WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

352 WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

9.1 JDBC resources

The JDBC API provides a programming interface for data access of relational databases from

the Java programming language. WebSphere Application Server V8.5 supports the following

JDBC APIs:

 JDBC 4.0

 JDBC 3.0

 JDBC 2.1 and Optional Package API (2.0)

In the following sections, we explain how to create and configure data source objects for use

by JDBC applications. This is the only method to connect to a database if you intend to use

connection pooling and distributed transactions.

The following database platforms are supported for JDBC:

 DB2

 Oracle

 Sybase

 IBM Informix®

 SQL Server

 Apache Derby (test and development only)

 Third-party vendor JDBC data source using SQL99 standards

9.1.1 JDBC providers and data sources

A data source represents a real-world source of data, such as a relational database. When a

data source object is registered with a JNDI naming service, an application can retrieve it

from the naming service and use it to make a connection to the associated database.

Information about the data source and how to locate it, such as its name, the server on which

it resides, its port number, and so on, is stored in the form of

properties on the DataSource

object. Storing this information in this manner makes an application more portable because it

does not need to hard code a driver name, which often includes the name of a particular

vendor. It also makes maintaining the code easier because if, for example, the data source is

moved to a different server, all that needs to be done is to update the relevant property in the

data source. None of the code using that data source needs to be touched.

To increase application performance and reduce workload on the database, connections to it

are typical pooled. In other words, when the application closes the connection, the connection

is returned to a connection pool, rather than being destroyed.

Data source

classes and JDBC drivers are implemented by the data source vendor. By

configuring a JDBC provider, you provide information about the set of classes that are used to

implement the data source and the database driver. Also, you provide the environment

settings for the DataSource object. A driver can be written purely in the Java programming

language or in a mixture of the Java programming language and the Java Native Interface

(JNI) native methods.

In the next sections, we describe how to create and configure data source objects and how to

configure the connection pools used to serve connections from the data source.

Chapter 9. Accessing relational databases from WebSphere 353

9.1.2 WebSphere support for data sources

The programming model for accessing a data source is:

1. An application retrieves a DataSource object from the JNDI naming space.

2. After the DataSource object is obtained, the application code calls the getConnection()

method on the data source to get a Connection object. The connection is obtained from a

pool of connections.

3. After the connection is acquired, the application sends SQL queries or updates to the

database.

In addition to the data source support for Java EE6, Java EE 5, J2EE 1.4, and J2EE 1.3

applications, support is also provided for J2EE 1.2 data sources. The two types of support

differ in how connections are handled. However, from an application point of view, they look

the same.

Data source support

The primary data source support is intended for J2EE 1.3 and J2EE 1.4 and Java EE 5 and

Java EE6 applications. Connection pooling is provided by two components: a JCA

Connection Manager and a relational resource adapter. See Figure 9-1.

Figure 9-1 Resource adapter in J2EE connector architecture

The JCA Connection Manager provides connection pooling, local transactions, and security

support.

Note: The @Resource annotation can be used to declare a reference to a datasource.The

container injects the data source referred to by @Resource into the component either at

runtime or when the component is initialized, depending on whether field/method injection

or class injection is used.

Application Server

Resource

Adapter

DB Connection

Pool

JCA

Connection

Manager

Datasource

Connection

Factory

Delegate

Application

JDBC Driver

DB Server

Connections