Robust Data Synchronization with IBM Tivoli Directory Integrator

416 Robust Data Synchronization with IBM Tivoli Directory Integrator

Introduction to JDBC drivers

According to the JDBC specification, there are four types of JDBC driver

architectures:

Type 1 - Drivers that implement the JDBC API as a mapping to another data

access API, such as Open Database Connectivity (ODBC). Drivers of this type

are generally dependent on a native library, which limits their portability. The

JDBC-ODBC Bridge driver is an example of a Type 1 driver.

Type 2 - Drivers that are written partly in the Java programming language and

partly in native code. The drivers use a native client library specific to the data

source to which they connect. Again, because of the native code, their portability

is limited.

Type 3 - Drivers that use a pure Java client and communicate with a middleware

server using a database-independent protocol. The middleware server then

communicates the client's requests to the data source.

Type 4 - Drivers that are pure Java and implement the network protocol for a

specific data source. The client connects directly to the data source.

Database connectivity to Oracle

Based on the JDBC driver architecture the following types of drivers are available

from Oracle.

1. Oracle JDBC Type 1

This is an Oracle ODBC (not JDBC) driver, that you connect to using a

JDBC-ODBC bridge driver. Oracle does supply an ODBC driver, but does not

supply a bridge driver. Instead, you can get one of these JDBC-ODBC bridge

drivers from http://java.sun.com/products/jdbc/drivers.html. This

configuration works fine, but a JDBC Type 2 or Type 4 driver will offer more

features and will be faster.

2. Oracle JDBC Type 2

There are two flavors of the Type 2 driver.

– JDBC OCI client-side driver

This driver uses Java native methods to call entrypoints in an underlying C

library. That C library, called OCI (Oracle Call Interface), interacts with an

Note: We only use Type 4 drivers with Tivoli Directory Integrator, but will

discuss other types as well for a better understanding.

Appendix A. Tricky connections 417

Oracle database. The JDBC OCI driver requires an Oracle client

installation of the same version as the driver. The use of native methods

makes the JDBC OCI driver platform specific. Oracle supports Solaris,

Windows, and many other platforms. This means that the Oracle JDBC

OCI driver is not appropriate for Java applets, because it depends on a C

library. Starting from Version 10.1.0, the JDBC OCI driver is available for

installation with the OCI Instant Client feature, which does not require a

complete Oracle client-installation. Please refer to the Oracle Call

Interface for more information.

– JDBC Server-Side Internal driver

This driver uses Java native methods to call entrypoints in an underlying C

library. That C library is part of the Oracle server process and

communicates directly with the internal SQL engine inside Oracle. The

driver accesses the SQL engine by using internal function calls and thus

avoiding any network traffic. This allows your Java code to run on the

server to access the underlying database in the fastest possible manner. It

can only be used to access the same database.

3. Oracle JDBC Type4

Again, there are two flavors of the Type 4 driver.

– JDBC Thin client-side driver

This driver uses Java to connect directly to Oracle. It implements Oracle's

SQL*Net Net8 and TTC adapters using its own TCP/IP based Java socket

implementation. The JDBC Thin client-side driver does not require Oracle

client software to be installed, but does require the server to be configured

with a TCP/IP listener. Because it is written entirely in Java, this driver is

platform-independent. The JDBC Thin client-side driver can be

downloaded into any browser as part of a Java application. (Note that if

running in a client browser, that browser must allow the applet to open a

Java socket connection back to the server.)

– JDBC Thin server-side driver

This driver uses Java to connect directly to Oracle. This driver is used

internally within the Oracle database. This driver offers the same

functionality as the JDBC Thin client-side driver, but runs inside an Oracle

database and is used to access remote databases. Because it is written

entirely in Java, this driver is platform-independent. There is no difference

in your code between using the Thin driver from a client application or from

inside a server.