QoS Engineering and Qoskets

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QoS Engineering and Qoskets
BBN Technologies Distributed Systems Department
George Heineman Praveen Sharma Joe Loyall Richard
Schantz
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Outline

• Goals
• Motivation
• QoS Engineering
• Qoskets
• Definition
• Current Status traditional BBN approach to QuO
  brought in
• Example
• Next Steps and Hard Problems

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Context

• Embrace standards-based middleware
• Support dynamic, adaptive end-to-end QoS
  management for distributed Real-time and Embedded
  systems
• There are numerous valid approaches for QoS

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Spectrum of QoS Approaches

• Target Focus
• Application-centric
• Infrastructure-centric
• Epoch Focus
• Design
• Assembly
• Deployment
• Run-time
• Individual solutions solve QoS-in-the-small but
  we must pay attention to larger Systems of
  Systems QoS

Epoch
...
Target
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Motivation

• Solutions to QoS will incorporate many parts
• We manage the complexity of large systems by
  decomposition
• How can we decompose QoS?
• Need to address QoS requirements
• Where?
• Separately? Solely in middleware infrastructure?
  Only within the application?
• When?
• At Design Time? Run Time?
• What artifacts are decomposed and reassembled?

Role Separation
Funct.Reqs.
QoSReqs.
Funct.Reqs.
QoSReqs.
Functional QoSRequirements
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QoS Behaviors as Components

• We are producing behaviors as components
• Decompose complex QoS requirements into primitive
  behaviors
• Develop/select qosket components to ensure these
  capabilities
• Integrate qosket component(s) into application
• Goals
• Show how to componentize QoS Behaviors
• Show how to compose them
• Remainder of talk
• How we are doing this
• State-of-the-Practice implementations
• Issues we have uncovered

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Structural Possibilities
Encapsulate QoS artifacts as components
Encapsulate one QoS artifact for each component
Create Specialized CCM container
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Qosket Definition

• A packaging of behavior and policy
• Encapsulates adaptive QoS behavior
• Described by QoS contracts
• A collection of cross-cutting implementations
• A unit of behavior reuse

QoS Categories
QoS Behaviors

• Network bandwidth usage
• CPU usage
• Domain-specific
• i.e., mission modes

• Prioritize tasks
• Scale/Pre-process data
• Alter application execution

End-to-end QoS can be achieved by composing
localized behaviors and decisions.
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State of the Practice

• BoldStroke non-standard
• We developed componentized OEP UAV scenario
  (available within MoBIES OEP Build 3.0)
• Currently integrating BBN QuO with BoldStroke
  (expected completion Spring 2004)
• Mico CCM standard, non-RT
• Fully integrated BBN QuO with Mico
• Praveen Sharma will present demonstration
  Thursday
• Contains first Qosket CCM implementation
• CIAO standard, RT
• Currently Integrating BBN QuO with CIAO (expected
  completion Spring 2004)

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BBN QuO Technology

• QuO CORBA implementation

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CCM Qosket Structure

• Packaging Qosket as a CCM component
• Facets/Receptacles
• Sinks/Sources
• Controlled by Contract
• Monitors external data
• Maintains contract region
• Contains QoS logic or interacts with QoS services

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Typical Example

• Distributed Sender/Distributor/Receiver example

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QoS Issues

• Problems to overcome within this simple example

1. Higher priority receivers must receive data
before lower priority receivers 2. Ensure that
all receivers receive an image within a fixed
time window the image can be scaled 3. Enable
receivers to have a minimum acceptable image
quality 4. Enable sender to perform opportunistic
processing when resources allow 5. and so on...
How can we ensure any (or all) of these needs are
met?
You may disagree with these set of problems, but
you must admit that these are exactly the sort of
issues that arise
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Qosket Example

• Final image of scaling, ordering, scheduling...
• TBD WILL ADD SOON

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Next Steps and Hard Problems

• Qosket vs. qosket component
• Design templates to rapidly develop qosket
  components
• Encapsulate and share reusable behaviors
• Coordinating multiple qosket components
• Avoid ad hoc interactions
• Model aware tool for targeting Qoskets
• Generate qosket components from common executable
  specifications for
• BoldStroke
• Mico CCM
• CIAO CCM
• Composing mutiple QoS behaviors
• Further investigate QoS mechanisms
• Develop processes for QoS engineering

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QoS Engineering Vision
design/develop new components
Reassemble application
Update qosket components
Qosket Engineering
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QoS Mechanisms

• Component-level interaction
• Current Qosket investigation
• Component/Container interceptors
• Alternative
• Customized containers
• Possible future work