CSC325 2010F, Class 01: An Introduction to the Course

Overview:
* What is a Web Application, Anyway?
* The Evolving Architecture of the Web.
* The Evolving Architecture of Web Applications.
* Goals of the Course.
* Resources.
* Student Introductions.

Admin:
* Because of Jeff Leep, the course web is in alpha stage, 
  and will remain so for the next few weeks.
* As many of you have noted, one of our textbooks has not been 
  published yet.  We'll work through that issue.
* Two non-listed textbooks will be distributed in class.  
  If you decide you want your own copy, they are available cheaply 
  online.
* I won't discuss a lot of the syllabus because 
  (a) many of you know my basic policies anyway, 
  (b) students rarely remember syllabus details, and 
  (c) it's all on the Web anyay.
* Don't forget CS Table today at noon in the Day PDR.
* Don't forget Happy Days this weekend.

What is a Web Application, Anyway?
* A program that is loaded off of the server and then run completely 
  in the browser that performs a specific task
  + Or perhaps there is a dialog between the browser and the server
* What triggers the communication between browser and server?
  * Old model: Click on links, fill in forms, click on buttons
    Each time you do something, we go to the server to load a new
    page
  * Newer model: Asynchronous communication
    * What's the difference between synchronous and asynchronous
    * Under asynchronous communication the client continues to do other
      work while waiting for a response
      * Lots of folks do it\  
        * You can see Digg continuing to update
        * Google Docs would not work with the traditional synchronous model
  * Newer model: Partial updates: A round-trip message may affect
    just a part of the page, rather than bringing up a whole new page
* Two very different perspectives
  * Traditional server model - Each transaction is a new page, and most
    of the code lives on the server
  * Modern app model - Most of the code lives on the client, lots of
    asynchronous partial updates
* Three issues
  * An application (program)
  * Run with client server model
  * Within the browser / web

The Evolving Architecture of the Web.
* Original architecture: Tim Berners-Lee
  * See now-erased whiteboard
* Flaws in this model
  * No inclusion of streamed data
  * Work is on the server - Find and send document
  * Security: The model seems to be "Anyone can access any document". Is
    that really what we want?
    * Solutions:
  * Security: Client needs to be sandboxed
  * Only one model of interactivity
  * No model for programs running on the server
    * Solution 1: Server plugins
    * Solution 2: Server-side scripts
      * Requires that we add something like forms to HTML
      * And a way to transmit that information to the server (HTTP)a
      * And that we change the server to run these scripts
  * No model for programs running in the browser
    * Java model: An application that runs within a web page on the browser
    * JavaScript: Smaller scripting of Web pages
  * No state model
    * Makes keeping track of the conversation hard
    * And when the user clicks "back", you are in deep trouble
      * Which is why Datahell reports so many errors
* No P2P
* Fortunately, each of these flaws has been addressed in some way or another

The Evolving Architecture of Web Applications.
* Mostly server-side scripting with a pure dialog model
  * Written in general purpose programming languages
* Then languages designed for scripting appeared (still dialog model)
  * PHP
* The libraries for scripting
* Libraries combined into Web Application Frameworks
  * Drupal
* Plus all the client-side stuff
  + AJAX

Goals of the Course.
* Every CS major (and some other people) needs experience building a
  large application as part of a team
* The Web is one of the main application models, so some students will
  want to learn that
  * And you can't learn the Web w/o learning about databases
* "Get your hands dirty"
* Along the way, we'll learn lots of concepts about design in the large
  and in the small

Technologies you will learn
* Apache (basics)
* PHP (Server-side Web scripting language)
* HTML, CSS, DOM
* Javascript (basics; client-side scripting language)
* AJAX
* Drupal
* MySQL (database)
Resources.

Student Introductions.