An Architecture for An Architecture for Configurable Dependability - - PowerPoint PPT Presentation

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An Architecture for An Architecture for Configurable Dependability - - PowerPoint PPT Presentation

Nov 19, 2023 305 likes •424 views

University Of Paderborn Software Engineering Group Prof. Dr. W. Schfer An Architecture for An Architecture for Configurable Dependability of Configurable Dependability of Application Services Application Services Matthias Tichy

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

An Architecture for Configurable Dependability of Application Services An Architecture for Configurable Dependability of Application Services

Matthias Tichy mtt@uni-paderborn.de Software Engineering Group University Of Paderborn

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Contents

  • Introduction
  • Architectural Principles for Dependability
  • Architecture
  • Improving Availability
  • Improving Reliability
  • Conclusion & Future Work
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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Introduction

  • Dependability

– Availability – Reliability – Safety – Security

<<deploy>>

Chart

MathInterface ChartInterface

Math

uther vivian

network <<deploy>>

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Architectural Principles

  • Service Registry

Provides support for dynamic online binding and spontanous networking.

  • Leasing

The leasing principle extends the allocation of resources with time.The lease represents a period of time during which the resource is offered.

  • Proxy

A proxy is the placeholder for another object.

  • Smart Proxy

Smarter version of the proxy, may be a placeholder for more than one object.

  • Redundancy

Redundant services prevent a single-point-of-failure.

  • Replication

Replicating is the process of maintaining multiple copies of the same entity at different locations.

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Architecture

  • Architecture provides means to achieve high availability for

application services

  • Reliability is highly

application specific

  • Every infrastructure

service is executed on every node – Redundancy of services – Replication of data – Service registry

Data access b: Check Register a.3: a.1: Start a.2: Create Responsibility : Monitor : Service Storage : Node : Application Service : Jini Lookup : Monitor Description Storage

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Architecture – Monitor (Availability)

  • For each application service instance, one monitor supervises its

execution configurable degree of availability

  • Coordination by monitor responsibilities (registry + leasing)

responsibility lease t service lease

new resp. monitor node failure service restarted

  • s. lease
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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Reliability

  • Highly application specific
  • 3 types:

– Stateless session service

  • No problem, just use another service instance

– Stateful session service

  • Relevant history must be replayed on another

service instance – Entity service

  • Replicate data and use an appropriate consistency

model

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Architecture – Responsibility Storage (Reliability)

  • Example for an entity service
  • Smart Proxy communicates via Multicast messages
  • Decentral majority voting
  • Redundancy, replication, smart proxy

Resp. „Mon2“

LAN

Resp. „Mon2“ Resp. „Mon5“

Messages:

Smart Proxy

Messages: Messages: Messages:

1: getData(„Chart“) 1: getData() 1: getData() 1: getData() 1: getData() 3: „Mon2“ 2: „Mon2“ 4: „Mon5“ 2: „Mon2“ 2: „Mon2“ 2: „Mon2“ 2: „Mon2“ 3: „Mon2“ 3: „Mon2“ 3: „Mon2“ 3: „Mon2“ 4: „Mon5“ 4: „Mon5“ 4: „Mon5“ 4: „Mon5“

Voting Voting Voting Voting

<<timeout>> <<timeout>> <<timeout>> <<timeout>>

„Mon2“ „Mon2“ „Mon2“ „Mon2“

Resp. „Mon2“

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Conclusion & Future Work

  • Architectural principles for dependability
  • Architecture based on these principles
  • Provides means to achieve a configurable degree of

availability

  • Example for providing application specific reliability
  • Implementation based on Jini
  • Seamless UML support for service-based architectures
  • Runtime measurements to adapt architecture

parameters

  • Complex embedded and real-time systems
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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Thank you for your attention! Thank you for your attention! Questions? Questions?

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University Of Paderborn Software Engineering Group

  • Prof. Dr. W. Schäfer

Service Description Storage (Reliability)

  • Redundant and distributed storage of the

service descriptions

  • Strong consistency (sequentiell)
  • Probability: P(Read) >> P(Write)
  • Algorithm „Weighted Voting“
  • Implemented in a smart proxy