Capabilities2 Server

Capabilities2 server allows interaction with the capabilities2 API. It is a reimplementation of the capabilities package using C++ (original capabilities package was written in Python 2.7). In addition to C++ reimplementation being more resource efficient, this package extends the capabilities package features in following ways,

1. Database support for storing capabilities.
2. Capability registration through service calls.
3. Abstracted providers through a runners API see capabilities2_runner

Specialising the capabilities2 server

The capabilities2 server is implemented as a ROS2 Component. The server can be specialised by composing it with another Component that adds domain logic.

Launch capabilities2 server

source install/setup.bash
ros2 launch capabilities2_server capabilities2_server.launch.py

Refer capabilities2_server/config/capabilities.yaml for the default node parameters loaded by the launch file.

System dependencies

The capabilities2 server depends on the following bondcpp ROS2 package. See the package.xml for the full list of dependencies. Notably, the capabilities2 server depends on the following system dependencies:

• sqlite3
• yaml-cpp
• tinyxml2

API

The capabilities2 server provides the following ROS2 API:

Services

The capabilities2 server exposes the following Service API (see capabilities2_msgs for data types):

Topic	Service Message	Description
~/get_interfaces	GetInterfaces.srv	Get the interfaces provided by the capabilities server
~/get_semantic_interfaces	GetSemanticInterfaces.srv	Get the semantic interfaces provided by the capabilities server
~/get_providers	GetProviders.srv	Get the providers available on the capabilities server
~/get_remappings	GetRemappings.srv	Get the remappings for a capability
~/get_capability_spec	GetCapabilitySpec.srv	Get a raw specifications for a capability
~/get_capability_specs	GetCapabilitySpecs.srv	Get all raw specifications in the capabilities server
~/get_running_capabilities	GetRunningCapabilities.srv	Get the currently running capabilities
~/establish_bond	EstablishBond.srv	Establish a bond with the capabilities server to use capabilities
~/use_capability	UseCapability.srv	Use a capability - must be bonded
~/free_capability	FreeCapability.srv	Free a capability (when done using it, when all users are done the capability is freed) - must be bonded
~/start_capability	StartCapability.srv	Start a capability (this is a forceful start, and ignores use and free logic)
~/stop_capability	StopCapability.srv	Stop a capability (this is a forceful stop, and ignores use and free logic)
~/register_capability	RegisterCapability.srv	Register a capability with the capabilities server
~/trigger_capability	TriggerCapability.srv	Trigger a capability - must be bonded
~/connect_capability	ConnectCapability.srv	Connect two running capabilities through the event system using a CapabilityConnection message - must be bonded

Topics

The capabilities2 server exposes the following Topics API:

Topic	Message	Description
~/events	CapabilityEventStamped.msg	Publish capability events
~/bonds	bond/Status.msg	Maintain bonds with capability users - Bond API

Additional Information

• Registering a capability
• Terminal based capability usage