CS848 Class Project: A Survey on QoS for Multi-tier Web Systems

1
CS848 Class ProjectA Survey on QoS for
Multi-tier Web Systems

• Huaning(Mike) Nie
• 2006.11.29

2
Agenda

• Motivation
• Background
• QoS in General
• Multi-tier Architecture
• QoS for Multi-tier Web System
• Proposed Solutions
• Future Work

3
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

4
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.

5
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

6
QoS for Multi-tier System

• Paper Weikum, G. Towards guaranteed quality and
  dependability of information services, 1999
• System-centric
• Reliability
• Availability
• MTTF/(MTTFMTTR)
• Response time goal
• Throughput

7
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.

8
This VS QoS for Streaming Multimedia

• Key differences
• QoS parameters
• Deliverables query result VS video or audio
• Main bottleneck

9
Proposed Solutions

• System-centric
• Reliability Availability
• Using replicas
• Response time goal
• Scheduling
• Queuing
• Resource allocation adjustment
• Buffer memory allocation, disk access control,
  etc.

10
Proposed Solutions

• Information-centric
• Timelineness (Currency)
• Good enough in SQL paper

11
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.

12
Future Work

• More approaches for information-centric
  requirement
• More approaches for database fast recovery
• Suggestions