I'll give it a shot. Let's take them one at a time:
$converter above is loaded from the class
Mage_Sales_Model_Convert_Order, which uses a core helper called
copyFieldset to copy order details into a shipment object. $order has to be of type array or
This method is actually at the core of Method 3, as it uses
Mage::getModel('sales/convert_order') in its constructor call.
Key differentiator of this method - it can take an array or an object
$order and generate a basic
$shipment object. It is a lower-level method used exclusively by the methods you put forth in Method 2, Method 3.
$shipment = Mage::getModel('sales/service_order', $order)
This seems to be the most popular way in Magento's Core of generating a shipment as it is used in both Shipment and Invoice controllers.
$order is used as a constructor argument to the instantiation of
Mage_Sales_Model_Service_Order, setting it as a protected property on the object.
You're then calling
prepareShipment and passing a quantity. As this method uses the converter class from Method 1, you
needn't specify more details such as order items pass item shipment qty details in the
prepareShipment argument, called here with
$this->_getItemQtys. To use this on your own context, all you need to do is pass the quantity of items in an array with the following format:
Key differentiator of this method - it gives you back a $shipment object, but with all items converted on it. It's plug-and-play.
I could not find evidence of using this method in the Core. It looks like a hack, to be honest. Here's the method:
$itemQty = $order->getItemsCollection()->count();
$shipment = Mage::getModel('sales/service_order', $order)->prepareShipment($itemQty);
$shipment = new Mage_Sales_Model_Order_Shipment_Api();
$shipmentId = $shipment->create($orderId);
Step 1 is exactly the same as Method 2 above. No difference. However, you get back a
$shipment object, which is replaced by a direct insantiation of
Mage_Sales_Model_Order_Shipment_Api. This is non-standard. The best-practice way of getting a shipment Api object would be to call
Next, it uses that overwritten, new Shipment API object to create a shipment from an
$orderId variable that hasn't been defined in your code. Again, this seems like a workaround.
Mage_Sales_Model_Order_Shipment_Api::create(), it seems like a one-stop-shop for generating a shipment as the most basic details needed to create the shipment is only an order
This is a hack that shouldn't be used by any module or extension. This API is meant to be consumed by features exposed via XML RPC / SOAP API requests and is intentionally basic to eliminate multiple step API requests.
Eventually Method 3 gets to the nitty-gritty, though, and via a call to Mage_Sales_Model_Order, it calls
prepareShipment, which is a higher-order abstraction for the familiar Method 2 above:
public function prepareShipment($qtys = array())
$shipment = Mage::getModel('sales/service_order', $this)->prepareShipment($qtys);
Key differentiator here - if you need a shipment, don't mind hacks, and only have an increment_id - use this method. Also useful information if you prefer to handle this via the SOAP API.
I hope that helps.