Red Hat Application Server, Manual

Page: 102 / 296

94 Chapter 8. Developing Entity Beans
Note that a
<
finder-method-jdbc-mapping
=
element for the
findByPrimaryKey
method is
not necessary, since the meaning of this method is known.
Additionally, note that for CMP 2.0, the information defining the behavior of the implementation of a
find
<
method
=
method is located in the standard deployment descriptor , as an EJB-QL query (that
is, this is not JOnAS-specific information). The same finder method example in CMP 2.0:
<
query
=
<
query-method
=
<
method-name
=
findLargeAccounts
<
/method-name
=
<
method-params
=
<
method-param
=
double
<
/method-param
=
<
/method-params
=
<
/query-method
=
<
ejb-ql
=
SELECT OBJECT(o) FROM accountsample o WHERE o.balance
=
?1
<
/ejb-ql
=
<
/query
=
8.8. Using CMP2.0 Persistence
The following sections highlight the main differences between CMP as defined in EJB 2.0 specifi-
cation (called CMP2.0) and CMP as defined in EJB 1.1 specification (called CMP1.1). Major new
features in the standard development and deployment of CMP2.0 Entity Beans are listed (compar-
ing them to CMP1.1), along with JOnAS-specific information. Mapping CMP2.0 Entity Beans to the
database is described in detail. Note that the database mapping can be created entirely by JOnAS,
in which case the JOnAS-specific deployment descriptor for an Entity Bean should contain only the
datasource and the element indicating how the database should be initialized.
8.9. Standard CMP2.0 Aspects
This section briefly describes the new features available in CMP2.0 as compared to CMP 1.1, and how
these features change the development of Entity Beans.
8.9.1. Entity Bean Implementation Class
The EJB implementation class:
•
Implements the bean’s business methods of the component interface
•
Implements the methods dedicated to the EJB environment (the interface of which is explicitly
defined in the EJB specification)
•
Defines the abstract methods representing both the persistent fields (cmp-fields) and the relationship
fields (cmr-fields).
The class must implement the
javax.ejb.EntityBean
interface, be defined as
public
, and be
abstract
(which is not the case for CMP1.1, where it must not be
abstract
). The abstract methods
are the
get
and
set
accessor methods of the bean
cmp
and
cmr
fields. Refer to the examples and
details in Chapter 8 Developing Entity Beans .