Page 1, 12 September 2015 Introduction to Component-Based Software Engineering Ivica Crnkovic...

, April 21, 2023

Introduction toIntroduction to

Component-Based Software Component-Based Software

EngineeringEngineeringIvica Crnkovic

Mälardalen University,

Department of Computer Engineering

Sweden

[email protected]

http://www.idt.mdh.se/~icc

, April 21, 2023

Topic overviewTopic overview

1 The challenges of SW- how can CBD help?

2 What is a software component?

3 Basic principles of component-based approach

4 Component-based Software Development Process

5 Problems and research issues

6 References

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The challenges of software development The challenges of software development

- how can component software help?- how can component software help?

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Challanges of Software EngineeringChallanges of Software Engineering

(The author of slides with blue background: Michel Chaudron, Tue)

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Answer: Component-based DevelopmentAnswer: Component-based Development

Idea:

Build software systems from pre-existing components (like building cars from existing components)

Building components that can be reused in different applications

Separate development of components from development of systems

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Component-Based Software Engineering (CBSE)Component-Based Software Engineering (CBSE)

Provides methods and tools for

Building systems from components

Building components as reusable units

Performing maintenance by replacement of components and introducing new components into the system

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application

Component#1

Component #

2

Component#3

Component#4

componentsComponent-based software construction (1)Component-based software construction (1)

Component

#1

Component #

2

Component#3

Component#4

construction

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Concentration on the business partsConcentration on the business parts

Business issues

GUI

Communication

GUI

Data model

Deployment

- - - - - -

INFRASTRUCTURE

StandardReusable parts

Application specific

“30 % of SW development effort is spent on infrastructure that adds no value”

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What is a software component?What is a software component?

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The software architecture of a program or computing system is the structure or structures of the system, which comprise software components [and connectors], the externally visible properties of those components [and connectors] and the relationships among them.”

Bass L., Clements P., and Kazman R., Software Architecture in Practice,

C1

C4

C2

C5C3

Architectural point of viewArchitectural point of view

1504/21/23

CORBA (Common Object Request Broker ArchitectureCORBA (Common Object Request Broker Architecture))

CORBAappsCORBAapps CORBAdomainsCORBAdomains CORBAfacilitiesCORBAfacilities

CORBAservicesCORBAservices

Another exampleAnother example

Object Management Architecture OverviewObject Management Architecture Overview

TransactionsTransactionsTransactionsTransactions EventEventEventEvent SecuritySecuritySecuritySecurity NamingNamingNamingNaming

Corba component modelCorba component model

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Frameworks - building Frameworks - building ““the real componentsthe real components””

Component Object Management - COM, Active X

Enterprise JavaBeans

CORBA components

.NET

Late binding - easy replacement

Word document

Excel document

My_application

Excel document

component

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Example: The architecture of a car control systemExample: The architecture of a car control system

Vehicle mechanics

ECU

Sensor ActuatorSensor

ECU


ECU


gateway

(CAN) BUS

brake injection

Infotaiment

ECU – Electronic Control Unit

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The architectural design challenge The architectural design challenge

Vehicle stability Suspension Drive by wire …… Complex functions

Local Control Functions


Basic functionsLocal Control Functions


How to implement complex functions based on local control functions?

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Problem: resource sharing Problem: resource sharing

Sensor 1

Sensor 2

Sensor 3

Sensor ..

Networkresources

++++++++++

++++++++++

++++++++++Sensor ..

Executionresources

Node 1

Node 2

Node 3

Node …

Node …

Actuator 1

Actuator 2

Actuator 3

Actuator …

Actuator …

Can functions of different criticality be allowed to share resources?

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sensors

Challenge – open and dependable platformChallenge – open and dependable platform

Vehicle

actuators

Engine Control Local brake Control Transmission ………local

Vehicle stability

Cruise control

Antispin Global (complex) functions

Hardware

Input/output drivers

MiddlewareECU ECU ECU

Applications

SOFTWARE COMPONENTS

Collision detection

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Challenge – open and dependable platformChallenge – open and dependable platform

Hardware

Input/output drivers

Middleware

ECU ECUECU

Applications C1 C2

RequirementsSeparation of hw from SW developmentSeparation of SW component development

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Szyperski: Software Component DefinitionSzyperski: Software Component Definition

Szyperski (Component Software beyond OO programming)

A software component is

a unit of composition

with contractually specified interfaces

and explicit context dependencies only.

A software component

can be deployed independently

it is subject to composition by third party.

Will you meet him?

http://www.comparch-events.org/pages/present.html

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Composition unitComposition unit

A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third party. –Clemens Szyperski

How much components fit together?

How much costs the glue code?

Components

Glue codeSystem

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What is a contract?What is a contract?

A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third party.

Interface – component specification

Contract - A specification attached to an interface that mutually binds the clients and providers of the components.

Functional Aspects (API)

Pre- and post-conditions for the operations specified by API.

Non functional aspects (different constrains, environment requirements, etc.)

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What is an explicit context dependency?What is an explicit context dependency?


Provided and Required Interface

Context dependencies - Specification of the deployment environment and run-time environment

Example: Which tools, platforms, resources or other components are required?

Do

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Late binding - dependencies are resolved at load or run-time.

What does it mean deployed independently?What does it mean deployed independently?

