This client can be utilized as an adapter for using the Shopify API with the ZendFramework version 2. The client requires PHP 5.3 for use. This is a community maintained library authored by Matthew Peterson and open sourced on GitHub. The client is endorsed for use on the Shopify API developer documentation's list of 3rd party libraries.
The daily deal space is hot, and has been for some time now. In the past year 23 million Americans have purchased a daily deal or group coupon according to a survey conducted for the American Institute of CPAs by Harris Interactive (source). Not to mention Freelance websites, such as Freelancer and Elance, have been flooded with thousands of "Groupon clone", "daily deal site" and related job postings - a general sign that many more businesses are still trying to get in.