Cbse With Embeded System

8/6/2019 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






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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 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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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

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0..*

1

0..* 1

[1] COMPASS Component Based Automoti e System Software,

http://www.infosys.tuwien.ac.at/compass


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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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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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Explicit Connector Example (RPCA)


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Outline






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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






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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 !

Documents

Cbse With Embeded System