Local Service for Real-Time Healthcare Platform Ecosystem

Business Challenge (Business Problem)

Healthcare units across the network needed to synchronize local on-premise databases with a centralized cloud-based real-time system. However, challenges such as intermittent internet connectivity, firewall restrictions, and the need for secure, continuous WebSocket communication made direct cloud connections unreliable.
The core problem was ensuring real-time synchronization of appointments, registrations, payments, and patient updates from over 500+ healthcare units, while maintaining data integrity, security, and connection resilience.

Vision & Strategy (High-Level Goal)

The goal was to design a lightweight, resilient local service capable of:

• Bridging the on-prem database with the WebSocket Gateway hosted in the cloud.

• Maintaining persistent and self-healing WebSocket connections to ensure uninterrupted real-time data exchange.

• Enabling secure and standardized communication across heterogeneous environments.
  This service would act as the foundation of the platform’s real-time capabilities, ensuring clinics could remain connected even in constrained or fluctuating network environments.

Architecture Solution (Architecture Design)

A. High-Level Flow

• Each healthcare unit runs a Local Windows Service that establishes a secure WebSocket connection with the cloud WebSocket Gateway.

• The service continuously performs ping-pong heartbeat events to maintain live connectivity.

• When an event (registration, appointment, or payment) occurs locally, the service sends it via WebSocket to the cloud in real time.

• Incoming cloud updates are reflected back into the local SQL Server database.

• Logs, errors, and connection health states are continuously monitored and auto-recovered.

(Visualized in the Context Diagram)

B. Components Interaction

• Local Database (SQL Server): Source of truth for clinic-level transactions.

• Local Service (C# .NET): Engine managing data exchange and maintaining persistent WS connections.

• WebSocket Gateway (Node.js): Central relay distributing real-time updates to and from all clinics.

• API Bridge: Facilitates coordination with the main Web API Gateway when REST-based operations are required.

• Logging & Monitoring Layer: Captures connection lifecycle events (connect, close, error, unexpected shutdown) with auto-recovery logic.

(Visualized in the Container Diagram)

C. Detailed Flow (Component View)

• Connection Layer:

  • Initiates WebSocket connection to the central gateway with JWT-based authentication and SSL (RSA private key + certificate).

  • Maintains active sessions through ping-pong and heartbeat validation.

• Schema Layer:

  • Defines a generalized request/response schema, supporting scalable message types without structural changes.

• Security Layer:

  • Utilizes crypto-js for encryption/decryption of sensitive payloads.

  • Employs jsonwebtoken for identity validation.

• Logging & Recovery Layer:

  • Implements daily rotating logs, categorized by connection events (connect, message, error, unexpected close).

  • Automatically removes stale or disconnected clients from the connection pool.

(Visualized in the Component Diagram)

Architectural Decision Records (ADRs)

• Language Selection:
  Implemented in C# (.NET Windows Service) due to the clinic’s existing infrastructure (SQL Server, .NET Desktop Apps), enabling seamless local integration.

• Cross-Technology Integration:
  Despite the backend using Node.js WebSocket Server, the hybrid model was chosen for compatibility, cost-effectiveness, and maintainability.

• Security Architecture:
  Enforced JWT-based authentication and RSA + SSL encryption for all data exchanges.

• Scalability Approach:
  Introduced generalized JSON schemas allowing future event types without code changes.

• Reliability:
  Built-in auto-reconnect and connection health monitoring mechanisms to handle network drops or firewall interruptions.

Key Achievements (Business Impact)

• Enabled 500+ remote healthcare units to stay connected with real-time synchronization.

• Reduced data sync failures by over 90% through robust auto-reconnect and monitoring.

• Improved security posture with end-to-end encryption and JWT authentication.

• Supported seamless integration of VoIP, appointment booking, and payment modules without architectural changes.

• Proved to be a future-proof design, sustaining long-term scalability and maintainability across mixed tech stacks.

• Established a key architectural foundation that now underpins all real-time operations within the healthcare platform ecosystem.