# Revisiting the Cosimulation Example

Let's take a closer look at the simple co-simulation from earlier.

# Building a federate programmatically

In sender.py, we had h.helicsCreateCombinationFederateFromConfig.

This read the following sender.json:

{
  "coreType": "zmq",
  "loglevel": 7,
  "name": "sender",
  "publications": [
    {
      "global": true,
      "key": "topicA",
      "required": true,
      "type": "double"
    }
  ],
  "timeDelta": 1.0
}

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We can replace the single call to create a federate using these lines:

fedinfo = h.helicsCreateFederateInfo()
h.helicsFederateInfoSetCoreType(fedinfo, h.helics_core_type_zmq)
h.helicsFederateInfoSetCoreInitString(fedinfo, "--loglevel=7")
h.helicsFederateInfoSetTimeProperty(fedinfo, h.helics_property_time_delta, 1.0)

topicA = h.helicsFederateRegisterGlobalPublication(fed, "topicA", h.helics_data_type_double, "")

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Additionally, we can create a Broker in the same process as one of the federates.

initstring = "-f 2 --loglevel=7"
broker = h.helicsCreateBroker("zmq", "", initstring)
assert h.helicsBrokerIsConnected(broker) == True

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We can use the same receiver.py and receiver.json from earlier.

Running it will give us the same output as earlier.

We should not forget to clean up after ourselves. We need to disconnect the broker before calling helicsCloseLibrary

while h.helicsBrokerIsConnected(broker):
    time.sleep(1)

h.helicsBrokerDisconnect(broker)

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You may want to consider using atexit:

import atexit

def f_at_exit():

    h.helicsFederateFinalize(fed)
    h.helicsFederateFree(fed)

    while h.helicsBrokerIsConnected(broker) is True:
        time.sleep(1)

    h.helicsBrokerDisconnect(broker)

    h.helicsCloseLibrary()

atexit.register(f_at_exit)

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