Web Development Blog » shopping cart

Easy payments using Paypal IPN

Olaf — Fri, 14 Mar 2008 15:33:58 +0000

There are several PHP scripts and classes to process PayPal payments using their native IPN (Internet payment notification) feature. Because the whole process is based on the data you need to send via a web form to the PayPal payment processor these script look very similar.

The payment / notification process is shown via the following graphic:

Inside the form there are several required values to process a payment. PayPal gives the advice to post them all to get everything working. The following variables get some special attention:

business = your PayPal email address
cmd = single payments or subscription service (_xclick or _xclick-subscriptions)
return = the URL where the buyer get back after the payment is processed
cancel_return = the URL where the buyer get back if he has cancelled the payment
notify_url = the location where your IPN script is located
rm = how you need the data submitted from PayPal to your IPN script (1=get, 2=post)
currency_code = the currency you accept for your payment
lc = the country version of PayPal where your buyer is send to

There are much more variables, but we think that the other variables (product, order and shipment information) speak for themselves. Find a complete form provided with the example files.

To run some IPN enabled payment process we need a small script which will double check if the data which is send to the IPN script is valid according the data which is stored on the PayPal server. This feature is very important if your e-commerce accepts automatic payments.

The following code is able to check if the payment is valid against the PayPal server. Use this test to decide if the payment is valid or not.

$url = 'https://www.paypal.com/cgi-bin/webscr';
$postdata = '';
foreach($_POST as $i =&gt; $v) {
$postdata .= $i.'='.urlencode($v).'&';
}
$postdata .= 'cmd=_notify-validate';
 
$web = parse_url($url);
if ($web['scheme'] == 'https') {
$web['port'] = 443;
$ssl = 'ssl://';
} else {
$web['port'] = 80;
$ssl = '';
}
$fp = @fsockopen($ssl.$web['host'], $web['port'], $errnum, $errstr, 30);
 
if (!$fp) {
echo $errnum.': '.$errstr;
} else {
fputs($fp, "POST ".$web['path']." HTTP/1.1\r\n");
fputs($fp, "Host: ".$web['host']."\r\n");
fputs($fp, "Content-type: application/x-www-form-urlencoded\r\n");
fputs($fp, "Content-length: ".strlen($postdata)."\r\n");
fputs($fp, "Connection: close\r\n\r\n");
fputs($fp, $postdata . "\r\n\r\n");
 
while(!feof($fp)) {
$info[] = @fgets($fp, 1024);
}
fclose($fp);
$info = implode(',', $info);
if (eregi('VERIFIED', $info)) {
// yes valid, f.e. change payment status
} else {
// invalid, log error or something
}
}

As mentioned before there are some complete solutions available on the internet. If your e-copmmerce site doesn’t have a complex product catalog you should use some static code from the PayPal website. For this guide we checked the PHP toolkit provided by PayPal.

Code condition
The first thing I noticed the code is not very clean and is using a coding style which is based on older PHP versions (f.e. for systems using register globals = On)

Implementation
After some code clean-up it was possible to use the included file together with my shopping cart script. Static variables are defined in one central configuration file and dynamic files are posted via the form in your web application.

IPN features
This script is written to handle the IPN validation process with different methods: cURL, fsockopen, and libcURL. I tried only the fsockopen option because this method looks good to me and should work on almost every web platform.

Documentation
There is a “Readme” file with the information about the most important features. A complete guide is not included and the information about subscription payments is missing in all files and documents. If you decide to start with the original files you should check also the comments within the configuration and example files.

Example files
The included files are good enough to jump start your paypal payment application. All files are included for a single buy button and also for processing the payment f.e. for the items from a shopping cart. The bad thing is that the bad coding style makes it not easy to integrate the script into you own application if you’re an PHP beginner.

As mentioned before I included my own example files to this PayPal payment guide. If you have questions about this code please post them to our forum, we’re glad to help. Don’t forget the code is provided as it is and we’re not responsible for the functions and/or risks while using this code. Download the example code here.Similar Posts:

Setting up an Internet shopping cart

Olaf — Sun, 11 Nov 2007 16:05:07 +0000

If you plan to sell physical products, digital products or even a large number of services from your website, you might be considering setting up a shopping cart. Many large eTailers offer checkout solutions for their websites, and as the Internet has grown more “mature”, there are an increasing number of shopping cart solutions available.

However, before outright buying a shopping cart system for your website, there is something that you should consider. Mainly, whether you will run the shopping cart from your website or whether you will purchase, or “rent”, a shopping cart system from a third party website.

Remotely hosted shopping cart solution

Usually a hosted shopping cart solution requires little technical knowhow and less setup time than a shopping cart that you would run from your own website. Other than adding products, defining prices and setting up the shopping cart template, if this is an option, you’ll be up and running in a few days to as little as a few hours.

Some hosted shopping cart solutions offer optional marketing packages which may (or may not) help you drive targeted traffic to your shopping website. While these all-in-one shopping cart packages are normally pricey, they can certainly help the new online shop to get the most out of their new website right away without having to take the time to learn how to market on their own.

