Developing State-enabled Applications With PHP

Installment 1

Developing State-enabled Applications With PHP

When a user is browsing through a website and is surfing from one web page to another, sometimes the website needs to remember the actions (e.g. choices) performed by the user. For example, in a website that sells DVDs, the user typically browses through a list of DVDs and selects individual DVDs for check out at the end of the shopping session. The website needs to remember which DVDs the user has selected because the selected items needs to be presented again to the user when the user checks out. In other words, the website needs to remember the State - i.e. the selected items - of the user's browsing activities.

However, HTTP is a Stateless protocol and is ill-equipped to handle States. A standard HTML website basically provides information to the user and a series of links that simply directs the user to other related web pages. This Stateless nature of HTTP allows the website to be replicated across many servers for load balancing purposes. A major drawback is that while browsing from one page to another, the website does not remember the State of the browsing session. This make interactivity almost impossible.

In order to increase interactivity, the developer can use the session handling features of PHP to augment the features of HTTP in order to remember the State of the browsing session. The are basically 2 ways PHP does this:

1. Using cookies
2. Using Sessions

The next installment discusses how to manage sessions using cookies...

Installment 2

Cookies

Cookies are used to store State-information in the browser. Browsers are allowed to keep up to 20 cookies for each domain and the values stored in the cookie cannot exceed 4 KB. If more than 20 cookies are created by the website, only the latest 20 are stored. Cookies are only suitable in instances that do not require complex session communications and are not favoured by some developers because of privacy issues. Furthermore, some users disable support for cookies at their browsers.

The following is a typical server-browser sequence of events that occur when a cookie is used:

1. The server knows that it needs to remember the State of browsing session

2. The server creates a cookie and uses the Set-Cookie header field in the HTTP response to pass the cookie to the browser

3. The browser reads the cookie field in the HTTP response and stores the cookie

4. This cookie information is passed along future browser-server communications and can be used in the PHP scripts as a variable

PHP provides a function called setcookie() to allow easy creation of cookies. The syntax for setcookie is: int setcookie(string name, [string val], [int expiration_date], [string path], string domain, [int secure])

The parameters are:

1. name - this is a mandatory parameter and is used subsequently to identify the cookie

2. value - the value of the cookie - e.g. if the cookie is used to store the name of the user, the value parameter will store the actual name - e.g. John

3. expiration_date - the lifetime of the cookie. After this date, the cookie expires and is unusable

4. path - the path refers to the URL from which the cookie is valid and allowed

5. domain - the domain the created the cookie and is allowed to read the contents of the cookie

6. secure - specifies if the cookie can be sent only through a secure connection - e.g. SSL enable sessions

The following is an example that displays to the user how many times a specific web page has been displayed to the user. Copy the code below (both the php and the html) into a file with the .php extension and test it out.

[?php //check if the $count variable has been associated with the count cookie if (!isset($count)) {

$count = 0; } else {

$count++; } setcookie("count", $count, time()+600, "/", "", 0); ?]

[html]

[head]

[title]Session Handling Using Cookies[/title]

[/head]

[body]

This page has been displayed: [?=$count ?] times.

[/body] [/html]

The next installment discusses how to manage sessions using PHP session handling functions with cookies enabled...

Installment 3

PHP Session Handling - Cookies Enabled

Instead of storing session information at the browser through the use of cookies, the information can instead be stored at the server in session files. One session file is created and maintained for each user session. For example, if there are three concurrent users browsing the website, three session files will be created and maintained - one for each user. The session files are deleted if the session is explicitly closed by the PHP script or by a daemon garbage collection process provided by PHP. Good programming practice would call for sessions to be closed explicitly in the script.

The following is a typical server-browser sequence of events that occur when a PHP session handling is used:

1. The server knows that it needs to remember the State of browsing session

2. PHP generates a sssion ID and creates a session file to store future information as required by subsequent pages

3. A cookie is generated wih the session ID at the browser

4. This cookie that stores the session ID is transparently and automatically sent to the server for all subsequent requests to the server

The following PHP session-handling example accomplishes the same outcome as the previous cookie example. Copy the code below (both the php and the html) into a file with the .php extension and test it out.

