Automated Response to Sensor Events

Automated Event-Driven Agent Responses

Defining Action Policies

ACTION_POLICIES = [
    {
        'name': 'HIGH_TEMP_ALERT',
        'topic': 'sensors/temperature',
        'condition': lambda v: v > 38,
        'priority': 'critical',
        'actions': ['TURN_ON_COOLING', 'ALERT_MAINTENANCE', 'LOG_EVENT']
    },
    {
        'name': 'HIGH_TEMP_WARNING',
        'topic': 'sensors/temperature',
        'condition': lambda v: 35 < v <= 38,
        'priority': 'warning',
        'actions': ['ALERT_MAINTENANCE', 'LOG_EVENT']
    },
    {
        'name': 'LOW_HUMIDITY',
        'topic': 'sensors/humidity',
        'condition': lambda v: v < 30,
        'priority': 'warning',
        'actions': ['TURN_ON_HUMIDIFIER', 'LOG_EVENT']
    }
]

def match_policies(topic: str, value: float) -> list:
    return [
        p for p in ACTION_POLICIES
        if p['topic'] == topic and p['condition'](value)
    ]

if __name__ == '__main__':
    matches = match_policies('sensors/temperature', 39)
    print('Matched policies for temperature=39:')
    for p in matches:
        print(f"  {p['name']} ({p['priority']}): {p['actions']}")

Action Queue

import queue
import threading
from datetime import datetime

action_queue: queue.Queue = queue.Queue(maxsize=500)

def enqueue_action(action_name: str, context: dict, priority: str = 'normal'):
    item = {
        'action': action_name,
        'context': context,
        'priority': priority,
        'enqueued_at': datetime.utcnow().isoformat()
    }
    try:
        action_queue.put_nowait(item)
        print(f'Enqueued: {action_name}')
    except queue.Full:
        print(f'WARNING: Action queue full, dropping {action_name}')

def action_worker(executor_fn):
    """Run in a background thread, executing actions from the queue."""
    while True:
        item = action_queue.get()
        try:
            executor_fn(item['action'], item['context'])
        except Exception as e:
            print(f'Action failed: {item["action"]} — {e}')
        finally:
            action_queue.task_done()

# Start worker thread:
# worker_thread = threading.Thread(target=action_worker, args=(execute_action,), daemon=True)
# worker_thread.start()

if __name__ == '__main__':
    enqueue_action('TURN_ON_COOLING', {'zone': 'server-room'}, priority='critical')
    enqueue_action('LOG_EVENT', {'msg': 'temperature nominal'})
    print('Queue size:', action_queue.qsize())

Event Deduplication

class EventDeduplicator:
    def __init__(self):
        # active_events: (topic, policy_name) -> event_start_time
        self._active: dict = {}

    def is_new_event(self, topic: str, policy_name: str) -> bool:
        key = (topic, policy_name)
        return key not in self._active

    def mark_active(self, topic: str, policy_name: str):
        self._active[(topic, policy_name)] = datetime.utcnow()

    def clear_event(self, topic: str, policy_name: str):
        key = (topic, policy_name)
        if key in self._active:
            duration = (datetime.utcnow() - self._active.pop(key)).seconds
            print(f'Event cleared: {policy_name} (lasted {duration}s)')

    def clear_topic_if_normal(
        self, topic: str, value: float, normal_fn
    ):
        if normal_fn(value):
            keys = [k for k in self._active if k[0] == topic]
            for k in keys:
                self.clear_event(k[0], k[1])

dedup = EventDeduplicator()
dedup.mark_active('sensors/temperature', 'HIGH_TEMP_ALERT')
print('New event?', dedup.is_new_event('sensors/temperature', 'HIGH_TEMP_ALERT'))

Cool-Down Period

from datetime import datetime, timedelta

class CoolDownManager:
    def __init__(self, cool_down_minutes: int = 15):
        self.cool_down = timedelta(minutes=cool_down_minutes)
        self._cleared_at: dict = {}  # (topic, policy) -> cleared_datetime

    def is_in_cool_down(self, topic: str, policy_name: str) -> bool:
        key = (topic, policy_name)
        cleared_at = self._cleared_at.get(key)
        if cleared_at is None:
            return False
        return datetime.utcnow() - cleared_at < self.cool_down

    def record_clear(self, topic: str, policy_name: str):
        self._cleared_at[(topic, policy_name)] = datetime.utcnow()

    def time_remaining(self, topic: str, policy_name: str) -> int:
        key = (topic, policy_name)
        cleared_at = self._cleared_at.get(key)
        if cleared_at is None:
            return 0
        elapsed = datetime.utcnow() - cleared_at
        remaining = self.cool_down - elapsed
        return max(0, int(remaining.total_seconds()))

cooldown = CoolDownManager(cool_down_minutes=15)
cooldown.record_clear('sensors/temperature', 'HIGH_TEMP_ALERT')
print('In cool-down?', cooldown.is_in_cool_down('sensors/temperature', 'HIGH_TEMP_ALERT'))

LLM-Assisted Action Decision

import anthropic
import json

def llm_decide_actions(
    sensor_readings: dict,
    active_policies: list
) -> list:
    client = anthropic.Anthropic(api_key='YOUR_API_KEY')
    context = json.dumps({
        'readings': sensor_readings,
        'triggered_policies': [p['name'] for p in active_policies]
    }, indent=2)
    prompt = (
        f'Current sensor state:\n{context}\n\n'
        'Multiple alert policies are active. '
        'Recommend an ordered list of actions to take. '
        'Consider conflicting effects (e.g., humidifier and cooling may conflict).\n'
        'Return JSON: {"recommended_actions": [str], "reasoning": str}'
    )
    response = client.messages.create(
        model='claude-opus-4-5', max_tokens=512,
        messages=[{'role': 'user', 'content': prompt}]
    )
    return json.loads(response.content[0].text)

