Message Passer

Example Path: examples/WebClient/MessagePasser

MessagePasser

A real-time messaging application that periodically sends timestamped messages to a remote server via HTTP POST requests.

Overview

MessagePasser is an embedded C++ application designed to communicate with a remote web service. The application continuously sends JSON-formatted messages containing device identification, uptime information, and timestamped messages to a specified HTTP endpoint.

Features

• Automatic Device Identification: Uses the device's MAC address as a unique identifier
• Real-time Communication: Sends HTTP POST requests with JSON payloads
• Uptime Tracking: Reports system uptime with each message
• Network Integration: Waits for active network connection (DHCP) before operation
• Periodic Messaging: Sends messages every 10 seconds automatically
• JSON Response Handling: Processes server responses and displays success status

Application Flow

1. Initialization: System initialization and diagnostics enablement
2. Network Setup: Waits up to 5 seconds for active network connection
3. Message Loop: Continuous loop that:
   • Creates timestamped messages
   • Sends JSON data to remote server
   • Processes server responses
   • Waits 10 seconds before next iteration

Message Format

The application sends JSON messages with the following structure:

{
  "DEVICEID": "AABBCCDDEEFF",
  "UPTIME": 12345,
  "MESSAGE": "At the tone the time will be: 12345"
}

Where:

• DEVICEID: 12-character hexadecimal string representing the device MAC address
• UPTIME: Current system uptime in seconds
• MESSAGE: Timestamped message string

Server Endpoints

The application is configured to communicate with:

• Primary: http://burnedcloud.herokuapp.com/messagehandler
• Alternative (commented): http://66.27.60.212:9090/

Implementation Details

Key Functions

• SendRxMessage(const char *msg): Modern JSON object-based message sending
• SendManualRxMessage(const char *msg): Manual JSON string formatting (alternative implementation)
• UserMain(void *pd): Main application entry point and message loop

Dependencies

The application requires several system libraries:

• init.h: System initialization
• stdio.h: Standard I/O operations
• ctype.h: Character type functions
• buffers.h: Buffer management
• json_lexer.h: JSON parsing capabilities
• webclient/http_funcs.h: HTTP client functionality
• netinterface.h: Network interface management

Network Requirements

• Active network interface with DHCP configuration
• Internet connectivity to reach the remote server
• HTTP POST capability

Configuration

Timing Parameters

• Network Wait: 5 seconds maximum for DHCP address acquisition
• Message Interval: 10 seconds between transmissions
• HTTP Timeout: 10 seconds for server response

Customization Options

• Server URL can be modified by changing the Url constant
• Message content can be customized in the UserMain function
• Timing intervals can be adjusted by modifying the OSTimeDly parameters

Output

The application provides console output including:

• Application startup confirmation
• Success/failure status for each HTTP request
• Server response messages
• Error notifications for failed requests

Use Cases

This application is suitable for:

• IoT device monitoring and reporting
• Remote system status updates
• Periodic data collection from embedded devices
• Network connectivity testing and validation

Technical Notes

• Built for embedded systems with real-time OS capabilities
• Uses system ticks for timing (TICKS_PER_SECOND)
• Implements proper JSON object building and parsing
• Includes system diagnostics for development/debugging