JavaScript and PHP
Week 10
LBSC 690
Information Technology
Agenda
•	Questions

•	PHP

•	Joomla!

•	Mythical person-month

•	Advanced Database topics
Some Details About Access
•	Joins are automatic if field names are same
–	Otherwise, drag a line between the fields
•	Sort order is easy to specify
–	Use the menu
•	Queries form the basis for reports
–	Reports give good control over layout
–	Use the report wizard - the formats are complex
•	Forms manage input better than raw tables
–	Invalid data can be identified when input
–	Graphics can be incorporated
Programming Tips
•	Attention to detail!
–	Careful where you place that comma, semi-colon, etc.

•	Write a little bit of code at a time
–	Add some functionality, make sure it works, move on
–	Don’t try to write a large program all at once

•	Debug by viewing the “state” of your program
–	Print values of variables using document.write
–	Is the value what you expected?
JavaScript Resources
•	Google “javascript”
–	Tutorials: to learn to write programs
–	Code: to do things you want to do

•	Engineering and Physical Sciences Library
Ways of Generating Web Pages
•	Static: Written in a markup language
–	HTML, XML

•	Dynamic: Generated using a program
–	Common Gateway Interface [Perl] (.cgi)
–	Java servlets

•	Dynamic: Generated from a database
–	Cold Fusion (.cfm)
–	PHP (.php)
Why Database-Generated Pages?
•	Remote access to a database 
–	Client does not need the database software

•	Serve rapidly changing information
–	e.g., Airline reservation systems

•	Provide multiple “access points”
–	By subject, by date, by author, …

•	Record user responses in the database
Issues to Consider
•	Benefits
–	Multiple views
–	Data reuse
–	Scalable
–	Access control

•	Costs
–	Formal modeling
–	Complex (learn, design, implement, debug)
–	Brittle (relies on multiple communicating servers)
–	Not crawlable
Downside
•	Brittle
–	Depends on multiple servers

•	Complex
–	Learning, design, implementation, debugging

•	Formally modeled

Three Ways to Serve Data
Microsoft “Data Access Pages”
•	Displays database content on Web pages
–	Not very useful for changing database content

•	Drag-and-drop design in Microsoft Access
–	“Reports” are designed for printing
–	“Pages” are designed for the Web

•	Requirements:
–	Microsoft Web Server (not Apache)
–	IE 5 or higher Web browser (not Firefox)
–	“Office Web Components” on client machine
•	IE 7 fails gracelessly without them!
Data Access Page Example

PHP Programming Environments
•	You need three systems on the same server:
–	PHP (programming language)
–	MySQL (DBMS)
–	Apache (Web server)

•	XAMPP Server
–	Includes GUI tools

•	OTAL (Sun Unix) supports Web deployment
–	Requires a text editor (e.g., emacs) or FTP
Making PHP
----- HTML stuff -----
<?php
	----- PHP stuff -----
?>
----- HTML stuff -----

http://---URL stuff---/xxxxx.php

•	Download and install XAMPP
–	http://www.apachefriends.org/en/xampp.html
–	Check to install Apache and MySQL as services
–	Check the Web server at http://localhost/
•	Download and install Joomla!
–	http://www.joomla.org
–	Unzip to c:\xampp\htdocs\joomla15
–	Configure it at http://localhost/joomla15/
•	Host Name: localhost
•	User Name: root
•	Database Name: joomla15
•	DO NOT install sample data
–	Delete c:\xampp\htdocs\joomla15\installation
Connecting PHP to MySQL
•	On XAMPP:
$dbc=mysql_connect (‘localhost’, ‘userid’, ‘password’);

•	On OTAL:
$dbc=mysql_connect(‘:/export/software/otal/mysql/run/mysqld.sock’,
				‘userid’, ‘password’);
Create a MySQL Database
•	“root” user creates database + grants permissions
–	Using the XAMPP console (or mysql –u root –p)
•	root has no initial password; just hit <enter> when asked
–	By the system administrator on OTAL (otal.umd.edu)
      CREATE DATABASE project;
      GRANT SELECT, INSERT, UPDATE, DELETE, INDEX, ALTER, CREATE, DROP ON project.* TO ‘foo’@’localhost’ IDENTIFIED BY ‘bar’;
      FLUSH PRIVILEGES;
•	Start mysql
–	MySQL console for XAMPP, ssh for OTAL
                                                                                         mysql –u foo –p bar
•	Connect to your database
      USE project;
Creating Tables
CREATE TABLE contacts (
  ckey	MEDIUMINT UNSIGNED NOT NULL AUTO_INCREMENT,
  id		MEDIUMINT UNSIGNED NOT NULL,
  ctype	SMALLINT UNSIGNED NOT NULL,
  cstring	VARCHAR(40) NOT NULL,
  FOREIGN KEY (id) REFERENCES persons(id) ON DELETE CASCADE,
  FOREIGN KEY (ctype) REFERENCES ctlabels(ctype) ON DELETE RESTRICT,
  PRIMARY KEY (ckey)
) ENGINE=INNODB;

•	To delete: DROP TABLE contacts;
Populating Tables
INSERT INTO ctlabels
  (string) VALUES
  ('primary email'),
  ('alternate email'),
  ('home phone'),
  ('cell phone'),
  ('work phone'),
  ('AOL IM'),
  ('Yahoo Chat'),
  ('MSN Messenger'),
  (‘other’);

•	To empty a table: DELETE FROM ctlabels;
“Looking Around” in MySQL
•	SHOW DATABASES;

•	SHOW TABLES;

