Appose Python

[!TIP] QUICK START: Appose Workshop

	Build environments based on community standards (pixi, mamba, uv)
	Run scripts in those environments as worker processes
	Share memory between processes to avoid copying data

What is Appose?

Appose is a library for interprocess cooperation with shared memory. The guiding principles are simplicity and efficiency.

Appose was written to enable easy execution of Python-based deep learning from Java without copying tensors, but its utility extends beyond that. The steps for using Appose are:

• Build an Environment with the dependencies you need.
• Create a Service linked to a worker, which runs in its own process.
• Execute scripts on the worker by launching Tasks.
• Receive status updates from the task asynchronously via callbacks.

For more about Appose as a whole, see https://apposed.org.

What is this project?

This is the Python implementation of Appose.

How do I use it?

The name of the package is appose.

PyPI/Pip

To use the PyPI package, add appose to your project dependencies.

Depending on how your project is set up, this might entail editing requirements.txt, setup.py, setup.cfg, and/or pyproject.toml.

If you are just starting out, we recommend using pyproject.toml (see this guide):

dependencies = [
  "appose"
]

Conda/Mamba

To use the conda-forge package, add appose to your environment.yml's dependencies section:

dependencies:
  - appose

Examples

Here is a minimal example for calling into Java from Python:

import appose

env = appose.java(vendor="zulu", version="17").build()
with env.groovy() as groovy:
    task = groovy.task("5 + 6")
    task.wait_for()
    result = task.outputs["result"]
    assert 11 == result

Note: The appose.java builder is planned, but not yet implemented.

Here is an example using a few more of Appose's features:

import appose
from appose.service import ResponseType
from time import sleep

golden_ratio_in_groovy = """
// Approximate the golden ratio using the Fibonacci sequence.
previous = 0
current = 1
for (i=0; i<iterations; i++) {
    if (task.cancelRequested) {
        task.cancel()
        break
    }
    task.update(null, i, iterations)
    v = current
    current += previous
    previous = v
}
task.outputs["numer"] = current
task.outputs["denom"] = previous
"""

env = appose.java(vendor="zulu", version="17").build()
with env.groovy() as groovy:
    task = groovy.task(golden_ratio_in_groovy)

    def task_listener(event):
        match event.responseType:
            case ResponseType.UPDATE:
                print(f"Progress {task.current}/{task.maximum}")
            case ResponseType.COMPLETION:
                numer = task.outputs["numer"]
                denom = task.outputs["denom"]
                ratio = numer / denom
                print(f"Task complete. Result: {numer}/{denom} =~ {ratio}")
            case ResponseType.CANCELATION:
                print("Task canceled")
            case ResponseType.FAILURE:
                print(f"Task failed: {task.error}")

    task.listen(task_listener)

    task.start()
    sleep(1)
    if not task.status.is_finished():
        # Task is taking too long; request a cancelation.
        task.cancel()

    task.wait_for()

Of course, the above examples could have been done all in one language. But hopefully they hint at the possibilities of easy cross-language integration.

Issue tracker

All implementations of Appose use the same issue tracker:

https://github.com/apposed/appose/issues