Using NEST with MUSIC¶

Introduction¶

NEST supports the MUSIC interface, a standard by the INCF, which allows the transmission of data between applications at runtime [1]. It can be used to couple NEST with other simulators, with applications for stimulus generation and data analysis and visualization and with custom applications that also use the MUSIC interface.

Basically, all communication with MUSIC is mediated via proxies that receive/send data from/to remote applications using MUSIC. Different proxies are used for the different types of data. At the moment, NEST supports sending and receiving spike events and receiving continuous data and string messages.

You can find the installation instructions for MUSIC on their Github Page: INCF/MUSIC

Reference¶

Sending and receiving spike events¶

A minimal example for the exchange of spikes between two independent instances of NEST is given in the example examples/nest/music/minimalmusicsetup.music.

It sends spikes using the music_event_out_proxy script and receives the spikes using a music_event_in_proxy.

stoptime=0.01

[from]
  binary=./minimalmusicsetup_sendnest.py
  np=1

[to]
  binary=./minimalmusicsetup_receivenest.py
  np=1

from.spikes_out -> to.spikes_in [1]

This configuration file sets up two applications, from and to, which are both instances of NEST. The first runs a script to send spike events on the MUSIC port spikes_out to the second, which receives the events on the port spikes_in. The width of the port is 1.

The content of minimalmusicsetup_sendnest.py is contained in the following listing.

First, we import nest and set up a check to ensure MUSIC is installed before continuing.

import nest

if not nest.ll_api.sli_func("statusdict/have_music ::"):
    import sys

    print("NEST was not compiled with support for MUSIC, not running.")
    sys.exit()

nest.set_verbosity("M_ERROR")

Next we create a spike_generator and set the spike times. We then create our neuron model (iaf_psc_alpha) and connect the neuron with the spike generator.

sg = nest.Create('spike_generator')
nest.SetStatus(sg, {'spike_times': [1.0, 1.5, 2.0]})

n = nest.Create('iaf_psc_alpha')

nest.Connect(sg, n, 'one_to_one', {'weight': 750.0, 'delay': 1.0})

We then create a voltmeter, which will measure the membrane potential, and connect it with the neuron.

vm = nest.Create('voltmeter')
nest.SetStatus(vm, {'record_to': 'screen'})

nest.Connect(vm, n)

Finally, we create a music_event_out_proxy, which forwards the spikes it receives directly to the MUSIC event output port spikes_out. The spike generator is connected to the music_event_out_proxy on channel 0 and the network is simulated for 10 milliseconds.

meop = nest.Create('music_event_out_proxy')
nest.SetStatus(meop, {'port_name': 'spikes_out'})

nest.Connect(sg, meop, 'one_to_one', {'music_channel': 0})

nest.Simulate(10)

The next listing contains the content of minimalmusicsetup_receivenest.py, which is set up similarly to the above script, but without the spike generator.

import nest

if not nest.ll_api.sli_func("statusdict/have_music ::"):
    import sys

    print("NEST was not compiled with support for MUSIC, not running.")
    sys.exit()

nest.set_verbosity("M_ERROR")

meip = nest.Create('music_event_in_proxy')
nest.SetStatus(meip, {'port_name': 'spikes_in', 'music_channel': 0})

n = nest.Create('iaf_psc_alpha')

nest.Connect(meip, n, 'one_to_one', {'weight': 750.0})

vm = nest.Create('voltmeter')
nest.SetStatus(vm, {'record_to': 'screen'})

nest.Connect(vm, n)

nest.Simulate(10)

Running the example using mpirun -np 2 music minimalmusicsetup.music yields the following output, which shows that the neurons in both processes receive the same input from the spike_generator in the first NEST process and show the same membrane potential trace.

     1       -70
     2       -70
     3       -68.1559
     4       -61.9174
     5       -70
     6       -70
     7       -70
     8       -65.2054
     9       -62.1583

     1       -70
     2       -70
     3       -68.1559
     4       -61.9174
     5       -70
     6       -70
     7       -70
     8       -65.2054
     9       -62.1583

Receiving string messages¶

Currently, NEST is only able to receive messages, and unable to send string messages. We thus use MUSIC’s messagesource program for the generation of messages in the following example. The configuration file (msgtest.music) is shown below

stoptime=1.0
np=1
[from]
  binary=messagesource
  args=messages
[to]
  binary=./msgtest.py

from.out -> to.msgdata [0]

This configuration file connects MUSIC’s messagesource program to the port msgdata of a NEST instance. The messagesource program needs a data file, which contains the messages and the corresponding time stamps. For this example, we use the data file, messages0.dat:

0.3     Hello
0.7     !

Note

In MUSIC, the default unit for time is seconds for the specification of times, while NEST uses miliseconds.

The script that sets up the receiving side (msgtest.py) of the example is shown in the following script.

