The Discrete Event System is used for abstract modeling of action potentials. This functionality is needed for running network simulations. Action potentials generated at the soma of one neuron, are translated to a discrete event, that is delivered at a post-synaptic target of a connected neuron. The DES component borrows ideas from previous research in discrete event simulation.
From a software architecture viewpoint, DES is a separate solver: it simulates action potential propagation in an efficient way. Splitting this functionality from the rest of the simulator, facilitates customization for modeling of sophisticated learning rules, especially related to STDP, diffusion and spillover.
Internally, the discrete event system contains two subcomponents, one component for event distribution that contains a connectivity matrix, a second component for event queuing.
Note: at the time of writing this component is distributed as part of the Heccer package. This is likely to change in the near future.