This article outlines the architecture depicted in the provided diagram, detailing its key components and their interactions. The architecture integrates several essential technologies and services to deliver a robust, secure, and scalable IT solution.

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1. Network Infrastructure

Router and Firewall

• Acts as the first line of defense against external threats.
• Facilitates secure communication between external clients (e.g., Android/iOS apps, web browsers) and the internal infrastructure.

Layer 2 Switch

• Provides internal network connectivity, ensuring efficient data transmission between servers and services.
• Operates at the data link layer to manage communication within the local network.

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2. Access and Proxy Layer

Nginx Reverse Proxy

• Handles incoming requests and routes them to appropriate backend services.
• Provides SSL termination, load balancing, and caching for optimized performance.
• Integrates with Keycloak for authentication and authorization.

Keycloak

• Centralized identity and access management system.
• Manages user authentication (e.g., OAuth2, OpenID Connect) and authorization.
• Ensures secure access to backend services and APIs.

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3. Application Layer

Apache with PHP-FPM

• Hosts the application logic, handling user requests and executing PHP scripts.
• Collaborates with Nginx for efficient request handling.
• Integrates with backend services such as MySQL, Redis, and RabbitMQ.

Redis

• Provides session handling for fast and reliable data storage.
• Ensures user session persistence and scalability for high-traffic applications.

RabbitMQ

• Message broker for asynchronous communication between services.
• Manages background task queues and decouples components for better performance.

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4. Database Layer

MySQL Master-Slave Configuration

• MySQL Master: Handles write operations and processes complex queries.
• MySQL Slave: Maintains a replicated copy of the master database for read operations, ensuring high availability and load balancing.
• Supports horizontal scalability and reduces the load on the master database.

Sphinx Full-Text Search

• Provides fast and efficient indexing and full-text search capabilities.
• Works alongside MySQL for enhanced data retrieval, especially in large datasets.

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5. Email and Communication Layer

Proxmox Mail Gateway

• Protects the email system from spam and malware.
• Acts as a relay between external email services and the internal mail server.

Mail Server (Postfix/Dovecot)

• Postfix: Handles email delivery.
• Dovecot: Manages email retrieval through POP/IMAP/Swift protocols.
• Integrated with SpamAssassin for spam filtering.

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6. External Interfaces

Clients

• Android/iOS Devices: Access the system via mobile apps.
• Web Browsers: Interact with the system through a web interface.
• IoT Devices: Extend functionality for smart devices and sensors.

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7. Data Flow and Communication

1. Client Interaction:
   • External devices (e.g., Android, web browsers) send requests via the internet.
   • Requests are routed through the router, firewall, and Layer 2 switch to reach the Nginx reverse proxy.
2. Authentication and Authorization:
   • Nginx forwards requests to Keycloak for user authentication and authorization.
   • Once validated, requests are sent to the backend application hosted on Apache with PHP-FPM.
3. Session and Cache Management:
   • Redis handles user sessions to ensure a seamless experience.
4. Database Operations:
   • Application writes data to the MySQL master database and reads from the MySQL slave for optimized performance.
   • Sphinx indexes data from MySQL for enhanced search capabilities.
5. Message Queues:
   • Background tasks and inter-service communication are managed via RabbitMQ.
6. Email Management:
   • Proxmox Mail Gateway processes incoming and outgoing emails, securing them from spam and malware.
   • Postfix and Dovecot handle email delivery and retrieval for end-users.

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8. Scalability and Reliability

• The architecture ensures scalability with a master-slave database setup and independent components.
• Fault tolerance is achieved through message queuing and replication.
• Reverse proxy and caching mechanisms enhance performance under heavy loads.

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Conclusion

This architecture is a well-structured solution for modern applications, balancing security, scalability, and performance. By leveraging industry-standard tools like Nginx, Keycloak, Redis, RabbitMQ, and MySQL, it provides a resilient and adaptable foundation for diverse use cases.