QoS Enabled Middleware: Adding QoS Management Capabilities to the CORBA Component Model

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QoS Enabled Middleware Adding QoS Management
Capabilities to the CORBA Component Model
Craig Rodrigues Gary Duzan
BBN Technologies

• Real-time CCM Meeting
• March 1, 2003

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Presentation Outline

• Overview of what CCM offers to DRE application
  developer
• Description of what CCM lacks in terms of QoS
  Management features
• Description of QoS Management strategies
  (in-band, out-of-band)
• Description of cross-cutting nature of QoS
  Management
• QoS management across multiple components
• QoS management between components and containers
• Further references and standards activity

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CCM Benefits for DRE Systems

• DRE systems consist of many Resource Consuming
  Components (RCC)
• An RCC is a processing entity which cooperates
  with other entities in the execution of a certain
  activity, and consumes some type of system
  resource (ie. CPU, network, etc.)
• CCM allows us to
• Specify the properties of an RCC
• Specify the services offered by the RCC (facets)
  and services required by the RCC (receptacles)
• Specify how an RCC can be connected to other
  components in a larger system (assembly)

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CCM lacks features for Specifying QoS for
Resource Consuming Components

• CCM does not give us
• Ways to specify end-to-end QoS requirements, i.e.
  QoS Characteristics and QoS Values
• Ways to specify adaptation strategies for how
  RCCs can coordinate with other entities in order
  to meet QoS requirements
• Ways to specify QoS management which cross
  multiple system and application level boundaries

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QoS Management in DRE Systems

• Managing end-to-end QoS involves managing
  resources which cross multiple system and
  application-level boundaries
• Network-level resource management
• QoS specific protocols such as RSVP and Diffserv
• Enhanced transport protocols (SCTP)
• Traffic shapers and firewalls
• Processor-level resource management
• CPU scheduling strategies
• CPU reservations
• Resource management of application specific
  behaviors
• Frame dropping
• Compression

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CCM Should Allow QoS Management to Cross-Cut
Components
ClientComponent
Service AComponent
Service BComponent
Service CComponent
QoS Management Infrastructure
QoS Management Infrastructure

• QoS is a cross-cutting concern that can affect
  the interaction between multiple components
• CCM must allow for complex component interactions
  that will result from implementing cross-cutting
  QoS management

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QuO Extends the Distributed Object Model to
Provide QoS Management
Application Developer
CORBA DOC MODEL
Mechanism Developer
Application Developer
CLIENT
CLIENT
operation()
OBJ REF
out args return value
Delegate
Delegate
QuO Developer
SysCond
SysCond
SysCond
QUO/CORBA DOC MODEL
SysCond
IDL SKELETON
MECHANISM/PROPERTY MANAGER
IDL STUBS
OBJECT ADAPTER
Mechanism Developer
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Adding QoS Management Capabilities to the CORBA
Component Model
in args
out args return value
Server/SinkComponent
Client/SourceComponent
Application Developer
events
COMPONENT MODEL
COMPONENT SKELETON
COMPONENT STUBS
Mechanism Developer
Network
ORB
ORB
IIOP
IIOP
Application Developer
QoSComponent Developer
QUO/COMPONENT MODEL
Mechanism Developer
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Important Places where QoS Can Be Inserted in a
Component-based DRE Application

• Interaction between components (in-band)
• Interaction between components and environment
  (out-of-band)
• Interaction between components and containers

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QuO Provides In-Band and Out-of-Band Adaptation
and Control

• In-band adaptation provided by the delegate and
  gateway
• A delegate decides what to do with a method call
  or return based upon the state of its contract
• Out-of-band adaptation triggered by transitions
  in contract regions
• Caused by changes in the system observed by
  system condition objects

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Adding QoS Management Between Components
(in-band)

• Modeling QoS infrastructure as components allows
  us to use standard component assembly mechanisms
  to introduce QoS behaviors to component-based DRE
  applications

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Adding QoS Management between Components and
Environment (out-of-band)

• Changes in environment as detected by monitoring
  SysConds (sensors) trigger adaptive behaviors
  through Callbacks (actuators)

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Inserting QoS Management Capabilities into CCM
between Components and Containers
ORB
RT Trader
RT Scheduling 2.0
CPU Scheduling
FT/RT Event
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QoS Management Behaviors can be Added to CCM by
Using Reusable Qoskets

• Qosket bundles a set of contracts (CDL), system
  condition objects (IDL), and QoS adaptive
  behavior (ASL)
• Qosket provides reusable QoS Management behavior
  to application
• Qoskets are cross-cutting, their interfaces will
  not map directly to CCM interfaces

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Conclusions

• Integrating QoS management into the CORBA
  Component Model will be important for developing
  component-based DRE applications
• QuO offers a middleware framework for QoS-enabled
  applications
• QuO functionality integrated with CCM would
  provide more flexible and reusable QoS Management
  behaviors

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Further References and Ongoing Standards Activity

• CORBA Component Model specification,
  http//doc.omg.org/ptc/02-08-03
• Quality of Service for CCM draft
  RFP,http//doc.omg.org/mars/03-01-18http//doc.o
  mg.org/mars/03-01-19
• UML Profile for QoS and FT Characteristics and
  Mechanisms, RFP responsehttp//doc.omg.org/realti
  me/02-09-01
• Co-authored by I-Logix, THALES, Tri-Pacific
• Supported by Lockheed Martin, ARTISAN, Softeam,
  and others

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Extra slides
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Overview of Quality of ServiceTerminology and
Concepts
source UML Profile for QoS RFP response
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QoS Basic Terminology

• QoS Characteristics
• Represent quantifiable characteristics of
  services.
• Specified independently of the elements they
  qualify, and represent non-functional aspects
  such as
• Latency, Throughput, Capacity
• Availability, Reliability, Integrity, Safety
• Error probability, Accuracy
• Confidentiality, Access Control

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QoS Basic Terminology

• QoS Value Definitions
• Quantification of QoS Characteristics
• for latency, we can quantify end-to-end delay of
  a function, the mean time of all executions, or
  the variance of time delay
• QoS Capability
• A way of grouping together QoS Characteristics
  for large, complex systems which may have many
  QoS Characteristics
• Performance refers to timeliness aspects of a
  system, and incorporates characteristics such as
  latency and throughput
• Dependability refers to the reliability of the
  service provided by a system, and incorporates
  characterstics such as availability,
  reliability, safety, integrity
• Security incorporates characteristics such as
  access control and confidentiality

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QoS Basic Terminology

• QoS Contract
• System requirements that include restrictions
  that the system must adhere to
• Can be specified in terms of QoS Values, which
  restrict QoS Characteristics, such as maximum
  latency