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France Télécom R&D ARTIST2 – 01/24/2005
A Component-Based QoSArchitecture forEmbedded Systems
Jean-Charles TournierFrance TélécomJeancharles.tournier@rd.francetelecom.com
Jean-Philippe Babau CITI / INSA LyonJean-philippe.babau@insa-lyon.fr
ARTIST 2 - Component Modelling and Composition
Paris, January 24th 2005
France Télécom R&D ARTIST2 - 01/24/2005 2
Context - 1/2
� Mobile embedded systems� Today
�Complex features�QoS constraints (real-time, safety, etc.)�Limited resources (CPU, memory, battery, etc.)�lead to dedicated, closed and monolithic systems
� Tomorrow: need for flexible systems�Dynamicity
–Add or remove applications on the fly
�Opening–Heterogeneous communication networks(GSM,GRPS, Bluetooth, etc.)
France Télécom R&D ARTIST2 - 01/24/2005 3
Context - 2/2
� Component Based Software Engineering (CBSE)� An easier way to build complex software by assembling, composingsoftware entities called components
� CBSE provides
� Adaptability� Reusability� Scalability
� Component frameworks (Think, OS-Kit, Coyote)� Provide composition of components from a functional point of view� But, no support for QoS management
France Télécom R&D ARTIST2 - 01/24/2005 4
Objectives
� Dynamically manage QoS constraints in component-basedsystems
� Define a QoS architecture� Open
�Independent of QoS management policies, Qos mechanisms and Qosspecifications
� Component-based� Supporting dynamic QoS management
France Télécom R&D ARTIST2 - 01/24/2005 5
Overview
�Our view of components
�Main QoS concepts
�Qinna
�Experiment
�Analysis
�Conclusions
France Télécom R&D ARTIST2 - 01/24/2005 6
CBSE - The Fractal Component Model
� Component� Run-time entity� Made of a content and a controller
� Content� Composed of a finite number of other components (recursive)� Under the control of the controller
� Controller� Reflexivity� E.g. Life-cycle, configuration, etc.
� Interface� Unique access points� Client or server
� Binding� Oriented connection between two components
�From a client interface to a server interface (type compatibility)
� Primitive or composite (component+binding)
France Télécom R&D ARTIST2 - 01/24/2005 7
CBSE - Fractal
� API� Life-Cycle, Reflexivity (BindingController and ContentController),Instanciation (Factory)
� ADL� A language for defining Fractal architectures (configuration)� A modular and an open (extensible) language to describe
�Components, interfaces and bindings�Attributes�Typing�Implementations�Deployment�Behaviour and QoS contracts�…
France Télécom R&D ARTIST2 - 01/24/2005 8
CBSE - The Think Framework
� Think� Framework for component-based operating systems� Conforms to the Fractal model� Everything is components
�Fine grain control over resources
� Two kinds of components� Hardware Abstraction Components
�Boot, exceptions, MMU, device drivers (screen, keyboard, serial port,…), etc.
� OS Services Components�Thread, scheduler (RR, priority, EDF,…), Network (Ethernet, IP, TCP,…), etc.
� Ported on ARM (Intel StrongARM, Intel xScale, Portal Player, Motorola Dragon Ball MX1),Intel x86, Hitachi H8 (Lego RCX)
� Provides a complete tools chain� ADL and IDL parsers, component compiler, etc.
France Télécom R&D ARTIST2 - 01/24/2005 9
Quality of Service architecture
GOOD
Performance
HIGH
Importance
GOODAVERAGEBAD
Adaptation
Specification
GOOD=25 f/sec{6,10} EDF80Kb Mem
Mapping
Sched_anal({6,10})
?
AdmissionTesting
set_prio({6,10})
Reservation
Initialization
25 f/sec?
