Automatic Item Check

The Scheduler Utility

You already know several ways to invoke a flow:

• Auto Start when the project loads.
• Call Flow from another flow.
• External event — HTTP, Email, Web Service, etc.
• Internal event — PSS publish.

When a flow needs to run on a clock, use the Scheduler. At deployment time, the Magic xpi Server reads its scheduler entries — one per timer event — and invokes each flow at the appropriate moment.

To add a scheduled trigger you need a Scheduler service plus a Scheduler trigger:

1. In Settings » Services, add a Scheduler service named AutomaticCheck.
2. Set Scheduler Type to Interval; leave Calculate Scheduler Runtime at Startup ticked; set Minutes to 2.

The Requests Auto Check Flow

1. Insert a flow named Requests Auto Check; move it above Check Item.
2. Drop a Scheduler utility into the Triggers area; configure it with name Request_Auto_Check and Service AutomaticCheck.
3. Drop a Data Mapper into the flow; name it Check Request Items.
4. Source: Database source RequestItems — RequestItems table, columns RequestId, ProductCode, Quantity, RequestPrice, WHERE [RequestItems].Status = 0.

The WHERE clause limits the query to only the lines that are still invalid — the ones worth re-checking.

Check Reason: A Helper Flow

Each invalid line is examined in a small helper flow:

1. Insert a flow named Check Reason; move it below Check Item.
2. Add flow variables: F.RequestNum (Numeric 5), F.ItemCode (Alpha 30), F.RequestQuantity (Numeric 9.2), F.RequestPrice (Numeric 9.2).
3. Add a Data Mapper as the first step; name it Check Item Reason.
4. Source: Database source FetchItems — Products table, columns CatalogPrice and StockQuantity, WHERE [Products].ProductCode = '<?F.ItemCode?>'.
5. Destination: Database destination UpdateItems, DB Operation Update; RequestItems table, columns Quantity and Status, WHERE RequestID = <?F.RequestNum?> AND ProductCode = '<?F.ItemCode?>'.

Connect CatalogPrice and StockQuantity to both destination columns, then set Calculated Values:

Wiring the Per-Item Call

Back in Requests Auto Check:

1. Open the Check Request Items step's configuration.
2. Add a Call Flow destination named Call_Request_Check; target the Check Reason flow.
3. Connect RequestId → F.RequestNum, ProductCode → F.ItemCode, Quantity → F.RequestQuantity, RequestPrice → F.RequestPrice.

Now every two minutes the scheduler invokes the flow, the Data Mapper iterates over invalid lines, and the helper flow checks each one and updates it if conditions allow.

Flow Enablement

The Enablement section of a flow's properties decides when the flow is allowed to run. Even if a trigger fires, a disabled flow is silently ignored.

Weekly and Monthly schedules are configured as Flow Enablement services in the Settings dialog — just like the Scheduler service. Define the service first, then assign it to the flow's Enablement Service property.

Exercise

Summary

You should now be able to:

• Configure a Scheduler service and trigger to run a flow on an interval or at a specific time.
• Use Flow Enablement to control the days and hours during which a flow can fire.
• Combine Data Mapper, Call Flow, and Scheduler to implement periodic automatic correction logic.