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Python script for server side of IoT BOT to monitor BLE tags (for AWS lambda)
# -*- coding: utf-8 -*-
from datetime import datetime, timedelta, timezone
import boto3
from boto3.session import Session
from boto3.dynamodb.conditions import Key
TIMEOUT_SEC = 180
def lambda_handler(event, context):
# 現在時刻を取得
JST = timezone(timedelta(hours=+9), 'JST')
now = datetime.now(JST)
now_ut = int(now.strftime('%s'))
now_dt = now.strftime('%Y/%m/%d %H:%M:%S (JST)')
try:
# dynamodbのテーブルに接続
region = "ap-northeast-1"
session = Session(
region_name = region
)
dynamodb = session.resource('dynamodb')
table = dynamodb.Table('{your_table_name}')
response = {}
# 入力がタグ情報の場合、テーブルにタグ情報を追加(状態は不在=0)
if 'tag_info' in event.keys():
response['inserted'] = []
for info in event['tag_info']:
tid = info['tid']
name = info['name']
table.put_item(
Item = {
'tid' : tid,
'name' : name,
'exists' : 0,
'utime' : now_ut,
'datetime' : now_dt
}
)
response['inserted'].append({'tid': tid, 'name': name})
# 入力がタグ状態の場合、タグ状態に基づいてテーブルを更新しアクションを決定
# アクション:1=出現,0=消失
if 'tag_detected' in event.keys():
response['updated'] = []
queryData = table.scan()
for data in queryData['Items']:
tid = data['tid']
name = data['name']
exists = data['exists']
utime = data['utime']
dtime = data['datetime']
if tid in event['tag_detected']:
table.update_item(
Key = {
'tid' : tid
},
UpdateExpression = "set #e=:e, utime=:ut, #d=:dt",
ExpressionAttributeNames = { "#e":"exists", "#d":"datetime" },
ExpressionAttributeValues = {
':e' : 1,
':ut' : now_ut,
':dt' : now_dt
}
)
if not exists:
response['updated'].append({
'name': name,
'action': 1
})
elif exists and now_ut > utime + TIMEOUT_SEC:
table.update_item(
Key = {
'tid' : tid
},
UpdateExpression = "set #e=:e",
ExpressionAttributeNames = { "#e": "exists" },
ExpressionAttributeValues = {
':e' : 0
}
)
response['updated'].append({
'name': name,
'action': 0
})
# モニターからの受信ログを記録
if 'monitor_name' in event.keys():
table_log = dynamodb.Table('BLETagMonitor_MonitorLog')
table_log.put_item(
Item = {
'name' : event['monitor_name'],
'utime' : now_ut,
'datetime' : now_dt
}
)
return response
except Exception as e:
print(e)
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