DB2 for Linux on iSeries: Implementation Guide

64 DB2 UDB for Linux on iSeries: Implementation Guide

Figure 3-25 ODBC driver and ODBC driver manager

The ODBC driver manager is a management facility which mediates the

application program and each ODBC driver. The ODBC driver is the RDBMS

dependent module to enable access to each database via ODBC.

On the Windows platform, the ODBC driver manager is provided as part of the

operating system, but on Linux there is no system-provided ODBC driver

manager. Although there are a number of open source or commercial ODBC

driver managers on the Linux platform, the open source unixODBC

(http://www.unixODBC.org/) is the formally supported ODBC driver manager of

DB2 UDB and DB2 Connect on Linux.

The ODBC driver to access DB2 is provided as a part of DB2 UDB or DB2

Connect product. Actually, the CLI library libdb2.so itself can be used as the

ODBC driver for DB2.

3.6.1 ODBC setup

First, we have to setup the ODBC environment, such as the ODBC driver

manager and data sources. SLES8 includes unixODBC-2.2.2-57 package and

unixODBC-devel-2.2.2-57 package. We use the unixODBC-2.2.2-57 as the driver

manager and unixODBC-devel-2.2.2-57 as the development package. The

devel

package is necessary to compile the ODBC application program.

Linux Application

written to ODBC API

ODBC Driver Manager for Linux

(unixODBC)

MySQL

ODBC Driver

PostgreSQL

ODBC Driver

LinuxOS/400

DB2 UDB

for iSeries

DRDA

DB2

ODBC Driver

Chapter 3. Connectivity with DB2 UDB for iSeries 65

The unixODBC usually has some other GUI applications, such as ODBCConfig

(Configuration tool) or Datamanager (Test tool) but they are not included in

SLES8. If you want to use these, you need to download the additional (or the full)

packages and install (or make) them. For unixODBC, refer to the Web site:

http://www.unixodbc.org

In this section, we directly update the ODBC configuration files by a text editor.

ODBC Driver Manager

In the default installation of SLES8, the unixODBC driver manager configuration

file is the text file /etc/unixODBC/odbcinst.ini, which is an empty file. We need

to add the lines for the ODBC driver that comes with DB2. In this section, we

refer to that driver as the DB2 ODBC Driver.

To configure the ODBC driver as the root user, using a text editor, add a new

stanza as illustrated in Figure 3-26.

Figure 3-26 Driver manager configuration

The library file libdb2.so is the DB2 ODBC Driver installed with the DB2

product. Actually it is the file we used as the CLI library in 3.5.2, “Compile and

run” on page 61. The DB2 CLI library also can be used as the DB2 ODBC driver.

We named the driver “DB2DRIVER” which is the name of the stanza. You can

choose any name here, but the name must be used in the datasource

configuration file.

ODBC data sources

The data source configuration file is /etc/unixODBC/odbc.ini, for the system

data sources, and ~/.odbc.ini for the user data sources ( ~ is the user’s home

directory). We use the system data source in our scenario.

To add two databases, AS05 on the OS/400 and SAMPLE on the Linux as the

ODBC system data source, edit the /etc/unixODBC/odbc.ini as the root user.

In our example (Figure 3-27), we add two stanzas: [OS400] for the remote

OS/400 database and [SAMPLE] for the local Linux database. These names must

be the same as the database alias registered in the DB2 database directory. The

driver name DB2DRIVER must be the same as the stanza name in the odbcinst.ini

file in Figure 3-26.

[DB2DRIVER]

Description = DB2 ODBC Driver

Driver = /home/db2inst1/sqllib/lib/libdb2.so

66 DB2 UDB for Linux on iSeries: Implementation Guide

Figure 3-27 System data sources configuration

That is all you need to do for the setup. As illustrated in the above example,

configuration is quite simple because all the connection information is held in the

DB2 node or database directory. You just need a few stanzas created in both the

odbcinst.ini and odbc.ini files for the entry of DB2 Connect databases.

Now you are ready to test the ODBC connection over the DB2 ODBC Driver. You

can use “isql” to test the ODBC connection.

[OS400]

Description = OS/400 Host partition AS05

Driver = DB2DRIVER

[SAMPLE]

Description = DB2 local sample database

Driver = DB2DRIVER