Eugene H. Spaord. Kernel Structures for a Distributed Operating System. PhD thesis, Georgia Institute of Technology, 1986.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....that technology. Objectorientation encourages modularization, increases reusability and maintainability, gives users programmers a single unified perspective of a system, as well as providing other advantages. Example systems are Chorus [Rozier et al. 88] Amoeba [Tanenbaum et al. 90] Clouds [Spafford 86] and Choices [Campbell et al. 91] Also, micro kernel technology is widely used for constructing operating systems. A micro kernel defines minimum functions, on top of which richer system functions are implemented. Systems such as V kernel [Cheriton 88] Mach [Accetta et al. 86] and the systems ....

Eugene Howard Spafford. Kernel Structures for a Distributed Operating System. PhD thesis, Georgia Institute of Technology, May 1986.

....send a message to any other object as long as it has a reference to that object. Like the servers in messagepassing systems, objects can reside on different nodes in a distributed system. Examples of object based operating systems include: HYDRA[W 74] Eden[LLA 81] Emerald[JLHB87] CLOUDS[Spa86] CEDAR[SZBH86] the Intel iAPX432 architecture[Int81] Amoeba [Mul87, TM81, TvR85] and CHORUS[RAN88, Mar88, BMR85] Object based approaches are more data driven than message passing approaches to operating system construction. They separate the abstractions of a system into different modules ....

....systems, one of efficiency. Efficiency in an object based system is a function of the expense, or weight , of objects and the implementation of message sends between objects. Object based systems span a spectrum of implementations. At one end of this spectrum are systems like CLOUDS[Spa86] and Elmwood[MLC 87] that are, in a sense, remote procedure call (RPC) BN84] object based, message passing systems. Such systems use the object message send paradigm to structure the servers of message passing systems. Objects encapsulate servers and object messages structure the messages ....

Eugene H. Spafford. Kernel Structures for a Distributed Operating System. Technical Report GIT--ICS--86/16, School of Information and Computer Science, Georgia Institute of Technology, 1986.

....might be more appropriate [11] The motivation for two distinct definition mechanisms is the need for two distinct implementations. In distributed object based systems such as Clouds and Eden, a local execution of the general invocation mechanism can take milliseconds or tens of milliseconds [21]. A more restrictive and efficient implementation is appropriate for objects that are known to be always local; for example, shared store can be used in preference to messages. While we believe in the importance of multiple implementations, we do not believe that these need to be visible to the ....

Eugene H. Spafford. Kernel Structures for a Distributed Operating System. PhD thesis, School of Information and Computer Science, Georgia Institute of Technology, May 1986. Also Georgia Institute of Technology Technical Report GIT-ICS-86/16.

....of the object thread paradigm. The lessons learned from the first implementation have been used to redesign the kernel and build a new version of the operating system called Clouds v.2. Clouds v. 2 uses an object thread paradigm which is derived from the object process action system [All83, Spa86, Wil87] used by Clouds v.1. However, most of the design and implementation of the system are substantially different. Clouds v.1 was targeted to be a testbed for distributed operating system research. Clouds v.2 is targeted to be a distributed computing platform for research in a wide variety of ....

....Memory in Clouds Currently, we define user objects in an extended C language. The language supports single inheritance on Clouds user objects using the C object structuring paradigm. Clouds v. 1 The first implementation of a kernel for Clouds was finished during 1986 and is described in [Spa86, Pit86] The kernel was broken up into four subsystems: object management, storage management, communications, and action management. A kernel supported extension of the nested action model of Moss [Mos81, All83, Ken86] made it possible for the programmer to customize synchronization and recovery ....

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Eugene. H. Spafford. Kernel Structures for a Distributed Operating System. PhD thesis, School of Information and Computer Science, Georgia Tech, Atlanta, Ga, 1986. (Available as Technical Report GIT-ICS-86/16).

....although system objects usually define their protection domain, protecting objects against malicious access is the responsibility of programming languages. 2. 2 Grain size of Objects There are several systems which provide coarsegrained objects for programmers: Eden[Almes et al. 85] Clouds[Spafford 86] Chorus [Rozier et al. 88] and Amoeba [Mullender et al. 90] Tanenbaum et al. 90] In these systems, the benefits of the object oriented framework are limited, because it is expensive to create or destroy an object, and to communicate with other objects. Although the size of an object tends to ....

Eugene Howard Spafford. Kernel Structures for a Distributed Operating System. PhD thesis, Georgia Institute of Technology, May 1986.

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Eugene H. Spaord. Kernel Structures for a Distributed Operating System. PhD thesis, Georgia Institute of Technology, 1986.

....If the program is restricted to using only one architecture within the distributed system, it will suffer needless delay. Distributed systems communicate by passing messages over an external communications channel. Such systems are often called multicomputers (as defined by Spafford in [41]) or loosely coupled systems, as opposed to tightly coupled parallel machines that communicate through shared memory. There are many examples of systems that share some of these qualities. Sharedmemory parallel processors such as the Sequent Symmetry [38] are homogeneous, tightly coupled systems. ....

Eugene H. Spafford. Kernel Structures for a Distributed Operating System. PhD thesis, Georgia Institute of Technology, 1986.

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