120 likes | 232 Views
CS848 Class Project: A Survey on QoS for Multi-tier Web Systems. Huaning(Mike) Nie 2006.11.29. Agenda. Motivation Background QoS in General Multi-tier Architecture QoS for Multi-tier Web System Proposed Solutions Future Work. Motivation.
E N D
CS848 Class Project:A Survey on QoS for Multi-tier Web Systems Huaning(Mike) Nie 2006.11.29
Agenda • Motivation • Background • QoS in General • Multi-tier Architecture • QoS for Multi-tier Web System • Proposed Solutions • Future Work
Motivation • More and more information service system emerge on the Internet. • Many of these service systems exhibit poor quality, such as: • Unpredictable response time • Useless query result • Unsuitable for mission-critical applications
Background: QoS in General • A traffic engineering term • A list of control mechanisms that can provide different level of priority to different customers; • Or Guarantee a certain level of performance to a data flow. • Applications require QoS: streaming multimedia, voice over IP, etc.
Background: Multi-tier Architecture • An extension of the classic client-server model • Usually three tiers: presentation, business services, data services • More complex logic, high scalability, easy deployment
QoS for Multi-tier System • Paper: Weikum, G. Towards guaranteed quality and dependability of information services, 1999 • System-centric: • Reliability • Availability • MTTF/(MTTF+MTTR) • Response time goal • Throughput
QoS for Multi-tier System • Information-centric • Accuracy • Comprehensiveness • Timelineness • Note: For some application the customer may only be interested in a portion of the query result.
This VS QoS for Streaming Multimedia • Key differences: • QoS parameters • Deliverables: query result VS video or audio • Main bottleneck
Proposed Solutions • System-centric • Reliability + Availability • Using replicas • Response time goal: • Scheduling • Queuing • Resource allocation adjustment • Buffer memory allocation, disk access control, etc.
Proposed Solutions • Information-centric • Timelineness (Currency) • “Good enough in SQL” paper
Proposed Solutions • Combined system and information goals: • Paper: Braumandl, R. Quality of service in an information economy, 2003 • Consider QoS in Query optimization, plan instantiation and plan execution.
Future Work • More approaches for information-centric requirement • More approaches for database fast recovery • Suggestions