Ordering design dillemas in README

ecommerce/ordering/README.md

@@ -21,7 +21,62 @@ This object is fully event sourced.
 | expired   |       |           |           |         |           |
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-#### Up and running
+### Design dilemmas
+
+
+#### God Domain
+
+The state machine mentioned above became a very central place to the whole application.
+Almost every other domain either reacts to this domain or triggers Ordering.
+
+This might be an issue, as we might end up with a God Domain.
+
+#### Duplication of states
+
+Some of the states here are actually duplicates of the states of the Order in other domains.
+
+#### Multiplication and naming of states
+
+We clearly have a naming issue here. 
+What is the actual difference between presubmit/submit/confirm/accept?
+Not all the names match between method names and event names.
+
+#### Order items
+
+We track order items here, but we actually don't really use it much. 
+It doesn't have any impact on the state machine.
+It's only needed to some read models, which can retrieve it from elsewhere - most notably the `Pricing`
+The implementation of `Basket`, because of this, seems duplicated to Pricing or Inventory.
+
+#### Checking availability in the controllers
+
+```ruby
+def add_item
+    read_model = Orders::OrderLine.where(order_uid: params[:id], product_id: params[:product_id]).first
+    if Availability::Product.exists?(["uid = ? and available < ?", params[:product_id], (read_model&.quantity || 0) + 1])
+      redirect_to edit_order_path(params[:id]),
+                  alert: "Product not available in requested quantity!" and return
+    end
+    ActiveRecord::Base.transaction do
+      command_bus.(Ordering::AddItemToBasket.new(order_id: params[:id], product_id: params[:product_id]))
+    end
+    head :ok
+  end
+```
+
+This code is duplicated for admin creating orders and clients creating orders.
+
+#### Mapping of events between domains
+
+UI -> Ordering::SubmitOrder -> Ordering::Presubmitted -> Reservation(process) -> Ordering::AcceptOrder
+
+Ordering::AcceptOrder -> Ordering::OrderSubmitted -> 
+
+  -> Shipment::SubmitShipment
+  -> Pricing::CalculateTotalValue
+
+
+### Up and running
 
 ```
 make install test mutate