Configuring and Managing MPE/iX Internet Services (August 2002)

Chapter 9
HP WebWise MPE/iX Secure Web Server
Working with Dynamic Shared Objects (DSOs)
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Working with Dynamic Shared Objects (DSOs)
DSOs are add-on modules that extend the functionality of Apache. These modules are self-contained code that
can provide a wide-range of additional Apache capabilities such as custom authentication and authorization,
custom logging, or creating new configuration directives.
Users can create their own Apache modules or use those written by others. For instance, the Apache Module
Registry (http://modules.apache.org/) is a web site with downloadable Apache modules. Some of these
modules are freely available while others have various license restrictions.
DSOs on MPE/iX can utilize Apache’s full Application Programming Interface (API) as well as Apache’s full
Extended Application Programming Interface (EAPI).
A DSO is an Apache module with the same structure as the modules compiled into the Apache binary. But
instead of being statically linked into the Apache program, the DSO module is created as a shared library
(NMXL). DSOs are loaded at Apache startup into Apache’s process space.
No recompilation of Apache is necessary to use DSOs. However, DSOs require a DSO-enabled Apache. Apache
for MPE/iX is enabled for DSOs starting with Apache 1.3.9 (A.01.00).
Using DSO modules keeps Apache memory usage low by running an Apache binary with core features only
and adding additional features with DSOs. DSOs also provide flexibility. An installation can pick and choose
which features to include in their web server.