IT452
NOTES FOR TODAY: Perl and Ajax
1. How does the webserver know what type of file the web browser just requested?
2. Create a text file, and rename it: temp.txt, temp.xml, temp.html. What happens?
3. Then what type of file is a perl script?
4. Javascript AJAX calls are the same interaction as typing the URL into the web browser.
a. responseText vs responseXML
5. Which field is filled when AJAX calls perl? responseText or responseXML?
6. HTML is for displaying on a webpage. Text and XML are for AJAX communication hidden from the user.
7. Perl lets you choose the format, and its output is sent character for character to the web browser. So be careful
what you print!
EXERCISES
1. Write a javascript function that creates and makes an asynchronous AJAX call to a Perl script called
“findburritos.pl”. The call should also send a search parameter to Perl. Call the parameter whatever you want;
for its value use the provided “searchValue” argument. (Just write the first part of the AJAX below)
function queryDB(searchValue) {
}
2. Now write the Perl script findburritos.pl. The script should query the “burritos” database table, and retrieve the
columns “name”, “size”, “cost” for each matching row. The script should then print the appropriate output so
that plain text is returned to the AJAX call.
#!/usr/bin/perl
use strict; use CGI::Carp qw( fatalsToBrowser );
use CGI qw( :standard );
use DBI; use DBD::mysql;
3. DIFFERENT PROBLEM. Write AJAX code that sends two parameters name and cost to the web server (invoking
the program query.pl) :
function queryDB(name, cost) {
xhr = window.ActiveXObject
? new ActiveXObject("Microsoft.XMLHTTP")
: new XMLHttpRequest();
// Start getting data from server
xhr.open(
….
}