Handle Infobip SMS delivery reports by setting up a webhook endpoint in your Node.js/Express application. This endpoint, specified by the notifyUrl parameter in your Infobip API request, receives real-time delivery updates in JSON format. Your application should then process this data, updating internal systems and triggering actions based on the delivery status (e.g., delivered, failed).

The notify URL is a crucial parameter in the Infobip SMS API. It's the publicly accessible URL of your application's webhook endpoint, where Infobip sends real-time delivery reports (DLRs). This URL must be reachable by Infobip for your application to receive status updates.

Infobip needs a callback URL (the notifyUrl) to send your application asynchronous updates about the delivery status of your SMS messages. This enables your system to react to successful deliveries, failures, or other status changes without constantly polling the Infobip API.

Use ngrok during local development with Infobip to create a publicly accessible URL for your webhook endpoint. Since Infobip needs to reach your local server for DLR callbacks, ngrok provides a tunnel from a public URL to your localhost, making testing and development easier.

You can implement retry mechanisms for failed Infobip SMS messages, but only for initial failures from the Infobip API (like network or 5xx errors), not for final statuses like 'UNDELIVERABLE'. Use exponential backoff to avoid overloading the system, but don't retry messages marked as permanently undeliverable by the carrier or Infobip.

The Infobip SMS notify content type is 'application/json'. This parameter specifies that delivery reports sent to your webhook endpoint will be in JSON format, making parsing and processing the data within your application more structured and efficient.

Set up Infobip DLR with Node.js by creating an Express.js server with two key endpoints: /send-sms to initiate message sending and /infobip-dlr to receive callbacks. The infobipService.js file contains the logic for sending SMS and handling API interactions using Axios.

The express.json() middleware in Express.js is essential for handling Infobip DLR callbacks. It parses incoming JSON payloads in POST requests, making the data accessible via req.body. This allows you to easily process delivery reports and update your application's internal state.

Dotenv helps manage environment variables securely when integrating with the Infobip API. It loads credentials like your API key from a .env file, keeping sensitive information out of your source code and version control.

To send SMS with the Infobip API and Node.js, use the sendSms function from infobipService.js. This function requires the recipient's phone number in international format and the message text. It handles constructing the API request, including headers, and making the request using Axios.

To test Infobip webhooks locally, expose your development server using ngrok and update the notifyUrl in your Infobip API requests to point to the generated ngrok HTTPS URL. This allows Infobip to reach your local server with DLR callbacks during development.

Structure a database for Infobip DLRs with a table for outgoing messages. Include fields for message details, Infobip message ID, recipient number, status, error codes, and timestamps. Index the infobip_message_id column for efficient lookup during callback processing.

Common status groups in Infobip DLRs include 'PENDING', 'UNDELIVERABLE', 'DELIVERED', 'EXPIRED', and 'REJECTED'. These groups provide a broad categorization of the message delivery status. More detailed status names within each group provide further information.

Best practices for logging Infobip DLRs include logging the full incoming request body to understand its structure and content. Log specific fields from each report, including messageId, status, recipient, and errors. Use structured logging and external logging services for improved analysis and alerting.

Implement security for your Infobip webhook endpoint by using HTTPS for secure communication. Optional security measures could include signature validation (if supported by Infobip) to verify the sender, and IP whitelisting if feasible. Basic input validation is also important for security and preventing unexpected input.