I spent most of yesterday trying to access a remote DB2 instance on a AS/400 eServer iSeries System i system¹⁾.

My first approach was to use the ibm_db2 PECL extension. Should be just a

pecl install ibm_db2

and you're ready to go. Except that this extension needs some libraries and headers from DB2 to compile.

I'll spare you the description of my various tries to find the correct download at IBM's website. The thing that finally worked for me was to download the whole DB2 Express-C database package (408MB).

When you install the whole thing, make sure you choose a “Custom” installation and tick the “Application Development” box. Otherwise you'll not get the needed header files.

After that, you can compile the PECL extension and add it to your php.ini. However it will only run when the correct environment variables are set for your PHP interpreter (eg. by sourcing /home/db2inst/sqllib/db2profile). Alternatively there's a php.ini option to set the path to your DB2 user.

Why this has to be done even when you don't plan to use a local DB2 is beyond me.

Once I had the PHP extension running I tried to connect to the DB2 at the AS/400 machine.

The manual explains that you can either use a “cataloged connection” or provide a full DSN to the DB in question.

As far as I understand, you can cataloge a remote database in your own, local DB2 setup and then connect to this alias. Since I tried to avoid the whole local DB2 stuff as much as possible, I went with the “uncataloged” option of providing a DSN.

Here's is what my final connect call looked like:

<?php
$handle = db2_connect('DATABASE=S123456E;HOSTNAME=192.1.1.55;PORT=446;PROTOCOL=TCPIP;UID=user;PWD=pass',null,null);
if($handle === false){
    die(db2_conn_errormsg());
}

And here is what I got back:

SQL8002N An attempt to connect to a host failed due to a missing DB2 Connect product or invalid license.

Turned out that this connector seems not to be allowed to talk to DB2 installs running on Series i machines .

Back to the drawing board.

ODBC is pretty common on Windows Servers but not so much in the Linux world, so this is why it was my second choice. Turned out it is the far easier and more straight forward way.

First of all you need to install UnixODBC and the PHP ODBC extension. Both should be available in your Linux distribution of choice.

Next you need the correct ODBC drivers from IBM. The package is called iSeries Access²⁾.

It's an rpm download only, so for non-RPM distributions you need to unpack the package yourself and move the files to the correct place:

rpm2cpio iSeriesAccess-6.1.0-1.2.i386.rpm | cpio -idmv
mv opt/ibm /opt/

Next, the installed libraries need to made known to the system:

echo "/opt/ibm/iSeriesAccess/lib/" >> /etc/ld.so.conf
ldconfig

And finally you need to register the driver with the ODBC system:

odbcinst -i -d -f /opt/ibm/iSeriesAccess/unixodbcregistration

That's it. Accessing the DB from within PHP now works like this³⁾:

<?php
$handle = odbc_connect('DRIVER={iSeries Access ODBC Driver};DATABASE=S123456E;SYSTEM=192.1.1.55;HOSTNAME=192.1.1.55;PORT=446;PROTOCOL=TCPIP','user','pass');
if($handle === false){
    die('failed to connect');
}

Of course you could also setup a ODBC instance alias, but I prefer to have my config in the application.

If you need to access a DB2 with PHP (from a Linux system) go with UnixODBC and don't waste your time with the native access.