Observation
improve_resssource()
Maintenance
degrade_toAVERAGE
Adaptation
Management
Concepts
France Télécom R&D ARTIST2 - 01/24/2005 10
Qinna
� A Component-Based QoS Architecture� Capturing the main QoS concepts� Generic� Dynamic� Reusable
� Qinna defines� A set of APIs� Component types� Data types� Inter-component relationships� Dynamic behavior
France Télécom R&D ARTIST2 - 01/24/2005 11
Qinna - QoSComponent
� Definition� Provides functional interfaces with QoS management needs
� Detail
QoSComponent
Local_Ct:T_CLFunc_Itf
(1..N)
Func_Itf
(0..N)
iLocalConstraint(1)
iQoSObserver(1)
France Télécom R&D ARTIST2 - 01/24/2005 12
Qinna - QoSComponentBroker
� Definition� Provides a QoSComponent with a fixed local constraint� Responsible for the admission testing and reservation for a class ofQoSComponents
� Detail
QoSComponentBroker
Global_Ct:T_CGiBrokerAdministration
(1)
iLocalConstraint
(0..N)
iQoSBroker(1)
France Télécom R&D ARTIST2 - 01/24/2005 13
Qinna - QoSComponentManager
� Definition� Initializes a QoSComponent from a QoS point of view� Implements initialization, maintenance and adaptation mechanisms for aclass of QoSComponents
� Detail
QoSComponentManager
Map_table:T_MTContracts:T_CT_MANAGER
iManagerAdministration
(1)
iQoSBroker (1)
iQoSManager(1)
iQoSManager (0..N)
iQoSAdapter(1)
iQoSMaintener(1)
France Télécom R&D ARTIST2 - 01/24/2005 14
Qinna - QoSComponentObserver
� Definition� Implements observation policy for a class of QoSComponents
� Detail
QoSComponentObserveriQoSObserverException (1)
iQoSObserverLifeCycle (1)iQoSObserver (1..N)
France Télécom R&D ARTIST2 - 01/24/2005 15
Qinna - QoSDomain
� Definition� Encapsulates all Qinna components� Implements adaptation and maintenance policies based on importancelevel
� Detail
QoSDomain
Contracts:T_CT_DOMAIN
iQoSDomain
(1..N)
iQoSAdapter (0..N)
iQoSObserverException(0..N)
iQoSManager (1..N)
iQoSMaintener (0..N)
iQoSObserverLifeCycle(0..N)
France Télécom R&D ARTIST2 - 01/24/2005 16
Qinna - Overview
QoSDomain
QoSComponentManager
QoSComponentBroker
QoSComponent1..N
1
1
1..N
11
QoSComponentObserver0..N
1
1..N
11
0..N
Functional services
Admission testingReservation
Management mechanisms(initialization,adaptation,maintenance)
Management policies(adaptation,maintenance)
Observationpolicy
France Télécom R&D ARTIST2 - 01/24/2005 17
Experiment
DOOM
Video
Threads
Memory
EDF
GUI
{4,20}
{4,10}
Thread QoS Level
40BAD
60GOOD
Memory QoSLevel (kb)
Video QoS Level
30{7,15}AVERAGE
{7,20}
{7,10}
Thread QoS Level
20BAD
50GOOD
Memory QoS Level(kb)
Doom QoS Level
France Télécom R&D ARTIST2 - 01/24/2005 18
Experiment - Qinna integration
QoSDoom
QoSDoomBroker
QoSDoomManager
QoSThread
QoSThreadBroker
QoSThreadManager
QoSEDF
QoSEDFBroker
QoSEDFManager
QoSVideo
QoSVideoBroker
QoSVideoManager
QoSDomain
GUI
Reserve(GOOD, LOW)
Reserve(GOOD)
Reserve(GOOD)
set(GOOD)
Map(GOOD):Thread={7,10}Mem=50KbDOOM=GOOD
Reserve( {7,10}) Reserve({7,10})Map({7,10}):Sched={7,10}Thread=given by
QoSEDF
Map({7,10}:Sched={7,10}
QoSThread
France Télécom R&D ARTIST2 - 01/24/2005 19
Analysis
� Dynamicity� Allows dynamic QoS management� Dynamic evaluation of QoS parameters� Allows dynamic architecture reconfiguration
� Reusability� Component-based� Separation policy/mechanism
� Genericity� Non QoS policy/mechanism/specification specific� Each component has its own QoS mechanisms� Management of heterogeneous QoS (real-time and non real-time)
� Real-time aspects� Admission testing can be omitted (hard real-time)� Performance depends on the implementation (avoid multiple admission testing)� Adaptation occurs in soft real-time
France Télécom R&D ARTIST2 - 01/24/2005 20
Conclusion
� Summary� Qinna: component-based QoS architecture� Some preliminary experiments including various QoS mechanisms, QoSpolicies and QoS specifications
� Benefits� Dynamicity� Reusability� Genericity
� Future work� Integrate complex QoS management policies� Quantitative evaluation (LOC, memory, delay overhead, etc.)� Supporting tools
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