tmp

equinox-fc/Domain/Domain.fsproj

@@ -15,7 +15,7 @@
         <Compile Include="InventorySeries.fs" />
         <Compile Include="InventoryEpoch.fs" />
         <Compile Include="Inventory.fs" />
-<!--        <Compile Include="InventoryTransaction.fs" />-->
+        <Compile Include="InventoryTransaction.fs" />
     </ItemGroup>
     <ItemGroup>
         <PackageReference Include="Equinox.Cosmos" Version="2.0.0-rc9" />

equinox-fc/Domain/InventoryTransaction.fs

@@ -1,3 +1,12 @@
+/// Process Manager used to:
+/// - Coordinate competing attempts to transfer quantities from stock; if balance is 3 one of contesting requests to remove 2 or 3 items must reach `Failed`
+/// - maintain rolling balance of stock levels per Location
+/// - while recording any transfers or adjustment in an overall Inventory record
+/// The Process is driven by two actors:
+/// 1) The 'happy path', where a given actor is executing the known steps of the command flow
+///    In the normal case, such an actor will bring the flow to a terminal state (Completed or Failed)
+/// 2) A watchdog-projector, which reacts to observed events in this Category by stepping in to complete in-flight requests that have stalled
+///    This represents the case where a 'happy path' actor died, or experienced another impediment on the path.
 module Fc.InventoryTransaction
 
 open System
@@ -6,14 +15,13 @@ open System
 [<RequireQualifiedAccess>]
 module Events =
 
-    let [<Literal>] CategoryId = "Transfer"
-    let (|For|) (inventoryId, transactionId) =
-        FsCodec.StreamName.compose CategoryId [InventoryId.toString inventoryId; InventoryTransactionId.toString transactionId]
+    let [<Literal>] CategoryId = "InventoryTransfer"
+    let (|For|) (inventoryId, transactionId) = FsCodec.StreamName.create CategoryId (InventoryTransactionId.toString transactionId)
 
+    type AdjustmentRequested = { location : LocationId; quantity : int }
     type TransferRequested = { source : LocationId; destination : LocationId; quantity : int }
     type Removed = { balance : int }
     type Added = { balance : int }
-    type AdjustmentRequested = { location : LocationId; quantity : int }
 
     type Event =
         | AdjustmentRequested of AdjustmentRequested
@@ -59,13 +67,9 @@ module Fold =
         | Events.Completed -> Completed
     let fold : State -> Events.Event seq -> State = Seq.fold evolve
 
-type Result =
-    {   /// Indicates whether this epoch is closed (either previously or as a side-effect this time)
-        isClosed : bool
-        /// Count of items added to this epoch. May be less than requested due to removal of duplicates and/or rejected items
-        added : int
-        /// residual items that [are not duplicates and] were not accepted into this epoch
-        rejected : Events.Event list }
+type Command =
+    | Adjust of Events.AdjustmentRequested
+    | Transfer of Events.TransferRequested
 
 let decideSync capacity requested (state : Fold.State) : Result * Events.Event list =
     let isFresh = function