Document relations for Orders and Managed Services

uncloud/README-object-relations.md

@@ -19,16 +19,29 @@ stack VM" can be a VM + a disk + an IPv4 address).
 Bills represent active orders of a month. Bills can be shown during a
 month but only become definitive at the end of the month.
 
-
 ## Orders
 
-When
+When customer X order a (set) of product, it generates an order for billing
+purposes. The ordered products point to that order and register an Order Record
+at creation.
+
+Orders and Order Records are assumed immutable => they are used to generate
+bills and should not be mutated. If a product is updated (e.g. adding RAM to
+VM), a new order should be generated.
+
+The order MUST NOT be deleted when a product is deleted, as it is used for
+billing (including past bills).
+
+### Order record
+
+Used to store billing details of a product at creation: will stay there even if
+the product change (e.g. new pricing, updated) and act as some kind of archive.
+Used to generate bills.
 
 ## Payment Methods
 
 Users/customers can register payment methods.
 
-
 ## Sample flows / products
 
 ### A VM snapshot
@@ -39,12 +52,10 @@ able to rollback the VM to a previous state.
 Creating a VM snapshot (-product) creates a related order. Deleting a
 VMSnapshotproduct sets the order to deleted.
 
-
 ### Object Storage
 
 (tbd by Balazs)
 
-
 ### A "raw" VM
 
 (tbd by Ahmed)
@@ -56,3 +67,16 @@ VMSnapshotproduct sets the order to deleted.
 ### A dual stack VM
 
 (tbd by Ahmed)
+
+### A managed service (e.g. Matrix-as-a-Service)
+
+Customer orders service with:
+	* Service-specific configuration: e.g. domain name for matrix
+	* VM configuration:
+		- CPU
+		- Memory
+		- Disk (soon)
+
+It creates a new Order with two products/records:
+	* Service itself (= management)
+	* Underlying VM