Red Hat Application Server, Руководство пользователя

Страница: 283 / 296

Chapter 40.
Configuring JDBC Resource Adapters
Instead of using the JOnAS database service for configuring DataSources, it is also possible to use
the JOnAS resource service and JDBC connectors compliant with the J2EE Connector Architecture
specification. The resulting functionality is the same, and the benefit is the management of pools
of JDBC PrepareStatements. This chapter describes how the JDBC Resource Adapters should be
configured to connect the application to databases.
40.1. Configuring Resource Adapters
For both container-managed or bean-managed persistence, the JDBC Resource Adapter (JDBC RA)
makes use of relational storage systems through the JDBC interface. JDBC connections are obtained
from a JDBC RA. The JDBC RA implements the J2EE Connector Specification using the DataSource
interface as defined in the JDBC 2.0 standard extensions. An RA is configured to identify a database
and a means to access it via a JDBC driver. Multiple JDBC RAs can be deployed either via the
jonas.properties
file or included in the autoload directory of the resource service. For complete
information about RAs in JOnAS, refer to Chapter 41 Configuring Resource Adapters . The following
section explains how JDBC RARs can be defined and configured in the JOnAS server.
To support distributed transactions, the JDBC RA requires the use of at least a JDBC2-XA-compliant
driver. Such drivers implementing the XADataSource interface are not always available for all rela-
tional databases. The JDBC RA provides a generic driver-wrapper that emulates the XADataSource
interface on a regular JDBC driver. It is important to note that this driver-wrapper does not ensure a
real two-phase commit for distributed database transactions.
The generic JDBC RAs of JOnAS provide implementations of the DriverManager, DataSource,
PooledConnection, and XAConnection interfaces. These can be configured using a JDBC-compliant
driver for some relational database management server products, such as Oracle, PostgreSQL, or
MySQL.
The remainder of this section, which describes how to define and configure JDBC RAs, is
specific to
JOnAS . However, the way to use these JDBC RAs in the Application Component methods is standard;
that is, via the resource manager connection factory references (refer to the example in Section 8.6
Writing Database Access Operations (Bean-Managed Persistence) in Chapter 8 Developing Entity
Beans ).
An RAR file must be configured and deployed (for example,
Oracle1.rar
for an Oracle RAR and
MySQL1.rar
for a MySQL RAR, as delivered with the platform).
To define a Resource “Oracle1” in the
jonas.properties
file, add its name “Oracle1” (name of
the RAR file) to the line
jonas.service.resource.services
or just include it in the autoload
directory. For more information about deploying an RAR, refer to Chapter 41 Configuring Resource
Adapters .
jonas.service.resource.services Oracle1,MySQL1,PostgreSQL1
The
jonas-ra.xml
file that defines a DataSource should contain the following information:
jndiname JNDI name of the RAR
URL The JDBC database URL: jdbc:
database_vendor_subprotocol
:...
dsClass Name of the class implementing the JDBC driver
user Database user name