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| Mode detection circuit for a dual purpose analog input |
| Referring to the drawing, a mode detection circuit in accordance with the present invention is ... |
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| Circuit for maintaining the state of an output despite changes in the state of input |
| It is an object of the present invention to provide a low voltage control circuit for maintaining ... |
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| Helicopter, high rotor load speed enhancement |
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| Mobile receiver |
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| Detent remover for a postage meter |
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| Anti-energy diversion system for electric utility meters |
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| Carriage for sorting-machines in particular, with independently actioned tiltable plate |
| I claim: 1. In a carriage for a sorting machine, the sorting machine having at least one track, a ... |
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| Yarn supply device group |
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Distributed process redundancy
| Details |
Inventors: Kidder, Joseph D.; Langrind, Nicholas A.; Sullivan, Jr., Daniel J.; Fox, Barbara A.; Whitesel, Richard L.;
Assignee: Equipe Communications Corporation (Acton, MA)
Primary Examiner: Beausoliel; Robert
Assistant Examiner: McCarthy; Christopher
Attorney, Agent or Firm: Engellenner; Thomas J., Mollaaghababa; Reza E. Nutter McClennen & Fish LLP
A distributed software redundancy design is disclosed to minimize network outages and other problems associated with component/process failures by spreading software backup (in the so-called "hot state") across multiple elements. The distributed redundancy architecture of the present invention also permits the location of the hardware backup element to float, that is, if a primary element fails, the functions can be transferred over to the backup element. When the failed primary element is replaced, the replacement hardware can serve as the hardware backup. If one or more of the primary processes on a particular element experiences a software fault, the processor on the line card may terminate and restart the failing process or processes. Once the process or processes are restarted, a copy of the last known dynamic state (i.e., the backup state) can be retrieved a from corresponding backup processes executing on a second line card and initiate an audit process to synchronize retrieved state with the dynamic state of associated other processes. |
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DETAILED DESCRIPTION A modular software architecture solves some of the more common scenarios seen in existing architectures when software is upgraded or new features are deployed.
Software modularity involves functionally dividing a software system into individual modules or processes, which are then designed and implemented independently.
Inter-process communication (IPC) between the modules is carried out through message passing in accordance with well-defined application programming interfaces (APIs).
A protected memory feature also helps enforce the separation of modules.
Modules are compiled and linked as separate programs, and each program runs in its own protected memory space.
In addition, each program is addressed with an abstract communication handle, or logical name.
The logical name is location-independent; it can live on any card in the system.
The logical name is resolved to a physical card/process during communication.
If, for example, a backup process takes over for a failed primary process, it assumes ownership of the logical name and registers its name to allow other processes to re-resolve the logical name to the new physical card/process.
Once complete, the processes continue to communicate with the same logical name, unaware of the fact that a switchover just occurred.
Like certain existing architectures, the modular software architecture dynamically loads applications as needed.
Beyond prior architectures, however, the modular software architecture removes significant application dependent data from the kernel and minimizes the link between software and hardware.
Instead, under the modular software architecture, the applications themselves gather necessary information (i.
e.
, metadata) from a variety of sources, for example, text files, JAVA class files and database views.
Metadata facilitates customization of the execution behavior of software processes without modifying the operating system software image.
A modular software architecture makes writing applications--especially distributed applications--more difficult, but metadata provides seamless extensibility allowing new software processes to be added and existing software processes to be upgraded or downgraded while the operating system is running
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Cell Phones 
