Create XML product feed extension for Shopify

Hello, i need you to create an extension for Shopify that creates and xml url with the field that i will tell you so i can give it to my customers that have Shopify to generate the xml and the fields i need, easily, with the installation of an extension. The field to generate are: DECLARATION: <?xml version="1.0" encoding="UTF-8"?> <products> <created_at>2010-04-08 12:32</created_at> ... </products> ATTRIBUTES: <products> root Node from all variants. <variant> <vendor> the name of the shop <mpn> the mpn of the parent product <sku> the sku of the variation <title> the title of the variation <description> the description of the variation/product <imgurl> the images of the variation <price> the sale price of the variation <compare_at_price> the regular price of the variation <quantity> the quantity of the variation <quantity_parent>the quantity of all the variations if possible <brand> the brand of the variation <category> the categories of the variation <gender> the gender of the variation <season> the season of the variation <material> the material of the variation <size>the size of the variation <tags> the tags of the variation </variant> IMPORTANT IS TO TAKE ALL THE ATTRIBUTES THAT ARE AVAILABLE OF THE STORE nice will be to have the option to create new field from the extension and attach the fields