Patches to modern operating systems, including bug fixes and security updates, and the reboots and downtime they require, cause tremendous problems for system users and administrators. The aim of this research is to develop a model for dynamic update of operating systems, allowing a system to be patched without the need for a reboot or other service interruption. In this work, a model for dynamic update based on operating system modularity is developed and evaluated using a prototype implementation for the K42 operating system. The prototype is able to update kernel code and data structures, even when the interfaces between kernel modules change. When applying an update, at no point is the system's entire execution blocked, and there is no additional overhead after an update has been applied. The base runtime overhead is also very low. An analysis of the K42 revision history shows that approximately 79% of past performance and bug-fix changes to K42 could be converted to dynamic updates, and the proportion would be even higher if the changes were being developed for dynamic update. The model also extends to other systems such as Linux and BSD, that although structured modularly, are not strictly object-oriented like K42. The experience with this approach shows that dynamic update for operating systems is feasible given a sufficiently-modular system structure, allows maintenance patches and updates to be applied without disruption, and need not constrain system performance.

"November, 2001" / Errata on back page. / Includes bibliographical references (p. 179-183) / xxii, 193 p. : ill. (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis proposes a highly integrated SOC (system on a chip) matrix-based parallel processor which can be used as a co-processor when integrated into the on-chip cache memory of a microprocessor in a workstation environment. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2002

Thesis (Ph.D)--Stanford University, 1999. / Title from PDF t.p. (viewed May 9, 2002). "August 1999." "Adminitrivia V1/Prg/19990826"--Metadata.

An active object system is a transition-based object-oriented system suitable for the design of various concurrent systems. An AOS consists of a collection of interacting objects, where the behavior of each object is determined by the transition statements provided in the class of that object. A transition statement is a condition-action pair, an equational assignment statement, or an event routine. The transition statements provided for each object can access, besides the state of that object, the states of the other objects known to it through its interface variables. Interface variables are bound to objects when objects are instantiated so that desired connections among objects are established. The major benefit of the AOS approach is that an active system can be hierarchically composed from its active software components as if it were a hardware system. An AOS provides better encapsulation and more flexible communication protocols than ordinary object oriented systems, since control within an AOS is localized. / Graduation date: 1992

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Thesis (MTech. degree in Information Networks)--Tshwane University of Technology, 2009. / With this research, we focus on utilizing a distributed file system to combat congestion problems in wireless networks. The Coda file system is our choice of a distributed file system, as it offers several services, such as data pre-fetching, hoarding of files, disconnected operation and data consistency.

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