7. TAS and ODBC
7.1 Solaris
Tango for Solaris includes the Merant ODBC driver pack, which Tango can use to connect to a wide array of databases, such as Informix, Sybase, Oracle, and now Microsoft SQL Server.
The .odbc.ini file (see below) should be located in the home directory of the Tango user account. It can be stored elsewhere, for centralization or what not, and located using an environment variable called ODBCINI.
7.2 Linux
Tango 2000 for Linux includes the iODBC driver manager, and a Pervasive.SQL driver is included with Pervasive.SQL for Linux. It will also work with Postgres SQL and MySQL drivers. Other drivers are available at http://www.unixodbc.com and http://www.iodbc.org
The .odbc.ini file (see below) should be located in /usr/local/tango/etc/odbc.ini which can be symlinked to /usr/local/psql/etc/odbc.ini if both are installed.
7.3 The odbc.ini Configuration File
The drivers are controlled by an ini file called .odbc.ini (note the leading period; it's a hidden file on Solaris.)
The file contains a list of Data Source Names followed by a definition section. It is a standard INI file format. So long as the DSN name used by a TAF is listed in this file, and the database schema is the same as the one on the development machine, the database access will work transparently.
Here is an example of a .odbc.ini file containing a single DSN called MyOracleDatabase, which is pointing to an Oracle database with a TNS name of 'LocalOracleDatabase'.
[ODBC Data Sources] MyOracleDatabase=
[MyOracleDatabase] Driver=/opt/PVSWtango/odbc/lib/VQor815.so ServerName=LocalOracleDatabase
All entries will have, at minimum, a Driver line; this points to a .so shared object which is the actual ODBC driver. There will be other lines dependant on the driver itself; server configuration, special flags, that sort of thing. Refer to the readmes and to the odbchelp.pdf file (on Solaris) or to specific driver documentation for those settings, as well as any environment settings required.
Note that ODBC drivers still often require database specific Client software; for example, the ODBC Oracle drivers require the same Oracle OCI client software that Tango requires for a native Oracle connection. Sybase client software must be installed for the Sybase ODBC driver to function, and so on. Again, see the odbchelp.pdf file, or driver documentation for specifics.
Anybody who would like to write small crib notes on configuring specific databases to work with Tango for Solaris or Linux through ODBC, feel free and send them to me and they'll be included in this HOWTO, with full credit of course.
7.4 Solaris, ODBC and Oracle
Certain versions of the Oracle client are missing key functionality that the Oracle ODBC drivers require, as well as the Tango native Oracle drivers.
The easiest way to check for this condition is to use the 'ivtestlib' program to attempt to load the Oracle ODBC driver. Become the Tango user, and move to $TANGO_HOME/lib. Look for a driver with 'or7' for Oracle 7, or 'or8' for Oracle 8. Depending on your version of Tango, the full name might be 'IVor714.so' or 'VQor714.so'. The last number before the .so is the ODBC version.
Once you have this file name, move one directory up, and then go into the 'bin' directory. There, execute the 'ivtestlib' program with the file name as an argument.
$ cd $TANGO_HOME/odbc/lib $ ls *or8* VQor814.so $ cd ../bin $ ./ivtestlib ../lib/VQor814.so Load of ../lib/VQor814.so successful, qehandle is 0xFF24120
If the Oracle drivers need to be patched, you'll see a long message ending in the fact that there is an 'undefined symbol slpmprodstab'. This will prevent Tango Oracle Native connections from working as well as ODBC. In the $TANGO_HOME/odbc/src/oracle directory is a readme.ora file and two scripts, one for Oracle 7 and the other for Oracle 8. The readme file details the creation of a new 'libclntsh.so' file, which is the main Oracle client library. In a nutshell, make sure you have ORACLE_HOME defined, and run the appropriate script for your version of Oracle. This will create the .so file and place it, by default, into $TANGO_HOME/odbc/lib. Then, make sure that that path appears in your LD_LIBRARY_PATH before any references to $ORACLE_HOME/lib does. You can also move the libclntsh.so file to your $ORACLE_HOME/lib directory, or create a link between $ORACLE_HOME/lib/libclntsh.so and the one you just created; the preexisting libclntsh.so is a link to another library anyway.
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