Overview
ISO/IEC TR 24718:2005 - "Guide for the use of the Ada Ravenscar Profile in high integrity systems" is a Technical Report that documents the motivations, definition, analysis techniques and usage examples for the Ada Ravenscar Profile. Adopted from a University of York technical report, it explains how a restricted subset of Ada tasking can be used to achieve determinism, schedulability analysis and memory-boundedness required for real‑time, high‑integrity systems. The guide shows how Ravenscar-conformant programs can be analysed, verified and mapped to small, certifiable run‑time systems.
Key Topics
- Ravenscar Profile definition: the specific subset of Ada tasking (applied via pragma Profile(Ravenscar)) designed for predictability and analysability.
- Deterministic execution and memory-boundedness: restrictions and runtime semantics that support bounded resources and predictable timing.
- Static models and restrictions: concepts such as a static existence model and static synchronization/communication model to avoid dynamic, non-deterministic behavior.
- Scheduling and timing analysis: guidance for schedulability checks including priority assignment, rate‑monotonic and response‑time analysis and documentation of run‑time overheads.
- Verification techniques: recommended static and formal analyses - static code analysis, information‑flow checks, execution‑order analysis, model checking and formal certification approaches.
- Practical examples: canonical patterns (cyclic tasks, event‑triggered tasks, protected objects, synchronization primitives) and a worked extended example illustrating implementation and verification considerations.
- Run‑time and safety considerations: discussion of dispatching, locking and queuing policies, runtime errors unique to Ravenscar, and restrictions such as exception handling policies.
Applications
- Designed for real‑time, safety‑ and mission‑critical systems where predictability and verifiability are essential. Typical application areas include avionics, rail, automotive, medical devices and industrial control - essentially any embedded system requiring high integrity and certification evidence.
- Useful for engineers who need to produce software that is amenable to formal analysis, static verification and certification to high assurance levels.
Who should use this standard
- Real‑time and embedded software architects and developers using Ada.
- Safety engineers and certification teams preparing evidence for high integrity assurance.
- Tool vendors and runtime implementers building small, analyzable Ada run‑time systems or static analysis and scheduling analysis tools.
Related standards
- ISO/IEC 8652 - Ada programming language standard.
- ISO/IEC TR 15942 - Guide for the use of Ada in high integrity systems.
These references provide the broader Ada language context and high‑integrity guidance that complement ISO/IEC TR 24718:2005.
Keywords: Ada Ravenscar Profile, ISO/IEC TR 24718:2005, high integrity systems, real‑time, determinism, schedulability analysis, memory‑boundedness, static analysis, model checking, Ada run‑time.