•	DESCRIBE tablename;

•	SELECT * FROM tablename;

Structured Query Language
DESCRIBE Flight;
Structured Query Language
SELECT * FROM Flight;
Structured Query Language
SELECT Company.CompanyName, Company.CompanyPhone, Flight.Origin, Flight.DepartureTime 
FROM Flight,Company
WHERE Flight.CompanyName=Company.CompanyName
   AND Flight.AvailableSeats>3;
Statements in PHP
•	Sequential
{…; …;…;}
Semicolons are required at the end of every statement
•	Conditional
if (3==i) {…} else {…}
•	Loop 
for ($i=0; $i<10; $i++) {…}
while ($row=mysql_fetch_array(…)) {…}
foreach ($array as $key => $value) {…} 
•	Braces are optional around a single statement
Variables
•	Name starts with a $
–	Case sensitive (assume everything could be!)

•	Hold a value
–	Number (integer, float)
–	String (double quotes, \ escape character)
–	TRUE, FLASE
–	NULL

•	Need not be declared (automatically “cast”)
Operators in PHP
•	Arithmetic operators
+  -  *  / 

•	Logical operators
<  <=  ==  !=  >=  >  &&  ||  !

•	String operator
.
Arrays in PHP
•	A set of key-element pairs
$days = array(“Jan”->31, “Feb”=>28, …);
$months = explode(“/”, “Jan/Feb/Mar/…/Dec”);
$_POST

•	Each element is accessed by the key
–	{$days[“Jan”]}
–	$months[0];
Functions in PHP
•	Declaration
function multiply($a, $b=3){return $a*$b;}

•	Invoking a method
$b = multiply($b, 7);

•	All variables in a function have only local scope
•	Unless declared as global in the function

Using PHP with (X)HTML Forms
<form action=“formResponseDemo.php”, method=“post”>
	email: <input type=“text”, name=“email”, value=“<?php echo $email ?>”, size=30 />
	<input type=“radio”, name=“sure”, value=“yes” /> Yes
	<input type=“radio”, name=“sure”, value=“no” /> No
	<input type=“submit”, name=“submit”, value=“Submit” />
	<input type=“hidden”, name=“submitted”, value=“TRUE” />
</form>

if (isset($_POST[“submitted”])) {
	echo “Your email address is $email.”;
} else {
	echo “Error: page reached without proper form submission!”;
}

Configuring Joomla!
•	Major divisions
–	Sections
–	Categories
•	Content
–	Articles
–	Links
–	Contact
•	Navigation
–	Menus
–	Search
 Discussion Point: 
Mythical Person-Month
•	Why is software development different from manufacturing car?

•	If it would take one person three months, why does it take four people SIX months?
Estimating Completion Time
•	Rules of thumb
–	1/3 specification
–	1/6 coding
–	1/2 test planning, testing, and fixing!

•	Add time for coding to learn as you go, but don’t take time away from the other parts!
–	Reread the section on “gutless estimating” if you are tempted

Ajax Applications
•	Google Maps
–	http://maps.google.com
•	Google Suggest
–	http://www.google.com/webhp?complete=1&hl=en
•	Sajax Tables
–	http://labs.revision10.com/?p=5
•	Sajax
–	http://www.modernmethod.com/sajax/
Trading People and Months is Hard
•	Sequential constraints

•	Communication

•	Training
Databases in the Real World
•	Some typical database applications:
–	Banking (e.g., saving/checking accounts)
–	Trading (e.g., stocks)
–	Airline reservations

•	Characteristics:
–	Lots of data
–	Lots of concurrent access
–	Must have fast access
–	“Mission critical”

Database Integrity
•	Registrar database must be internally consistent
–	Enrolled students must have an entry in student table
–	Courses must have a name

•	What happens:
–	When a student withdraws from the university?
–	When a course is taken off the books?

Integrity Constraints
•	Conditions that must always be true
–	Specified when the database is designed
–	Checked when the database is modified

•	RDBMS ensures integrity constraints are respected
–	So database contents remain faithful to real world
–	Helps avoid data entry errors
Referential Integrity
•	Foreign key values must exist in other table
–	If not, those records cannot be joined

•	Can be enforced when data is added
–	Associate a primary key with each foreign key

•	Helps avoid erroneous data
–	Only need to ensure data quality for primary keys
Concurrency
•	Thought experiment: You and your project partner are editing the same file…
–	Scenario 1: you both save it at the same time
–	Scenario 2: you save first, but before it’s done saving, your partner saves

Concurrency Example
•	Possible actions on a checking account
–	Deposit check (read balance, write new balance)
–	Cash check (read balance, write new balance)
•	Scenario:
–	Current balance: $500
–	You try to deposit a $50 check and someone tries to cash a $100 check at the same time
–	Possible sequences: (what happens in each case?)

Database Transactions
•	Transaction: sequence of grouped database actions
–	e.g., transfer $500 from checking to savings
•	“ACID” properties
–	Atomicity
•	All-or-nothing
–	Consistency
•	Each transaction must take the DB between consistent states.
–	Isolation:
•	Concurrent transactions must appear to run in isolation
–	Durability
•	Results of transactions must survive even if systems crash
Making Transactions
•	Idea: keep a log (history) of all actions carried out while executing transactions
–	Before a change is made to the database, the corresponding log entry is forced to a safe location

•	Recovering from a crash:
–	Effects of partially executed transactions are undone
–	Effects of committed transactions are redone
Before You Go
	On a sheet of paper, answer the following (ungraded) question (no names, please):

	What was the muddiest point in today’s class?