action-example

Action Example

Demonstrates the action communication pattern with multiple clients: two clients send goals to a single server, receive intermediate feedback, and get final results. Each client filters responses by its own tracked goal IDs. Supports cancellation of in-progress goals.

Architecture

timer (2s) --> action-client-1 --> goal   --> action-server --> feedback --> action-client-1
                                                            --> result   --> action-client-1
timer (3s) --> action-client-2 --> goal   -->               --> feedback --> action-client-2
                                                            --> result   --> action-client-2

Both clients use the same binary -- the YAML wires them as separate nodes with different timers. Feedback and results fan out to all clients; each filters by its own tracked GOAL_ID.

Nodes

action-client-1 / action-client-2 (Rust, same binary) -- Sends goals at 2s / 3s intervals with a countdown value. Tracks active goals by GOAL_ID in a HashMap. Receives feedback (progress updates) and result (final status). Logs are prefixed with the node ID (DORA_NODE_ID) to distinguish output.

action-server (Rust) -- Manages up to 64 active goals and 128 pending cancellations from any number of clients. On each input event, decrements the countdown for all active goals, sends feedback with current progress. When a goal reaches zero, sends a result with GOAL_STATUS_SUCCEEDED. Accepts cancel inputs for goal cancellation. Uses prefix matching (starts_with("goal") / starts_with("cancel")) to handle multiple named inputs.

Key Concepts

• Multi-client fan-in/fan-out: multiple clients share one server; feedback/results fan out, clients correlate by ID
• Goal ID: unique identifier created via DoraNode::new_goal_id() (UUID v7)
• Metadata keys: GOAL_ID and GOAL_STATUS propagated on all action messages
• Bidirectional: server outputs feed back to client inputs
• Same binary, multiple nodes: YAML declares distinct nodes pointing to the same executable

See docs/patterns.md for the full pattern specification.

Run

cargo build -p action-example-client -p action-example-server
dora run dataflow.yml

Or in distributed mode:

dora up
dora start dataflow.yml --attach
# Ctrl+C to detach, then:
dora stop --all && dora down

What This Demonstrates

Feature	Where
Multi-client action pattern	Two clients, one server
new_goal_id() for unique goal IDs	Client
GOAL_ID / GOAL_STATUS metadata	YAML + both nodes
Cancel wiring (extensibility)	YAML declares cancel output/input
Concurrent goal tracking	Server HashMap with max 64 goals
Same binary, multiple nodes	YAML dataflow