Parameters

ROS 2 uses a node-scoped parameter system where parameters belong to specific nodes. The OLO client provides parameter access methods that handle both simple parameter names and full node paths.

`listNodeParameters(nodeName, options)`

List parameter names for a specific ROS 2 node.

Parameters:

nodeName (string) - Node name (e.g., '/robot_state_publisher')
options (object) - Optional configuration:
- depth (number) - Recursion depth (0 = all parameters, default)
- prefixes (array) - List of parameter prefixes to filter

Returns: Promise<Array<string>> - Array of parameter names

// List all parameters for a node
const params = await oloClient.core.listNodeParameters('/robot_state_publisher');
console.log(`Found ${params.length} parameters:`);
params.forEach(p => console.log(`  ${p}`));

// List parameters with specific prefix
const qosParams = await oloClient.core.listNodeParameters('/robot_state_publisher', {
    prefixes: ['qos_overrides']
});

// Iterate all nodes and list their parameters
const nodes = await oloClient.core.listNodes();
for (const node of nodes) {
    try {
        const nodeParams = await oloClient.core.listNodeParameters(node, { depth: 0 });
        console.log(`${node}: ${nodeParams.length} parameters`);
    } catch (e) {
        console.log(`${node}: Unable to list parameters`);
    }
}

`getParameter(paramName)`

Get ROS 2 parameter value with automatic discovery.

Parameters:

paramName (string) - Parameter name or full path
- Simple name: 'robot_description' (searches across all nodes)
- Full path: '/robot_state_publisher/robot_description' (direct node access)

Returns: Promise<any> - Parameter value

// Get parameter by simple name (searches all nodes)
const robotDesc = await oloClient.core.getParameter('robot_description');

// Get parameter by full path (direct access)
const robotDesc = await oloClient.core.getParameter('/robot_state_publisher/robot_description');

// Get a boolean parameter
const simTime = await oloClient.core.getParameter('use_sim_time');

`getNodeParameter(nodeName, paramName)`

Get parameter value from a specific ROS 2 node.

Parameters:

nodeName (string) - Node name (e.g., '/robot_state_publisher')
paramName (string) - Parameter name (e.g., 'robot_description')

Returns: Promise<any> - Parameter value

// Direct node parameter access
const robotDesc = await oloClient.core.getNodeParameter('/robot_state_publisher', 'robot_description');
const simTime = await oloClient.core.getNodeParameter('/move_group', 'use_sim_time');

`setParameter(paramPath, value)`

Set ROS 2 parameter value using full node path.

Parameters:

paramPath (string) - Full parameter path (e.g., '/robot_state_publisher/my_param')
value (any) - Parameter value (boolean, number, string, or arrays)

Returns: Promise<Object> - Set parameter result

// Set different parameter types
await oloClient.core.setParameter('/my_node/enable_feature', true);           // boolean
await oloClient.core.setParameter('/my_node/max_velocity', 0.5);             // double
await oloClient.core.setParameter('/my_node/retry_count', 3);                // integer
await oloClient.core.setParameter('/my_node/robot_name', 'my_robot');        // string
await oloClient.core.setParameter('/my_node/joint_names', ['joint1', 'joint2']); // string array

`setNodeParameter(nodeName, paramName, value)`

Set parameter value on a specific ROS 2 node.

Parameters:

nodeName (string) - Node name (e.g., '/robot_state_publisher')
paramName (string) - Parameter name
value (any) - Parameter value

Returns: Promise<Object> - Set parameter result

// Set parameter on specific node
await oloClient.core.setNodeParameter('/my_node', 'max_velocity', 0.5);

`deleteParameter(paramPath)`

Delete ROS 2 parameter (not supported).

Note: ROS 2 does not support parameter deletion in the same way as ROS 1. Parameters are managed by their respective nodes and cannot be deleted externally.

Parameters:

paramPath (string) - Full parameter path

Returns: Promise - Throws error as deletion is not supported

// This will throw an error
try {
    await oloClient.core.deleteParameter('/my_node/my_param');
} catch (error) {
    console.log(error.message); // "Parameter deletion is not supported in ROS 2"
}

Parameter Discovery Methods

`listNodeParameters(nodeName, options)`

List parameter names for a specific node.

Parameters:

nodeName (string) - Node name
options (object, optional) - List options
- depth (number) - Parameter depth (default: 0 = all)
- prefixes (Array) - Parameter name prefixes to filter

Returns: Promise<Array<string>> - Parameter names for the node

// List all parameters for a node
const params = await oloClient.core.listNodeParameters('/robot_state_publisher');
console.log('Available parameters:', params);

// List parameters with specific prefix
const robotParams = await oloClient.core.listNodeParameters('/move_group', {
    prefixes: ['robot_description']
});

ROS 2 Parameter Types

ROS 2 supports the following parameter types:

Type	JavaScript Type	Example Value
`PARAMETER_BOOL`	boolean	`true`, `false`
`PARAMETER_INTEGER`	number (integer)	`42`, `-10`
`PARAMETER_DOUBLE`	number (float)	`3.14`, `-0.5`
`PARAMETER_STRING`	string	`"hello"`, `"robot_name"`
`PARAMETER_BYTE_ARRAY`	Uint8Array	`new Uint8Array([1, 2, 3])`
`PARAMETER_BOOL_ARRAY`	Array<boolean>	`[true, false, true]`
`PARAMETER_INTEGER_ARRAY`	Array<number>	`[1, 2, 3, 4]`
`PARAMETER_DOUBLE_ARRAY`	Array<number>	`[1.1, 2.2, 3.3]`
`PARAMETER_STRING_ARRAY`	Array<string>	`["joint1", "joint2"]`

Parameter Naming Conventions

Node-Scoped Parameters:

All ROS 2 parameters belong to specific nodes
Parameter names are local to their node
Access via full path: /node_name/parameter_name

Common Parameter Examples:

// Robot description (URDF)
await oloClient.core.getParameter('/robot_state_publisher/robot_description');

// Simulation time flag
await oloClient.core.getParameter('/move_group/use_sim_time');

// Planning parameters
await oloClient.core.getParameter('/move_group/planner_configs/RRTConnectkConfigDefault/range');

// Controller parameters
await oloClient.core.getParameter('/joint_trajectory_controller/joints');

Best Practices

1. Use Simple Names for Discovery:

// Let the client find the parameter across nodes
const robotDesc = await oloClient.core.getParameter('robot_description');

2. Use Full Paths for Performance:

// Direct access when you know the node
const robotDesc = await oloClient.core.getParameter('/robot_state_publisher/robot_description');

3. Handle Parameter Not Found:

try {
    const value = await oloClient.core.getParameter('my_parameter');
    console.log('Parameter value:', value);
} catch (error) {
    if (error.message.includes('not found')) {
        console.log('Parameter does not exist');
    } else {
        console.error('Failed to get parameter:', error);
    }
}

4. Check Node Existence Before Setting:

const nodes = await oloClient.core.listNodes();
if (nodes.includes('/my_node')) {
    await oloClient.core.setParameter('/my_node/my_param', 'value');
} else {
    console.log('Node /my_node not found');
}

On This Page

Getting Started

API Reference

Standalone Client Development

Parameters

`listNodeParameters(nodeName, options)`

`getParameter(paramName)`

`getNodeParameter(nodeName, paramName)`

`setParameter(paramPath, value)`

`setNodeParameter(nodeName, paramName, value)`

`deleteParameter(paramPath)`

Parameter Discovery Methods

`listNodeParameters(nodeName, options)`

ROS 2 Parameter Types

Parameter Naming Conventions

Best Practices