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 4.4.1 release of ApplixWare on Linux. Refer to the Linux Sys Admin on-line book for more detailed information.
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.
At the bottom of axnet.cnf, find the line that starts with
#libFor elfodbc /ax/...
Change line to read
libFor elfodbc applixroot/applix/axdata/axshlib/libwhich will tell elfodbc to look in this directory for the ODBC support library. If you have installed applix somewhere else, change the path accordingly.
Create .odbc.ini as described above. You may also want to add the flag
TextAsLongVarchar=0to the database-specific portion of .odbc.ini so that text fields will not be shown as **BLOB**.
Testing ApplixWare ODBC Connections
Bring up Applix Data
Select the Postgres database of interest.
Select Query->Choose Server.
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).
Select the database in the box that was launched by Browse, then click OK.
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.
The 'Ready' message will appear in the lower left corner of the data window. This indicates that you can now enter queries.
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.
The following messages can appear while trying to make an ODBC connection through Applix Data:
elfodbc can't find libodbc.so. Check your axnet.cnf.
libodbc.so cannot find the driver listed in .odbc.ini. Verify the settings.
The driver process has terminated due to some other problem. You might not have an up-to-date version of the Postgres ODBC package.
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.
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.Author: Contributed by Steve Campbell on 1998-10-20.
One good tool for debugging connection problems uses the Unix system utility strace.
Debugging with strace
Start applixware.
Start an strace on the axnet process. For example, if
ps -aucx | grep axshows
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
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.
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
Copy /opt/applix/axdata/eng/Demos/sqldemo.am to a local directory.
Edit this local copy of sqldemo.am:
Search for 'null_clause = "NULL"
Change this to null_clause = ""
Start Applix Macro Editor.
Open the sqldemo.am file from the Macro Editor.
Select File->Compile and Save.
Exit Macro Editor.
Start Applix Data.
Select *->Run Macro
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).
You should now be able to access the demo tables.
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: ======= ApplixWare must be configured correctly in order for it to be able to access the Postgres ODBC software drivers.
Enabling ApplixWare Database Access
Note that these instructions are for the 4.4.1 release of ApplixWare on Linux. Refer to the Linux Sys Admin on-line book for more detailed information.
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.
At the bottom of axnet.cnf, find the line that starts with
#libFor elfodbc /ax/...
Change line to read
libFor elfodbc applixroot/applix/axdata/axshlib/libwhich will tell elfodbc to look in this directory for the ODBC support library. If you have installed applix somewhere else, change the path accordingly.
Create .odbc.ini as described above. You may also want to add the flag
TextAsLongVarchar=0to the database-specific portion of .odbc.ini so that text fields will not be shown as **BLOB**.
Testing ApplixWare ODBC Connections
Bring up Applix Data
Select the Postgres database of interest.
Select Query->Choose Server.
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).
Select the database in the box that was launched by Browse, then click OK.
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.
The 'Ready' message will appear in the lower left corner of the data window. This indicates that you can now enter queries.
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.
The following messages can appear while trying to make an ODBC connection through Applix Data:
elfodbc can't find libodbc.so. Check your axnet.cnf.
libodbc.so cannot find the driver listed in .odbc.ini. Verify the settings.
The driver process has terminated due to some other problem. You might not have an up-to-date version of the Postgres ODBC package.
One good tool for debugging connection problems uses the Unix system utility strace.
Debugging with strace
Start applixware.
Start an strace on the axnet process. For example, if
ps -aucx | grep axshows
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
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.
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
Copy /opt/applix/axdata/eng/Demos/sqldemo.am to a local directory.
Edit this local copy of sqldemo.am:
Search for 'null_clause = "NULL"
Change this to null_clause = ""
Start Applix Macro Editor.
Open the sqldemo.am file from the Macro Editor.
Select File->Compile and Save.
Exit Macro Editor.
Start Applix Data.
Select *->Run Macro
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).
You should now be able to access the demo tables.
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. |
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.