desmod¶
Full-featured, high-level modeling using SimPy.
The desmod package provides a variety of tools for composing, configuring,
running, monitoring, and analyzing discrete event simulation (DES) models. It
builds on top of the simpy simulation kernel, providing features useful
for building large-scale models which are out-of-scope for simpy itself.
An understanding of SimPy is required to use desmod effectively.
Components¶
The primary building-block for desmod models is the
Component class. Components provide a means for
partitioning the system to be modeled into manageable pieces. Components can
play a structural role by parenting other components; or play a behavioral role
by having processes and connections to other components; or sometimes play both
roles at once.
The desmod.dot.component_to_dot() function may be used to create a
DOT language representation of the component hierarchy and/or the component
connection graph. The resulting DOT representation may be rendered to a variety
of graphical formats using GraphViz tools.
Configuration¶
It is common for models to have configurable paramaters. Desmod provides an
opinionated mechanism for simulation configuration. A single, comprehensive
configuration dictionary captures all configuration for the simulation. The
configuration dictionary is propogated to all Components via the
SimEnvironment.
The various components (or component hierarchies) may maintain separate configuration namespaces within the configuration dictionary by use of keys conforming to the dot-separated naming convention. For example, “mymodel.compA.cfgitem”.
The desmod.config module provides various functionality useful for
managing configuration dictionaries.
Simulation¶
Desmod takes care of the details of running simulations to allow focus on the act of modeling.
Running a simulation is accomplished with either
simulate() or
simulate_factors(), depending whether running a
single simulation or a multi-factor set of simulations. In either case, the key
ingredients are the configuration dict and the model’s top-level
Component. The simulate()
function takes responsibility for taking the simulation through its various
phases:
- Initialization: where the components’ __init__() methods are called.
- Elaboration: where inter-component connections are made and components’ processes are started.
- Simulation: where discrete event simulation occurs.
- Post-simulation: where simulation results are gathered.
# TODO: simulation results
Monitoring¶
# TODO: tracers, probes, logging, etc.