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Language HIGH LEVEL Overview

Language HIGH LEVEL Overview. More to come in future classes. Languages. HTML CSS Javascript PHP / Ruby / Java / ASP / Perl. Client-server model. When searching on Google: Your PC’s browser requests a webpage from Google’s server Google’s server processes that request

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Language HIGH LEVEL Overview

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  1. Language HIGH LEVEL Overview More to come in future classes

  2. Languages • HTML • CSS • Javascript • PHP / Ruby / Java / ASP / Perl

  3. Client-server model When searching on Google: Your PC’s browser requests a webpage from Google’s server Google’s server processes that request Google’s server sends your browser an HTML file Your PC’s browser renders what you see as a webpage from that HTML

  4. Simplest Reply: HTML Page • Server simply sends you a single .html file • Only HTML, no other programming required • Said to be “static” – never changes • Cannot have any interaction • Cannot pull content from a database • Cannot read or save other files • Cannot log in or log out

  5. HTML • HTML serves one purpose: layout content on a webpage • Hyper Text Markup Language • Created by Tim Burners-Lee at CERN in 1991 • Today universal, open standard supported on all browsers: Internet Explorer, Firefox, Chrome, Opera, and more • Also now called “XHTML” – basically the same

  6. HTML - Example

  7. HTML + CSS • Problem: HTML was limited in how you could display things. • Solution: Cascading Style Sheets • Compliments HTML – more control over how things look, in bulk manner • Introduced idea of “separating form from content” • CSS can be embedded in HTML or be sent by the server as a second document

  8. HTML + CSS - Example

  9. JavaScript (JS) • Client side script – runs in your browser - NOT THE SERVER • Server sends JS in HTML or as a separate file • Makes the web page interactive • Mouseovers • Clocks • Alert boxes • Drag-and-drop • Much more complicated than CSS or HTML – big leap • Warnings • Older browsers can’t work with newer commands • Can be disabled by browsers (approx 1-3%) • Code is 100% viewable – people can steal

  10. Server Architecture Servers run programs, just like your PC: • Operating System (OS) • Manages server’s hardware and other programs • Linux, Windows • Web Server Software (HTTP) • Process’s client requests, sends response • Apache, LigHTTPD, IIS • Database (DB) • Optional, used for large web apps • Stores tables of information – i.e. user info • MySQL, Postgres, Oracle, Microsoft SQL • Scripting Language Processor • Depends on the language your site is coded in • The “processor” will read your script and execute it

  11. Server-side Languages • Scripting language generally determines architecture • PHP, Ruby, ASP, Java, Perl • Executes code on the server • Saves files, logs users in/out, queries the database • Totally invisible to client • Sends client HTML once completed

  12. Common Web App Architectures

  13. PHP • “PHP Hypertext Processor” (recursive acronym) • LAMP architecture • Linux for OS • Apache for webserver software • MySQL for database • PHP for programming • Advantages: • Large developer base • All open source • Very scalable • Great documentation at PHP.net • Disadvantages: • Slower development than Ruby or ASP • Sites that use PHP in parts or all of their site: • Facebook.com • Wikipedia.com • Wordpress.com

  14. PHP Example <html> <head> <title>PHP Test</title> </head> <body> 1+1 = <?php echo 1+1; ?> </body> </html> Executed by web server

  15. What the browser sees <html> <head> <title>PHP Test</title> </head> <body> 1+1 = 2 </body> </html> Executed by web server

  16. Ruby (on Rails) • Ruby is the language • Almost always used with Rails – the framework • Advantages: • Developed specifically for modern web apps • Fastest to develop on • Tight integration between server, DB, front and back ends • Easy to make API’s • Disadvantages: • Poor scalability (so far) • Samples of sites using Ruby: • Twitter.com – fail whale • Basecamp.com – 37 signals maintains Rails

  17. ASP • “Active Server Pages” - Microsoft’s web programming language • Primarily for use if you want to go Microsoft across the board • Windows for OS • IIS for web server • Microsoft SQL server for DB • Advantages: • Comes with a workflow & website framework • “Enterprise” - geared towards large companies • Microsoft provides customer service • Disadvantages: • Proprietary • Expensive • Not as popular as PHP or Ruby • Samples of sites using ASP: • Microsoft.com

  18. Other Languages Java • By Sun/Oracle • Fallen out of popularity for web apps Python / Django • Google has historically used Django • Runs quickly on the server Perl • Early Language • Not designed for web, slow development

  19. AJAX • “Asynchronous JavaScript and XML” – is a technique, not a language • How it works • Javascript sends requests to server • Server-side script (PHP) processes request • Server sends back XML • Browser updates the webpage • Samples of sites using AJAX: • http://maps.google.com • http://www.kayak.com

  20. Maps.Google.com

  21. Web Hosting

  22. My Preferred Configuration Hosting: Dedicated Servers at LiquidWeb.com OS: CentOS 5 (Linux) Server: Apache 2 DB: MySQL 5 SS-Script: PHP 5 Framework: Proprietary Benefits: Open source, low cost, stable, scalable, easy development, large developer pool

  23. Why is this important? Dot Com 1.0 mistake: • I have a great website idea. • I’ll just pay some guy to make it. • Then I’ll make millions!

  24. Successful Web Companies With Technical founders Without Technical Founders (quasi-technical)

  25. Dot Com 1.0 Reality • You can’t tell a good contractor from a bad one • Your contractor tells you all your terrible ideas are great just so you’ll hire him • ½ of your billings go towards waste-of-time-phone calls • You end up with a terrible site • It’s programmed in Java and completely unmaintainable • You don’t have the capacity to improve it or even fix bugs • Your “amazing idea” will be copied by a better technical company in a week • They’ll make millions and you just wasted $50,000

  26. Web 2.0 Lessons • Every founder needs a basic level of technical proficiency • At least one founder needs to be technically advanced • Ideas are worthless, the best execution wins • Web companies need to be technically driven • Products need to be constantly iterated and improved

  27. Learn More • W3Schools.com • Go to any webpage, right click, “View Source”

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