you have notmentioned technology to be used for eCommerce application.
Assuming since you have used Javaranch to post your question, you are looking for Java based eCommerce solution.
You can use BroadLeaf Commerce solution (http://www.broadleafcommerce.org/). It is an open source Spring MVC based ecommerce tool. By the way , this tool has sample Coffee/Restuarant application which can be a very good point to start.