| 1. |
|
|
| 2. |
- Andler, Sten F., et al.
(författare)
-
DeeDS : Towards a Distributed and Active Real-Time Database Systems
- 1996
-
Ingår i: ACM Sigmod Record. ; 25:1, s. 38-40
-
Tidskriftsartikel (refereegranskat)abstract
- DeeDS combines active database functionality with critical timing constraints and integrated system monitoring. Since the reactive database mechanisms, or rule management system, must meet critical deadlines, we must employ methods that make triggering of rules and execution of actions predictable. We will focus on the scheduling issues associated with dynamic scheduling of workloads where the triggered transactions have hard, firm or soft deadlines, and how transient overloads may be resolved by substituting transactions by computationally cheaper ones. The rationale for a loosely coupled general purpose event monitoring facility, that works in tight connection with the scheduler, is presented. For performance and predictability, the scheduler and event monitor are executing on a separate CPU from the rest of the system. Real-time database accesses in DeeDS are made predictable and efficient by employing methods such as main memory resident data, full replication, eventual consistency, and prevention of global deadlocks.
|
|
| 3. |
- Berndtsson, Mikael, et al.
(författare)
-
Issues in Active Real-Time Databases
- 1996
-
Ingår i: Active and Real-Time Database Systems (ARTDB-95). - London : Springer. - 9783540199830 - 9781447130802 - 3540199837 ; , s. 142-157
-
Konferensbidrag (refereegranskat)abstract
- Active databases and real-time databases have gained increased interest in recent. Both active and real-time databases are considered as important technologies for supporting non-traditional applications such as computer integrated manufacturing (CIM), process control and air-traffic control. These applications are often event driven and need to react to events in a timely and efficient manner. In this paper we address the problem of merging active databases and real-time databases. Active real-time database is a fairly new area, in which very little research has been carried out so far. However, the use of active real-time database applications has a great potential. In this paper we address several issues and open questions such as semantics, assignment of time constraints and rule selection, which need to be considered when designing active real-time databases.
|
|
| 4. |
- Berndtsson, Mikael, et al.
(författare)
-
Workshop Report : The First International Workshop on Active and Real-Time Database Systems (ARTDB-95)
- 1996
-
Ingår i: SIGMOD record. - : Association for Computing Machinery (ACM). - 0163-5808 .- 1943-5835. ; 25:1, s. 64-66
-
Tidskriftsartikel (refereegranskat)abstract
- This report is a summary of the First International Workshop on Active and Real-Time Database Systems (ARTDB-95) [1], held at the University of Skövde in June 1995. The workshop brought together researchers and practitioners from both the active database community and the real-time database community. The major aims of ARTDB-95 were to identify motivations, problems and requirements when combining active and real-time capabilities.
|
|
| 5. |
- Hansson, Jörgen, 1970-
(författare)
-
Value-driven multi-class overload management in real-time database systems
- 1999
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In complex real-time applications, real-time systems handle significant amounts of information that must be managed efficiently, motivating the need for incorporating real-time database management into real-time systems. However, resource management in real-time database systems is a complex issue. Since these systems often operate in environments of imminent and transient overloads, efficient overload handling is crucial to the performance of a real-time database system.In this thesis, we focus on dynamic overload management in real-time database systems. The multi-class workload consists of transaction classes having critical transactions with contingency transactions and non-critical transactions. Non-critical transaction classes may have additional requirements specifying the minimum acceptable completion ratios that should be met in order to maintain system correctness. We propose a framework which has been implemented and evaluated for resolving transient overloads in such workloads.The contributions of our work are fourfold as the framework consists of (i) a new scheduling architecture and (ii) a strategy for resolving transient overloads by re-allocating resources, (iii) a value-driven overload management algorithm (OR-ULD) that supports the strategy, running in O(n log n) time (where n is the number of transactions), and (iv) a bias control mechanism (OR-ULD/BC). The performance of OR-ULD and OR-ULD/BC is evaluated by extensive simulations. Results show that, within a specified operational envelope, OR-ULD enforces critical time constraints for multi-class transaction workloads and OR-ULD/BC further enforces minimum class completion ratio requirements.
|
|
| 6. |
- Mellin, Jonas, et al.
(författare)
-
Refining Design Constraints using a System Services Model of a Real-Time DBMS
- 1995
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the DeeDS prototype, active database functionality and critical timing constraints are combined with integrated monitoring techniques. In the scope of DeeDS, this paper presents a mathematical model which is used to derive two important design constraints; worst-case minimum delay and maximum frequency of events. This model is based on a dual-processor hybrid-monitoring solution. Furthermore, different interaction styles between the scheduler and the event monitor are evaluated.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
