Programming with NDIP

Last updated on 2025-07-28 | Edit this page

Overview

Questions

How can I interact with the NDIP platform programmatically from Python?
What is the nova-galaxy library, and how does it simplify NDIP operations?
How do I define an NDIP tool and specify its input parameters using nova-galaxy?
Where can I find information about what NDIP tool to use and parameters to set?

Objectives

Explain the purpose of the Connection, Outputs, Datastore, Tool, and Parameters classes in nova-galaxy.
Describe the basic workflow for running an NDIP tool using nova-galaxy.
Connect to NDIP using the Connection class.
Define an NDIP tool and set its parameters using the Tool and Parameters classes.
Run the tool and create a datastore.

Programming with NDIP

In this episode, we will start using the nova-galaxy library to interact with the NDIP platform and run a neutron analysis tool. First, ensure you have set your GALAXY_URL and GALAXY_API_KEY as environment variables, as explained in the Summary and Setup Episode. We also need to add nova-galaxy as a project dependency.

Callout

From the command line, type poetry add nova-galaxy@^0.7.0. This command will add the nova-galaxy library to the pyproject.toml file as a project dependency. Then run poetry install to update your project dependencies.

Callout

The nova-galaxy library allows us to create powerful python scripts which can leverage NDIP to run tools and workflows, upload data, download results, and more. Although future episodes of this tutorial largely focus on the creation of GUI applications, a GUI is not required to create powerful applications backed by NDIP.

Interacting with NDIP via `nova-galaxy`

The nova-galaxy library is your gateway to interacting with NDIP programmatically from Python. It provides a set of classes and functions that simplify common NDIP operations, such as connecting to the platform, running tools, and managing data.

We will be using the following key classes from nova-galaxy in this episode:

Connection: The main entry point for interacting with NDIP. You instantiate the Connection class with your NDIP URL and API key to establish a connection.
Tool: Represents a tool available on the NDIP platform. You can define a Tool object by its ID (which corresponds to a tool XML definition in NDIP).
Parameters: Used to define the input parameters for a tool. You add parameters to a Parameters object, specifying the parameter names and values.
Datastore: Configures Galaxy to group outputs of a tool to group outputs of a tool together. Should not directly instantiated. Instead use Connection.create_data_store() after starting a connection.
Output: Contains the output datasets and collections for a tool.
Dataset: A singular file which can be uploaded to Galaxy to be used in tools or downloaded from Galaxy to local storage.
DatasetCollection: A group of files which can be uploaded to Galaxy to be used in tools or downloaded from Galaxy to local storage.

The basic workflow for running a tool with nova-galaxy involves these steps:

Connect to NDIP: Create a Connection instance with your credentials.
Define the Tool: Create a Tool instance, specifying the ID of the NDIP tool you want to run.
Set Parameters: Create a Parameters instance and add the necessary input parameters and their values for the tool.
Run the Tool: Use the tool.run() method to submit the job to NDIP. This typically involves creating a datastore to hold the job's input and output data.

Understanding an NDIP tool

NDIP tools consist of two parts. The first component is the core logic of the tool which will be containerized and run by NDIP. This is the component that we will be focusing on throughout the tutorial and containerization will be discussed in Episode 8. The second component is the tool's XML file which is added to the Galaxy Tool Repository. The XML file is responsible for describing the tool's inputs, outputs, location, how it is executed, and other details to NDIP.

Let's take a look key parts of the XML file for the Fractal Tool that we will use shortly.

The first line gives the name, version, and unique id for a tool. This ID is used in the example below to tell NDIP which tool we are attempting to use.

<tool id="neutrons_fractal" name="Fractals" version="0.2.0" python_template_version="3.5">

This line tells NDIP where the tool's container can be found.

        <container type="docker">savannah.ornl.gov/ndip/tool-sources/playground/fractal:0.1</container>

This section defines the tool's inputs. In this example, the tool requires an input by the name Option. The valid values for Option are mandlebrot, julia, random, and markus.

