Safety-Critical Java Case Studies

We have recently put together a set of Safety-Critical Java applications. The implementation of these applications is open source, you can find them in our oSCJ repository, in directories oSCJ/examples and oSCJ/tools/checker/examples. The directories now contain more than 3O KLOC of Safety-Critical Java application code, here is a description of the most interesting case studies:

Quicksort is benchmark based on the quicksort algorithm. The application periodically sorts an array of objects that are allocated in an upper-scope, thus introducing a cross-scope manipulation of objects into the algorithm.

Thruster case-study simulates a spacecraft thruster engine. Control of the engine requires a 100-millisecond periodic activity to adjust the valve settings to avoid mechanical drift and, therefore, obtain an even fuel flow. Inspired by [Wellings-JTRES10].

Fast-MD5 implements a periodic execution of the Fast-MD5 encryption algorithm of a fixed string within its most inner memory area.

Webserver is an application handling http requests and was developed as a case study within the SquawkVM project to evaluate SCJ implementation running on SUN SPOTS embedded devices.

CDx-SCJ is an open-source family of benchmarks that can be used to measure performance of various hard and soft real-time platforms. The CDx benchmark consists of a periodic task that takes air traffic radar frames as input and predicts potential collisions.

Railsegment, developed by Kelvin Nilsen at Atego, is a complex simulator of a train control software that is responsible for collecting the data about speed and position of the train, analyzing them in real-time and adjusting the train speed according to the route plan.

Jpapabench is a SCJ benchmark based on the Paparazzi project which provides an open-source implementation of an autopilot for unmanned aerial vehicles (UAVs). The autopilot has been successfully tested on several real devices. The JPapabench is developed by Michal Malohlava at MFF UK, see the JPapabench webpage.

We believe that these applications are a representative set of SCJ case studies that demonstrate many SCJ concepts on real examples. 

A family of real-time Java benchmarks

Be sure not to miss a new publication on the Collision Detector (CDx) benchmark [PDF]. Tomas Kalibera and his team put together an updated journal publication on CDx.

The article also reports on our performance comparison of the oSCJ platform running on LEON3 boards. Although the paper reports 50% overhead of the oSCJ in comparison to the C version of the benchmark, we are happy to announce that in the last few months we have been able to further decrease the overhead to ~28%.

The figure shows are new measurement of the improved performance of oSCJ. Further, our most recent experiments suggest that we can do even better. Stay tuned.