Andy Wellings Andy Wellings Home Page See our new book on Analysable Real-Time Systems Andy Wellings is an Emeritus Professor in the Department of Computer Science, University of York, U.K. His research interests are focused on two related areas of computing: the design, use and implementation of real-time programming languages and operating systems; and the design and use of general purpose distributed operating systems. Professor Wellings has published over 350 technical papers and reports, including five textbooks. Andy's research interests revolve around architecture-neutral real-time systems. These are real-time systems whose target architectures are unknown at systems design time. Architecture-neutral real-time systems are typically intended for embedded systems or hand-held devices; however, they are also applicable to Internet applications. The target architecture is unknown because: they have to be executable on the widest range of architectures possible in order to increase their portability; their lifetime is expected to be greater than ten years and, therefore, they have to be immune to technology obsolescence; their site of execution may vary. Architecture-neutral real-time systems are at odds with traditional real-time systems because traditional systems typically need: known (or bounded) processing resource demand - by definition the resources needed by an architecture-neutral system will depend on the power of the site hosting its execution; efficient and predictable execution - most architecture-neutral systems are interpreted where efficiency is often a secondary concern; techniques such as Just-In-Time compilation lead to better average-case executions but have less predictability and poorer worst-case behaviour; static allocation - predictability in a real-time multiprocessor or distributed environment is often achieved by sacrificing flexibility; for example, statically allocating threads to processors in order to avoid scheduling anomalies (such as Graham's and Dhall's anomaly); by definition static allocation is not possible in an architecture-neutral system. Current software technologies that can be used as a basis for architecture-neutral computing include: Microsoft's .Net framework, Sun's Java, Bell Labs' Inferno, and OSF's ANDF. Of these, only Java (with the Real-Time Specification - RTSJ) addresses real-time behaviour. Andy is very active in the Java Community Process, being directly involved in JSR 282 - which is developing the next version of the RTSJ JSR 302 - which is developing a real-time safety critical version of Java JSR 50 - which is developing a distributed version of the RTSJ He is also interested in the Ada programming language and helps run the the International Series on Real-Time Ada Workshops. His work has fed into the Ada 2005/12 languages. Here is a list of the real time group's publications. Andy's publications are included there. The following books are available: The fourth edition of ``Real-Time Systems and their Programming Languages'' published by Addison Wesley. Concurrent and Real-Time Programming in Java published by Wiley Concurrent and Real-Time Programming in Ada published by Cambridge University Press Here is a link to a local HTML version of the Ada 95 Reference Manual. Professor Wellings can be found in the Computer Science Building on Campus East, CSE 119 and on extension 5539. You can click here to automatically email him. Click here to return to the departmental home page. Click here to return to the real-time research page.
