2015-09-23Séverine Sentilles1 Advanced Component-Based Software Engineering Overview of several component models

23-04-21 Séverine Sentilles 1

Advanced Component-Based SoftwareEngineering

Overview of several component models


Agenda

Unified Modelling Language (UML) Picolo Fractal BIP Autosar


Unified Modelling Language(UML)


Component diagram

Three representations for a component

But access points are required• Utilisation of interfaces

• Utilisation of port

C<<component>>

C<<component>>

C


Interfaces

Role:• Specification of the access point• Required functionalities• Provided functionalities

2 existing representation• The most descriptive• The compact

• The compact

<<interface>>

ProvidedItf

<<component>>C

<<interface>>

RequiredItf

<<component>>C

ProvidedItf RequiredItf


Ports

Role:• Access point to the internal structure of the

component

• Can have 0 or several interfaces

Representation:

<<component>>C


Relationship between components

Use the notion of connector• Roughly a way to link components together & make

them ”communicate” via a request of services

Generalisation of the means of communication Example:

• Client-server• Pipe&filter• Message exchange

Can also be called horizontal composition

<<component>>Client

<<component>>Server

IdenticalItf


Vertical composition

Can also be called hierarchical composition Role

• To increase the component granularity

• To expose the content of the component

Use the notion of delegation connector (between two ports)

<<component>>C

<<component>>A

<<component>>B


Profile UML

Extension of the UML model in order to adapt it to the particular requirements of a context

Uses• Stereotypes• Tagged values• OCL Constraints

Examples:• Profile for EJB components• Profile for a software architecture


EJB Profile


Agenda



Picolo


Characteristics

A simple component model

• to understand how components work

• Not suited for building real applications

Programing language: Python

Developed by:

• LIFL (FRANCE)

From “Picolo: A Simple Python Framework for Introducing Components Principles, 2005”


The component model

From “Picolo: A Simple Python Framework for Introducing Components Principles, 2005”


Agenda



The Fractal component model


Characteristics

Hierarchical, Reflexive, Open Allow the sharing of components Extensible

Several implementation• Julia (Java)• Think (C)• FracTalk (smalltalk)• FracNet (.NET)

Developed by• France Telecom R&D (FRANCE)• INRIA (FRANCE)


Components Existence at compile-time and run-time “3” types

• Primitive• Composite• (Shared)

Divided in 2 parts• Membrane

• Management of the extra-functional properties (Controllers)• Ex: Binding, Life-cycle, state, etc.• Extensible (open set of control capabilities)

• Content (management of the functional properties) Reflexive capabilities

• execution and internal structure of component can be made explicit

• through well-defined interfaces• Extendable/adaptable (to fit the programmer’s constraints and

objectives)


Interfaces

Access point to the components Characteristics:

• Client (required)/Server (provided)

• Mandatory/optional

• Simple/multiple Some predetermined interface (used in the membrane)

• Binding-controller-itf

• Lifecycle-controller-itf

• Name-controller-itf

• …


Communication

2 types:• Primitive binding:

• link a server interface to a client interface within a component

• Composite binding:

• Communication path between an arbitrary number of component interfaces

• primitives bindings

• and/or binding components (stub, skeleton, adapters, etc.)


Julia

Small, efficient, extensible run-time framework Programming language: Java Relies on a combination of interceptors and mixins (for the

programming of the reflective features)


Example

The Serveur Component:

@FractalComponent(controllerDesc="primitive")@Provides(

interfaces=@Interface(name="s",signature=Service.class) )

public class ServeurImpl implements Service {public void print( String msg ) {

System.out.println(msg);} }


Example

The Client Component:

@FractalComponent(controllerDesc="primitive")@Provides(

interfaces= @Interface(name="r",signature=Runnable.class)

)public class ClientImpl implements Runnable {

@Requires(name="s")private Service service;

public void run() {service.print("Hello world!");} }


ExampleAssembling the components:

<definition name="HelloWorld"><interface name="r" role="server"signature="java.lang.Runnable" />

<component name="client" name="Client"><interface name="r" role="server" signature="java.lang.Runnable" /><interface name="s" role="client" signature="Service" /><content class="ClientImpl" /></component>

<component name="server" name="Server"><interface name="s" role="client" signature="Service" /><content class="ServerImpl" /></component>

<binding client="this.r" server="client.r" /><binding client="client.s" server="server.s" /> </definition>


Fractal and the main principles of the CBSE

Reusability• Utilisation of type system, communication semantic,

component semantic=> risk to have a conflict/incompatibility between component

developed independently Substituability

• Possible ? Extensibility

• At design-time: ok

• At run-time: with the introspection mechanism ? Composability:

• Behaviour superimposed by the ”parent-component” to the subcomponents (extra-functional properties)


Agenda



BIP


Characteristics Framework for modelling heterogeneous real-time components Developed by Verimag (FRANCE) Hierarchical Structured in 3 layers <B, I, P>:

• B: Behavior

• I: Interaction (a set of connectors describing the interactions between transition of the behavior)

• P: Priority rules (set of constraints describing scheduling policy for interaction)

Behavior

Interaction

Priority

A BIP componentStructure


Components

A component consists of:• A set of ports : action names used for synchronization with

other components.

