Message Processing Application

Overview

The Message Processing Application is a Spring Boot–based service responsible for sending messages, tracking their delivery status, and maintaining a message history.
It is designed to be concurrent-safe, idempotent, and resilient under high load.

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Features

• Message creation and sending
• Asynchronous message processing worker
• Message history persistence
• Opt-out support by phone number
• OpenAPI / Swagger UI support

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Technology Stack

• Java 21
• SpringBoot
• Hibernate
• Spring Validation
• Springdoc OpenAPI
• H2 (in-memory db)

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Core Components

• MessageController and OptOutController
  • REST APIs for sending messages and opt-out
• MessageService
  • Orchestrates message creation and processing
• MessageWorker
  • Handles concurrent message delivery
• MessageHistoryService
  • Persists message history entries
• GatewayRegistry
  • Routes messages to delivery gateways

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Message Processing Flow

• Client sends a message via API
• Message is persisted with status PENDING
• Worker picks up the message
• Status transitions:
  • PENDING → SENT → DELIVERED / BLOCKED / FAILED
• Message history is stored
• Optimistic locking ensures only one worker processes a message

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API Documentation

Swagger UI is available at: http://localhost:8080/swagger-ui/index.html

Running the Application

Prerequisites:

• Java 21
• Maven

Run locally

mvn clean spring-boot:run

Testing

Run tests:

mvn test