This is my read me
# Medics Event Publisher

The Medics Event Publisher is a Node.js application designed to handle almost real-time event publishing for the medics. It integrates with Kafka for reliable event processing, MySQL for storing event data, and provides a scalable and robust solution for managing thousands of transactions per second. It's designed to handle high volumes of transactions and ensure data consistency, even when the Kafka service is temporarily unavailable.

## Table of Contents

- [Overview](#overview)
- [Features](#features)
- [Project Structure](#project-structure)
- [Installation](#installation)
- [Configuration](#configuration)
- [Usage](#usage)
- [Dockerization](#dockerization)
- [Error Handling](#error-handling)
- [Concurrency and Performance](#concurrency-and-performance)
- [Backpressure Handling](#backpressure-handling)
- [Worker Threads](#worker-threads)
- [Metrics and Monitoring](#metrics-and-monitoring)
- [Dependencies](#dependencies)
- [Further Development](#further-development)
- [License](#license)

## Overview

The Medics Event Publisher is a critical component of the hospital information management system, responsible for real-time event processing and publishing. It ensures the seamless flow of transactions, such as bills, receipts, advances, refunds, lab reports, and goods receipt notes, from the Medics application to downstream systems.

## Features

- Real-time event processing and publishing with Kafka.
- MySQL integration for storing event data.
- Error handling and retry mechanisms for robustness.
- Backpressure handling to manage high-throughput scenarios.
- Scalable architecture to handle thousands of transactions per second.

## Project Structure

The project follows a modular structure for better organization:

- `medics-event-publisher.js`: Main entry point for the application.
- `src/`: Source code directory.
  - `config/`: Configuration files.
    - `config.json`: Configuration settings for Kafka, MySQL, and other services.
  - `services/`: Reusable service modules.
    - `KafkaService.js`: Handles Kafka integration, message publishing, and retry logic.
    - `Logger.js`: Provides a logging service for the application.
    - `SQLConnectionManager.js`: Manages MySQL database connections.

## Installation

1. Clone the repository:

   ```bash
   git clone git@gitlab:medics/medics-event-publisher.git
   ```

````

2. Install dependencies:

   ```bash
   cd medics-event-publisher
   npm install
   ```

## Configuration

- Update the `config/config.json` file with the appropriate configurations for Kafka, MySQL, and other services.

## Usage

1. Run the application:

   ```bash
   node medics-event-publisher.js
   ```

2. Monitor health status:

   Open a web browser and visit `http://localhost:<PORT>/health` to check the health status of the application.

## Dockerization

To run the application in a Docker container, follow these steps:

1. Build the Docker image:

   ```bash
   ./build.sh
   ```

2. Run the Docker container:

   ```bash
   ./run.sh
   ```

## Error Handling

The application handles errors at various levels to ensure robustness. It logs errors, retries message publishing in case of failures, and provides detailed error messages in case of critical issues.

## Concurrency and Performance

The use of worker threads enables parallel event processing, improving the application's performance. Adjust the `MAX_WORKERS` variable in the configuration to control the number of worker threads.

## Backpressure Handling

Backpressure handling is implemented to manage scenarios of high throughput. The application pauses producing or buffers messages when necessary to alleviate backpressure.

## Worker Threads

The application utilizes worker threads for concurrent event processing. Each worker thread has its own database connection and is responsible for processing a batch of events.

## Metrics and Monitoring

The application collects and monitors various metrics to assess its health and performance. Metrics include but are not limited to:

- Kafka producer metrics (e.g., message throughput, latency).
- Database connection pool metrics.
- Worker thread utilization and performance metrics.

## Dependencies

- `kafkajs`: Kafka library for Node.js.
- `mysql2`: MySQL library for Node.js.
- `node-locksmith`: Lock management library for handling application instances.
- `winston`: Logging library for Node.js.

## Further Development

While the Medics Event Publisher is currently a robust solution for real-time event processing, there are opportunities for further development:

- **Enhanced Monitoring**: Integrate with a comprehensive monitoring solution for in-depth insights into application performance.
- **Dynamic Configuration**: Implement dynamic configuration reloading to allow for on-the-fly adjustments without restarting the application.
- **Additional Retry Strategies**: Explore and implement additional retry strategies for message publishing, considering exponential backoff and jitter.
````