Object tracking in distributed systems
department or school: Science, Faculty of
department or school: Computer Science, Department of
data provider: DSpace
degree campus: UBCV
creator: Xu, Yingchun
issued: 2008-09-22T23:50:09Z
issued: 1993
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Object mobility (or process migration) is a very important feature in modern distributed systems. By allowing objects to migrate from one machine to another preemptively, the sys-tem can provide several benefits. These include sharing load, reducing communication cost, increasing availability, and improving invocation performance. One problem with object mobility is object tracking. Several schemes exist to handle the problem. A forwarding address scheme is used in DEMOS/MP and Emerald. To reduce the number of forwarding messages, DEMOS/MP uses an urgent updating policy to compress the message path. Whenever an object is moved, an updating message is sent to the last node immediately. In Emerald, a lazy updating policy is adopted. When an object migrates, no updating message is sent. The new location is piggybacked on each reply message. This can also compress the message path for later invocations. The difference between the two is that DEMOS/MP places the cost on object migration while Emerald places the cost on object invocation. They both use the same updating policy for all objects. We adopt a philosophy in which objects with different behaviors use different updating policies. Objects are divided into two groups: active objects and quiet objects. Active objects are defined as objects which move more often than they are invoked. Quiet objects are invoked more often than they are moved. To optimize object moving and invoking, active objects should use a lazy updating policy while quiet objects should use an urgent updating policy. We call this policy the adaptive updating policy. The object tracking function is separated from Emerald and implemented as an independent protocol layer, OFP. A reliable datagram protocol, RDP has been designed to support OFP. Experiments are done to validate the protocols' performance. The protocols are implemented on the x-kernel platform.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/2342
extent: 6604724 bytes
format: application/pdf
note: Object Tracking In Distributed SystemsbyYingchun XuB.Sc., South China Institute of Technology, China, 1984M.Sc., Beijing University, China, 1989A THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCEINTHE FACULTY OF GRADUATE STUDIESDEPARTMENT OF COMPUTER SCIENCEWe accept this thesis as conformingto the required standardUniversity of British ColumbiaApril 1993©Yingchun Xu, 1993In presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that the Library shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives. It is understood that copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.(Signature) Department ofThe University of British ColumbiaVancouver, CanadaDate oDE-6 (2/88)AbstractObject mobility (or process migration) is a very important feature in modern distributedsystems. By allowing objects to migrate from one machine to another preemptively, the sys-tem can provide several benefits. These include sharing load, reducing communication cost,increasing availability, and improving invocation performance.One problem with object mobility is object tracking. Several schemes exist to handle theproblem. A forwarding address scheme is used in DEMOS/MP and Emerald. To reduce thenumber of forwarding messages, DEMOS/MP uses an urgent updating policy to compress themessage path. Whenever an object is moved, an updating message is sent to the last nodeimmediately.In Emerald, a lazy updating policy is adopted. When an object migrates, no updatingmessage is sent. The new location is piggybacked on each reply message. This can also compressthe message path for later invocations. The difference between the two is that DEMOS/MPplaces the cost on object…
has type: Thesis/Dissertation
date issued: 1993-05
is shown at: 10.14288/1.0051426
language: eng
degree discipline: Computer Science
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/2342