Hermes Device Manager (hermes-dm)

Hermes-DM is a lightweight, high-performance, and asynchronous device manager that provides a native, modern software interface for classic test and measurement hardware.

By leveraging ZeroMQ (ZMQ) for swift, non-blocking message passing and SCPI (Standard Commands for Programmable Instruments) for hardware communication, Hermes allows you to seamlessly control, monitor, and log data from generic lab instruments.

Features

• Asynchronous Architecture: Built on top of ZeroMQ for high-throughput, low-latency telemetry logging.
• Generic SCPI Support: Easily extensible to any programmable instrument (Power supplies, Oscilloscopes, DMMs, etc.).
• Decoupled Logging: Devices stream data asynchronously, isolating measurement constraints from data storage layers.
• Lightweight Footprint: Avoids heavy industrial middleware framework bloat.

Architecture Overview

┌─────────────────────────────────────────────────────────────┐
│ BACKGROUND DAEMON (hermes-daemon)                           │
│                                                             │
│  [ SCPI Instruments ] ◄──── (PyVISA) ────► [ Async Server ] │
│                                                 │     │     │
│  [ SQLite DB Logs ] ◄────── (Database) ─────────┘     │     │
└───────────────────────────────────────────────────────┼─────┘
                                                        │
                      (ZeroMQ: Ports 5555 REP & 5556 PUB)
                                                        │
┌───────────────────────────────────────────────────────▼─────┐
│ USER ENVIRONMENT (hermes_dm.client)                         │
│                                                             │
│  [ HermesClient Library ]                                   │
│            │                                                │
│            ▼                                                │
│  [ Standalone Scripts | Jupyter Notebooks | GUI App ]       │
└─────────────────────────────────────────────────────────────┘

Installation

pip install hermes-dm

Quick Start

Hermes operates on a robust Client-Server architecture to ensure your hardware polling never blocks your user interfaces or scripts.

1. Start the Background Daemon

Run this in your terminal to start the background hardware manager:

hermes-daemon --db-dir ./lab_data --cmd-port 5555

2. Control via Python Script

In a separate terminal, Jupyter notebook, or GUI, use the client library to issue commands to the daemon:

from hermes_dm.client import HermesClient

# Connect to the background daemon
client = HermesClient(host="localhost", port=5555)

# Connect the hardware (driver logic is handled by the daemon)
client.connect_device(
    name="Main_PSU",
    model="Keithley2410",
    identifier="TCPIP::111.222.33.44::INSTR"
)

# Configure the instrument
client.configure_device("Main_PSU", {"source_mode": "VOLT", "output_enabled": True})

# Start continuous asynchronous logging to SQLite
client.start_logging()

Developer Guide

Welcome! This section covers everything you need to know to set up a local development environment, understand the underlying architecture, and contribute to hermes-dm.

System Architecture Overview

hermes-dm uses a decoupled, event-driven, client-server architecture designed for high-performance, non-blocking laboratory hardware control.

• The Hermes Client: A lightweight, synchronous Python API exposed to user scripts or notebooks. It handles telemetry requests, sends command packets over ZeroMQ, and translates backend JSON error states back into native Python exceptions.
• The Hermes Daemon: A persistent, asynchronous background process (asyncio) handling incoming network traffic via ZeroMQ.
• Isolated Thread Pools: To prevent slow hardware I/O (like instrument connection scans or legacy GPIB commands) from locking up the main asynchronous network event loop, the daemon uses dedicated OS thread pools (asyncio.to_thread and custom ThreadPoolExecutor instances) to isolate synchronous PyVISA drivers.

Environment Setup

Follow these steps to set up an isolated development environment running your code in editable mode with all developer tools active.

1. Clone the repository and navigate to the root directory:

   git clone [https://github.com/cbeiraod/hermes-dm.git](https://github.com/cbeiraod/hermes-dm.git)
   cd hermes-dm
   

2. Create a virtual environment:

   python -m venv .venv
   

3. Activate the environment:

   • Linux / macOS: source .venv/bin/activate
   • Windows (Cmd): .venv\Scripts\activate.bat
   • Windows (PowerShell): .venv\Scripts\Activate.ps1

4. Install the package in editable mode with development extras:

   pip install -e ".[dev]"
   

   Note: If you are using Zsh, make sure to wrap the target in quotes: pip install -e ".[dev]"

   Optionally, install the package in editable mode with development, testing, and documentation extras:

   pip install -e ".[dev,docs]"
   

5. Install the local Git hooks:

   python -m pre_commit install
   

Development Tools Stack

We use a modern, consolidated tool stack to enforce code quality, verify async test patterns, and automate package distribution.

Running Tools Standalone

• Running the Test Suite: To execute all test suites with verbose execution details:

  pytest -v
  

• Running Linter/Formatter Manually: While pre-commit intercepts formatting issues during git tracking, you can trigger individual sweeps manually:

  ruff check --fix     # Evaluates code quality rules and auto-fixes violations
  ruff format          # Enforces your project's code style rules across all files
  

• Simulating a Pre-commit Run: If you want to evaluate all files against the entire pre-commit stack (including trailing whitespace, end-of-file fixers, and forgotten debug statements) without committing code:

  python -m pre_commit run --all-files
  

• Building Documentation Locally: To compile your .rst design layout and extract code docstrings via Sphinx into a responsive, dark-mode-ready static HTML site using the Furo theme:

  python -m sphinx -b html docs/ docs/_build/html
  

  After compilation, open docs/_build/html/index.html in your browser to preview the output.

• Executing a Release Version Bump: To safely increment versions across your pyproject.toml and package __init__.py while auto-generating tracking commits and release candidate tags:

  bump-my-version bump minor
  

CI/CD Infrastructure (GitHub Actions)

Automation pipelines are tracked inside .github/workflows/. They isolate compute footprints to keep automation efficient and free.

1. Continuous Integration (ci.yml)

Triggers automatically on every push to main, pull request tracking, or creation of version tags (v*.*.*).

• Fail-Fast Lint Gate: Automatically triggers a clean cloud environment to test the full codebase against pre-commit. If formatting is irregular or a stray breakpoint() is exposed, the job drops immediately.
• Linux Test Core: Executes the complete async test matrix under an optimized caching system to evaluate package installs in seconds.
• Extended Multi-OS Testing: To control costs, tests targeting Windows and macOS runners are restricted. They execute only when a formal version release tag (e.g., v0.2.0) is discovered or when manually requested via the GitHub Actions UI.

2. PyPI Package Deployment (Coming Soon)

• Triggers exclusively on published GitHub Releases.
• Automatically triggers the build pipeline, verifies package architecture integrity via twine check, and deploys clean production wheels securely onto the Python Package Index (PyPI).

License

This project is licensed under the zlib/libpng License - see the LICENSE file for details.