As you might guess, for

pmnc.the_system.execute(...)

to work, module the_system.py must exist somewhere within the cage. It indeed should be present in modules/the_system.py. The contents of the module is predetermined and you need not to modify it. But to bring the module to existence you must. This is the first thing you do to set up a connection to another external system - copy _static/connection_template.py to modules/the_system.py

Once the module is in place, the reference to its execute method becomes resolvable, but what external system does it refer to ? No way to tell unless you configure it. And this therefore is the second and the last step to create a new connection - edit the config/config_connections.py to include the new connection. Excerpt from config/config_connections.py (see the file for real samples):

from foo_connection import FooConnection

def config_dynamic(config):

	config.set("the_system.connection", FooConnection)
	config.set("the_system.connection.0.first_argument", "aaa")
	config.set("the_system.connection.1.second_argument", "bbb")
	...

	config.set("the_system.timeout", 30.0)
	config.set("the_system.pool_size", 4)

This way you specify the class for the connection adapter, a set of arguments passed to its constructor and the timeout and the pool size.

Once you do this, the connection pool is ready to use.

One other thing to mention is that the configuration file config_connections.py is reloadable (just like all the other configuration files), but what happens if you modify and save the settings for an external system connection ? Upon the next call to execute the change is detected, all the existing connections are disconnected, one is reconnected with the new settings and the execute call proceeds with the new settings. There appears to be a noticeable hiccup when this happens, but no calls are lost or failed in transition.