Installing Oracle XE, ORDS and Apex on CentOS - Part Two: Installation

This is part two in a series of blog posts about how to install Oracle 11g Express Edition (XE) with Oracle Application Express (Apex) on a CentOS Linux server, with Apex served by Oracle REST Data Services (ORDS) running on top of Tomcat and Apache.

Let's get right to it, starting with Oracle XE.

Installing Oracle XE

This is actually quite straightforward, assuming you have followed the prerequisite steps in part one.



As part of the installation, we created a user called oracle. It is useful to set up the default environment of this user to include the path to the sqlplus executable, so we can start sqlplus from anywhere.



Now, let's log in to Oracle as SYS and check that everything looks OK:



At this point you have an Oracle XE instance running, which also includes Apex 4.0 and the Embedded PL/SQL Gateway (EPG) running on port 8080. That is nice, but it's an old Apex version and the EPG web server is not really suited for heavy usage. We want the latest Apex version, and we want to use ORDS. Read on...

Installing Java

ORDS and Tomcat are both Java applications, so we need to install Java. Actually, we need the Java JDK (Java Development Kit), as opposed to just the Java JRE (Java Runtime Environment). There may already be something called the OpenJDK on the CentOS server, but we want the Oracle-supplied JDK, so let's remove OpenJDK and install the JDK that we downloaded from Oracle:

To have the Java binaries available from anywhere, we add the Java path to the bash profile of the root user:

Installing Tomcat

To install Tomcat, we will download the installation file directly to the server using the wget command, and then unzip it. Create a tomcat user to run the tomcat process.

To avoid conflicts with Oracle XE running the Embedded PL/SQL Gateway on port 8080, change Tomcat's default port number to 8090 by editing the server.xml file. (Note: Because we will put Apache in front of Tomcat, we won't ever access Tomcat directly on port 8090, and we will soon disable EPG, but let's just avoid possible conflicts anyway by assigning different ports.) It's also important to set the URIEncoding to UTF-8.

Next we need to create a script that can be used to start, stop and restart Tomcat as a service. Save the following as tomcat under /etc/init.d/


Then we need to set up the above script to run automatically if the server is rebooted.

Installing ORDS

The Oracle Rest Data Services (ORDS) installation consists of unzipping the installation file, running the configuration to specify database details, and then copying the ords.war file into the Tomcat webapps folder.

Installing Apache

The last step in completing our web stack is to install the Apache HTTP server and place it "in front of" Tomcat. This means that all requests to the server go to Apache first. Requests for static files (images, Javascript and CSS) is served directly by Apache. Requests for dynamic content (ie the actual HTML pages generated by Apex via ORDS) is served by Tomcat, using Apache as a proxy.

Installing Apache is very straightforward:

Then we need to add our custom configuration. By default, Apache is set up to read any .conf file placed in the /conf.d/ subfolder, so let's create an apex.conf file there. Note that these additional config files are read and processed in alphabetical order, so name your custom config accordingly if you use multiple config files.

Installing (upgrading to) latest Apex version

Finally, we need to upgrade the Apex installation that came bundled with Oracle XE to the latest and greatest Apex version (version 5.0 at the time of writing).

This is done by unzipping the Apex installation file, then running the Apex installation script via sqlplus. There are two different Apex installations to choose from: Either a full installation that includes the Application Builder (suitable for a development environment), and a more lightweight and secure "runtime-only" installation (suitable for test and production environments). Running the full installation on the standard 1GB server at DigitalOcean should take about 12-15 minutes.


We also need to make sure the apex_public_user schema is unlocked (and stays that way!).

We need to copy all the static Apex files (images, CSS, Javascript) to the Apache web folder.

When running on top of ORDS, Apex 5 uses the "RESTful Service" feature to serve any application-specific or workspace-specific static files, so we need to configure Apex with REST:

Now (finally!), if everything works, we should be able to access the new Apex installation by going to the following URL:

  http://servername/ords/apex

If everything works, you should see this familiar page:

Did it work? Great, now enjoy Apex 5! But wait, we are not fully done yet! In the next part of this series, I will describe various additional configuration that you should perform for a more secure and scalable server.

Stay tuned!