Abstract: Apparatus and method of cluster computing are described. The present invention provides a useful compromise between the manageability, power, and ease of use of centralized systems and the reliability, fault-tolerance, upgradability, and scalability of distributed systems. Moreover, the present invention provides fault-tolerance and security while adhering to real-time to respond constraints or bounds. The invention is described in preferred embodiment examples in the context of two clustered applications: a telecommunication switch-controller and a Web servers, although many practical applications will benefit from the present invention.

Abstract: In a fault-tolerant computer system, a primary replica supervisor is interposed between an operating system and a primary replica of an application program being executed by a primary processor. An object-code editor locates calls to the operating system and loops in the application program and inserts instruction sequences that enable the replica supervisor to intercept the calls to the operating system, results returned by the operating system as a result of the calls and asynchronous events delivered by the operating system to the replica. A backup replica supervisor is similarly interposed between an operating system and a backup replica of the application program being executed by a backup processor. The primary replica interacts with an environment.

Abstract: Group communication technology, such as the Horus process, is used to implement a fault-tolerant high performance, reactive, real-time distributed IN coprocessor. The architecture of the distributed IN coprocessor comprises workstation clusters, external adaptors and an update interface interconnected by high speed communication links. Each workstation of the IN architecture represents a query element, so all the databases used by the IN coprocessor in the course of servicing incoming requests are split between query elements, provided that each of the workstations has access to the information stored in a certain database or databases.

Abstract: In a fault-tolerant computer system, a primary replica supervisor is interposed between an operating system and a primary replica of an application program being executed by a primary processor. An object-code editor locates calls to the operating system and loops in the application program and inserts instruction sequences that enable the replica supervisor to intercept the calls to the operating system, results returned by the operating system as a result of the calls and asynchronous events delivered by the operating system to the replica. A backup replica supervisor is similarly interposed between an operating system and a backup replica of the application program being executed by a backup processor. The primary replica interacts with an environment.