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90 Chapter 8. Developing Entity Beans
conn.close();
}
A DataSource object associates a JDBC driver with a database (as an ODBC datasource). It is created
and registered in JNDI by the EJB server at launch time (refer also to Chapter 4 Configuring JDBC
DataSources ).
A DataSource object is a resource manager connection factory for
java.sql.Connection
objects,
which implements connections to a database management system. The Enterprise Bean code refers
to resource factories using logical names called Resource manager connection factory references .
The resource manager connection factory references are special entries in the Enterprise Bean envi-
ronment. The bean provider must use resource manager connection factory references to obtain the
datasource object as follow:
•
Declare the resource reference in the standard deployment descriptor using a
resource-ref
ele-
ment.
•
Look up the datasource in the Enterprise Bean environment using the JNDI interface (refer to
Chapter 12 Enterprise Bean Environment ).
The deployer binds the resource manager connection factory references to the actual resource factories
that are configured in the server. This binding is done in the JOnAS-specific deployment descriptor
using the jonas-resource element.
8.6.1. Database Access Operation Example
The declaration of the resource reference in the standard deployment descriptor looks like the follow-
ing:
0
resource-ref
1
0
res-ref-name
1
jdbc/AccountExplDs
0
/res-ref-name
1
0
res-type
1
javax.sql.DataSource
0
/res-type
1
0
res-auth
1
Container
0
/res-auth
1
0
/resource-ref
1
The
2
res-auth
3
element indicates which of the two resource manager authentication approaches is
used:
• Container
: the deployer sets up the sign-on information.
• Bean
: the bean programmer should use the getConnection method with user and password param-
eters.
The JOnAS-specific deployment descriptor must map the environment JNDI name of the resource to
the actual JNDI name of the resource object managed by the EJB server. This is done in the
2
jonas-
resource
3
element.
0
jonas-entity
1
0
ejb-name
1
AccountExpl
0
/ejb-name
1
0
jndi-name
1
AccountExplHome
0
/jndi-name
1
0
jonas-resource
1
0
res-ref-name
1
jdbc/AccountExplDs
0
/res-ref-name
1
0
jndi-name
1
jdbc_1
0
/jndi-name
1
0
/jonas-resource
1
0
/jonas-entity
1
The ejbStore method of the same Account example with bean-managed persistence is shown in the
following example. It performs JDBC operations to update the database record representing the state
of the Entity Bean instance. The JDBC connection is obtained from the datasource associated with the