Databases Reference
In-Depth Information
How It Works
The Oracle XML DB HTTP server contains the embedded PL/SQL gateway, which is installed together
with a standard Oracle database installation. The embedded PL/SQL gateway runs in the Oracle XML DB
HTTP server. This is illustrated in Figure 1-1.
Figure 1-1.
Using Oracle XML DB HTTP as your web server
This deployment is a two-tier model and is easy to setup. The APEX engine and embedded PL/SQL
gateway exist in the same database. Do note that a two-tier deployment may not be desirable in some
cases, especially from the perspective of security. For example, if you are planning to expose your APEX
applications to the Internet, this deployment model may not be desirable because the HTTP listener
can't be separated from the database, so you would be exposing the database directly to the Internet as
well.
Another disadvantage that arises from the tight coupling between the web server and the database is
that in the event of database downtime, your web server will be down as well; this will prevent access to
static data such as static web pages or images.
An embedded PL/SQL gateway also does not provide mid-tier load balancing or failover features. To
scale your systems, you will need to depend on Oracle Real Application Clusters (RAC) technology at the
database level. For these reasons, the embedded PL/SQL gateway is suited more for smaller
deployments or standalone systems.
Note
The Oracle XML DB HTTP Server with embedded PL/SQL gateway is not supported prior to Oracle
Database Version 11
g
.
The Oracle HTTP Server and mod_plsql approach is essential for enterprise deployments due to the
more extensive set of configuration and log settings available to the administrator as well as from a
security standpoint. The Oracle HTTP Server runs on Apache and uses the
mod_plsql
plug-in to
communicate with the APEX engine. The
mod_plsql
plug-in maps HTTP requests to stored procedures in
the Oracle database over a Net8/SQL*Net connection. Figure 1-2 illustrates the Oracle HTTP server
deployment in detail.
