Boots – shoes – and leggings
Patent
1994-01-24
1996-01-30
Kriess, Kevin A.
Boots, shoes, and leggings
395600, 395650, 3642843, 3642844, 364285, 3642813, G06F 1516
Patent
active
054887232
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a software system for a monitoring/control installation of redundant architecture and comprising a first processor (1) connected to a second processor (2) via a communications network (10), the software system comprising a first object-oriented program constituted by first objects to be run by the first processor, a second object-oriented program constituted by second objects that are replicas of at least certain first objects and that are to be run by the second processor, the second objects and said certain first objects encapsulating data, updating means being provided for maintaining consistency between the data of the second objects and the data of said certain first objects during running of said certain first objects.
An object-oriented program is particularly suited to the diversity of supervisory functions in a monitoring/control installation, because of the modular structure of the program. There are numerous existing object-oriented programming languages on the market that enable programs to be made that can include several thousand software objects. Conventionally, a software object encapsulates data and methods that operate on the data of the object.
It is advisable, and often even a requirement, for an industrial monitoring/control installation to tolerate failures so as to guarantee continuity of service.
Redundancy techniques are a well known solution to failure tolerance.
U.S. Pat. No. 4 958 270 describes a data-processing system of redundant architecture comprising two processors running programs which are not necessarily object-oriented programs. The program run by the first processor handles data recorded in a first data base, and the program run by the second processor handles data recorded in a second data base. An updating system is also provided for maintaining consistency between the first data base and the second data base. The updating system is constituted by a program run by the second processor so as to: processor; operations; simultaneously with updating thereof; and second data base.
In the redundancy technique described in that document, the second processor is used only to pass on the changes made in the first data base to the second data base. Since the second processor is relieved of some of the processing performed by the first processor, the second processor can be used for other tasks. That redundancy technique may be referred to as "semi-active redundancy".
SUMMARY OF THE INVENTION
An aim of the invention is to provide a monitoring/control installation comprising at least two processors running object-oriented programs in parallel using a semi-active redundancy technique.
Object-oriented programs make it possible to concentrate all of the data that is to be retained (i.e. non-volatile data), e.g. relating to alarms, trends, archives, orders given by operators, etc. in only a small number of the program objects. Therefore, the changes made on the non-volatile data of the few objects of the first program that are run by the first processor are passed on to the few replica objects of the second program that are run by the second processor, without all the objects of the second program being implemented. In particular, when the monitoring/control installation is operating normally, it is desirable for only those objects of the second program which encapsulate non-volatile data to be run in parallel with those objects of the first program which encapsulate such non-volatile data, so as to reduce the processing load on the second processor, while guaranteeing service continuity should a failure occur in the first processor. Replication granularity must therefore be an object.
Furthermore, it is desirable to achieve this aim without calling into question the existing structure of the objects of the first program.
To this end, the invention provides an object-oriented software system characterized in that the updating means comprise a first dynamic object messaging mechanism used by the first objects, and a second dyna
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Baradel Christophe
Eychenne Yves
Kohen Bruno
Cegelec
Kriess Kevin A.
Toplu Lucien
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