    <inputs>
        <param name="option" type="select" display="radio" label="Select Option">
            <option value="mandelbrot" selected="true">Mandelbrot Set</option>
            <option value="julia">Julia Set Animation</option>
            <option value="random">Random Walk</option>
            <option value="markus">Markus-Lyapunov Fractal</option>
        </param>
    </inputs>

This section describes the output from the tool. The Fractal tool results in a single output file named output. Tool outputs will be discussed more below.

    <outputs>
        <data auto_format="true" name="output" label="$option">
        </data>
    </outputs>

A comprehensive list of tools, and links to their XML, can be found in Calveras documentation on the tools page.

Setting up the Fractal tool

Let's create a Fractal class that uses nova-galaxy to run the neutrons_fractal tool on NDIP. You can find the complete code for this episode in the code/episode_3 directory.

1. Fractal Class (src/nova_tutorial/app/models/fractal.py) (Create):

To get started, let's create the Fractal class. Create an empty file at src/nova_tutorial/app/models/fractal.py. Add the following pieces of code to the newly created file.

Imports: The Fractal Class will start by importing the necessary classes from nova-galaxy:

PYTHON

import os
from nova.galaxy import Connection, Parameters, Tool

__init__ method: In the __init__ method, we initialize the Fractal class. Note how we retrieve GALAXY_URL and GALAXY_API_KEY from environment variables. This establishes how we will connect to NDIP:

PYTHON

class Fractal:
    def __init__(self):
        self.fractal_type = "mandelbrot"  # Default fractal type
        self.galaxy_url = os.getenv("GALAXY_URL")
        self.galaxy_key = os.getenv("GALAXY_API_KEY")

run_fractal_tool method: This method encapsulates the logic for running the fractal tool. Let's examine the key steps within this method:
- Instantiate Connection, Tool, and Parameters: We create instances of the Connection, Tool, and Parameters classes:

PYTHON

    def run_fractal_tool(self):
        conn = Connection(galaxy_url=self.galaxy_url, galaxy_key=self.galaxy_key)
        tool = Tool(id="neutrons_fractal")
        params = Parameters()
        params.add_input(name="option", value=self.fractal_type)

Note that we create a Tool object with the id="neutrons_fractal". This tells nova-galaxy which NDIP tool we want to run. The obvious question at this point is how do we know the id of the tool and what parameters it expects? We can look at the tool's launch page in calvera for some hints but ultimately we have to look at the tool's xml file.

Connect and Run the Tool: The with conn.connect() as galaxy_connection: block establishes a connection to NDIP and ensures proper handling of the connection:

PYTHON

        with conn.connect() as galaxy_connection:
            data_store = galaxy_connection.create_data_store(name="fractal_store")
            data_store.persist()
            print("Executing fractal tool. This might take a few minutes.")
            output = tool.run(data_store, params)
            output.get_dataset("output").download("tmp.png")
        print("Fractal tool finished successfully.")

The line data_store.persist() saves your datastore after the with block is exited. Without calling this method, all tools, running or finished, along with their results will be discarded after the with block finishes execution.

2. main.py - Calling the Model (src/nova_tutorial/app/main.py) (Modify):

We are now going to modify the existing main.py file. Change the main method to match the code below.

Instantiate and Run: In the main() function, we create an instance of Fractal and call the run_fractal_tool() method, wrapped in a try...except block for basic error handling:

PYTHON

import sys
from .models.fractal import Fractal

def main() -> None:
    fractal = Fractal()
    try:
        fractal.run_fractal_tool()
    except Exception as e:
        print(f"Error running fractal tool: {e}")

Running the tool

To run the code, use the following command in the top level of your nova_tutorial project:

BASH

poetry run app

You should see Fractal tool finished successfully. printed to the console.

Tool output

Tool execution often results in some type of output. In the Fractal example, the tool output is a singular image file. A tool can have multiple outputs and sometimes these outputs are grouped together in a collection. In nova-galaxy, a singular file is called a Dataset and a group of files is called a DatasetCollection. The Dataset and DatasetCollection classes support the following methods:

upload(Datastore): Uploads the Dataset(DatasetCollection) to the specified Datastore on Galaxy.
download(file_path): Downloads the Dataset(DatasetCollection) from Galaxy to the local path.
get_content(): Retreives the content of the Dataset(DatasetCollection) without saving it to a local file path.