We first import NEST and create an instance of the music_message_in_proxy. We then set the name of the port it listens on to msgdata. The network is simulated in steps of 10 ms.

#!/usr/bin/python3

import nest

mmip = nest.Create ('music_message_in_proxy')
nest.SetStatus (mmip, {'port_name' : 'msgdata'})

# Simulate and get message data with a granularity of 10 ms:
time = 0
while time < 1000:
    nest.Simulate (10)
    data = nest.GetStatus(mmip, 'data')
    print data
    time += 10

We then run the example using

mpirun -np 2 music msgtest.music

which yields the following output:

Nov 23 11:18:23 music_message_in_proxy::pre_run_hook() [Info]:
        Mapping MUSIC input port 'msgdata' with width=0 and acceptable latency=0
        ms.

Nov 23 11:18:23 NodeManager::prepare_nodes [Info]:
        Preparing 1 node for simulation.

Nov 23 11:18:23 MUSICManager::enter_runtime [Info]:
        Entering MUSIC runtime with tick = 0.1 ms

Nov 23 11:18:23 SimulationManager::start_updating_ [Info]:
        Number of local nodes: 1
        Simulation time (ms): 10
        Number of OpenMP threads: 1
        Number of MPI processes: 1

Nov 23 11:18:23 SimulationManager::run [Info]:
        Simulation finished.
({'messages_times': array([], dtype=float64), 'messages': ()},)

Nov 23 11:18:23 NodeManager::prepare_nodes [Info]:
        Preparing 1 node for simulation.

Nov 23 11:18:23 SimulationManager::start_updating_ [Info]:
        Number of local nodes: 1
        Simulation time (ms): 10
        Number of OpenMP threads: 1
        Number of MPI processes: 1

Nov 23 11:18:23 SimulationManager::run [Info]:
        Simulation finished.
({'messages_times': array([], dtype=float64), 'messages': ()},)

.
.

Nov 23 11:18:23 NodeManager::prepare_nodes [Info]:
        Preparing 1 node for simulation.

Nov 23 11:18:23 SimulationManager::start_updating_ [Info]:
        Number of local nodes: 1
        Simulation time (ms): 10
        Number of OpenMP threads: 1
        Number of MPI processes: 1

Nov 23 11:18:23 SimulationManager::run [Info]:
        Simulation finished.
({'messages_times': array([ 300.,  700.]), 'messages': ('Hello', '!')},)

Receiving continuous data¶

As in the case of string message, NEST currently only supports receiving continuous data, but not sending. This means that we have to use another of MUSIC’s test programs to generate the data for us. This time, we use constsource, which generates a sequence of numbers form 0 to w, where w is the width of the port. The MUSIC configuration file (conttest.music) is shown in the following listing:

stoptime=1.0
[from]
  np=1
  binary=constsource
[to]
  np=1
  binary=./conttest.py

from.contdata -> to.contdata [10]

The receiving side is again implemented using a PyNEST script (conttest.py). We first import the NEST and create an instance of the music_cont_in_proxy. we set the name of the port it listens on to msgdata. We then simulate the network in steps of 10 ms.

#!/usr/bin/python3

import nest

mcip = nest.Create('music_cont_in_proxy')
nest.SetStatus(mcip, {'port_name' : 'cont_in'})

# Simulate and get vector data with a granularity of 10 ms:
time = 0
while time < 1000:
   nest.Simulate (10)
   data = nest.GetStatus (mcip, 'data')
   print data
   time += 10

The example is run using

mpirun -np 2 music conttest.music

which yields the following output:

Nov 23 11:33:26 music_cont_in_proxy::pre_run_hook() [Info]:
        Mapping MUSIC input port 'contdata' with width=10.

Nov 23 11:33:26 NodeManager::prepare_nodes [Info]:
        Preparing 1 node for simulation.

Nov 23 11:33:26 MUSICManager::enter_runtime [Info]:
        Entering MUSIC runtime with tick = 0.1 ms

Nov 23 11:33:28 SimulationManager::start_updating_ [Info]:
        Number of local nodes: 1
        Simulation time (ms): 10
        Number of OpenMP threads: 1
        Number of MPI processes: 1

Nov 23 11:33:28 SimulationManager::run [Info]:
        Simulation finished.
(array([ 0.,  1.,  2.,  3.,  4.,  5.,  6.,  7.,  8.,  9.]),)

.
.

Nov 23 11:33:28 NodeManager::prepare_nodes [Info]:
        Preparing 1 node for simulation.

Nov 23 11:33:28 SimulationManager::start_updating_ [Info]:
        Number of local nodes: 1
        Simulation time (ms): 10
        Number of OpenMP threads: 1
        Number of MPI processes: 1

Nov 23 11:33:28 SimulationManager::run [Info]:
        Simulation finished.
(array([ 0.,  1.,  2.,  3.,  4.,  5.,  6.,  7.,  8.,  9.]),)