File organization (Computer science)

In this thesis, a delta service extends a mobile file system cache in order to minimize the amount of data transferred over wireless communications links. Network bandwidth stands as one of the resource limitations impacting the design of mobile computer applications. At the mobile file system service level, caching and compression provide resource conservation in distributed applications. This thesis proposes a delta service to enhance caching services characteristic of mobile computer file systems. Well established a mechanisms for sequence comparison and software configuration management, file deltas have applicability to mobile computer and distributed file system caching environments. Study of the delta service uses trace-driven simulation methodology incorporating traces obtained in a real world distributed environment. A mobile computer client cache model will corroborate existing studies regarding suitable cache size for disconnected client operation. A delta service model will extend the mobile computer client cache model of various cache sizes in order to gauge the bandwidth savings on the link obtained by the delta service.

Modern computer systems have strong requirements for security. The decentralization of the security functions is becoming necessary due to the complexity and physical distribution of many systems. This study uses a previous model of authorization for decentralized security administration. The concept of file classes is proposed and used for the entire system design as a main motive. Algorithms for delegation of administrative access rights with revocation are designed and implemented. For development of software, top-down and bottom-up methods are adopted. The strategy for design is borrowed from the object-oriented approach. The special "unit" feature of the implementation language--Meridian-Pascal, serves as a window to observe the interaction and coordination of the fundamental data representations. Four basic table structures are defined to control the authorization system. For the delegation and revocation of the administrative access rights, two graph structures are used and implemented to illustrate the logical view of the operations.

This thesis gives an evaluation of DOS 3.2 file system performance in the current IBM PC AT environment, and it presents a survey of alternative file system and high density storage integration strategies. The current file system is evaluated to determine the nature of its algorithms and structures. In particular, the file system is examined from a disk access perspective and from the perspective of alternative disk and file management strategies used in UNIX*2 file systems.