Lens Events API (WebSocket) - Archetype AI Documentation

The Lens Events API enables real-time control and data streaming for active lens sessions via WebSocket connections. This allows you to interact with Newton models, configure input streams, and receive real-time inference results.

Connection Setup

1. Create a Lens Session

First, create a lens session using the REST API:

curl https://api.u1.archetypeai.app/v0.5/lens/sessions/create \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"lens_id": "lns-fd669361822b07e2-237ab3ffd79199b9"}'

The response includes a session_endpoint for WebSocket connection:

{
  "session_id": "lsn-250313c2177253cbaa7a73542edd90",
  "lens_id": "lns-fd669361822b07e2-237ab3ffd79199b9",
  "session_endpoint": "wss://api.archetypeai.dev/v0.5/lens/sessions/lsn-250313c2177253cbaa7a73542edd90",
  "status": "SESSION_STATUS_CREATED"
}

2. Connect to WebSocket

import websocket
import json

session_endpoint = "wss://api.archetypeai.dev/v0.5/lens/sessions/lsn-250313c2177253cbaa7a73542edd90"
socket = websocket.create_connection(
    session_endpoint, 
    header={"Authorization": f"Bearer {API_KEY}"}
)

def send_and_receive_event(socket, event_data):
    socket.send_binary(json.dumps(event_data).encode())
    response = json.loads(socket.recv())
    return response

For JavaScript, use the Sec-WebSocket-Protocol header to pass authentication and protocol version.

Event Message Format

All event messages are JSON objects with a required type field and optional event_data field:

{
  "type": "event.type",
  "event_data": {
    // Event-specific data
  }
}

Session Events

session.status

Query the current status of the active session.

event_message = {"type": "session.status"}
response = send_and_receive_event(socket, event_message)
print(f"Session status: {response}")

Response Example:

{
  "status": "SESSION_STATUS_RUNNING",
  "session_id": "lsn-250313c2177253cbaa7a73542edd90",
  "uptime_seconds": 145.2,
  "last_activity": 1741843135.1848276
}

session.validate

Run validation checks on the current session, including health checks and model connectivity.

event_message = {"type": "session.validate"}
response = send_and_receive_event(socket, event_message)

if response.get("valid"):
    print("Session is valid and ready")
else:
    print(f"Validation failed: {response.get('errors')}")

Response Example:

{
  "valid": true,
  "checks": {
    "session_health": "pass",
    "model_connectivity": "pass",
    "sensor_nodes": "pass"
  },
  "errors": []
}

session.read

Read pending event messages from the platform, such as log messages or asynchronous inference results.

Each client should generate a unique client_id to enable parallel reading. Use a new client_id to reset message stream playback.

import uuid

client_id = str(uuid.uuid4())[:8]  # Generate unique 8-character ID

event_message = {
    "type": "session.read",
    "event_data": {"client_id": client_id}
}
response = send_and_receive_event(socket, event_message)

for message in response.get("messages", []):
    print(f"[{message['timestamp']}] {message['type']}: {message['data']}")

Response Example:

{
  "messages": [
    {
      "timestamp": 1741843200.123,
      "type": "inference.result",
      "data": {
        "result": "A construction worker wearing a hard hat and safety vest",
        "confidence": 0.95,
        "processing_time_ms": 245
      }
    },
    {
      "timestamp": 1741843201.456,
      "type": "log.info",
      "data": "Frame processed successfully"
    }
  ],
  "client_id": "a1b2c3d4"
}

session.destroy

Destroy the active session directly via the control stream.

event_message = {"type": "session.destroy"}
response = send_and_receive_event(socket, event_message)
print(f"Session destroyed: {response}")

# Close WebSocket connection
socket.close()

Input Stream Configuration

input_stream.set

Configure input data streams to automatically feed data through the lens.

RTSP Video Stream

Connect a real-time video camera using RTSP protocol:

event_message = {
    "type": "input_stream.set",
    "event_data": {
        "stream_type": "rtsp_video_streamer",
        "stream_config": {
            "rtsp_url": "rtsp://camera.example.com:554/stream",
            "target_image_size": [360, 640],
            "target_frame_rate_hz": 0.2
        }
    }
}
response = send_and_receive_event(socket, event_message)
print(f"RTSP stream configured: {response}")

CSV File Reader

Connect a CSV file for data streaming:

event_message = {
    "type": "input_stream.set",
    "event_data": {
        "stream_type": "csv_file_reader",
        "stream_config": {
            "file_id": "jena_climate_2009_2016.csv"
        }
    }
}
response = send_and_receive_event(socket, event_message)
print(f"CSV stream configured: {response}")

Available Input Stream Types

rtsp_video_streamer

Description: Real-time video streaming from RTSP camerasConfiguration Parameters:

rtsp_url (string): RTSP stream URL
target_image_size (array): [height, width] in pixels
target_frame_rate_hz (float): Frames per second to process

Use Cases: Security cameras, live monitoring, real-time analysis

csv_file_reader

Description: Stream data from uploaded CSV filesConfiguration Parameters:

file_id (string): ID of uploaded CSV file

Use Cases: Time series analysis, batch data processing, historical data analysis

sensor_streamer

Description: Direct sensor data streamingConfiguration Parameters:

Configuration varies by sensor type

Use Cases: IoT sensors, accelerometers, temperature sensors

Direct Model Queries

model.query

Send direct queries to Newton models with custom data payloads.

