Installed applications use a data source to obtain
connections to a relational database. A data source is analogous to
the Java Platform, Enterprise Edition (Java EE) Connector Architecture (JCA) connection
factory, which provides connectivity to other types of enterprise
information systems (EIS).
A data source is associated with a JDBC provider, which supplies
the driver implementation classes that are required for JDBC connectivity
with your specific vendor database. Application components transact
directly with the data source to obtain connection instances to your
database. The connection pool that corresponds to each data source
provides connection management.
You can create multiple data sources with different settings, and
associate them with the same JDBC provider. For example, you might
use multiple data sources to access different databases within the
same vendor database application. WebSphere® Application
Server requires JDBC providers to implement one or both of the following
data source interfaces, which are defined by Sun Microsystems. These
interfaces enable the application to run in a single-phase or two-phase
transaction protocol.
- ConnectionPoolDataSource - a data source that supports
application participation in local and global transactions, excepting
two-phase commit transactions. When a connection pool data source
is involved in a global transaction, transaction recovery is not provided
by the transaction manager. The application is responsible for providing
the backup recovery process if multiple resource managers are involved.
Note: A
connection pool data source does support two-phase commit transactions
in these cases:
- the data source is making use of Last
participant support. Last participant support enables a single
one-phase commit resource to participate in a global transaction with
one or more two-phase commit resources.
- the JDBC provider is DB2® for z/OS® Local
JDBC provider (RRS).
For more information, consult the article, Using one-phase and
two-phase commit resources in the same transaction.
- XADataSource - a data source that supports application
participation in any single-phase or two-phase transaction environment.
When this data source is involved in a global transaction, the product
transaction manager provides transaction recovery.
Prior to version 5.0 of the application server, the function of
data access was provided by a single connection manager (CM) architecture.
This connection manager architecture remains available to support Java 2 Platform, Enterprise Edition (J2EE) 1.2
applications, but another connection manager architecture is provided,
based on the JCA architecture supporting the J2EE 1.3 application
style, J2EE 1.4 and Java EE
applications.
These architectures are represented by two types of data sources.
To choose the right data source, administrators must understand the
nature of their applications, EJB modules, and enterprise beans.
- Data source (WebSphere Application Server V4) - This
data source runs under the original CM architecture. Applications
using this data source behave as if they were running in Version 4.0.
- Data source - This data source uses the JCA standard architecture
to provide support for J2EE version 1.3 and 1.4, as well as Java EE applications. It runs under the JCA
connection manager and the relational resource adapter.
Choice of data source
- J2EE 1.2 application - all EJB 1.1 enterprise beans, JDBC applications,
or Servlet 2.2 components must use the 4.0 data source.
- J2EE 1.3 (and subsequent releases) application -
- EJB 1.1 module - all EJB 1.x beans must use the 4.0 data
source.
- EJB 2.0 (and subsequent releases) module - enterprise beans that
include container-managed persistence (CMP) Version 1.x, 2.0, and
beyond must use the new data source.
- JDBC applications and Servlet 2.3+ components - must use the new data
source.