
• The script is run on the client
• And for server-side scripting
• The script is run on the server
• The end goal is to produce an HTML page to send
  back to the client

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Server-side Technologies

• There are two main types of server scripting
• Tag-based where the developer creates an HTML
  page and then embeds the script inside special
  scripting tags
• Code-based where the developer writes a program
  that outputs HTML

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SSI

• Stands for Server-Side Includes
• SSI code modules can be plugged into a web server
  and defining sets of commands
• Pseudo tag-based scripting is used to access
  specific commands
• Not real tags, just specially formatted HTML
  comments
• Example of a date last modified include
• Old technology that doesnt scale well

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JSP

• Stands for JavaServer Page
• A Sun product
• Actual tag-based scripting
• The current date and time is
• Tags can be
• Generic scriptlet or expression tags that
  contain actual Java code within the tag itself
• Custom tags, where the code is stored in another
  place
• Can use all the power of the Java language

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JSP Custom Tags
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JSP

• Other issues that JSPs handle well are
• Session management involves carrying information
  from one page to the next
• Concurrency involves letting multiple users
  access a single JSP at the same time
• Web server needs to have integrated JSP support
• Tomcat extension to Apache
• IBMs WebSphere Application Server (WAS)

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ASP

• Stands for Active Server Page
• A Microsoft version of JSPs
• Normal scripting language is VBScript
• Can leverage all the com objects developed in VB
• Web server needs to have integrated ASP support
• Microsofts IIS

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PHP

• Stands for PHP Hypertext Preprocessor
• An Open Source version of JSPs
• Scripting language is Perl/C based
• The main benefits are that it is free and open
  source
• The main drawback is that it doesnt leverage off
  an existing code base (Java or VB)
• Web server needs to have integrated PHP support
• Apache

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ColdFusion

• ColdFusion is a set of products from Macromedia
• Development environment
• Scripting language (CFML)
• Application/Web server
• Yet another tag-based version of JSPs
• Integrated rapid development is one of its pros
• The main drawback is that it doesnt leverage off
  an existing code base (Java or VB)

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Servlets

• Servlets are specially setup Java programs that
  run inside the web server
• Servlets are the first code-based server-side
  technology we have seen
• Script is actual code that happens to produce
  HTML tags as output

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Servlet Example
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Servlets

• Because Servlets are actual Java programs they
  can leverage the large Java codebase
• Fully integrated into the web server
• Special features to handle session management and
  concurrency
• Can work together with JSPs
• JSPs are used to design the front-end
• Servlets are used to design the back-end

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Perl

• Perl is a UNIX scripting language originally
  designed for text parsing
• Since a lot of web scripting is text based, Perl
  can be used as a code-based web scripting
  language
• However, Perl is an difficult language in which
  to write maintainable code

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Perl

• Perl also doesnt have all the session management
  and concurrency handling mechanisms available in
  other scripting language
• Originally Perl had to run as a separate process
  from the web server (not integrated)
• CGI (Common Gateway Interface protocol)
• Now there are ways to get Perl integrated into
  certain web servers
• Mod_perl with Apache

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Summary

• Client-side (Enhanced GUIs)
• Tightly integrated (Rollovers, Validation)
• JavaScript, VBScript
• Run as separate programs (Demos, Games)
• Applets, Flash/Shockwave
• Server-side (Customized responses, DB access)
• Tag-based (Page design, Simple coding)
• JSP, ASP, PHP, Coldfusion, SSI
• Code-based (Back-end processing, Serious coding)
• Servlets, Perl