Remotely hosted shopping carts may also include, or optionally include, a payment gateway, meaning that you can accept credit card payments with their software. If a shopping cart solution does not offer this, you will need to acquire a merchant account on your own.

Hosting your own shopping cart system

While generally seen as a much more affordable solution for website owners to add the functionality of a shopping cart to what they have to offer, running a shopping cart on your own website will have its share of challenges if you are technically deficient.

What you need to run a shopping cart on your own website

1) A domain name. This should be an obvious step, but this is the first part of the process.

2) A hosting accountt that allows scripts to be executed and allows for one or more databases. Probably the most popular hosting accounts run with these basic configurations:

Linux operating system with Apache
Php/Perl script execution
MySQL databases

Because this is a very common setup for web hosting accounts, many free and paid shopping cart systems will run on hosting accounts with these features.

3) A shopping cart system. There are a lot of different types of ecommerce software and here are a few of the more popular open-source shopping cart solutions:

Zen-Cart
Zen Cart is a well-known provider of a free shopping cart system. While the administration back-end can be confusing because of the amount of options available, once you get the hang of things, Zen Cart can be an asset to your company because of its feature rich interface.

OsCommerce
Much like Zen Cart, Os Commerce is a feature rich shopping cart that also happens to be free. Released as Open Source software, Os Commerce has a solid community of supporters that help with the creation of plugins and modules, making this a feature rich shopping cart solution as well.

Cube Cart
Cube Cart is another free, yet versatile shopping cart system. Requiring only PHP and access to one MySQL database, the minimal requirements for this shopping cart solution are easily met by most paid web hosting accounts online today.

4) Payment processor / merchant account. If you’re catering to an online audience, you need to have a way to accept digital payments, such as credit cards. Depending on how you want to run your business, you can have all of the transactions handled online, such as through companies like PayPal.com, Moneybookers.com, Charge.com, Authorize.net and so on.

Some of the listed companies will also offer what is called a “virtual terminal” where you have the ability to key in your customers’ credit card information yourself, which would allow you to take phone orders. Even though this is turning into a digital world more and more, accepting checks as payment will help you to reach a greater number of people. Because the internet is still relatively new, there are many people who don’t trust technology enough to input their credit card information into a website; offering to accept checks as well as credit cards may be a worthwhile consideration.

5) SSL – Encrypted website pages. When you accept credit card payments on your website, you are obligated, at least ethically if not legally, to protect your customers’ financial information. With some payment processors all credit card information is entered on a third party website where you should not have to worry about protecting credit card numbers and such. However, if your customers key their credit card numbers into a form on your website, you need to have security measures in place so that the transmission of their credit card information is encrypted during transmission.

Setting up encrypted pages of your website requires a bit of technical knowhow, so this is something to consider when you are weighing out whether you should acquire the use of a remotely hosted shopping cart system or setting one up one your own website.

Running a shopping cart system is easily seen as a convenient solution when you are offering multiple products or services online. Choosing the right setup for your business needs should be weighed out with not only your budget in mind, but your decision should also be based on your technical capabilities as well.

Blog sponsor: Shopping Cart Templates – Get your online business up and running quickly with our eCommerce templates.Similar Posts:

Build a web shop with osCommerce

Olaf — Tue, 24 Jul 2007 06:34:55 +0000

osCommerce is the e-commerce software which can be downloaded for free and makes it possible to setup an online shopping site. osCommerce is a full featured web application and makes online shopping possible easy for the shop holder an the customer. Released under the GNU General Public License (open source), osCommerce came into existence in the year 2000 and is the brain that runs approximately more than 15.500 online stores.

For making an e-commerce site attractive to the prospective customers it is very important that the look of the web shop and the services that it provides are highly professional. osCommerce helps to make this task easier as it has several advanced features that makes it possible to maintain the inventory of the products and display the products online, deals with the payments and processes the orders, thus in effect it takes care of most of the functions of an e-commerce store. The free software osCommerce can installed within minutes and the new shop owner is able to insert his products immediately.

Developed by the community

osCommerce is an open source software making it accessible to any user who wishes to use it for whatever purpose it may be. This has provided the required dynamic angle to osCommerce as there are changes made on a continuous basis to incorporate the requirements of the prospective customer. The software provides both the front end and back end solution and is by default available in English, Spanish and German. Other languages are provided by the big osCommerce community.

osCommerce templates

sCommerce has features like templates which make it easy for a beginner also start an online e-commerce store. The osCommerce templates are pre-designed templates which make it very easy to build your own e-commerce site. You can start off easily and have a look at the completed design of your site in no time. The osCommerce templates make it possible to make all the changes required and incorporate all that is required to make the site attractive to the online customer.

Those templates are developed by expert web designers and web developers and have a variety of colors, themes and options to choose from. osCommerce templates are often not free and you need to pay a nominal charge for getting the templates and having a great looking website. osCommerce templates offer a great advantage as they are very reasonable as compared to what you would pay to hire a web designer and get a site designed especially for you.

osCommerce provides you with tremendous flexibility and saves on time and cost. First and foremost you should be sure of the look you want, the services that you would like to offer your customers, the budget and then decide on the templates that would meet your requirements.