Clients

Skill: Clients — Programming Language Libraries

Objective

Generate producer/consumer scripts in Rust, Go, Python, or Java for testing Danube messaging features. Each language has its own SKILL.md with installation, API reference, and complete code examples.

Language Selection

AI Decision: Which Language?

Ask the user which language they prefer. If unclear, use this fallback:

Feature Matrix

All four clients support the same features:

Common API Pattern

All clients use the same builder pattern:

1. Create client → DanubeClient.builder().service_url("http://...").build()
2. Create producer → client.new_producer().with_topic(...).with_name(...).build()
3. Create consumer → client.new_consumer().with_topic(...).with_subscription(...).with_subscription_type(...).build()
4. Register on broker → producer.create() / consumer.subscribe()
5. Send/receive → producer.send(payload) / consumer.receive()
6. Acknowledge → consumer.ack(message)

Python Virtual Environment

Many scenarios use Python for test scripts (e.g., test_mqtt_ingestion.py, schema validation, producer/consumer scripts). The AI must use a virtual environment to avoid system package conflicts.

Use a single .venv at the repo root — not per test run. This is persistent across all $TEST_RUN sessions and avoids re-installing dependencies on every run.

# Create once (if .venv doesn't exist)
python3 -m venv .venv

# Activate before running any Python
source .venv/bin/activate

# Install scenario-specific dependencies
pip install danube-client            # Core Danube client
pip install paho-mqtt==1.6.1         # Edge/MQTT scenarios
pip install -r scenarios/edge-mqtt/scripts/requirements.txt  # Or use requirements files

The .venv/ directory is git-ignored. When starting a new test session, check if .venv exists and activate it — only create a new one if it's missing.

Installation

The AI should auto-install the client library for the chosen language. Read the specific language SKILL.md for the install command.

Sub-Skills

Read the specific language SKILL.md for full API reference and code examples:

• clients/rust/SKILL.md — Rust async client (Tokio)
• clients/python/SKILL.md — Python async client (asyncio)
• clients/go/SKILL.md — Go client (context-based, gRPC)
• clients/java/SKILL.md — Java 21+ client (virtual threads, Flow.Publisher)