Migrating without breaking anything
The centerpiece is migrating the service layer from a legacy framework to a modern web API — more than 200 service operations — while carefully preserving backward compatibility, from legacy routes and request/response contracts to authentication behaviour, error handling and server communication. Every step is backed by automated parity and integration tests, because in a running industrial system there is no room for a migration that quietly changes behaviour.
Modern authentication and more
On top of that we implemented modern authentication and single sign-on across the web UI, auth services, API and control server, with secure token exchange and trusted-login flows that still interoperate with the existing mechanisms. Further work covers session management, authorization, server communication, alarm handling, configuration services, logging, exception mapping, and secure signal read/write operations — the full breadth of a platform that has to be both modern and completely dependable.
Technology
Built with .NET and ASP.NET Core Web API in C#, bridging to the legacy layer through WCF, with Keycloak and OpenID Connect/OAuth 2.0 for authentication, REST APIs and SCADA server integration, SQL Server for data, IIS for hosting and NLog for logging.
