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Hadrian-Actors is an application that wraps the Hadrian software library as a PFA multi-processor. It can load many PFA files as a directed acyclic graph of connected scoring engines that pass input and output from one to another. It is configured by a topology file that describes these interconnections and implements the scoring engines as actors with message-passing.

The syntax of the topology file is described here. External PFA files, embedded PFA files, external JAR and shell processes are all supported, as well as Avro and JSON input formats (one JSON document per line).

Before you begin…

Download the pre-built Hadrian-Actors JAR and its dependencies (the hadrian-standalone-jar-with-dependencies would suffice: just put them both on the same classpath). This article was tested with Hadrian 0.8.2; newer versions should work with no modification.

Help document

A good place to start is Hadrian-Actors’s own help text, which will always show the latest options.

Usage: java -jar hadrian-actors.jar [options] topology.json|yaml

  --log log4j.xml
        URL to configure log4j (default is in 'jar -xf hadrian-actors.jar resources/log4j.xml')
  --monitorFreqSeconds 1.0
        number of seconds between monitor INFO messages
  --queueMemoryLimit <value>
        used/max memory above which data will be dropped from queues
        topology description file
        print this help message

Hadrian-Actors builds an actor-based workflow within a single process.
The workflow can be as general as a directed acyclic graph (DAG), can
contain PFA engines (inline or from external files), executable
functions in external JAR files, and executable scripts, provided by a
shell command.  At any stage, results can be saved to a file or named

For details, see the documentation of the topology file.