OpenSim allows you to simulate an OpenWSN network without physical devices.

How it works

A simulated network behaves exactly like a network with real hardware. You can interact with the OpenVisualizer, communicate with your nodes from the Internet. The difference is that each node is emulated on your computer, rather than being real hardware.

OpenSim does so by compiling the mote code as a Python extension module, and creating an instance of the resulting class for each emulated mote. When the simulation is running, these emulate motes communicate with the rest of the OpenVisualizer architecture (see Architecture) over the eventBus.

As illustrated in the diagram below, the emulated motes interact with the eventBus the exact say way a moteProbe instance (connected to a hardware mote) does.

The OpenVisualizer is not aware it is talking with emulated motes, and from a networking point of view, interacting with the emulated motes is exactly the same as interacting with real motes.

Preparing for a simulation

Directory organization

The OpenSim environment combines elements from the following repositories:

• https://github.com/openwsn-berkeley/openwsn-fw
• https://github.com/openwsn-berkeley/openwsn-sw

The OpenSim environment assumes that you have cloned them at the same level. That is, you need to have the openwsn-sw/ and openwsn-fw/ directories side-by-side on your computer.

Installation requirements

• You need to be able to run the OpenVisualizer, so make sure installed the elements necessary for the OpenVisualizer to run.
• Your computer needs to have gcc installed to be able to compile the firmware as a Python extension module. On Linux, that should be the case by default. On Windows, we recommend http://www.mingw.org/.

Compiling firmware

Before you can run a simulation, you need to compile the OpenWSN firmware as a Python extension module. For that, navigate to the openwsn-fw/ directory, and enter the following command:

scons board=python toolchain=gcc oos_openwsn

You can see an example output of this command on the OpenWSN builders:

• on Travis-ci (Linux environment) at https://travis-ci.org/openwsn-berkeley/openwsn-fw

This command creates the following Python extension module.

openwsn-fw/firmware/openos/projects/common/oos_openwsn.pyd

The OpenSim infrastructure automatically adjusts its path to find this extension module, no need to move this file.

Running a simulation

Running a simulation is exactly like running the OpenVisualizer, but specifying that this is a simulation.

As with the OpenVisualizer, there are several options, listed below

using the graphical user interface

In order to easily run a simulated network based on the code, you can use the OpenSim integration provided by OpenVisualizer; so, in your ./openwsn-sw/ folder:

python openVisualizerGui.py --sim True -n <NumEmulatedMotes>

runs a session of OpenVisualizer in Simulator mode with a network of <NumEmulatedMotes> simulated motes.