2. Imports

First, import the necessary classes and functions. Note the HydraLib imports. HydraLib provides several functions which make connecting plugins to Hydra easier.

Of particular interest are JsonConnection which does all the hard work of connecting to Hydra and provides functions for making server function calls, namely the call function.

Next are the write_progress and write_output functions. These help Hydra Modeller keep track of what is happening within the plugin as it’s running. The more of these you put in, the more a user will understand what is happening, which will help them if something goes wrong. The outut of the two functions look like this, and are printed to stdout. Hydra Modeller reads from stdout while the plugin is running and displays the output of these two functions:

• write_progress(1, 3) >> ”!!Progres 1/3”
• write_output("Parsing") >> ”!!Output Parsing”

Finally there’s the HydraPluginError. When you want to raise an exception, this is typically the one to raise as it specifically designed to work with these plugins.

#Library for parsing command-line arguments.
import argparse as ap

#Python utility libraries.
from HydraLib.HydraException import HydraPluginError
from HydraLib.PluginLib import JsonConnection,\
                              create_xml_response,\
                              write_progress,\
                              write_output
#General library for working with JSON objects
import json
#Used for working with files.
import os, sys