If a tool run results in a Dataset or DatasetCollection, an Output is returned from the run method. Output is an encapsulation of the output datasets and collections from a Tool. A tool execution can result in multiple Dataset and DatasetCollection, therefore, these are all grouped in the Outputs class for easier consumption.

In the Fractal example, the Tool.run command returns an instance of the Output class which we save to the variable output. The Fractal tool xml file defines that successful execution of the tool will result in a Dataset named output. This Dataset is then downloaded to the local file path image.png.

PYTHON

    output = tool.run(data_store, params)
    output.get_dataset("output").download("image.png")

The Outputs can be used by the rest of your application, saved, or simply discarded. Outputs is also iterable, so you can use a for-loop to loop through all the contained datasets and collections. If your Datastore is persisted (using the persist() method), then a copy of the Datasets and DatasetCollections will reside on the NDIP platform, so it is not necessary to maintain a local copy.

Asynchronous tool execution

At times, it may be desirable to execute a tool or workflow without waiting on the result. The class Tool method run has an optional wait parameter. The default is true so that the tool is run in a blocking manner. However, by setting the parameter to false, the tool will be run asynchronously in a non-blocking manner. It is beyond the scope of this episode, but if you were to attempt modify the example to run the tool asynchronously, your code might look something like this.

PYTHON

        params1 = Parameters()
        params1.add_input(name="option", "mandelbrot")
        tool1.run(data_store, params1, wait=False)

        params2 = Parameters()
        params2.add_input(name="option", "julia")
        tool2.run(data_store, params2, wait=False)

        # wait on both tools to finish
        while(!tool1.get_results() || !tool2.get_results())
            await sleep(1)

        # do stuff

Note, when run in this manner, the output of tool.run() will be None. In order to retrieve results, you can use tool.get_results(). If the tool has not finished execution, this will also return None. As soon as results are available, the method will provide the results, exactly like the blocking execution.

Next Steps

In this section, you learned how to use the nova-galaxy library to run a tool on NDIP. In the next sections, we will expand on this to create a full user interface to make this functionality accessible to the end user.

Challenge

Run with Different Fractal Types Modify the FractalViewModel class to default to a different fractal type (e.g., julia). Run the application again and verify that it still works.

Show me the solution

The simplest way to accomplish this is to change the default for fractal type in the Fractal class. You can easily observe the change in galaxy.

Challenge

Introduce an Error Introduce an error into the code by changing the tool id to something different. What ouput do you see? What if you change the fractal_type to an invalid option such as mandel instead of mandelbrot?

Show me the solution

In both cases, an error is received from the ndip-galaxy library. When changing the tool id, a Tool not found error will be returned. When selecting an invalid parameter, a parameter 'option': an invalid option was selected error will be returned.

References

Nova Documentation: https://nova-application-development.readthedocs.io/en/latest/
nova-galaxy documentation: https://nova-application-development.readthedocs.io/projects/nova-galaxy/en/latest/
nova-trame documentation: https://nova-application-development.readthedocs.io/projects/nova-trame/en/stable/
nova-mvvm documentation: https://nova-application-development.readthedocs.io/projects/mvvm-lib/en/latest/
Calvera documentation: https://calvera-test.ornl.gov/docs/

Key Points

Nova-Galaxy can be used to create powerful python scripts which leverage the functionality of NDIP.
Tools are run remotely on the NDIP platform
Nova-Galaxy is used to connect to NDIP and run tools
The fractal tool is started remotely and run on NDIP.

Programming with NDIP

Overview

Questions

Objectives

Programming with NDIP

Callout

Callout

Interacting with NDIP via nova-galaxy

Understanding an NDIP tool

Setting up the Fractal tool

PYTHON

PYTHON

PYTHON

PYTHON

PYTHON

Running the tool

BASH

Tool output

PYTHON

Asynchronous tool execution

PYTHON

Next Steps

Challenge

Show me the solution

Challenge

Show me the solution

References

Key Points

Interacting with NDIP via `nova-galaxy`