1. CS 7: Introduction to Computer Programming Java and the Internet Sections 1.4-1.6,2.1

2. Review What are the 3 control structures? Project 1 handed out

3. Overview Internet Java and the Internet Applets Java and GUIs

4. The Internet

5. Collections of Computers Network System for connecting ≥ 2 computers so can share resources internet Connection of ≥ 2 networks Internet The world-wide connection of computers that are accessible to the public IntraNet An network set up confined to a particular organization

6. Computer Roles Client computer / software that gets information from another computer Web Browser - client software to get Internet Resources Server computer / software that provides a service to a client Protocol set of rules defining how two systems communicate

7. Application Layer Protocols FTP File Transfer Protocol Moving files between computers HTTP HyperText Transfer Protocol Moving hypertext between computers HyperText - text documents with links to other text documents FTPS, HTTPS, SSH Secure communication

8. What’s the address? IP address 32-bit address to identify computer Each computer connected has unique IP Ex: 130.49.222.47

9. URLs Uniform Resource Locator address to resource (files or request some processing be done) from the Internet http://www.cs.pitt.edu/~hoffmanp/cs7.html http protocol www.cs.pitt.edu Fully qualified domain name (FQDN) of server machine Domain name servers (DNS) convert FQDN to IP address (130.49.220.23) ~hoffmanp/cs7.html Path to resource on the server

10. Internet vs. WWW World Wide Web (WWW) - 2 definitions set of resources that can be gotten using the HTTP protocol set of HTTP servers ("web servers") The WWW Works on top of the Internet

11. Java and the Internet

12. Java Why use Java? Portable Internationalization (Unicode) Network features Many features and libraries promoting networking Applets can be distributed over Internet Designed with security in mind Swing classes make creating GUIs easier, portable

13. Applets Java programs that can be embedded in HTML to run on your browser Examples: http://www.cse.ucsc.edu/~pohl/JBD/chap8/MiniCa lcApplet.html http://www.cse.ucsc.edu/~pohl/JBD/chap8/MiniCa lcApplet.html Games http://java.sun.com/applets/other/Hangman/index.html http://www.npac.syr.edu/projects/java/magic/Magic.html Education http://www.dhpc.adelaide.edu.au/projects/vishuman2/ http://www.stat.sc.edu/~west/javahtml/CLT.html

14. Difference Between Applets and Applications Applets – little applications Run under a browser No main() method Security restrictions

15. Applet Loader Applets loaded over the Internet are loaded by an applet class loader Uses verifier to check there are no Stack overflows / underflows Invalid register accesses and store Illegal data conversion Uses the applet security manager

16. Untrusted Applets Put in a “Sandbox”. Restrictions on Files, directories Programs on your machine System properties Connecting to other computers Windows the applet creates

17. Trusted Applets Trusted applets don’t have these restrictions Trusted applets are applets that either: Are installed on your machine Are a signed applet with an identity you mark as trusted

18. Graphical User Interface (GUI) User-Interface (UI) Text-based (DOS) GUI (Windows XP) Windows Icons Java has the Swing classes

19. Working from home PuTTY F-Secure SSH Client Windows, Mac, UNIX and new lines

20. Getting Comfortable with UNIX