https://github.com/apajon/lifecore_ros2
lifecore_ros2 is a modular ROS 2 framework designed to structure robotic applications around lifecycle-aware components. It provides a clean separation between nodes and components, enforces strict lifecycle management, and enables scalable, maintainable architectures for complex robotic systems.
https://github.com/apajon/lifecore_ros2
component-based distributed-systems lifecycle middleware modular-architecture rclcpp real-time-systems robot-framework robot-software robotics ros2 software-architecture
Last synced: 25 days ago
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lifecore_ros2 is a modular ROS 2 framework designed to structure robotic applications around lifecycle-aware components. It provides a clean separation between nodes and components, enforces strict lifecycle management, and enables scalable, maintainable architectures for complex robotic systems.
- Host: GitHub
- URL: https://github.com/apajon/lifecore_ros2
- Owner: apajon
- License: apache-2.0
- Created: 2026-04-02T22:53:55.000Z (about 2 months ago)
- Default Branch: main
- Last Pushed: 2026-04-24T20:29:50.000Z (about 1 month ago)
- Last Synced: 2026-04-24T20:36:26.958Z (about 1 month ago)
- Topics: component-based, distributed-systems, lifecycle, middleware, modular-architecture, rclcpp, real-time-systems, robot-framework, robot-software, robotics, ros2, software-architecture
- Language: Python
- Homepage:
- Size: 851 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: .github/CODE_OF_CONDUCT.md
- Security: .github/SECURITY.md
- Support: .github/SUPPORT.md
- Roadmap: ROADMAP.md
Awesome Lists containing this project
README
# lifecore_ros2
[](https://github.com/apajon/lifecore_ros2/actions/workflows/ci.yml) [](https://github.com/apajon/lifecore_ros2/actions/workflows/docs.yml) [](https://github.com/apajon/lifecore_ros2/actions/workflows/release.yml)
[](LICENSE)[](https://apajon.github.io/lifecore_ros2/)
lifecore_ros2 is a minimal lifecycle composition library for ROS 2 Jazzy — no hidden state machine.
*The `examples/composed_pipeline.py` walk-through highlights the key distinction the library makes explicit: **deactivate ≠ cleanup** — `/pipeline/*` topics persist across deactivate and only disappear on cleanup.*
## Why lifecore_ros2 exists
**Audience.** This library is for teams building modular ROS 2 nodes that need reusable lifecycle-aware components, especially in larger robotics stacks, embedded systems, or runtime-orchestrated applications.
**Problem framing.** ROS 2 provides a powerful managed-node lifecycle (`configure → active → deactivate → cleanup`). In practice, using it for anything beyond a trivial node leads to recurring problems:
- lifecycle logic gets scattered across monolithic node classes with no clear ownership
- ROS resource setup and teardown (publishers, subscriptions, timers) are easy to make inconsistent — resources allocated in the wrong place or released too late
- runtime gating ("only process messages when active") is hand-rolled differently each time, with no shared, tested pattern
- reusable lifecycle-aware building blocks are awkward in raw `rclpy` because the lifecycle contract is on the node, not on reusable sub-units
lifecore_ros2 solves these four problems with a small, explicit composition layer. It does not replace or extend the ROS 2 lifecycle state machine — it makes the lifecycle contract expressible at the component level.
**Non-goals.** It is not a full application framework, not a plugin system, and not a replacement for native ROS 2 lifecycle semantics.
## Architecture at a glance
```mermaid
flowchart LR
Lifecycle[ROS 2 Lifecycle]
Node[LifecycleComponentNode]
Components[LifecycleComponent instances]
Lifecycle <--> Node
Node <--> Components
Lifecycle -. drives .-> Components
```
## What the library provides
A small set of lifecycle-aware building blocks:
| Symbol | Role |
|---|---|
| `LifecycleComponentNode` | Lifecycle node that owns and drives registered `LifecycleComponent` instances |
| `LifecycleComponent` | Base class for a lifecycle-aware managed entity (abstract by convention — override `_on_*` hooks) |
| `TopicComponent` | Base class for topic-oriented components (pub/sub) |
| `LifecyclePublisherComponent` | Lifecycle-gated ROS publisher |
| `LifecycleSubscriberComponent` | Lifecycle-gated ROS subscriber |
| `LifecycleTimerComponent` | Lifecycle-gated ROS timer |
| `ServiceComponent` | Base class for service-oriented components (server/client) |
| `LifecycleServiceServerComponent` | Lifecycle-gated ROS service server |
| `LifecycleServiceClientComponent` | Lifecycle-gated ROS service client |
| `when_active` | Decorator that guards any method to the active state |
| `LifecoreError` and subclasses | Typed exceptions for boundary violations |
| `lifecore_ros2.testing` | Reusable fakes, fixtures, assertions, and helpers for lifecycle-focused tests |
## Design rules and non-goals
The framework stays lifecycle-native, keeps ownership in `LifecycleComponentNode`, and treats component hooks as explicit extension points rather than hidden orchestration.
See [docs/architecture.rst](docs/architecture.rst) for lifecycle design rules, [docs/patterns.rst](docs/patterns.rst) for usage patterns, and [ROADMAP.md](ROADMAP.md) for non-goals and deferred scope.
