How to extend business logic in Infor LN with DAL2

Add a DAL2 business logic extension

1. 1Open Infor LN Studio and connect to your development VRC (Version-Release-Customer) package combination.
2. 2In the Package Explorer, create or open a custom package that is separate from Infor's standard packages; never edit a standard package directly.
3. 3Create a Java class that extends the business logic handler for the table you want to affect, targeting the event you need (for example a validate or before-store event).
4. 4Write the condition or default in the handler using the DAL2 API to read and set field values on the business object.
5. 5Register the handler against the table and event, specifying the sequence relative to any standard handlers already on that event.
6. 6Compile the package in LN Studio and resolve any dependency or field-reference errors against the base table definition.
7. 7Deploy the package to a test VRC and run the affected session end to end to confirm the handler fires as expected.
8. 8Check the LN application log for handler execution and for any exceptions thrown from your class.
9. 9Promote the package through test and acceptance VRCs before production, following your normal Infor LN change control process.

Handler types and events

A common pattern: reject and default in one place

// Illustrative DAL2 handler pattern (conceptual, not a literal SDK signature)
public class SalesOrderLineValidator extends BusinessLogicHandler {
  public void beforeStore(BusinessObject bo) {
    if (bo.getDecimal("orderedQuantity") < 0) {
      throw new BusinessLogicException("Ordered quantity cannot be negative");
    }
    if (bo.getString("customClass") == null) {
      bo.setString("customClass", "STANDARD");
    }
  }
}

Common pitfalls

• !Editing the standard DAL directly instead of using a DAL2 extension, which gets lost on the next patch or upgrade.
• !Registering a handler without checking the execution order of existing standard handlers, causing double validation or a skipped default.
• !Assuming a DAL2 extension will keep working after an LN upgrade without re-testing it against the new VRC.
• !Throwing raw exceptions instead of a clear business logic exception, so end users see a generic error instead of a useful message.
• !Mixing DAL2 Java logic and classic 4GL DAL customization on the same table, so business rules end up split across two technologies.
• !Deploying straight to production without promoting through test and acceptance VRCs and re-checking dependent sessions like order-to-invoice.