| Run 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 researched and developed independently by us. 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.In order to meet the real-time requirement of transaction process, firstly, ARTs-EDB builds the data model describing time and transaction model which has time limitation and relations among transactions, secondly, traditional database doesn't limit the number of transactions in database, the running time of transaction will be increased for the maybe probability of frequently data exchange between inner memory and outer memory, which also results in the unpredictability. ARTs-EDB increases the response time of transaction through the transaction admission processing, controlling the number of transaction and ensuring no access to outer memory during running time.ARTs-EDB uses the earliest deadline first algorithm to compute priority by the deadline of transaction, and schedules transactions based on the priorities. When the transactions having different priorities compete for inner memory or other resource, ARTs-EDB carrys on transaction preempting scheduling according to priority.ARTs-EDB maintains the consistency and integrality of data with the strong two phases lock protocol according to priority, which supports the concurrency process of nested transactions with policy of inheriting locks.
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