PostgreSQL Programmer's Guide
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# ApplixWare

## Configuration

ApplixWare must be configured correctly in order for it to be able to access the Postgres ODBC software drivers.

Enabling ApplixWare Database Access

These instructions are for the `4.4.2` release of ApplixWare on Linux. Refer to the Linux Sys Admin on-line book for more detailed information.

1. You must modify `axnet.cnf` so that `elfodbc` can find `libodbc.so` (the ODBC driver manager) shared library. This library is included with the ApplixWare distribution, but `axnet.cnf` needs to be modified to point to the correct location.

   As root, edit the file ``applixroot`/applix/axdata/axnet.cnf`.

   1. At the bottom of `axnet.cnf`, find the line that starts with

          #libFor elfodbc /ax/...

   2. Change line to read

          libFor elfodbc applixroot/applix/axdata/axshlib/lib

      which will tell elfodbc to look in this directory for the ODBC support library. Typically Applix is installed in `/opt` so the full path would be `/opt/applix/axdata/axshlib/lib`, but if you have installed Applix somewhere else then change the path accordingly.

2. Create `.odbc.ini` as described above. You may also want to add the flag

       TextAsLongVarchar=0

   to the database-specific portion of `.odbc.ini` so that text fields will not be shown as `**BLOB**`.

Testing ApplixWare ODBC Connections

1. Bring up Applix Data

2. Select the Postgres database of interest.

   1. Select Query->Choose Server.

   2. Select ODBC, and click Browse. The database you configured in `.odbc.ini` should be shown. Make sure that the Host: field is empty (if it is not, axnet will try to contact axnet on another machine to look for the database).

   3. Select the database in the box that was launched by Browse, then click OK.

   4. Enter username and password in the login identification dialog, and click OK.

   You should see "`Starting elfodbc server`" in the lower left corner of the data window. If you get an error dialog box, see the debugging section below.

3. The 'Ready' message will appear in the lower left corner of the data window. This indicates that you can now enter queries.

4. Select a table from Query->Choose tables, and then select Query->Query to access the database. The first 50 or so rows from the table should appear.

## Common Problems

The following messages can appear while trying to make an ODBC connection through Applix Data:

Cannot launch gateway on server

  `elfodbc` can't find `libodbc.so`. Check your `axnet.cnf`.

Error from ODBC Gateway: IM003::[iODBC][Driver Manager]Specified driver could not be loaded

  `libodbc.so` cannot find the driver listed in `.odbc.ini`. Verify the settings.

Server: Broken Pipe

  The driver process has terminated due to some other problem. You might not have an up-to-date version of the Postgres ODBC package.

setuid to 256: failed to launch gateway

  The September release of ApplixWare v4.4.1 (the first release with official ODBC support under Linux) shows problems when usernames exceed eight (8) characters in length. Problem description ontributed by Steve Campbell.

> Author: Contributed by Steve Campbell on 1998-10-20.

The axnet program's security system seems a little suspect. axnet does things on behalf of the user and on a true multiple user system it really should be run with root security (so it can read/write in each user's directory). I would hesitate to recommend this, however, since we have no idea what security holes this creates.

## Debugging ApplixWare ODBC Connections

One good tool for debugging connection problems uses the Unix system utility strace.

Debugging with strace

1. Start applixware.

2. Start an strace on the axnet process. For example, if

       % ps -aucx | grep ax

   shows

       cary   10432  0.0  2.6  1740   392  ?  S  Oct  9  0:00 axnet
       cary   27883  0.9 31.0 12692  4596  ?  S   10:24  0:04 axmain

   Then run

       % strace -f -s 1024 -p 10432

3. Check the strace output.

   > Note from Cary: Many of the error messages from ApplixWare go to `stderr`, but I'm not sure where `stderr` is sent, so strace is the way to find out.

For example, after getting a "`Cannot launch gateway on server`", I ran strace on axnet and got

    [pid 27947] open("/usr/lib/libodbc.so", O_RDONLY) = -1 ENOENT
    (No such file or directory)
    [pid 27947] open("/lib/libodbc.so", O_RDONLY) = -1 ENOENT
    (No such file or directory)
    [pid 27947] write(2, "/usr2/applix/axdata/elfodbc:
    can't load library 'libodbc.so'\n", 61) = -1 EIO (I/O error)

So what is happening is that applix elfodbc is searching for libodbc.so, but it can't find it. That is why axnet.cnf needed to be changed.

## Running the ApplixWare Demo

In order to go through the ApplixWare Data Tutorial, you need to create the sample tables that the Tutorial refers to. The ELF Macro used to create the tables tries to use a NULL condition on many of the database columns, and Postgres does not currently allow this option.

To get around this problem, you can do the following:

Modifying the ApplixWare Demo

1. Copy `/opt/applix/axdata/eng/Demos/sqldemo.am` to a local directory.

2. Edit this local copy of `sqldemo.am`:

   1. Search for 'null_clause = "NULL"

   2. Change this to null_clause = ""

3. Start Applix Macro Editor.

4. Open the sqldemo.am file from the Macro Editor.

5. Select File->Compile and Save.

6. Exit Macro Editor.

7. Start Applix Data.

8. Select *->Run Macro

9. Enter the value "`sqldemo`", then click OK.

   You should see the progress in the status line of the data window (in the lower left corner).

10. You should now be able to access the demo tables.

## Useful Macros

You can add information about your database login and password to the standard Applix startup macro file. This is an example `~/axhome/macros/login.am` file:

    macro login
    set_set_system_var@("sql_username@","tgl")
    set_system_var@("sql_passwd@","no$way")
    endmacro

Caution
You should be careful about the file protections on any file containing username and password information.

## Supported Platforms

psqlODBC has been built and tested on Linux. There have been reports of success with FreeBSD and with Solaris. There are no known restrictions on the basic code for other platforms which already support Postgres.

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