Alarm Data Transmission Protocol

📌 Overview

• tcpjson: Based on TCP + JSON
• http: Based on HTTP POST (multipart)

Both support sending alarm metadata and a JPEG image.

✅ Alarm Data Format (Common JSON)

{
  "type": "carehome",
  "camIP": "192.168.1.88",
  "curTime": "2025-06-18T16:25:00",
  "stats": {
    "emergency": 1,
    "alert": 1
  },
  "image": "base64-encoded-image-data"
}

Field	Type	Description
type	string	Fixed value: "carehome"
camIP	string	Camera IP address
curTime	string	Alarm trigger time formatted in ISO 8601 standard
stats	object	Status indicators, including emergency, alert, notice
image	string (Base64)	Encoded JPEG image

Details of the stats field:

• emergency: Indicates the elderly person has fallen or is lying on the ground. This is a critical emergency that requires immediate attention.
• alert: Indicates the elderly person is sitting or kneeling on the ground, which is a serious condition needing concern.
• notice: Indicates the elderly person has been sitting in a wheelchair without movement for an extended period. This is a condition that should be monitored.

🔗 Protocol 1: TCP + JSON

• Protocol: TCP
• Example Address: 192.168.0.35:9001

Data format:

#lonrock-carehome#{JSON_CONTENT}$$

• #lonrock-carehome#: Start marker
• $$: End marker

Example:

#lonrock-carehome#{
  "type": "carehome",
  "camIP": "192.168.1.88",
  "curTime": "2025-06-18T16:25:00",
  "stats": {"emergency":1},
  "image": "/9j/4AAQSkZJRgABAQAAAQABAAD..."
}$$

🌐 Protocol 2: HTTP POST

• Protocol: HTTP 1.1 POST
• URL Format: http://<ip>:<port>/<path> (e.g. http://192.168.0.35:8080/alarm)
• Content-Type: multipart/form-data

Form fields:

Field	Type	Description
content	text	JSON alarm info (without image Data)
image	file	JPEG image file

Example of content:

{
  "type": "carehome",
  "camIP": "192.168.1.88",
  "curTime": "2025-06-18T16:25:00",
  "stats": {
    "alert": 1
  }
}

Example of image: Upload a JPEG file, such as alarm.jpg

🧪 Server Implementation Notes

For TCP + JSON:

• Listen on TCP socket and detect message boundaries using start/end markers
• Parse JSON and decode image from Base64

For HTTP POST:

• Use multipart/form-data parser to extract content and image
• Save image to disk and process alarm info from JSON

📎 Notes & Recommendations

• Alarm client does not retry on failure; failed messages will be lost
• Keep server listening and ports open to avoid connection issues