The Recorder application is one of the HELICS apps available with the library Its purpose is to provide a easy way to capture data from a federation It acts as a federate that can “capture” values or messages from specific publications or direct endpoints or cloned endpoints which exist elsewhere

Command line arguments

allowed options:

command line only:
  -? [ --help ]          produce help message
  -v [ --version ]       display a version string
  --config-file arg      specify a configuration file to use

  --local                specify otherwise unspecified endpoints and
                         publications as local( i.e.the keys will be prepended
                         with the player name
  --stop arg             the time to stop the player
  --quiet                turn off most display output

allowed options:

  -b [ --broker ] arg    address of the broker to connect
  -n [ --name ] arg      name of the player federate
  --corename arg         the name of the core to create or find
  -c [ --core ] arg      type of the core to connect to
  --offset arg           the offset of the time steps
  --period arg           the period of the federate
  --timedelta arg        the time delta of the federate
  --rttolerance arg      the time tolerance of the real time mode
  -i [ --coreinit ] arg  the core initialization string
  --separator arg        separator character for local federates
  --inputdelay arg       the input delay on incoming communication of the
  --outputdelay arg      the output delay for outgoing communication of the
  -f [ --flags ] arg     named flag for the federate

allowed options:

  --tags arg             tags to record, this argument may be specified any
                         number of times
  --endpoints arg        endpoints to capture, this argument may be specified
                         multiple time
  --sourceclone arg      existing endpoints to capture generated packets from,
                         this argument may be specified multiple time
  --destclone arg        existing endpoints to capture all packets with the
                         specified endpoint as a destination, this argument may
                         be specified multiple time
  --clone arg            existing endpoints to clone all packets to and from
  --capture arg          capture all the publications of a particular federate
                         capture="fed1;fed2"  supports multiple arguments or a
                         semicolon/comma separated list
  -o [ --output ] arg    the output file for recording the data
  --allow_iteration      allow iteration on values
  --verbose              print all value results to the screen
  --marker arg           print a statement indicating time advancement     every <arg> seconds of the simulation
                         is the period of the marker
  --mapfile arg          write progress to a map file for concurrent progress

also permissible are all arguments allowed for federates and any specific broker specified:

Command line reference

the player executable also takes an untagged argument of a file name for example

helics_recorder record_file.txt --stop 5

Recorders support both delimited text files and json files some examples can be found in

Player configuration examples

config file detail


a simple example of a recorder file specifying some subscriptions

#FederateName topic1

sub pub1
subscription pub2

# signifies a comment

if only a single column is specified it is assumed to be a subscription

for two column rows the second is the identifier arguments with spaces should be enclosed in quotes



s, sub, subscription

subscribe to a particular publication

endpoint, ept, e

generate an endpoint to capture all targeted packets

source, sourceclone,src

capture all messages coming from a particular endpoint

dest, destination, destclone

capture all message going to a particular endpoint


capture all data coming from a particular federate


capture all message going from or to a particular endpoint

for 3 column rows the first must be either clone or capture for clone the second can be either source or destination and the third the endpoint name [for capture it can be either “endpoints” or “subscriptions”] NOTE:not fully working yet for capture

JSON configuration

recorders can also be specified via JSON files

here are two examples of the text format and equivalent JSON

#list publications and endpoints for a recorder

e src1

JSON example

  "subscriptions": [
      "key": "pub1",
      "type": "double"
      "key": "pub2",
      "type": "double"
  "endpoints": [
      "name": "src1",
      "global": true

some configuration can also be done through JSON through elements of “stop”,”local”,”separator”,”timeunits” and file elements can be used to load up additional files


Recorders capture files in a format the Player can read see Player the --verbose option will also print the values to the screen.

Map file output

the recorder can generate a live file that can be used in process to see the progress of the Federation This is occasionally useful, though for many uses the Tracer will be more useful when it is completed