Databases Reference
In-Depth Information
Figure 1-2.
Using the Embedded PL/SQL Gateway
This diagram often has DBAs raising their hands in shock and horror. However, there are examples
where this simplified architecture is desirable, which I'll cover later in the chapter.
The Oracle HTTP Server (OHS)
The Oracle HTTP Server has been around for quite some time. In fact, I looked around to see if I could
find the first references to it but couldn't find a definitive date for its first release, although I did find
references to it in the Oracle Database 8.1.7 release and the Oracle iAS (Oracle Internet Application
Server) software. So one way of looking at the OHS is that it's a very tried and tested configuration. Of
course ,the other way of looking at it is that it's pretty old (are you a glass half full or half empty person?).
So what is the Oracle HTTP Server? Simply put, it's a web server that is based on the Apache HTTP
Server, which has been modified, tweaked, and optimized to connect to the Oracle Database via a
custom Apache Module (a plug-in) called
mod plsql
. It is this
mod plsql
module that enables a web
browser to directly access the data and code in the database.
When the OHS was first released, it was based on Apache version 1.3 and only relatively recently
have versions based on Apache version 2.0 been made available. The Apache release history is very
complex and full of intricacies, so it's not as simple as saying “Ah, version 2.0
must
be better than version
1.3”, you should think of version 1.3 and 2.0 as branches of the code and not that version 2.0 is
necessarily better than 1.3.
So, in summary, the OHS based on Apache 1.3 has been out a very long time and has been used in a
large number of situations and has proved to be a very stable web server (when configured correctly!).
The OHS based on Apache 2.0 is a much more recent release, but does offer some advantages over
version 1.3.
From my own personal experience, I have found the OHS based on Apache 1.3 very stable and have
used it many (many!) times; however, since using the OHS based on Apache 2.0, my preferred option is
now to use the 2.0 release over the 1.3 release (for reasons which I'll explain later).
Installing the OHS
I'll make no apologies for it, but I'm a Unix guy. I used Windows many (
many!)
years ago, but these days
I predominantly use Mac and Linux (or other Unixes), so when it comes to configuring our databases
and web servers we typically use Linux (Oracle Enterprise Linux) or Solaris. So in this section I'll cover
installing and configuring via Linux. The installation for Windows will obviously be different but is well
documented. The configuration side of things is very similar on any platform since it is done via the
Apache configuration files.
