An Execution Module Of Transaction For Active Real-time Embedded Database ARTs-EDB

Runing under embedded environment, real-time database has great difference on transaction processing from traditional database. Traditional database doesn't consider the time limitation of data and transaction, whose object is average performance and system throughout, while active real-time embedded database tries its best to assure more transactions committed before their deadlines on the basis of their priorities.ARTs-EDB is an embedded active real-time database system researched and developed independently.Having the characters of flexibility, briskness and good migration, the multi-thread and modularized process structure and transaction execution model meets embedded micro-kernel construction, which is the foundation of the whole system construction.The normal flat transaction model is not satisfied for the need of ARTs-EDB.So a nested transaction model is builded.Every transaction of ARTs-EDB have a transaction process block,which addresses the ID,needed resource and status of it and exist during its lifecycle.For satisfied the effective and time constrains'ececution of transactions,first of all, transaction priority assignment should take into account transaction'deadline, scheduling transaction should take into account transaction priority.Second ,in order to load all needed data into memory before transactions'exectution,transactions need pre-analysis.Last,because the depend of transactions,when a begin,commit or abort operation of transactions occur,should take active mechanism into count.ARTs-EDB build a effective execution model of transaction.First, transaction admiting and releasing makes sure the max numbers of transactions in memory,and the data they need also in memory.Second,the highest priority transaction executes first by transaction scheduling.