Hi, I have a product: $myzopedir Products EProduct __init__ # empty EProduct.py class EProduct: def writeData(self): f = open('/home/oscar/data/test_out.jpg', 'wb') f.write(self.data) f.close() return 'Export succeed' On Zope, I created a new ZClass, EBook which is Subclassing, CatalogAware, Image and EProduct