User login flow diagram spanning presentation, application, data, and authentication logic layers on OCI. The flow captures credential entry, database validation, password verification, and token generation with error handling paths returning users to the login page on failure. This architecture demonstrates secure authentication best practices including separation of concerns across tiers and explicit account/password validation gates. Fork and customize this diagram on Diagrams.so to adapt the flow for multi-factor authentication, social login, or OCI Identity and Access Management integration. The modular layer design allows teams to map each component to specific OCI services like API Gateway, Compute, and Database Cloud Service.