1. CGI Programming

2. What is it? CGI –Common Gateway Interface Standard way to pass information back to the Web Server –GET Query String –POST Standard Input

3. What is CGI? CGI is platform independent CGI is language independent Perl is the most popular development language

4. CGI Environment CGI uses a subset of the OS environment for the application Can access native applications on server Runs as the server userid (normally) See showenv.pl

5. CGI/HTML Data is passed to a CGI program from a HTML file with the Form tag –Method = GET –Method = POST

6. Parsing Data If request is passed via GET, use QUERY_STRING environmental variable If request is passed via POST, you must read in the data from STDIN (the CONTENT_LENGTH environmental variable specifies how much data to read)

7. Parse Some Data See advance.htm See simple_parse.pl See sample_cgipm.pl

8. Form Verification Need to verify data before processing Bad data can be a security risk Assume all data is initially bad see verify.pl (In real life also use JavaScript )

9. Cookies: State Management HTTP is stateless Cookies are the standard method for state management Can use hidden fields, mangled URLs, etc see cookie.htm see cookie.pl Cookies are not evil! :)