See [Examples Repository Plan](docs/planning/examples_repo.rst) for the companion repository planning.
See [CHANGELOG.md](CHANGELOG.md) for shipped changes or the [GitHub Releases](https://github.com/apajon/lifecore_ros2/releases) page for tagged releases.
## Prerequisites
- Python 3.12 or newer
- ROS 2 Jazzy installed on the system
- `uv` available in the workspace
`rclpy` is expected to come from the system ROS installation. It is intentionally not declared as a normal PyPI dependency.
## Quickstart
Clone the repository, source ROS 2 Jazzy, and sync the local development environment:
```bash
git clone https://github.com/apajon/lifecore_ros2.git
cd lifecore_ros2
source /opt/ros/jazzy/setup.bash
uv sync --extra dev
```
Run the smallest composed lifecycle example already in the repository:
```bash
uv run python examples/minimal_node.py
```
From another terminal in the same ROS 2 environment, drive the node through configure and activate:
```bash
source /opt/ros/jazzy/setup.bash
ros2 lifecycle set /minimal_lifecore_node configure
ros2 lifecycle set /minimal_lifecore_node activate
```
For the full walkthrough, see [docs/quickstart.rst](docs/quickstart.rst). For validation and documentation commands, see [docs/getting_started.rst](docs/getting_started.rst). For the activation-gated subscriber example, continue with [examples/minimal_subscriber.py](examples/minimal_subscriber.py) or [docs/examples.rst](docs/examples.rst).
## Lifecycle reading path
The documentation now follows the same lifecycle vocabulary as the framework:
- Configure: environment, prerequisites, ROS resource creation model
- Activate: runtime enablement and activation gating
- Run: examples, API usage, composed execution flow
- Transition: ownership, propagation, and error handling rules
- Shutdown: cleanup, release, and lifecycle end-state expectations
Recommended order:
1. [docs/quickstart.rst](docs/quickstart.rst)
2. [docs/getting_started.rst](docs/getting_started.rst)
3. [docs/concepts/mental_model.rst](docs/concepts/mental_model.rst)
4. [docs/architecture.rst](docs/architecture.rst)
5. [docs/patterns.rst](docs/patterns.rst)
6. [docs/testing.rst](docs/testing.rst)
7. [docs/examples.rst](docs/examples.rst)
## Shortest-path example — subscriber
[examples/minimal_subscriber.py](examples/minimal_subscriber.py) is the next runnable example if you want to see activation-gated message delivery after the minimal node quickstart.
See [examples/minimal_subscriber.py](examples/minimal_subscriber.py) for the complete runnable file, [docs/api_friction_audit.rst](docs/api_friction_audit.rst) for the regression baseline, and [docs/examples.rst](docs/examples.rst) for the walkthrough.
> Component + node definition: **24 lines** (regression baseline — see
> [`docs/api_friction_audit.rst`](docs/api_friction_audit.rst)).
## Publisher and subscriber examples
Run the publisher and observe activation gating:
```bash
uv run python examples/minimal_publisher.py
# in another terminal:
ros2 lifecycle set /publisher_demo_node configure
ros2 lifecycle set /publisher_demo_node activate
ros2 topic echo /chatter
```
Messages appear only after `activate`. Deactivation stops them.
For the subscriber path, use the quickstart above or the full example walkthrough in [docs/examples.rst](docs/examples.rst).
## Public API overview
All exported symbols and their stability levels are documented in [ROADMAP.md](ROADMAP.md#public-api-and-extension-model).
The extension model and API buckets are defined in [docs/architecture.rst](docs/architecture.rst) and [docs/api.rst](docs/api.rst).
## Current limitations
- the public API is in the `0.x` series — experimental stability level; minor bumps may include breaking changes
- companion examples repository `lifecore_ros2_examples` is *planned — not yet published*; see `ROADMAP.md` for scope and the first applied example (sensor-fusion pipeline)
## License
This project is licensed under the Apache-2.0 License — see [LICENSE](LICENSE).
## Documentation
Documentation: https://apajon.github.io/lifecore_ros2/
Full documentation lives under `docs/` and is built with Sphinx:
```bash
uv sync --extra dev --group docs
uv run --group docs python -m sphinx -b html docs docs/_build/html
```
Key pages:
- `docs/getting_started.rst` — setup and validation commands
- `docs/architecture.rst` — lifecycle design rules, error policy, member conventions
- `docs/patterns.rst` — recommended patterns and anti-patterns
- `docs/testing.rst` — reusable lifecycle test fakes, fixtures, assertions, and helpers
- `docs/migration_from_rclpy.rst` — before/after comparison with raw rclpy
- `docs/api.rst` — generated API reference
- `docs/examples.rst` — example walkthroughs
## Versioning
Versioning uses Conventional Commits and python-semantic-release. Preview the next version:
```bash
uv run --group release semantic-release version --print
```
Release (version commit + tag, skip hosted release if no token):
```bash
uv run --group release semantic-release version --no-vcs-release
git push origin main --follow-tags
```
See [ROADMAP.md](ROADMAP.md#versioning-strategy) for promotion-to-1.0.0 criteria.