Image QA Example

import base64

# Load and encode image
with open("construction_site.jpg", "rb") as img_handle:
    base64_img = base64.b64encode(img_handle.read()).decode("utf-8")

event_message = {
    "type": "model.query",
    "event_data": {
        "model_version": "Newton::c1_6_241117d4362cc9",
        "template_name": "image_qa_template_task",
        "instruction": "Answer the following question about the image:",
        "focus": "Describe the safety equipment visible in the image.",
        "max_new_tokens": 512,
        "data": [{
            "type": "base64_img",
            "base64_img": base64_img
        }],
        "sensor_metadata": {}
    }
}

response = send_and_receive_event(socket, event_message)
print(f"Newton response: {response['result']}")

Object Detection Example

event_message = {
    "type": "model.query",
    "event_data": {
        "model_version": "Newton::c1_6_241117d4362cc9",
        "template_name": "image_bbox_template_task",
        "instruction": "Localize all objects in the picture and build bounding box around them.",
        "focus": "Input: [person,car,hard_hat,safety_vest]",
        "max_new_tokens": 512,
        "data": [{
            "type": "base64_img",
            "base64_img": base64_img
        }],
        "sensor_metadata": {}
    }
}

response = send_and_receive_event(socket, event_message)
print(f"Detected objects: {response['result']}")

Newton Model Templates

Available Templates

Image QA Template
Object Detection Template

Template Name: image_qa_template_taskPurpose: Generate narrative descriptions of imagesParameters:

instruction: Question or instruction for the model
focus: Specific aspect to focus on (e.g., “safety equipment”, “project status”)
max_new_tokens: Maximum response length (typically 512)

Output: Natural language descriptionExample Response:

{
  "result": "The image shows construction workers wearing yellow hard hats and high-visibility safety vests. Safety equipment is properly worn according to regulations.",
  "confidence": 0.92,
  "processing_time_ms": 340
}

Template Name: image_bbox_template_taskPurpose: Detect and localize objects with bounding boxesParameters:

instruction: Object detection instruction
focus: List of objects to detect (e.g., “Input: [person,car,dog]”)
max_new_tokens: Maximum response length

Output: Structured bounding box coordinatesExample Response:

{
  "result": "person: [0.15, 0.20, 0.45, 0.80]\nhard_hat: [0.25, 0.15, 0.35, 0.25]\nsafety_vest: [0.20, 0.35, 0.40, 0.65]",
  "confidence": 0.88,
  "processing_time_ms": 280
}

Error Handling

Handle WebSocket errors and connection issues:

import websocket
import json
import time

def robust_websocket_connection(session_endpoint, api_key):
    max_retries = 3
    retry_count = 0
    
    while retry_count < max_retries:
        try:
            socket = websocket.create_connection(
                session_endpoint,
                header={"Authorization": f"Bearer {api_key}"},
                timeout=30
            )
            return socket
        except Exception as e:
            retry_count += 1
            print(f"Connection attempt {retry_count} failed: {e}")
            if retry_count < max_retries:
                time.sleep(2 ** retry_count)  # Exponential backoff
            else:
                raise e

def safe_send_and_receive(socket, event_data, timeout=30):
    try:
        socket.settimeout(timeout)
        socket.send_binary(json.dumps(event_data).encode())
        response = json.loads(socket.recv())
        return response
    except websocket.WebSocketTimeoutException:
        raise Exception("WebSocket timeout - no response received")
    except websocket.WebSocketConnectionClosedException:
        raise Exception("WebSocket connection closed unexpectedly")

Best Practices

Connection Management

Always authenticate WebSocket connections with your API key
Implement connection retry logic with exponential backoff
Set appropriate timeouts for requests (30 seconds recommended)
Close connections properly to free resources

Event Handling

Use unique client_id for each client to enable parallel processing
Handle asynchronous events properly with session.read
Implement error handling for malformed responses
Log events for debugging and monitoring

Performance Optimization

Use appropriate image sizes for video streams (360x640 recommended)
Set reasonable frame rates (0.2 Hz for most use cases)
Monitor processing times and adjust accordingly
Batch similar queries when possible

Next Steps

Examples Repository

Explore complete working examples

Session Management

Monitor and manage active sessions

File Upload API

Upload files for CSV streaming

Troubleshooting

Solve common WebSocket issues

API Reference

Documentation Index

​Connection Setup

​1. Create a Lens Session

​2. Connect to WebSocket

​Event Message Format

​Session Events

​session.status

​session.validate

​session.read

​session.destroy

​Input Stream Configuration

​input_stream.set

​RTSP Video Stream

​CSV File Reader

​Available Input Stream Types

​Direct Model Queries

​model.query

​Image QA Example

​Object Detection Example

​Newton Model Templates

​Available Templates

​Error Handling

​Best Practices

​Next Steps

Examples Repository

Session Management

File Upload API

Troubleshooting

Connection Setup

1. Create a Lens Session

2. Connect to WebSocket

Event Message Format

Session Events

session.status

session.validate

session.read

session.destroy

Input Stream Configuration

input_stream.set

RTSP Video Stream

CSV File Reader

Available Input Stream Types

Direct Model Queries

model.query

Image QA Example

Object Detection Example

Newton Model Templates

Available Templates

Error Handling

Best Practices

Next Steps