1. Copyright © 2001 Praxis Critical Systems Limited  New and Exciting Things in the World of SPARK Roderick Chapman Praxis Critical Systems

2. Copyright © 2001 Praxis Critical Systems Limited  Contents Release 6 What does the “R” stand for? SPARK and Security

3. Copyright © 2001 Praxis Critical Systems Limited  Release 6 - Language Modular types –Good for interfacing, crypto, checksums etc. –Binary modulus only. –No modular subtypes. Does anyone use them?!? –No unary arithmetic operators (-, +, abs). All rather useless. External variables –Variables which are known to be “connected” to the outside world. –Automatic treatment of volatility. –Allows far simpler modeling of I/O, clocks, delays and so on. “Null” derives annotation –Easier handling of testpoints, and other code “outside the SPARK boundary”

4. Copyright © 2001 Praxis Critical Systems Limited  Release 6 - Plan Commercial customers - soon! Universities - after that… “High Integrity Ada: The SPARK Approach” 3rd edition, including new Examiner and Simplifier. –“Difficulties” with current publisher will be addressed!

5. Copyright © 2001 Praxis Critical Systems Limited  SPARK - What does the “R” stand for? Don’t ask - but we might just change it to “Ravenscar” A Protected Object behaves like a volatile abstract state machine, but we know how to model those! External variables also mean we can include Ada.Real_Time and delay until.

6. Copyright © 2001 Praxis Critical Systems Limited  Ravenscar (2) Library level tasks and their analysis is easy - they just look like parameterless procedures. Elimination of bounded errors (e.g. blocking in a PO body) is also possible via extended annotations and static analysis thereof. Will be implemented in release 7.

7. Copyright © 2001 Praxis Critical Systems Limited  Something different SPARK and High-Security Systems SPARK is well-known in safety-critical arena. It also turns out that SPARK is well-suited to the needs to high-security software developments. The relevant standards (UK ITSEC, US Orange Book, Common Criteria) are at least as demanding as the comparable safety-critical standards. SPARK is the only language that meets the highest levels of Common Criteria requirements.

8. Copyright © 2001 Praxis Critical Systems Limited  Messages to go home with SPARK has a proven technical and commercial track-record in meeting the most stringent software standards (00-55, DO-178B, CENELEC) SPARK is also well-suited to the development of highly secure software systems. –All the depressingly common “implementation slips” that plague secure systems are eliminated in SPARK- e.g. dataflow error, “buffer overflow” Watch out for the Common Criteria