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Configuring Zato for Python Oracle DB connections

2019-11-06, by Dariusz Suchojad

If you need to configure Zato for Oracle DB connections and you want to ensure the highest performance possible, this is the post which goes through the process step-by-step. Read on for details.

Overview

Note that Zato 3.1+ is required. The tasks involved are:

  • Installing Zato
  • Installing an Oracle client
  • Installing cx_Oracle
  • Greenifying the Oracle client
  • Starting servers
  • Creating database connection definitions
  • Confirming the installation

Installing Zato

  • Choose your preferred operating system and follow the general installation instructions - Oracle DB connections will work the same no matter the system Zato runs on

  • Create a Zato environment with as many servers as required. Again, there are no Oracle-specific steps at this point yet.

Installing an Oracle client

  • Download an Oracle client and install it on all the systems with Zato servers

  • Add the client's installation path to LD_LIBRARY_PATH. For instance, if the client is installed to /opt/zato/instantclient_19_3, add the following to ~/.bashrc:

    export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/zato/instantclient_19_3

Installing cx_Oracle

  • cx_Oracle is a Python driver for Oracle DB, it can be installed using pip, as user zato, on each Linux instance that Zato servers use:

    $ cd /opt/zato/current
$ ./code/bin/pip install cx_Oracle

Greenifying the Oracle client

  • This step is crucial for achieving the highest performance of SQL queries

  • For each Zato server installed, open its server.conf file and find stanza [greenify]

  • If there is no such stanza in server.conf, create it yourself

  • Modify the stanza to greenify the libclntsh.so library - this is a library that the Oracle client ships with. For instance, if the client's installation path is /opt/zato/instantclient_19_3, the full path to the library is /opt/zato/instantclient_19_3/libclntsh.so

  • The stanza should read as below, assuming the installation path as above:

[greenify]
/opt/zato/instantclient_19_3/libclntsh.so=True
  • Note that entries in this stanza are followed by =True, which is a signal to Zato that a particular library should be processed

Starting servers

  • Start Zato servers

  • For each, make sure that an entry such as below is saved in server logs

    INFO - Greenified library `/opt/zato/instantclient_19_3/libclntsh.so.19.1`

Creating database connection definitions

  • Go to web-admin and create a new Oracle DB connection via Connections -> Outgoing -> SQL, as below:

  • Update the newly created connection's password by clicking Change password

  • Click Ping to confirm the connectivity to the remote server

  • This concludes the process, the connection is ready for use in Zato services now

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