This document describes the Supervisor Monitor Scheduler (SMS) version 4.4. SMS is a product of the European Centre for Medium-range Weather Forecasts (ECMWF) and was written in the Meteorological Applications Section (MetApps)
SMS has been used at ECMWF for almost two decades to run the Centre's meteorological operational system (EMOS). During its existence, SMS has undergone many changes, partly because of changes in EMOS itself, and partly because computing techniques and practices have changed.
Version I of SMS was designed and implemented by Claude Guillerand and Tony Stanford and ran operationally from August 1979 until April 1981. Version II was produced by Claude Guillerand and Frank Hollmann and ran operationally from April 1981 until November 1988. Version III, or V3A was produced by Neil Wallace and V3B by Alistair Mills. Version III run from November 1988 till May 1992. SMS V4 has run operationally since May 1992.
Versions I and II were integrated to the computers control program and were tightly coupled to the operating system. From version 3 the SMS has been running as a normal user program.
SMS version 3 was written in PASCAL by Cray Research Ltd (UK) and used the filesystem for communication between processes. Version 4 was written in C and uses remote procedure calls (RPC) for inter-process communication (IPC) and X-Windows/Motif for graphical user interface. Version 4.4 is written in ANSI-C. It was intended that SMS should meet today's challenges by giving more visual interaction to users. Many built-in limits were removed and version 4 uses dynamic data structures. Although SMS version 4 was designed for running the EMOS program suite, it is a general purpose application. The basic functionality of previous version was maintained in version 4. For example all scripts written for version 3 for individual tasks could be used in version 4. However, a complete version 3 suite definition would have to be rewritten for version 4.
The authors acknowledge the help received from many staff members at ECMWF, and also from the source code of SMS version 3, which was taken as the basis for the design of version 4 with additions by ECMWF.
Most of the additions since version 4.0 are derived from SMS users needs. The use of SMS grew and thus some refinements became necessary to implement. Version 4.3 has a host of new features, a very few 4.0-4.2 features have been removed, but some have been changed. In version 4.4 the protocol was changed and again, new features were added.