[?php //starts a session session_start();

//informs PHP that count information needs to be remembered in the session file if (!session_is_registered("count")) {

session_register("count");

$count = 0; } else {

$count++; }

$session_id = session_id(); ?]

[html]

[head]

[title]PHP Session Handling - Cookie-Enabled[/title]

[/head]

[body]

The current session id is: [?=$session_id ?]

This page has been displayed: [?=$count ?] times.

[/body] [/html]

A summary of the functions that PHP provides for session handling are:

1. boolean start_session() - initializes a session

2. string session_id([string id]) - either returns the current session id or specify the session id to be used when the session is created

3. boolean session_register(mixed name [, mixed ...]) - registers variables to be stored in the session file. Each parameter passed in the function is a separate variable

4. boolean session_is_registered(string variable_name) - checks if a variable has been previously registered to be stored in the session file

5. session_unregister(string varriable_name) - unregisters a variable from the session file. Unregistered variables are no longer valid for reference in the session.

6. session_unset() - unsets all session variables. It is important to note that all the variables remain registered.

7. boolean session_destroy() - destroys the session. This is opposite of the start_session function.

The next installment discusses how to manage sessions using PHP session handling functions when cookies are disabled...

Installment 4

PHP Session Handling - Without Cookies

If cookies are disabled at the browser, the above example cannot work. This is because although the session file that stores all the variables is kept at the server, a cookie is still needed at the browser to store the session ID that is used to identify the session and its associated session file. The most common way around this would be to explicitly pass the session ID back to the server from the browser as a query parameter in the URL.

For example, the PHP script generates requests subsequent to the start_session call in the following format: http://www.yourhost.com/yourphpfile.php?PHPSESSID=[actual session ID]

The following are excerpts that illustrate the discussion:

Manually building the URL:
$url = "http://www.yoursite.com/yourphppage.php?PHPSESSID=" . session_id(); [a href="[?=$url ?]"]Anchor Text[/a]

Building the URL using SID:
[a href="http://www.yoursite.com/yourphppage.php?[?=SID ?]"]Anchor Text[/a]

Used with the author's permission.

This article is written by John L.
John L is the Webmaster of designer banners (designer banners).

tidy up service Winnetka ..
In The News:

Third-party security breach at Discord exposes sensitive user information including government IDs, highlighting cybersecurity risks from external service providers.
Survey of 1,000 students shows teens using AI for personal relationships while two-thirds of parents remain unaware of their children's AI usage.
Cybersecurity experts warn about a ShadowLeak vulnerability that weaponized ChatGPT's Deep Research agent to steal personal data from Gmail accounts through hidden commands.
Tesla's Full Self-Driving system faces federal investigation following 58 reports of crashes, with six vehicles running red lights before colliding with other cars.
The Fox News AI Newsletter brings you the latest developments on artificial intelligence, with news on OpenAI moving to soon allow erotica for adult users.
Eric Schmidt alerts that hackers can reverse-engineer AI models to bypass safety measures, citing examples like the jailbroken ChatGPT variant called DAN.
Cybercriminals exploit Microsoft Teams through impersonation, malicious links and fake profiles to gather intel and deliver ransomware to personal and work devices.
Google, Dior, Allianz and dozens of other companies lost sensitive customer data in Salesforce-related breaches affecting millions of records across multiple sectors.
Apple launches iOS 26 with new Preview app that combines document editing, PDF annotation and scanning features into one streamlined iPhone experience.
New AI road monitoring system uses sensor-embedded fabric to predict infrastructure problems, potentially reducing maintenance costs and traffic disruptions for cities.
Holiday charity scams target retirees through lookalike organization names, untraceable payment requests, and data broker information to steal donations.
The Federal Trade Commission says criminals are posing as IRS agents, law enforcement officers or other officials, often over the phone or online, to steal thousands of dollars at a time.
AI phishing scams now use voice cloning and deepfake technology to trick victims, but Kurt "CyberGuy" Knutsson reveals warning signs to watch for.
Inversion Space unveils Arc, a reusable reentry vehicle that can deliver up to 500 pounds of cargo from orbit to anywhere on Earth in under an hour.
Red flags like processing fees, urgent countdowns and requests for full Social Security numbers expose fraudulent settlement sites targeting consumers.
Comprehensive analysis of Google Maps, Waze and Apple Maps examines usability, routing accuracy, data handling and features across the top navigation platforms.
Expert analysis reveals whether wired Ethernet or wireless Wi-Fi connections are safer for home internet use, plus practical steps to secure your network from attackers.
Australian construction robot Charlotte uses sand, crushed brick and recycled glass to 3D print fireproof, floodproof homes with reduced carbon footprint.
Cybercriminals are using fake invitation emails to trick recipients into downloading malware and stealing personal information and data.
Flying drones could help retailers fight a 93% increase in theft rates as Flock Safety promotes airborne security systems to track suspects and deter crime.
The Fox News Artificial Intelligence Newsletter brings you the latest news on the emerging technology every Saturday, highlighting top stories.
Hacker group Radiant stole data from 8,000 children at Kido nursery chain, demanding ransom and directly contacting parents with intimidation tactics.
As 18 states implement bell-to-bell cell phone bans, creative students use Google Docs, iMessage on MacBooks and Post-It notes to stay connected in class.
A sheriff's captain says deputies often spend hours writing reports between calls, but Axon's AI program, Draft One, helps them save crucial time in the field.
Sora 2, OpenAI's new video-generation app, can create AI-generated videos based on a singular prompt. The results are both mind-blowing and terrifying.

