This project discusses about transaction scheduling and concurrency control in time critical programs. In a time critical application, the transactions are linked to time constraints on their completion times. It is essential to the performance of the system to meet the time constraints of the transactions. In this investigation, we’ve picked 2 standard time critical apps, programmed stock market trading systems and mobile computing systems for command and control, as examples…
After researching their system properties, we’ve discovered 2 factors that can significantly impact the predictability in transaction execution in these systems. They’re triggering of transactions and interactions between different kinds of transactions in the system. Activating of transactions is essential to the system to respond to the changes in system environment. It’s quite common to find out that a time critical application, i.e., programmed trading and investing system, might have several types of transactions with several properties and functionality requirements. The transaction scheduling techniques and concurrency control protocols offered from earlier research work in real-time database systems research might not be ideal for scheduling of mixed transactions. In this report (Transaction scheduling and concurrency control for time critical applications), we initially analyze how triggering of transactions impacts the system functionality in real-time database systems. Committing a triggered transaction needs meeting the deadline constraints of its triggering transaction along with the data deadlines of its accessed temporal data objects. Generations of triggered transactions could also increase the system work load and also the likelihood of data conflicts. Various techniques for assigning deadlines and priorities to the triggered transactions are offered with the aim to fulfill the timing requirements of triggered transactions particularly for the more critical ones. The effectiveness of the new techniques and their relationships with various coupling modes has been examined employing simulation…
In the 2nd portion of the dissertation (Transaction scheduling and concurrency control for time critical applications), a broad real-time database system model is outlined in which numerous types of real-time transactions, i.e., hard, soft and non-real-time, are co-existed in the system. Due to the different performance prerequisites of hard and soft real-time transactions, these suggested concurrency control protocols are certainly not ideal to mixed real-time database systems (MRTDBS). Methods for fixing data clashes between different kinds of transactions in a MRTDBS are considered and formulated so the performance requirement of each individual transaction type may be accomplished and, simultaneously, the entire system performance can be enhanced. Ultimately, we check out the positioning update problem in mobile real-time database systems…
Several new mobile computing apps require offering support to location-dependent continuous queries (LDCQs) on moving objects. The effect of a location dependent query relies on the current locations of the moving objects on which the query has been issued as well as the location of the mobile user, that issues the query. When the query is specified as continuous, the requesting client can get continuously changing end result. To be able to give accurate and well-timed results to requesting clients, the locations of moving objects in the system plus the locations of the requesting clients must be closely checked. Although various update generation approaches have been suggested in the literature, those methods principally try to boost utilization of the limited wireless bandwidth. The correctless and timeliness of query results reported to the requesting clients have been vastly disregarded. An adaptive tracking method for managing the locations of moving objects is proposed. The purpose of AMM is to take care of the correctness of the results of query evaluation without significantly increasing the wireless data transfer demands…
Source: City University of Hong Kong
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