Collections

In the BOM, arrays and collections represent a set of objects. In the BAL, you must set a collection domain on a collection of type java.util.Collection.

In the BOM, collections are members that are semantically linked to a BOM class with a one-to-many relationship.

Collections appear in business rules with BAL operators and constructs such as:

• <an object> is one of <objects>
• the number of <objects> in <objects>

In the following example, the action rule uses collections:

definitions
 set 'company1' to a company;
 set 'customer1' to a customer in the employees of 'company1';
if 
  the number of books in the items of the shopping cart of 'customer1' is more 
than 5
 …

You can represent a set of objects in the BOM in two ways:

• Array (java.lang.Object[])

• Collection (java.util.Collection)

Both are mapped to the concept of collection of objects in the BAL. From a BAL perspective, a collection is an element with multiple-cardinality. From a BOM perspective, it is an array, or a BOM member with a collection domain.

A collection is treated as a collection of objects in the BAL only if it has a collection domain. A collection domain specifies the cardinality and the type of collection elements, for example, 0,* class Customer.

When you edit a business rule using the Content Assist box in designer, you can access the constructs relative to collections if the member is of type:

• array

• java.util.Collection and has a collection domain.

public class Company {
   Employee[] getEmployees();
}

public class Company {
   java.util.Collection getEmployees() domain 0, * class Employee;
}