There are currently seven plugins included with msession.

#
# Standard Plugins
#
flexplug.cpp
The flex plugin is a generic personality module. It provides
a mechanism for personality plugin features to be handled by
function-only plugins. By naming and registering pre-defined 
functions, a function-only plugin makes its services available
to the personality module. The flex plugin is loaded by default
when no other personality is loaded. An error will be output
if the it is not found.

#
# Example plugins
#
plugin.cpp
This is an example plugin which shows all the features of
a personality plugin, and may be used as the basis for a new
personality plugin.

fnplug.cpp
This is an example of the function only plugin. It provides
an escape function for the flex plugin and a user callable 
function testable from the msession-test.php script in the
examples directory.

#
# Save/Restore Plugns
#
fileplug.cpp
This is a file-based finction-only plugin that implements
serialize and restore functionality for the flex plugin.
You will need to use the "-S" option on the command line
to specify a file path for the msession data file.

sqlplug.cpp:
This is a SQL function-only plugin that implements serialize 
and restore functionality.  You will need to have either 
PostgreSQL and/or ODBC installed to build this plugin, and 
be familiar with how to build code which links to either as it is 
not always the same on all systems.  You will also need to 
set the options correctly in phoenix.

psessplug.cpp
This is a SQL function-only plugin that implements serialize 
and persistent session functionality. The build notes for 
sqlplug.cpp also apply.

#
# Utility Plugins
#
protplug.cpp
The protection plugin disables listing all sessions and
listing all session with a particular variable. It allows
listing all sessions which have a variable and a value. This
plugin is intended to protect sites with more than one domain
and more than one user from accidentally finding and manipulating
sessions which don't belong to them.

execplug.cpp
The execute plugin allows an msession server to execute an
OS level program and return its stdout as text data. An
API number was assigned to this function, but the code
was implemented as a plugin for security. If you are 
paranoid that someone can take control of your system
you need not load the plugin.
