gem 'active_fulfillment'

# The authentication options differ per service.
service = ActiveFulfillment.service('name').new(login: 'abc', password: 'def')

# To fulfill an order:
service.fulfill(order_id, shipping_address, line_items, options = {})

# To find out how much stock is left
service.fetch_stock_levels(options = {})

# To obtain tracking numbers.
service.fetch_tracking_numbers(order_ids, options = {})