Client Archive Server

Problem

The organization needed a modern and secure document archiving platform while continuing to depend on legacy SQL Server systems for branch and organizational data. Storing large physical documents directly within the main application would increase infrastructure load and complicate file management. The system also required strict branch-level access control and complete traceability of sensitive operations.

Solution

Client Archive Server was developed as a modern integration layer between users, legacy systems, and an external document archive service. MongoDB stores client data, document metadata, counters, and audit logs, while SQL Server remains the source for legacy branch information. Physical files are streamed through a secure proxy to the external Archive Service. The platform also implements RBAC, branch-level isolation, and comprehensive audit logging for operations such as creation, upload, deletion, and download.

Architecture

The system uses Next.js 15 and React 19 with the App Router, combining the frontend and API Gateway within a unified application. MongoDB with Mongoose handles modern application data, while a dedicated MSSQL connection pool integrates with the legacy system. A resilient proxy layer handles communication with the external Archive Service using retries, timeouts, and exponential backoff. Authentication, permissions, database connections, audit logging, and archive communication are separated into dedicated utility and service layers to improve maintainability and scalability.

Challenges

Integrating with a legacy SQL Server system without disrupting existing workflows. Implementing access control based on both user roles and organizational branches. Handling large document uploads and downloads without storing physical files in the main application. Maintaining reliability when the external Archive Service becomes temporarily unavailable. Creating detailed and auditable logs for sensitive operations. Maintaining performance as the number of branches, users, and documents grows.

Results

The result is a modern and scalable document archiving platform that bridges legacy infrastructure with a modern application layer without requiring a complete replacement of the existing system. Users can manage clients and documents through a unified interface with strict role and branch-based permissions, while physical files are handled by a dedicated external archive service. The platform also provides strong traceability through comprehensive audit logs and a flexible architecture that can support additional features and integrations in the future.