1. CS 4720 Dynamic Web Applications CS 4720 – Web & Mobile Systems

2. CS 4720 Last Week 2 We know what servers are –Apache: standard web server that sends files –MySQL: database server that sends formatted data –Tomcat: web server that rolls in a Java compiler We know what our clients are looking for –Browsers want HTML –Stand-alone clients want whatever we tell them to want

3. CS 4720 Dynamic-ness... ish. Plain HTML is fine for plain websites where information never changes (That's so 1999.) A dynamic website is one where the webpage changes based on: –Browser input (post, get) –Session variables (information stored in browser) –Stored variables (cookies) –Other (time of day, location, etc.) 3

4. CS 4720 Dynamic-ness... ish. We have to remember that even though this is a “dynamic” website, there is still a server/client, call/response going on here Image courtesey websiteoptimization.com 4

5. CS 4720 Dynamic-ness... ish. We provide a set of variables to the server and an HTML page is generated on the fly according to those variables Think of it this way: it's like a standard Java console app that you've programmed before, but the output now has to be HTML 5

6. CS 4720 PHP PHP: Hypertext Preprocessor –Actually, it originally stood for “personal home page” Scripting / interpreted language Useful for both web sites and for stand-alone scripts (like perl) Latest version even includes objects! 6

7. CS 4720 Acceptance of PHP PHP has become a widely used web programming language Specific PHP modules have been created for: –Nearly every web server software system –MySQL (works REALLY well together) –Other database systems –Windows API extensions –Many compression formats 7

8. CS 4720 Why do I like it? It's easy to setup –It's rare to find stuff for a linux server that “just works” It's easy / comfortable to code it –Java-like syntax, with none of the hassles Powerful –You can do a lot of interesting things with PHP Fast (to code and to run) –Compare this with JSP when we get to it… 8

9. CS 4720 PHP for Java Developers Dynamic typing –A method can return a boolean on one line and a String on the next All variables start with $ You use -> for methods in objects, not. You use. for concatenation, not + “” and '' work very similarly Strings can contain variables and are dynamically replaced at runtime 9

10. CS 4720 PHP for Java developers In an HTML page, a php section starts with If error printing isn't turned on on the server, you'll have to deal with the white screen of death Remember that here you're output has to be HTML! –i.e. to drop a line, echo Other than that, some keyword changes 10

11. CS 4720 W3Schools http://www.w3schools.com/php/default.asp Great website for quick tutorials about a lot of web stuff Look at some of the tutorials here (Also http://www.phpclasses.org/) 11

12. CS 4720 PHP and Forms One of the biggest uses of PHP is interpreting HTML forms PHP can pull the data out of the returned fields and use them as variables It can then: –Print them –Store them to a database (or other file) –Use them to generate other content Post vs. Get 12

13. CS 4720 PHP and Forms Build two pages: –A PHP file that will determine whether or not a user has posted a comment to this site by looking for a cookie If they haven't posted, the user should see an HTML form that will asks them to post their name and a comment; otherwise, thank them for the comment –A PHP file that will take the results of the form submission, print it to the screen, and make a cookie on the user's machine indicating they have left a comment 13

14. CS 4720 JSP So, how is JSP different? Let's look at JSP syntax… 14