Automatic Configuration of Componentbased Distributed Systems

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Automatic Configuration of Component-basedDistrib
uted Systems

• Fabio kon
• Advisor Roy H. Campbell
• Department of Computer Science
• University of Illinois at Urbana-Champaign
• http//choices.cs.uiuc.edu/fabio

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Introduction

• Component-based technology
• Building complex applications from off-the-shelf
  components.
• Recent technologies
• Activex controls
• Enterprise Java Beans
• CORBA Component Model (CCM)
• 2K Distributed (meta-)Operating System

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Problem

• Little or no support for managing
  inter-component dependencies.
• Components are created by different groups w/
  different methodologies
• Systems are not reliable.
• Difficult to support fault-tolerance.
• Difficult to support dynamic reconfiguration.
• Too many components added to the system.

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Proposed Solution

• OS and/or middleware must manage component
  dependencies.
• Represent component dependence explicitly.
• Two kinds of inter-component dependence
• Prerequisites
• Dynamic runtime dependencies
• Use them to support automatic configuration.

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Prerequisites

• What a component needs to run
• nature of hardware resources
• share of the hardware resources
• software services (i.e., components) it requires
• Video Client example
• PC with MPEG decoding card
• 50 of 200MHZ CPU
• CORBA Video Service

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Handling Prerequisitesin 2K
Prerequisite Parser
Prerequisite Resolver
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Prerequisite Parser

• Prerequisite can be
• 1.Name in the 2K Implementation Repository
• 2.Name in the CORBA Naming Service
• 3.ServiceTypeName and Constraint for the CORBA
  Trading Service.
• 4.Component IOR (i.e., CORBA reference)

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Simple Prerequisite Description Format (SPDF)

• hardware requirements
• machine_type SPARC
• native_os Solaris
• min_ram 5MB
• optimal_ram 40MB
• min_vm 30MB
• optimal_vm 40MB
• software requirements
• FileSystem IR/sys/storage/DFS1.0 (optional)
• TCPNetworking IR/sys/networking/BSD-sockets
• WindowManager IR/sys/WinManagers/simpleWin
• JVM IR/interp/Java/jvm1.2 (optional)

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Prerequisite Resolver

• Caching Pull-based Policy
• 1. Locate prerequisite in the local machine
• 2. If not present, contacts Implementation
  Repository or Trader.
• The cache is a local repository of component
  implementations and IORs.

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Dynamic Runtime Dependence

• Represent dynamic inter-component dependencies.
• Created on-the-fly by the Prerequisite Resolver.
• System and application components can inspect and
  reconfigure the Dependence Graph.

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ComponentConfiguratorFramework
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Dynamic Reconfiguration
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Updating the JVM

• int WebBrowserConfiguratoreventOnHookedComponent
  
• (ComponentConfigurator cc, Event
  e)
• if (cc JVMConfigurator)
• if (e REPLACED)
• try
• FrozenObjs fo currentJVM-gtfreezeAllObjs
  ()
• currentJVM JVMConfigurator-gtimplementation
  ()
• currentJVM-gtmeltObjects (fo)
• catch (Exception exp)
• throw new ReconfigurationFailed(exp)
• else ...

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Application Multimedia Distribution
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The Multimedia Reflector

• Applications
• Live Multimedia Streaming
• Stored Content Streaming
• Audio/Videoconference
• Multiple Channels
• Multiple input and output Connections
• Multiple Connection types

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Applying the Framework

• Prerequisites
• used to customize the components of each
  Reflector
• Resource reservation (memory and CPU)
• ComponentConfigurators
• represent intra- and inter-Reflector dependencies
• support fault-tolerance

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Related Work(in Operating Systems)

• SOS (prerequisites)
• Customizable OSes
• Choices, Exokernel
• Microkernels
• Mach, SPIN, MicroChoices, L4

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Related Work(in Dynamic Configuration)

• Previous work focuses on application
  architecture
• Software buses (POLYLITH)
• Software Architecture
• Architecture Description Languages
• We focus on dependencies
• The OS is also component-based and adaptable
• Dynamic (runtime) reconfiguration
• Resource management

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Implementation Status and Ongoing Work

• Completed
• ComponentConfigurator Framework.
• local C version applied to dynamicTAO.
• AutoConfig Service with SPDF.
• Ongoing work
• Caching Prerequisite Resolver.
• Apply CORBA version to the Multimedia
  Distribution System.
• Measure performance and space overhead.

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What I want to show with my Thesis

• Component technologies must pay attention to
  component dependencies.
• Middleware-based dependence management can make
  systems
• easier to administer
• automatically configurable
• more reliable
• dynamically adaptable

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How to contact me

• E-mail f-kon_at_cs.uiuc.edu
• More Information
• 2K Web site
• http//choices.cs.uiuc.edu/2K
• ComponentConfigurator source code and docs
• http//choices.cs.uiuc.edu/2k/ComponentConfigurato
  r

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The 2K Architecture