In order for the 4D for OCI plug-in to function properly, you first need to install the files (libraries) needed to run the Oracle Call Interface (OCI). 
In just a few simple steps, you can download the Oracle Instant Client and install it.
  - Download the appropriate instantclient-basic-[...] package for your platform here: http://www.oracle.com/technetwork/database/features/instant-client/index-097480.html
 Notes: For 4D for OCI, download instantclient-basic-windows.x64-11.1.0.4.0.zip.
- Unzip the packages into a single directory (e.g., C:\oracle\) and rename the subfolder as "instantclient" to get a path such as: C:\oracle\instantclient
- In the environment variables:
  - Add the ORACLE_HOME variable and set it to the path defined in step 2 (e.g.: C:\oracle\instantclient)
- Edit the PATH variable and add this same path at the beginning
 
- Add a "network" subfolder to this path with an "admin" subfolder (e.g.: C:\oracle\instantclient\network\admin)
- In this "admin" subfolder, create a "tnsnames.ora" file with the parameters to your Oracle server. 
 For example:
 
 XE =
 (DESCRIPTION =
 (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.10.10)(PORT = 1521))
 (CONNECT_DATA =
 (SERVER = DEDICATED)
 (SERVICE_NAME = XE)
 )
 )
Here are the steps to install the Oracle Instant Client and make it work with 4D for OCI:
  - Download the appropriate instantclient-basic-[...] package for your platform here: http://www.oracle.com/technetwork/topics/intel-macsoft-096467.html
 Notes: For 4D for OCI, download instantclient-basic-macos.x64-11.2.0.4.0.zip.
- Copy the required Oracle library to the proper location:
  - Copy all the dylib files from instantclient-basic-[…].zip archive to /usr/local/lib (for example). 
 The dylib files can be copied to one of the following paths:
  - $(HOME)/lib
- /usr/local/lib
 
  - Execute the command 'cd /usr/local/lib && sudo ln -sf libclntsh.dylib.11.1 libclntsh.dylib'.
- Execute the command 'chmod 777 /usr/local/lib/libclntsh.dylib'.
 Note: Since 4D for OCI was designed with version 11.2.0.4.0, in order to avoid problems, we link it to “libclntsh.dylib” instead of the versioned file name. Note for El Capitan version: Only the $(HOME)/lib and /usr/local/lib directories are not restricted under El Capitan. 
- Use a text editor to create a “/etc/tnsnames.ora” file and type entries like the example below:
 
 oracle4d =
 (DESCRIPTION =
 (ADDRESS_LIST =
 (ADDRESS = (PROTOCOL =TCP)(HOST = 10.96.0.61)(PORT = 1521))
 )
 (CONNECT_DATA =
 (SERVICE_NAME = oracle4d)
 )
 )
Tip: If you experience connection failure, you may want to use SQLPlus from Oracle. You can download the instantclient-sqlplus-macos.x64-11.2.0.4.0.zip file here: http://www.oracle.com/technetwork/topics/intel-macsoft-096467.html