Commerce Engine minions

Abstract

Overview of the Commerce Engine minions that perform key processes along with examples.

The Sitecore XC Commerce Engine leverages the use of minions as basic units of work to perform specific tasks in a process. Predefined Commerce Engine minions perform key processes in the following areas:

  • Commerce transactional processes (for example, orders and sales activities)

  • Commerce entity indexing (for example, indexing of orders, customers, or catalog items)

  • Management operations (dev-ops operations, for example)

Minions perform basic actions on lists.  Some of the common tasks that minions perform include: 

  • Watching a list

  • Adding items to a list

  • Deleting items from a list

  • Moving items from one list to another

A minion can perform a single task and stop. Alternatively, a minion can iterate a list and call a pipeline to perform business functions on items in that list. 

This topic contains the following:

A minion policy defines each minion. The minion policy (MinionPolicy) is a configuration that specifies the name of the minion, the list the minion must watch (ListToWatch), and the fully qualified assembly name (FullyQualifiedName) of the minion.

Minion policies are defined in the .json file that contains policies specific to an environment. Like other configuration, minion policy settings are registered in the Commerce Engine during the bootstrapping process.  

The following shows an example of minion policy settings:

{
  "$type":"Sitecore.Commerce.Core.MinionPolicy, Sitecore.Commerce.Core",
  "WakeupInterval": "[HOW FREQUENT THE MINION RUNS]",
  "ListToWatch": "[MINION LIST NAME]",
  "FullyQualifiedName": "[FULLY QUALIFIED NAME OF THE MINION]",
  "ItemsPerBatch": "[HOW MANY ITEMS THE MINION IS GOING TO FETCH AT ONCE]",
  "SleepBetweenBatches": "[HOW LONG THE MINION WAITS TO FETCH NEW ITEM FROM THE LIST]",
}

The Commerce Engine makes use of a boss minion, which acts as a parent minion that delegates work to children minions to perform. Each child minion defines a list that it is acting on. This allows minions to scale without the contention of multiple minions reading from a single list.  

The pending order process provides a good example of a boss minion implementation that scales. The PendingOrdersMinionBoss is defined as a parent minion configured to watch the PendingOrders list. The main task of the the boss minion is to distribute pending orders to its children minions for processing. The PendingOrdersMinionBoss has two children minions defined. Each child watches its own list of pending orders (PendingOrder.1 and PendingOrder.2, respectively) that it processes independently. 

Below is an example of a scaling minion configuration showing a parent boss minion that contains two children minion definitions.

{
 "$type": "Sitecore.Commerce.Core.MinionBossPolicy, Sitecore.Commerce.Core",
 "Children": {
   "$type": "System.Collections.Generic.List`1[[Sitecore.Commerce.Core.MinionPolicy, Sitecore.Commerce.Core]], mscorlib",
   "$values": [
     {
       "$type": "Sitecore.Commerce.Core.MinionPolicy, Sitecore.Commerce.Core",
       "WakeupInterval": "00:05:00",
       "ListToWatch": "PendingOrders.1",
       "FullyQualifiedName": "Sitecore.Commerce.Plugin.Orders.PendingOrdersMinion, Sitecore.Commerce.Plugin.Orders",
       "ItemsPerBatch": 10,
       "SleepBetweenBatches": 500
      },
      {
       "$type": "Sitecore.Commerce.Core.MinionPolicy, Sitecore.Commerce.Core",
       "WakeupInterval": "00:05:00",
       "ListToWatch": "PendingOrders.2",
       "FullyQualifiedName": "Sitecore.Commerce.Plugin.Orders.PendingOrdersMinion, Sitecore.Commerce.Plugin.Orders",
       "ItemsPerBatch": 10,
       "SleepBetweenBatches": 500
      }
     ]
    },
    "WakeupInterval": "00:05:00",
    "ListToWatch": "PendingOrders",
    "FullyQualifiedName": "Sitecore.Commerce.Plugin.Orders.PendingOrdersMinionBoss, Sitecore.Commerce.Plugin.Orders",
    "ItemsPerBatch": 10,
    "SleepBetweenBatches": 500