Upgrading from mosaik 2 to 3

Mosaik 3 has some new features which required some API changes. For the time being simulators implementing mosaik-api 3 are still supported, but you will get a deprecation warning at the beginning. In case that you don’t want to use any of the new features you could stay with mosaik 2. But otherwise the upgrade to mosaik 3 is quite easy, as you will see in the following sections:

Component’s type

Simulation components now have a type (time-based, event-based, or hybrid) to indicate which simulation time paradigm they implement. See details here. The type is set in the component’s meta data, which the component returns to mosaik via the API’s init function.

Time resolution

A global time resolution is now defined for each scenario indicating how to translate mosaik’s integer time to simulated time. It can be set at the instantiation of the simulation’s World in the setup of the scenario and is set to 1. by default. It’s value is passed to the components via the init function.

Max_advance time

max_advance tells the simulator how far it can advance its time without risking any causality error, i.e. it is guaranteed that no external step will be triggered before max_advance + 1. It is determined for each step and passed to the component as third positional argument of the API’s step function.

Sticking with mosaik 2

In case that you don’t want to upgrade to mosaik 3, the mosaik dependency must be pinned to version 2.x.

When installing mosaik with pip, you get the latest mosaik 2.x version via:

pip install 'mosaik<3'

You can also specify this constraint in a requirements files:


Or in the install_requires list in a setup.py file: