Update readme (#62)

Author: ruhan1

README.md

@@ -1,40 +1,159 @@
-# indy-metadata-service
+# Indy Metadata Service
 
+A Quarkus-based microservice for managing metadata operations in the Indy artifact repository system. This service handles metadata file management, special path operations, and provides REST APIs for metadata-related operations.
 
-## Prerequisite
-1. jdk11
-2. mvn 3.6.2+
+## Overview
 
-## Configure services
+The Indy Metadata Service is part of the CommonJava Indy ecosystem and provides:
 
-To make it run, Infinispan and Kafka need to be configured. Please see the example in `application.yaml`.
+- **Metadata Management**: Automatic cleanup and management of metadata files (e.g., `maven-metadata.xml`, `package.json`)
+- **Group-Aware Operations**: Metadata updates propagate through repository group hierarchies
+- **Event-Driven Architecture**: Reactive processing of file events via Kafka
+- **RESTful APIs**: HTTP endpoints for metadata operations
+- **Multi-Package Support**: Support for Maven, NPM, and other package types
 
-## Try it
+## Architecture
 
-### 1. Start the cache server and the message broker
+### Core Components
 
-It needs a remote cache server(Infinispan) as well as the message broker(Kafka) for event handler. To ease the setup, we have provided a `docker-compose.yml` file which start the containers and bind the network ports.
+- **MetadataController**: Main business logic controller
+- **MetadataHandler**: Handles metadata deletion and cleanup operations
+- **FileEventConsumer**: Processes file events from Kafka for automatic metadata cleanup
+- **MetadataResource**: JAX-RS REST endpoints
 
-```
-docker-compose up
-```
+## API Endpoints
 
-### 2. Start gateway in debug mode
-```
-$ mvn quarkus:dev
+### Metadata Operations
+
+```http
+GET    /api/metadata/{packageType}/{type}/{name}/{path}
+DELETE /api/metadata/{packageType}/{type}/{name}/{path}
+GET    /api/metadata/{packageType}/{type}/{name}
 ```
 
-### 3. Verify the installation 
+**Parameters:**
+- `packageType`: Package type (maven, npm, etc.)
+- `type`: Store type (hosted, group, remote)
+- `name`: Store name
+- `path`: File path within the store
+
+## Configuration
+
+### Application Properties
+
+Key configuration options in `application.yaml`:
+
+```yaml
+quarkus:
+  http:
+    port: 8081
+    read-timeout: 30m
+    limits:
+      max-body-size: 500M
+
+kafka:
+  bootstrap:
+    servers: "localhost:9092"
 
+storage-service-api/mp-rest/url: http://localhost
+repo-service-api/mp-rest/url: http://localhost
 ```
-http://localhost:8080/swagger-ui/
+
+### Environment Variables
+
+- `KAFKA_BOOTSTRAP_SERVERS`: Kafka broker addresses
+- `STORAGE_SERVICE_API_MP_REST_URL`: Storage service URL
+- `REPO_SERVICE_API_MP_REST_URL`: Repository service URL
+
+## Development
+
+### Prerequisites
+
+- Java 11+
+- Maven 3.6+
+- Docker & Docker Compose (for local development)
+
+### Building
+
+```bash
+# Compile and run tests
+mvn clean compile test
+
+# Package the application
+mvn package
+
+# Run in development mode
+mvn quarkus:dev
 ```
 
-### 4. Check the entries on cache server
+### Docker Development
 
+```bash
+# Build the Docker image
+docker build -f src/main/image/Dockerfile.jvm -t indy-metadata-service .
+
+# Run with Docker Compose (includes Kafka)
+docker-compose up
 ```
-http://localhost:11222/console/
+
+### Local Development Setup
+
+1. Start Kafka and Zookeeper:
+   ```bash
+   docker-compose up zookeeper kafka
+   ```
+
+2. Configure external services (storage and repository services)
+
+3. Run the application:
+   ```bash
+   mvn quarkus:dev
+   ```
+
+## Event Processing
+
+The service processes two types of Kafka events and maintains consistency across repository group hierarchies:
+
+> **Important**: When a metadata file is updated in any repository, the service automatically propagates these changes up through the entire group hierarchy. For example, if a POM file is uploaded to a hosted repository, the metadata will be regenerated not only for that repository but also for all groups that contain it, all the way up to the root group.
+
+### File Events (`file-event` topic)
+- Triggers metadata cleanup when POM files or package tarballs are uploaded/deleted
+- Automatically clears corresponding metadata files in hosted repositories
+- **Group Propagation**: Updates cascade through all repository groups containing the affected repository
+
+### Promote Events (`promote-complete` topic)
+- Handles promotion completion events
+- Manages metadata updates across repository groups
+
+
+## Monitoring & Observability
+
+- **OpenTelemetry**: Distributed tracing support
+- **Structured Logging**: JSON-formatted logs with configurable levels
+- **Health Checks**: Built-in Quarkus health endpoints
+- **Metrics**: Application metrics via Micrometer
+
+## Testing
+
+```bash
+# Run unit tests
+mvn test
+
+# Run integration tests
+mvn verify
+
+# Run specific test class
+mvn test -Dtest=MetadataResourceTest
 ```
 
+## Dependencies
+
+- **Quarkus**: Reactive framework and runtime
+- **RESTEasy**: JAX-RS implementation
+- **SmallRye Reactive Messaging**: Kafka integration
+- **OpenTelemetry**: Observability
+- **Maven Repository Metadata**: Maven-specific metadata handling
 
+## License
 
+Licensed under the Apache License, Version 2.0. See the [LICENSE](LICENSE) file for details.