Tools for interacting with Informix

In the settings file you will see ODBC connection strings whose first arguments are "informix". This referes to the ODBC configurations described below for Unix systems.

/etc/odbcinst.ini

[Informix]
Driver = /opt/ibm/informix/lib/cli/libifcli.so
APILevel=1
ConnectFunctions=YYY
DriverODBCVer=03.51
FileUsage=0
SQLLevel=1
smProcessPerConnect=Y

/etc/odbc.ini

[INFORMIX-PYTHON]
Driver = Informix
Server = servername
Port = 0000
User = xxx
Password = xxx
Database = databasename

/opt/ibm/informix/etc/sqlhosts

For the value of "Server" above, you must include that name in the sqlhosts file like so:

#INFSERVER    COMPROT         HOSTNAME        PORTNAME
servername        onsoctcp        hostname          informix

The /etc/services entry for informix should look like this:

informix    18001/tcp           # informix

Connecting via ODBC

import pyodbc
cnxn = pyodbc.connect("DSN=MSSQL-PYTHON;UID=xxxx;PWD=xxxx")

cursor = cnxn.cursor()
# show tables
result     = connection.execute("exec sp_tables")

row = result.fetchone()
print row

Client configuration on Informix server

In the past, using a client-server architecture with IBM Informix database software required adding an entry on the database server with the client details, either in a .rhosts file in a specific user directory or the/etc/hosts.equiv file. If one of these was not present the client would receive an -956 error when attempting to connect to the server:

listener-thread: err = -956: oserr = 0: errstr = client@clientmachine.company.com[clientmachine.company.com]: Client host or user client@clientmachine.company.com[clientmachine.company.com] is not trusted by the server.

While .rhosts or /etc/hosts.equiv worked, it was often inconvenient to place a .rhosts file in the home directory of each user that needed to connect, and root prilivleges are usually required to add or edit a hosts.equiv in the /etc directory.

Starting in IBM Informix 11.70 and higher, IBM addressed this issue with a special configuration parameter that can be placed in $INFORMXIDIR/etc and is owned by the database server user (informix in most cases). The parameter is specified by REMOTE_SERVER_CFG in the onconfig file for an instance:

REMOTE_SERVER_CFG trusted_clients.file

The file can have any name you wish as long as it exists.

The format of the file is the same as hosts.equiv with a client hostname and user ID separated by white space:

clientmachine.company.com  client

clientmachine.company.com  other_user

The benefits of this mechanism are both the database administrator (DBA) having the ability to add and edit trusted client users without involving a system administrator, and the ability of the DBA to add the trusted user configuration file on the fly with onmode -wm:

onmode -wm REMOTE_SERVER_CFG=trusted_clients.file

Once executed, the above command will take immediate effect until the database server is stopped. To write the configuration parameter to the onconfig file permanently, use onmode -wf:

onmode -wf REMOTE_SERVER_CFG=trusted_clients.file