1 Homework / Exam Exam 3 –Solutions Posted –Questions? HW8 due next class Final Exam –See posted schedule Websites on UNIX systems Course Evaluations

2 Final Exam –See posted day, time, and location –It will be 1-1/2 hours – not 3 hours Watch your for any late breaking announcements! Review HW7 and HW8 See the posted practice final exam Review Session Next Class

3 Websites on UNIX Systems Many websites are hosted on UNIX Systems My website is supported on our www server in the same way that I will be teaching now Learn a few basic rules and HTML coding and you can have your own website! Warning: For your educational or personal use only – No commercial websites allowed!

4 The Big Picture UNIX System Apache Server Software Browser Software PC/MAC The Internet TCP/IP Software TCP/IP Software File System HTML Files HTTP Protocol

5 Browser Browser interacts with user to get URL Browser converts URL to an IP address Opens a connection to IP address and port 80 Sends an HTTP “request” containing URL Receives HTTP “response” containing HTML Interprets and displays the HTML

6 Web Server Apache server on UNIX system (Typical) –Interacts with browser clients via HTTP –Accesses HTML files on UNIX file system –Standard mapping from URL to path/file name maps tohttp:// ~bobw/public_html/index.html –This home page can have links to other pages

7 HTTP Protocol Application Layer Protocol –Requests –Responses Sent using TCP connections over IP TCP = Transport Control Protocol IP = Internet Protocol

8 To set up your website Use mkdir to create a sub-directory on your home directory named: public_html Edit and save a text file containing HTML document (program) in that directory as: index.html Use chmod to allow “others” read access Remember UNIX is case sensitive!

9 Basic HTML Document Display Title Contents of body defines what the browser displays

10 Hello World HMTL File ~yourname/public_html/index.html Your Name’s Hello World Website Hello world!

11 Proper Nesting of and … … Start/End on one line is OK Start/End on one line is OK

12 Basic HTML Tags Various font/format control pairs Headings Level 1 Paragraph Bold Italics Center Text Some format control tags are not a tag pair: Break (new line)

13 Basic HTML Tags Unordered Lists (Bullets at start of each line) List Item Ordered Lists (Numbers at start of each line) List Item 1 List Item 2

14 Links to Other Files Display a hyper-link to another html file: Display Text Display a link to download a non-html file: Display Text Display an image from a non-html file: (Note: not a tag pair)

15 HTML Forms and/or Get Requests Forms defined using tags Many useful form “widgets”: –Text (Free Format Text Entry) –Check Boxes/Radio Boxes (on or off) –Select (Multiple Choice) Browser submits data to server programs: GET or POST methods Simple “GET” = URL followed by ?request: e.g.: url?parameter1=value1&parameter2=value2

16 HTML Forms and/or Get Requests Webpage reflect.html sends either: –A POST request via submitting the form or –A GET request via the encoded URL Reflect.html form using “post” method: <form name = "reflect" method="post“ action= " Reflect.html encoded “get” URL: <a href=" reflect.cgi?Name=John+Jones&Phone= "> Get Request to reflect.cgi Program URL is:

17 Dynamic Web Pages The URL points to an “executable program” file instead of to a “static” HTML document file The program generates response based on input request parameters and data stored on the server It writes response in HTML format to stdout These programs can be scripts PERL, PHP, etc. or Java servlets (e.g. generated from.jsp files) They can also be compiled C programs!

18 CGI C Programs Compile your C program with executable file name suffix.cgi (e.g. makefile definition) reflect.cgi:reflect.c makefile gcc -o reflect.cgi reflect.c Save executable file in a sub-directory in your public_html directory (e.g. “cgi-bin”)

19 CGI C Programs Environment variable REQUEST_METHOD contains indicator of type of input (Get/Post) reflect.cgi figures out request method used: char *rm = getenv(“REQUEST_METHOD”); For a “Get” request, reflect.cgi uses: char *s = getenv(“QUERY_STRING”); For a “Post” request, reflect.cgi uses: int len = atoi(getenv("CONTENT_LENGTH")); /* and reads len characters via getchar */

20 CGI C Programs reflect.cgi just responds to browser with standard html “boilerplate” and a copy of the input data in the body without parsing it: arguments = 1, /home/bobw/public_html/cgi-bin/reflect.cgi cgiRequestMethod = GET QUERY_STRING: Name=John+Jones&Phone= A production cgi program would parse this input data, process it, and provide a response in html to the browser

21 Course Evaluations Please fill out the course evaluation forms Give to assigned student for turn-in Thank you