Add Advanced Features (Messages, QoS, Executors, Components)

[Michi-Tsubaki]

Overview

This PR adds advanced ROS2 features to ROS2.jl, including dynamic message handling, custom QoS profiles, multi-threaded executors, and component management.

Changes

New Module: src/messages.jl

• get_available_message_types(): Query all available message types
• create_msg_dynamic(): Create messages at runtime
• get_message_fields(): Introspect message structure
• is_valid_message_type(): Validate message type
• QoSProfile: Custom Quality of Service configuration
• DEFAULT_QOS, SENSOR_DATA_QOS: Predefined QoS profiles

New Module: src/advanced.jl

• MultiThreadedExecutor: Concurrent message processing
• LifecycleNode: Node lifecycle management
• ComponentManager: Dynamic component loading/unloading
• set_domain_id(), get_domain_id(): Domain ID configuration

New Examples

• examples/example_messages.jl: Dynamic message creation and introspection
• examples/example_advanced.jl: Multi-threaded execution, QoS, and components

API Examples

Dynamic Messages

using ROS2

init()
node = ROSNode("dynamic_example")

# Query available types
available_types = get_available_message_types()
println("Available types: $(length(available_types))")

# Create message dynamically
twist_msg = create_msg_dynamic("geometry_msgs.msg.Twist")
twist_msg.linear.x = 1.0
twist_msg.angular.z = 0.5

# Introspect message
fields = get_message_fields("geometry_msgs.msg.Twist")
println("Fields: $fields")

shutdown()

Multi-threaded Executor

using ROS2

init()
set_domain_id(1)

node = ROSNode("advanced_node")

# Create multi-threaded executor
executor = MultiThreadedExecutor(4)
add_node(executor, node)

# Custom QoS
custom_qos = QoSProfile("best_effort", "volatile", "keep_last", 10)
pub = Publisher(node, "data", "std_msgs.msg.String")

spin_executor(executor)

Component Management

using ROS2

init()

# Manage components
manager = ComponentManager("ComponentManager")
components = list_components(manager)

response = load_component(manager, "composition", "composition::Talker", "talker")
if response.success
    println("Loaded: $(response.unique_id)")
    unload_component(manager, response.unique_id)
end

shutdown()

Features

• Runtime message type discovery and creation
• Custom QoS for reliability and performance tuning
• Parallel message processing with thread pools
• Dynamic node loading without recompilation
• Lifecycle state management
• Domain ID configuration for network isolation

Testing

Tested with:

• ROS2 Humble on Ubuntu 22.04
• ROS2 Jazzy on Ubuntu 24.04
• Dynamic message creation with various message types
• Multi-threaded execution with high-frequency publishing
• Component loading with demo nodes

Dependencies

• composition_interfaces (for component management)
• rclcpp_components (for component containers)

Backward Compatibility

Fully backward compatible. All existing code continues to work without modifications.