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1@Stateless
2@TransactionAttribute(TransactionAttributeType.REQUIRED)
3public class OrdersService {
4 
5    @PersistenceContext(unitName = "orders-pu")
6    private EntityManager em;
7 
8    @Resource(mappedName = "jdbc/OracleDS")
9    private DataSource oracleDs;
10 
11    public long reserveInventory(long orderId, String sku, int qty)
12            throws NamingException, SQLException {
13 
14        Context ctx = new InitialContext();
15        DataSource ds = (DataSource) ctx.lookup(
16            "java:comp/env/jdbc/OracleDS");
17 
18        CallableStatement cs = ds.getConnection()
19            .prepareCall("{ call SP_RESERVE_INVENTORY(?, ?, ?, ?) }");
20        cs.setLong(1, orderId);
21        cs.setString(2, sku);
22        cs.setInt(3, qty);
23        cs.registerOutParameter(4, Types.REF_CURSOR);
24        cs.execute();
25 
26        ResultSet rs = (ResultSet) cs.getObject(4);
27        if (rs != null && rs.next()) {
28            return rs.getLong("RESERVATION_ID");
29        }
30        return -1L;
31    }
32}