• A set of control states: synchronization points.

• A set of variables used to store (local) data.

• A set of transitions modeling atomic computation steps.

Ports

States

Transitions

Variables


component

Compound component:• new components from existing components


Communication styles

Interactions• Synchronous

• Rendez-vous

• Broadcast

• Utilisation of connectors• Set of ports from different components that can be

involved in an interaction

• Ex: p1, p2, p3 ports of 3 distincts components, then the connector {p1,p2,p3} has => 7 interactions: p1, p2, p3, {p1,p2}, {p1,p3}, {p2,p3}, {p1,p2,p3}.

Synchronization


Priorities

used to filter interactions among the feasible ones depending on given conditions


BIP and the main principles of CBSE

Reusability• existing components can be combined to generate

complex components using platform glue Substituability

• ? Extensibility

• ? Composability:

• Utilization of parameterized binary composition operator

• The product of two components consists in composition layer by layer


Example

Defining a component

component Reactiveport in, outdata int x, ybehavior

state emptyon in provided 0 < x do y:=f(x) to full

state fullon out to empty

endend


Example

Defining an interaction

connector C1 = p1|p2|p3

behavior

on p1|p2|p3 provided ¬(x1 = x2 = x3)

do x1, x2, x3 := MAX(x1, x2, x3)

end


Agenda



Autosar


Chacteristics

Automotive Open System Architecture Goal: Separation of concerns

• Software components deals with application logic and can be developed independently of the underlying hardware and os

• Middleware-layer handles aspects of remote communication, component lifecycle, scheduling, timing as well as OS abstraction.

configurable/customizable run-time environment Adding new functions

• product variants, platforms


Developed by


View


Layered architecture

Components


Components

Independent of the infrastructure Ports and connectors No imposed size

• Reusable piece of functionality (filter)• An entire automotive functionality

Sensors/actuators• Particular components• Encapsulate the dependencies of the application on specific

sensors/actuators crossing module boundaries (function distribution)

• one function: several SW components one/several ECUs• one ECU: several SW Components from different

functions / vendors


Component (cont)

Owns a description (SW-C Description)• Operations and datas provided/required

• Requirements on the infrastructure

• Resources needed (CPU-time, memory)

• Information regarding the specific implementation of the component


Component connexion


Communication style

Communication style• Client/server

• Synchronous communication pattern(The client can be blocked)

• Sender/Receiver• Asynchronous communication pattern

(the sender is not blocked)

• Event is considered as a subcategory of sender/receiver


Autosar and the main principles of CBSE

Reusability• ok

Substituability• At run-time: No

(the desired system is static after design time)

Extensibility:• ?

Composability:• ?


Literature Unified Modelling Language (UML) Picolo

• Picolo: A Simple Python Framework for Introducing Components Principles• http://www.win.tue.nl/~mchaudro/cbse2006/PicoloTalk.pdf• http://www.win.tue.nl/~mchaudro/cbse2006/Picolo%20Introducing%20Components%20using

%20Python.pdf

Fractal• The Fractal Component Model and Its Support in Java

• http://fractal.objectweb.org/doc/pub/SPE06.pdf

• Fractal tutorial at ICAR 2006 (in French)• http://sardes.inrialpes.fr/ecole/2006/cours-fractal.pdf

BIP• Modeling Heterogeneous Real-time Components in BIP

• http://www-verimag.imag.fr/%7Easync/BIP/publications/BIP-invited-paperSEFM06.pdf

• A Methodology and Supporting Tools for the Development of Low-Footprint and Safe Embedded Systems

• http://www-verimag.imag.fr/%7Easync/BIP/publications/BIP2THINK.pdf AUTOSAR

• AUTOSAR: Technical Overview• http://www.autosar.org/download/AUTOSAR_TechnicalOverview.pdf

• AUTOSAR: Standardization of software architecture in automotive industry• http://symposium.itea2.org/symposium2006/main/presentations/day_2/

AUTOSAR_Standardization_of_software_architecture_in_automotive_industry.pdf?PHPSESSID=433abcfec16c19b0dbb2554976

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2015-09-23Séverine Sentilles1 Advanced Component-Based Software Engineering Overview of several component models