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Topic Management

listTopics(refresh = false)

Get list of available ROS topics.

Parameters:

  • refresh (boolean) - Force refresh from server

Returns: Promise<Array> - Array of topic objects with name, type, and throttling info

JS
const topics = await oloClient.core.listTopics(); // Returns: [{ name: '/cmd_vel', type: 'geometry_msgs/Twist', throttling: null }, ...]

getTopicInfo(topicName)

Get information about a specific topic.

Parameters:

  • topicName (string) - Topic name

Returns: Object|null - Topic information or null if not found

subscribe(topicName, callback, options)

Subscribe to a ROS topic.

Parameters:

  • topicName (string) - Topic name to subscribe to
  • callback (function) - Callback function for received messages
  • options (object, optional) - Subscription options
    • messageType (string) - Override message type (skips topic lookup if provided)
    • throttleRate (number) - Throttle rate in milliseconds
    • queueLength (number) - Queue length

Returns: Promise<string> - Subscription ID (topic name)

Note: If messageType is not provided, the function will automatically look up the topic type. If the topics cache is empty (e.g., after a reconnection), the function will automatically fetch topics before subscribing. You can also manually provide the messageType option to skip the topic lookup entirely.

JS
await oloClient.core.subscribe('/sensor_data', (message) => { console.log('Received:', message); }, { throttleRate: 100, // Limit to 10 messages per second queueLength: 1 // Only keep latest message });

unsubscribe(topicName)

Unsubscribe from a topic.

Parameters:

  • topicName (string) - Topic name to unsubscribe from

unsubscribeAll()

Unsubscribe from all topics.