Analyzing Rules Of Active Database Based On Propagation Algorithm

Rules are the important part which active database can realize active capability. Database can control and analyze changes of inside and outside,and actively react on events without customers'intervention. In recent years,people pay more attention to analyzing and design rules of active database . But there are some complicated behaviors of handling rules conducted by triggering of rules and each other. These rules take it difficulty to accurately forecast behavior characters of rules.We realize that termination,confluence,observable determinism should be satisified by rules during research. These characters can guarantee results accurately.This paper analyzes the character of rules using the way of connection drawing with algebra based on propagation algorithm. At first this paper discusses rules of propagation algorithm. Propagation algorithm is the static way of analying C-A rules. It determines how to be influenced data inquiry by data modification.The secondly , analyzes the termination. This paper discusses related definition , executive model , trigger graph and activation deactivate graph . At last,this paper analyzes the trigger , active , activation deactivate connection of rules in executive graph based on propagation algorithm , so it can more accurately decide the termination of rules.The thirdly , analying the confluence . This paper discusses the interchange ability , confluence and partly confluence . This paper decides whether two rules satisified the interchange qualification based on propagation algorithm , then decides whether the two rules satisified the confluence.The last analying observable determinism .Because observable determinism is included by data inquiry and rollback events , this paper makes the results of data inquiry abstract through propagation algorithm's analysis by models of rule. Using running condition graph (RCG) analyzes the results of execution of rules .If these results are the same or single , selected executive sequence of these rules don't affect the result of observable determinism . In connection with rollback events , this paper makes the execution abstract by the same models of rule. At last , this paper pushes the execution in the shed orderly. At the end of these execution , this paper popes the execution from the shed , becomes the reversal of operations of rules. Then using the results realizes the observable determinism .