Executing Actions via MQTT

import json
import uuid
from datetime import datetime, timedelta

ACTION_TOPICS = {
    'TURN_ON_COOLING': 'devices/hvac/commands',
    'TURN_OFF_COOLING': 'devices/hvac/commands',
    'TURN_ON_HUMIDIFIER': 'devices/humidifier/commands',
    'ALERT_MAINTENANCE': 'notifications/maintenance',
    'LOG_EVENT': 'logs/agent_events'
}

def execute_action(action_name: str, context: dict, mqtt_client) -> str:
    topic = ACTION_TOPICS.get(action_name)
    if not topic:
        print(f'No topic defined for action: {action_name}')
        return 'unknown_action'

    request_id = str(uuid.uuid4())[:8]
    ttl = (datetime.utcnow() + timedelta(minutes=5)).isoformat()
    payload = json.dumps({
        'action': action_name,
        'request_id': request_id,
        'context': context,
        'ttl': ttl
    })
    mqtt_client.publish(topic, payload, qos=1)
    print(f'Executed {action_name} -> {topic} (req={request_id})')
    return request_id

if __name__ == '__main__':
    class FakeMQTT:
        def publish(self, topic, payload, qos=1):
            pass

    execute_action('TURN_ON_COOLING', {'zone': 'server-room'}, FakeMQTT())

Action Acknowledgement

import threading
from collections import defaultdict

class AckTracker:
    def __init__(self, timeout_seconds: int = 30):
        self.timeout = timeout_seconds
        self._pending: dict = {}  # request_id -> {'action', 'send_time', 'ack_event'}

    def register(self, request_id: str, action_name: str):
        event = threading.Event()
        self._pending[request_id] = {
            'action': action_name,
            'send_time': datetime.utcnow(),
            'ack_event': event
        }
        # Schedule timeout check
        t = threading.Timer(self.timeout, self._on_timeout, args=[request_id])
        t.daemon = True
        t.start()

    def acknowledge(self, request_id: str):
        entry = self._pending.pop(request_id, None)
        if entry:
            entry['ack_event'].set()
            print(f'Ack received for {entry["action"]} (req={request_id})')

    def _on_timeout(self, request_id: str):
        if request_id in self._pending:
            action = self._pending.pop(request_id)['action']
            print(f'TIMEOUT: No ack for {action} (req={request_id}) — retry?')

Full Sensor Event Pipeline

class IoTAgentPipeline:
    def __init__(self, mqtt_client):
        self.mqtt = mqtt_client
        self.dedup = EventDeduplicator()
        self.cooldown = CoolDownManager(cool_down_minutes=15)
        self.ack_tracker = AckTracker(timeout_seconds=30)

    def on_sensor_message(self, topic: str, value: float):
        policies = match_policies(topic, value)
        self.dedup.clear_topic_if_normal(
            topic, value,
            normal_fn=lambda v: v <= 35  # below warning threshold
        )

        for policy in policies:
            name = policy['name']
            if not self.dedup.is_new_event(topic, name):
                continue  # already active, skip
            if self.cooldown.is_in_cool_down(topic, name):
                print(f'In cool-down: {name}')
                continue

            self.dedup.mark_active(topic, name)
            ctx = {'topic': topic, 'value': value, 'policy': name}
            for action in policy['actions']:
                enqueue_action(action, ctx, policy['priority'])

Escalation Path

import requests

def escalate_to_human(
    reason: str,
    sensor_data: dict,
    webhook_url: str = 'https://hooks.slack.com/services/YOUR/SLACK/WEBHOOK'
):
    message = {
        'text': (
            f'*IoT Agent Escalation* \n'
            f'Reason: {reason}\n'
            f'Sensor data: {sensor_data}\n'
            f'Time: {datetime.utcnow().isoformat()}'
        )
    }
    try:
        response = requests.post(webhook_url, json=message, timeout=5)
        response.raise_for_status()
        print(f'Escalation sent: {reason}')
    except requests.RequestException as e:
        print(f'Escalation failed: {e}')
        # Fall back: log to file
        with open('escalations.log', 'a') as f:
            import json
            f.write(json.dumps({'reason': reason, 'data': sensor_data}) + '\n')

Testing the Event Pipeline

import time

def test_high_temp_policy_fires_once():
    dedup = EventDeduplicator()
    cooldown = CoolDownManager(cool_down_minutes=0)  # disable cooldown for test
    pipeline = IoTAgentPipeline(None)
    pipeline.dedup = dedup
    pipeline.cooldown = cooldown

    actions_fired = []
    action_queue.queue.clear()

    # Fire same event 5 times in a row
    for _ in range(5):
        pipeline.on_sensor_message('sensors/temperature', 40.0)

    # Only 1 set of actions should have been enqueued
    actions = list(action_queue.queue)
    assert len(actions) > 0, 'At least one action should fire'
    print(f'Actions enqueued: {len(actions)} (expected: just 1 event worth)')
    return True

result = test_high_temp_policy_fires_once()
print('Test passed:', result)

Knowledge Check

Recap: Automated Response to Sensor Events