cbse with embeded system
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Explicit Connectors in
Component Based
Software Engineering for
DistributedEmbedded Systems
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Overview
This talk is about Component Based Software Engineering
components
connectors
contracts Embedded Systems Software
distributed
dependable
resource constrained
Software Development Process Model Driven Development
Validation and Verification of CompositionModels
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Contribution
We show how to simplify the development of
component based distributed embeddedapplications by introducing explicit
component connectors within modeldriven SE (UML 2).
how to support validation ofcommunication properties at model level.
which types of contracts are required formodel level validation of communicationwithin composed structures.
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Outline
Overview of the Automotive EmbeddedSystems Domain.
Component Based Software Engineeringand Model Driven Development fordistributed embedded systems.
Contract Types in Composition Models.
Example Composition with ExplicitConnectors and Contracts.
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Automotive Embedded Systems
Overview
Today's vehicle networks are truly distributedelectronic systems (70+ nodes (=ECUs) [1]).
Cars contain numerous (10+) heterogeneous time orevent driven bus systems
CAN, LIN, FlexRay, MOST
x-by-wire
steering aids, ABS, ESP(DSC)
remote window and lock control
engine control
airbag control
navigation systems
entertainment systems
[1] P. Hansen. New s-class mercedes: Pioneering electronics. The Hansen
Report on Automotive Electronics, 18(8):12, October 2005.
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Automotive Embedded Systems
Typical Properties
Software is mission critical highly dependable
hard real-time
typically statically scheduled and bound
Lifetime is rather long (10-14 years) modular design
exchangeable components (modules)
Systems are produced in high quantities(56.3 million cars in 2005) costs have to be small
bug fixes are extremely expensive
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Outline
Overview of the Automotive EmbeddedSystems Domain.
Component Based Software Engineeringand Model Driven Development fordistributed embedded systems.
Contract Types in Composition Models.
Example Composition with ExplicitConnectors and Contracts.
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Component Based Software Engineering
Overview
Components are considered to be trusted element of execution
with a well defined usagedescription
contracts component contracts interface contracts
conforming to a component model interaction standard composition standard
deployment standard
CBSE is a well known paradigm in classical softwareengineering. Applications are built by
assembling components
deploying composed structures within a system environment
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Component Based Software Engineering
Component Composition
Association (connection) of provided and required interfaces interaction and communication implicit validation is typically an interface type check, sometimes also a protocol check
Distributed Interaction (Communication) Fat Components Light Weight Components + Middleware
Adapter
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Component Based Software Engineering
COMPASS[2] Metamodel
PROCEDURAL_INTERFACE
PORT
id
INTERFACE
ersion
id
COMPONENT
ersion
id
CONNECTOR
id
ASSEMBLY
id
DATA_INTERFACE
P
O
I E
0..*
1
1..*
1
EQ I
E
0..*
1
P
O
I E
*
*
EQ I
E
*
*
EQ I
E0..*
1
1
1
0..*
1 2
1
P
O
I E
0..*
1
0..* 1
[1] COMPASS Component Based Automoti e System Software,
http://www.infosys.tuwien.ac.at/compass
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Component Based Software Engineering
Explicit Connectors
First class architectural entities embodyingcomponent interaction life cycle differs from that of a component
at composition time connectors are abstract
representations of interaction properties connectors materialize after the components
deployment has been specified connector fragments are component like artefacts
Hide matters of communication and distribution fromthe application components
simplifies application components application development no longer requires detailed
communication subsystem know-how, when using OTSconnector
communication properties are bound to the connectors
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Component Based Software Engineering
Connector Fragmentation
Connectors are fragmented if components are deployed over process/address space boundaries. components are deployed over different nodes.
Separation into connector fragments is referred to as deploymentanomaly.
Emerging contracts provide more detailed communication properties
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Component Based Software Engineering
Explicit Connector Example (RPCA)
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Outline
Overview of the Automotive EmbeddedSystems Domain.
Component Based Software Engineeringand Model Driven Development fordistributed embedded systems.
Contract Types in Composition Models.
Example Composition with ExplicitConnectors and Contracts.
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Component Based Software Engineering
Contracts
Specify provided and required attributes ofassociated model elements.
Five main categories: Component Contract
e.g. memory footprint, ECU restrictions Interface Contract
e.g. operation signatures, temporal properties ofoperations
Port Contract e.g. behavior protocols
Connector Contract e.g. resource requirements, channel attributes (latency,
)
Platform Contract e.g. bus timing (in time-driven busses), ECU attributes
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Outline
Overview of the Automotive EmbeddedSystems Domain.
Component Based Software Engineeringand Model Driven Development fordistributed embedded systems.
Contract Types in Composition Models.
Example Composition with ExplicitConnectors and Contracts.
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Example
CompositionComponent Contract
Memory Usage
ECU restrictions
Component Contract
Memory Usage
ECU restrictions
Interface Contract
Interface Type
Operation Signatures
WCET
Interface Contract
Interface Type
Operation Signatures
WCET
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Example
Deployment Specification
Platform Contract
Memory Provision ECU specification
Platform Contract
Memory Provision
ECU specificationPlatform Contract
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Example
Connector Transformation
Connector Contract
Calculated Interface Contract
Provides properties of the server component but extends them by thecommunication subsystems constraints.
WCET of operation at server is 0.01s WCET of connector fragments is 0.01s BusCycle length = 0.1s (has to be consumed)provided execution time = 0.12s !! Violation of Contract !
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Conclusion
The introduction of explicit connectors allows the usage of OTS embedded connectors
encapsulating communication logic eliminates needs for heavy weight middleware
simplifies the development of application components
provides information on required system resources
allows a model level validation of compositionalconstraints beyond simple type checks
Future Work Generate custom tailored middleware from application
models and connector building blocks. Develop a more precise meta-model for contracts.
Thank You !
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