Default Services In Sugarcoat Components

In addition to the standard ROS2 Lifecycle Node services, Sugarcoat Components provide a powerful set of built-in services for live reconfiguration. These services allow you to dynamically adjust inputs, outputs, and parameters on-the-fly, making it easier to respond to changing runtime conditions or trigger intelligent behavior in response to events. Like any ROS2 services, they can be called from other Nodes or with the ROS2 CLI, and can also be called programmatically as part of an action sequence or event-driven workflow in the launch script.

Replacing an Input or Output with a different Topic

You can swap an existing topic connection (input or output) with a different topic online without restarting your script. The service will stop the running lifecycle node, replace the connection and restart it again.

• Service Name: /{component_name}/change_topic

• Service Type: automatika_ros_sugar/srv/ReplaceTopic

📥 Request

Field	Type	Description
direction	uint8	Direction of the topic to replace. Use 0 for INPUT_TOPIC, 1 for OUTPUT_TOPIC.
old_name	string	The full name of the currently connected topic you want to replace.
new_name	string	The full name of the new topic to connect.
new_msg_type	string	Fully qualified message type of the new topic (see supported types).

📤 Response

Field	Type	Description
success	bool	Indicates whether the topic replacement was successful.
error_msg	string	If unsuccessful, this provides a description of the failure.

Example

To replace the output topic name of the AwesomeComponent created in the previous example, we can send the following service e call to the node:

ros2 service call /awesome_component/change_topic automatika_ros_sugar/srv/ReplaceTopic "{direction: 1, old_name: '/voice', new_name: '/audio_device_0', new_msg_type: 'Audio'}"

Updating a configuration parameter value

This ChangeParameter service allows updating a single configuration parameter at runtime. You can choose whether the component remains active during the change, or temporarily deactivates for a safe update.

• Service Name: /{component_name}/update_config_parameter

• Service Type: automatika_ros_sugar/srv/ChangeParameter

📥 Request

Field	Type	Description
name	string	Name of the parameter to change with nested attributes if needed
value	string	New value for the parameter (as a string, internally converted to proper type).
keep_alive	bool	If true, the component stays active during update. If false, it will deactivate, apply the change, and then reactivate.

📤 Response

Field	Type	Description
success	bool	Indicates if the parameter was successfully updated.
error_msg	string	If failed, provides a descriptive error message.

Example

Lets change the loop_rate for our AwesomeComponent to 1Hz with restarting the node:

ros2 service call /awesome_component/update_config_parameter automatika_ros_sugar/srv/ChangeParameter "{name: 'loop_rate', value: '1', keep_alive: false}"

Updating a set of configuration parameters

The ChangeParameters service allows updating multiple parameters at once, making it ideal for switching modes, profiles, or reconfiguring components in batches. Similar to ChangeParameter service, you can choose whether the component stays active or temporarily deactivates during the update.

• Service Name: /{component_name}/update_config_parameters

• Service Type: automatika_ros_sugar/srv/ChangeParameters

📥 Request

Field	Type	Description
names	string[]	List of parameter names to update
values	string[]	New values for each parameter, given as strings (converted internally).
keep_alive	bool	If true, component remains active. If false, it will deactivate, apply updates, then reactivate.

📤 Response

Field	Type	Description
success	bool[]	A list of success flags for each parameter update.
error_msg	string[]	A list of error messages (or empty strings) corresponding to each parameter.

Example

Lets change multiple parameters at once for our AwesomeComponent with restarting the node:

ros2 service call /awesome_component/update_config_parameters automatika_ros_sugar/srv/ChangeParameters "{names: ['loop_rate', 'fallback_rate'], values: ['1', '10'], keep_alive: false}"

Reconfiguring the Component from a given file

The ConfigureFromFile service lets you reconfigure an entire component from a YAML, JSON or TOML configuration file while the node is online. This is useful for applying scenario-specific settings, or restoring saved configurations—all in a single operation.

• Service Name: /{component_name}/configure_from_file

• Service Type: automatika_ros_sugar/srv/ConfigureFromFile

📥 Request

Field	Type	Description
path_to_file	string	Absolute path to the file containing the parameters under the component name.
keep_alive	bool	If true, keeps the component active during the update. If false, deactivates before applying changes, then reactivates.

📤 Response

Field	Type	Description
success	bool	Indicates whether the file re-configuration update was successful.
error_msg	string	If failed, provides a descriptive error message.

Example

Example YAML configuration file for our AwesomeComponent:

/**: # Common parameters for all components
  fallback_rate: 10.0

# Parameters specific to component under component name
awesome_component:
  loop_rate: 100.0

Executing a Component’s method

The ExecuteMethod service enables runtime invocation of any class method in the component. This is useful for triggering specific behaviors, tools, or diagnostics during runtime without writing additional interfaces.

• Service Name: /{component_name}/execute_method

• Service Type: automatika_ros_sugar/srv/ExecuteMethod

📥 Request

Field	Type	Description
name	string	The name of the method to invoke (as registered by the component).
kwargs_json	string	A JSON-formatted string containing the method’s keyword arguments. Example: "{'some_kwarg': 1.2}"

📤 Response

Field	Type	Description
success	bool	Indicates whether the method call was successful.
error_msg	string	If failed, provides a descriptive error message.