The main way to interact with a running simulation is TraCI which gives the complete flexibility of doing cross-platform, cross-language, and networked interaction with sumo acting as a server. One major drawback is the communication overhead due to the protocol and the socket communication. To have a more efficient coupling without the need for socket communication, the TraCI API is provided as a C++ library with the following properties:

  • C++ interface based on static functions and a few simple wrapper classes for results which can be linked directly to the client code
  • Function signatures similar to TraCI
  • Pre-built language bindings for Java and Python (using SWIG)
  • Support for other programming languages via SWIG


The following things currently do not work (or work differently than with the TraCI Python client):

  • running with sumo-gui does not work on Windows and is still highly experimental on other platforms
  • subscriptions that require additional arguments (except for vehicle.getLeader)
  • stricter type checking
    • the TraCI client sometimes accepts any iterable object where Libsumo wants a list
    • TraCI client may accept any object where Libsumo needs a boolean value
    • TraCI automatically converts every parameter into a string if a string is needed, Libsumo does not
  • using traci.init or traci.connect is not possible (you always need to use traci.start / libsumo.start)
  • with traci every TraCIException will generate a message on stderr, Libsumo does not generate this message
  • libsumo by itself cannot be used to connect multiple clients to the simulation (though connecting normal TraCI clients to a libsumo instance is possible)
  • running parallel instances of libsumo requires the multiprocessing module (in python)

Building it#

It currently requires cmake and swig being installed together with the developer packages for Python (and Java if needed), for Windows see Windows CMake. You need to (re-)compile sumo yourself under Windows following the remarks above, under Linux see Installing/Linux_Build (it is probably just a matter of calling cmake and make again if you previously did a build without swig). For the python bindings you will get a and a (or .pyd on Windows). If you place them somewhere on your python path you should be able to use them as described below.


Make sure to add "/your/path/to/sumo/tools" to the PYTHONPATH environment variable.

Using libsumo#

If you want to use the (experimental) GUI then you need to have sumo-gui in your start command instead of sumo or define the environment variable LIBSUMO_GUI.


import libsumo
libsumo.start(["sumo", "-c", "test.sumocfg"])

Existing traci scripts can be reused (subject to the limitations mentioned above) by calling

import libsumo as traci

In case you have a lot of scripts you can also set the environment variable LIBSUMO_AS_TRACI to a non empty value which will trigger the import as above.


Please note the extra #define for enabling GUI code which is not needed if you do not or cannot use the GUI (Windows).

Example Code (test.cpp)#

#include <iostream>
#define HAVE_LIBSUMOGUI  // if you are on Windows or have libsumo compiled yourself without GUI you should remove this line
#include <libsumo/libsumo.h>

using namespace libsumo;

int main(int argc, char* argv[]) {
    Simulation::start({"sumo", "-c", "test.sumocfg"});
    for (int i = 0; i < 5; i++) {

compiling on Linux (make sure SUMO_HOME is set and sumo has been built)#

g++ -o test -std=c++11 -I$SUMO_HOME/src test.cpp -L$SUMO_HOME/bin -lsumocpp

running on Linux#



You might want to use the available Maven package.

Example Code (

import org.eclipse.sumo.libsumo.Simulation;
import org.eclipse.sumo.libsumo.StringVector;

public class Test {
    public static void main(String[] args) {
        Simulation.start(new StringVector(new String[] {"sumo", "-c", "test.sumocfg"}));
        for (int i = 0; i < 5; i++) {

compiling on Linux (make sure SUMO_HOME is set and sumo has been built)#

javac -cp $SUMO_HOME/bin/libsumo-1.8.0-SNAPSHOT.jar

running on Linux#

java -Djava.library.path=$SUMO_HOME/bin -cp $SUMO_HOME/bin/libsumo-1.8.0-SNAPSHOT.jar:. Test