Enhance Your Website With A Yahoo-Style Directory

Does your website have a links/resources page?Do you exchange reciprocal... Read More

Running An Effective Website

Running an effective website is a continuous process. I have... Read More

Beyond Web Usability: Web Credibility

If you've been developing websites on Mars for the past... Read More

The Cost Of A Web Site

Just starting out, you can start with a simple informational... Read More

Where on Earth is Your Websitee?

You've just finished congratulating your marketing team. After six months... Read More

Three Way Linking - Webmaster Strategy

Three way linking and concerns.For many years SEO experts were... Read More

How to Maximize the Value of Every Visitor to Your Website

While most marketers are beginning to understand the critical importance... Read More

Selecting a Web Content Management Product

So you want to take a look at a real... Read More

Are You Losing Sales Because of These 4 Simple Website Mistakes?

Losing website sales and traffic is sometimes simply a case... Read More

Web accessibility for screen magnifier users

The needs of screen magnifier users are overlooked when implementing... Read More

Using Psychology Easily on Your Website to Make More Sales!

Psychology is a long word which everyone thinks, "no, that's... Read More

Why Your Brick-and-Mortar Biz Needs A Website

The internet has taken over our lives with a vengeance,... Read More

Web Content: How Much Should I Pay?

When web content gets discussed on webmaster bulletin boards, the... Read More

Web Content Strategy 101

Your content is what gets you in search engines, speaks... Read More

5 Essential Traits Of A Home Business Website

So you've decided to start an online work at home... Read More

Website Imperatives and Solutions

When you take a look at the most visited sites... Read More

Marketing Your Business Online

As a business you can't afford to ignore the Internet... Read More

Improve Web Sales Figures Forever And Ever Amen!

"How do I improve web site sales figures?" The CEO... Read More

Develop a Solid Website Presence

Starting an internet business can be confusing to non-veterans. The... Read More

Getting One-way Inbound Links: the 5 Major Strategies

With search engines putting a damper on direct reciprocal links,... Read More

Create Huge Income From Your Web Site - 10 Easy Ways

The cost of setting up a web site is dirt... Read More

The 5 Biggest Mistakes Almost All Web Designers Make

Huge Mistake #1: Creating a Website with Flash -- Did... Read More

What Works and What not Works for Your Internet Business

"Build it and they will come."--Filed of Dreams (1989) If... Read More

Content Management ? The New Standard in Web Design

The evolution of web development parallels the model of technology... Read More

Successful Commercial Sites

Do you make your website just to entertain yourself or... Read More

kitchen deep cleaning Lake Forest ..