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۹۷ BTOODM A Bi Temporal Object Oriented Data Model Hadi Elyasi h elyasi@cc iut ac ir Date of Submission 2011 05 07 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mohammad Ali Montazeri montazeri@cc iut ac ir Abstract Time is a subject that has been discussed and researched on since ancient Scientist and other more andmore have studious of understood the time while time and science progressed Time is a human constructand useful for describing detail of objects By use of time we can record and memorize our facts andexperiences that happened late With due attention to these capabilities predict some events that expect occuron the future Temporal Mining Thus we reach these concepts only when have been an explicitly definitionof time On the other hand Conventional database systems do not offer the possibility of dealing with timevarying data The content of a database represents a snapshot of the reality in that only the current data arerecorded without the possibility of maintaining the complete history of data over time Numerous proposalsfor extending the relational data model to incorporate the temporal dimension of data have appeared in thepast several years While most of these have been historical databases incorporating in some fashion a validtime dimension to the data model and the query languages others have been rollback databases incorporating a transaction time dimension or bitemporal databases incorporating both of these temporaldimensions A bitemporal database is a database with exactly one system supported valid time and exactlyone system supported transaction time These two temporal dimensions to data are the valid time of a fact asthe time when the fact is true in the modeled reality and the transaction time of a database fact as the timewhen the fact is stored in the database We analyze the interrelationships among these two dimensions and athird dimension which we call the reference time The reference time provides a means to refer to the state ofthe database as it would appear to an observer looking at the database at that time Most object orientedsystems owe their origins to the programming language Smalltalk Objects the basic data constructs used inthese systems have proven to be both a powerful and flexible modeling construct The power of objectsarises in part from their ability to encapsulate both structure and behavior The flexibility with which objectscan be used as modeling constructs is due to the sets of data types that can be combined to define objects theability to nest the structure of objects And The ability to encapsulate operations or methods on these objectsin the manner of abstract data types In the object oriented approaches temporal dimensions can be defined atthe object level like as TMAD OSAM T or at the attribute level like as TOOSQL OOTempSQL TF ORM T Chimera or at the both levels like as OODAPLEX TIGUKAT Some of these studies support only a singletime dimension valid or transaction time others support bitemporal time Depending of the system timestamp values may be instant interval or instant sets and histories are seen as temporal functions orsequence of snapshots Most studies adopt a discrete model of time Durations instants and intervals are thebasic data type that can be manipulated directly thought classical operation order arithmetic operations Most proposals offer only a fixed set of standard time unit In OSAM T OODAPLEX TIGUKAT new timeunits can be implemented at the application level by adding specialized classes with include conversionmethods So we propose a new data model that covers object oriented concepts by considering time aspectson it Keywords Object Oriented Database Bi Temporal Database Snapshot Database Time Point Time Interval Valid Time Transaction Time

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مدل داده شي گراي دو زماني

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