Expert Topic for 1770

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Expert Topic for 1770

• QoS-Enabled Middleware

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Content

• Introduction
• Key Technical issues for DRE
• Component Middleware
• Limitation of DOC
• Static QoS Provisioning
• Dynamic QoS Provisioning
• Conclusion

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Introduction

• COTS (Commercial off-the-shelf) middlewares
  CORBA, RMI, COM
• Business-oriented QoS requirements
• Data persistence, confidentiality, and
  transactional support.
• DRE (Distributed Real-time Embedded) systems
• Processor allocation, network latency, jitter,
  bandwidth

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Key Technical issues for DRE

• Reducing the complexity of managing large-scale
  DRE software
• Component middleware
• Real-time QoS requirements
• Statically task prioritization, communication
  bandwidth reservation
• Dynamically runtime reallocation
  reprioritization for handling bursty CPU load.

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Component Middleware

• Reusable services, create applications rapidly
• CORBA Component Model CCM
• Interfaces for collaboration
• Component strategies via metadata (XML)
• Persistence
• Event notification
• Transaction
• Load balancing
• Security

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Limitation of DOC

• DOC (Distributed Object Computing)
• Distributed computing Object-oriented design
• CORBA 2.x (DOC middleware standard) limitations
• Lack of functional boundaries
• Lack of generic server standards
• Lack of software configuration and deployment
  standards

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Component Middleware addresses DOC limitations

• Virtual boundary around app component,
  well-defined interfaces
• Standard container mechanism, generic component
  servers
• Infrastructure to assemble, package, deploy
• CORBA Component Model CCM

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Limitations of Component Middleware for DRE

• End-to-end QoS provisioning
• Many interacting components
• Component server for some resources (thread
  pools)
• Component implementation not right level for QoS
  provision
• Conflicting policies high throughput, low
  latency
• End-to-end QoS context a priori
• Solution Separating programming and QoS concerns
• Functional paths flows of information
• QoS systemic paths end-to-end interaction,
  failure detection, recovery

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Static QoS Provisioning

• Fixed set of QoS demand
• Tightly bounded predictability for system
  functionality
• Simplest solution available
• QoS provisioning integral part of component
• Decouple QoS provisioning from component
  functionality
• Aspect-oriented techniques
• Crosscut multiple interacting components,
  end-to-end QoS behavior

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Static QoS Provisioning with CIAO

• QoS-enable implementation of CCM
• Extends TAO (The ACE ORB), support component,
  end-to-end QoS at system assembly
• Application assembly descriptor
• QoS-enabled containers
• CPU resources priority models, priority levels
• Communication resources reserving and allocating
  communication resources, RSVP protocol
• Usage
• decouple QoS provisioning functionality
• Compose static QoS provisioning capabilities into
  the application via the component assembly and
  deployment phases

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Dynamic QoS Provisioning

• Allocation and management of resources at runtime
• Events triggers reevaluation and reallocation of
  resources
• Dynamic QoS middleware capabilities
• Monitor DRE system, detect changes
• Adapt to change, adjust the resource usage
• Dynamic QoS abstractions and mechanism for DRE
  systems
• Design formalisms level of service, measured QoS
• Runtime capabilities adapt behavior
• Management mechanisms dynamic control of
  resources

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QuO (Quality Object) Framework

• Allows DRE developers to specify
• QoS requirements
• System elements that must be monitored and
  controlled to measure and provide QoS
• Behavior for adapting to QoS variations that
  occur at runtime.
• QuO needs
• Contracts level of service
• Delegates local proxies for remote components
• System Condition objects interfaces to
  resources, mechanisms, and ORBs

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Conclusion

• DRE app QoS predictability, latency, and
  dependability
• DRE app historically been custom-programmed
• expensive to build and maintain, adapt new
  functional needs
• tight coupling between custom DRE software
  modules
• increases the time and effort required to develop
  
• QoS provisioning crosscuts multiple layers in
  applications
• end-to-end enforcement
• Component QoS-enable middleware
• Static, dynamic provisioning
• www.dre.vanderbilt.edu/CIAO
• quo.bbn.com

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Discussion

• End-to-end QoS in IP networks