Non-Functional Requirements Non-functional requirements are the main forces driving architecture and design decisions, not the functional requirements. Because non-functional requirements mainly drive our design so you can begin developing your architecture while functional requirements are still incomplete or unstable. Non-functional requirements: Quality requirements Design Qualities: Conceptual Integrity, Maintainability and Reusability. Runtime Qualities: Availability, Interoperability, Manageability, Performance, Reliability, and Scalability.System and User Qualities: Supportability, Testability, Usability. Cross Cutting Concerns Security, Configuration, Communication, Caching, Exception Handling, State Management, Logging, Monitoring. IT ConstraintsSystems Management, Installation, Integration with other systems, Company Standards/Policies. Others Constraints/factors:Legal, Packaging, Licensing, Cost, Time to market.