External Variables

See virtual in Type Annotations. The values for external variables are usually set by the environment that launches the constraint solver engine. Use external variables to import runtime data from the context header (such as Quote or Sales Transaction) into the configuration model, with the contextPath annotation to denote header fields, or with tagName annotation to denote lineItem fields. See External Variable Annotations section.

If the external variable isn't mapped to any external data source, it must have a default value. Otherwise, it may remain unbound and cause errors.

Here's a basic declaration syntax.

1extern int MAX_VALUE = 9999;
2extern decimal(2) threshold = 1.5;

Example: Using External Variables with Context Path Annotation

In this example, the constraint engine needs access to the quote header (Sales Transaction) field, which defines the shipping location to enforce region-specific compliance requirements. The contextPath annotation is used to map the field (SalesTransaction.ShippingCountry) to an external CML variable (ShippingCountry).

1// External variable declaration with context path annotation
2@(contextPath = "SalesTransaction.ShippingCountry")
3extern string ShippingCountry; // ShippingCountry Value is pulled from the Quote/Order header

See the full example in Using ContextPath and tagName annotations.

External Variable Annotations

Here are the details of external variable annotations.