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Resource management in application level message transfer systems

University of British Columbia

This thesis is concerned with the design of the resource management components of application level, store-and-forward message transfer systems. Although these systems have for some time been used to transport electronic mail, there has been little investigation into designs that emphasize performance and correctness aspects. Current message transfer systems are loosely structured in that there is little, if any, end-to-end resource management. The thesis begins by characterizing the message handling environment and comparing the message transfer approach to that of connection-based file transfer. Current message transfer systems have a fundamental limitation in that the largest message that can be transferred is determined by the amount of storage available at any of the intermediate hosts along the message's route. Major components of a message transfer system and design alternatives are discussed. Existing schemes that deal with solutions designed for lower networking levels are reviewed and shown to be inadequate in addressing the problems in the message handling environment. A framework for designing message transfer systems is presented. Systems adhering to the design methodology address performance issues in a structured way. Two new techniques are central to this framework: message fragmentation and the message stream. Message fragmentation is introduced as a means of delivering arbitrary size messages. The message stream abstraction is the basis of flow control and congestion control. A hierarchical technique for deadlock prevention in the message handling environment is introduced. In this method, the structured buffer pool approach is used as a top level and is integrated with a second method at the bottom level to produce a practical, deadlock-free message transfer system. Methods for providing transit buffer management and recipient buffer space allocation are discussed. A simulation study of some of the performance aspects of message streams and recipient buffer space allocation is presented.

Text

2010-10-10

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http://hdl.handle.net/2429/29060

Craniofacial Science

University of British Columbia

Graduate