Platform (framework)Platform (framework)

connector

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Components and Interfaces - UML definitionComponents and Interfaces - UML definition

Component

Interface

Operation

*

in-interfaces*

*

*

Name

1

1

1 1

1

1

Parameter

1

*

Type

1 *

OutParameterInParameter

InOutParameter

*

out-interfaces

*

Component – a set of interfacesrequired (in-interfaces)provided (out-interfaces)

Interface – set of operationsOperations – input and output parameters of

certain type

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Contractually specified interfaces in a UML metamodelContractually specified interfaces in a UML metamodel

Interface

Component

*

in-interfaces*

*

out-interfaces

*

State

1 *

Constraint

*

*

* 1

Invariant

1

*

1

*

Operation

*

*

Parameter

1

*

PreCondition

* 1

PostCondition

1 *

1

*

InParameter OutParameter

*

*

*

*

*

*

*

2

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Is Szyperski definition enough?

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Component specificationComponent specification

Components are described by their interfaces

(A black box character)

glass boxglass box

black boxblack box

white boxwhite box

grey boxgrey box

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Nice components that can be composed (put together)

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Another definitionAnother definition

A software component is a software element that confirms a component model can be independently deployed composed without modification according to a

composition standard.

A component model defines specific interaction and composition standards.

G. Heineman, W. Councel, Component-based software engineering, putting the peaces together, Addoson Wesley, 2001

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Summary CBSE – basic definitionsSummary CBSE – basic definitions

The basis is the Component

Components can be assembled according to the rules specified by the component model

Components are assembled through their interfaces

A Component Composition is the process of assembling components to form an assembly, a larger component or an application

Component are performing in the context of a component framework

All parts conform to the component model

A component technology is a concrete implementation of a component model

c1 c2

Middleware

Run-time system

framework

Component Model

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Component TechnologyComponent Technology

Component Component Framework

Platfo

rmP

latform

Co

mp

on

ents

Co

mp

on

ents

RepositoryRepository

Supporting ToolSupporting Tool

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Basic principles

of

Component-based approach

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Main principles: (1) ReusabilityMain principles: (1) Reusability

Reusing components in different systems

The desire to reuse a component poses few technical constraints.

Good documentation (component specification…)

a well-organized reuse process

Similar architecture

….

C1

C1 C2

C3 C4

Application A1

C1 C5

C6 C7

Application A2

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Main principles: (2) SubstitutabilityMain principles: (2) Substitutability

Alternative implementations of a component may be used.

The system should meet its requirements irrespective of which component is used.

Substitution principles Function level Non-functional level

Added technical challenges Design-time: precise definition of

interfaces & specification Run-time: replacement

mechanism

C1 C2

C3 C4

Application A1

C1´ C2

C3 C4

Application A1

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Substitution principleSubstitution principle

Substituting a component Y for a component X is said to be safe if:

All systems that work with X will also work with Y

From a syntax viewpoint, a component can safely be replaced if:

The new component implements at least the same interfaces as the older components

From semantic point of view?

Contractual interface holds (pre-, postconditions and invariants)

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Substitution principleSubstitution principle

Principle:

A component can be replaced if the new component Provide a sub-range of the output

Can accept larger range of input

CONDITION. Everything which comes from the firstTube fits to the second

C -C - C´ C´Input(c) <_ Input(c’)Input(c) <_ Input(c’)Output(C) _> Output(C’)Output(C) _> Output(C’)

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Main principles: (3) ExtensibilityMain principles: (3) Extensibility

Comes in two flavors:

extending components that are part of a system

Increase the functionality of individual components

Added technical challenges:

Design-time: extensible architecture

Run-time: mechanism for discovering new functionality

C1 C2 C3

C1 C2+ C3

C1 C2 C3

C1 C2 C4 C3

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Main principles: (4) ComposabilityMain principles: (4) Composability

Composition of components

P(c1 o c2) =P(c1) o P(c2) ??

Composition of functions

Composition of extra-functional properties

Many challenges

How to reason about a system composed from components? Different type of properties

Different principles of compositions

C1 C2

assembly

C

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23-04-21Séverine Sentilles 67

Components in Unified Modelling Components in Unified Modelling

Language (UML)Language (UML)

23-04-21Séverine Sentilles

68

Component diagramComponent diagram

Three representations for a component

But access points are required

Utilisation of interfaces

Utilisation of port

C<<component>>

C<<component>>

C

InterfacesInterfaces Role:

Specification of the access point Required functionalities Provided functionalities

2 existing representation The most descriptive The compact

<<interface>>ProvidedItf

<<component>>C

<<interface>>

RequiredItf

<<component>>C

ProvidedItf RequiredItf

70

PortsPorts

Role:

Access point to the internal structure of the component

Can have 0 or several interfaces

Representation:

<<component>>C


71

Relationship between componentsRelationship 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


72

Vertical compositionVertical 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


73

Profile UMLProfile 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


74

EJB ProfileEJB Profile


75

The component model PICOLOThe component model PICOLO

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

UML Metamodel

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Component-based software development Component-based software development

processprocess

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Time to Market – “Classical” Development Process?Time to Market – “Classical” Development Process?

Requirements

Specification

Design

Implementation

Test

Product LifecycleProblems:Problems:•Time To MarketTime To Market•High CostsHigh Costs•Meeting deadlinesMeeting deadlines•VisibilityVisibility

Operation & Maintenance

TIMETIME

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Development processDevelopment process COTS and outsourcing require different development

processes

Requirements

Specification

Design

Implementation

Test

Find & Select

Adapt

Deploy

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Development process – emphasize reuseDevelopment process – emphasize reuse

Managing COTS in the early stage of the development process

Requirements

Specification

Design

Implementation

Test

Deploy

Find & Select

Adapt

Test

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CBDCBD – separation of development processes – separation of development processes

Requirements

Specification

Design

Implementation

Test

Deploy

Find & Select

Adapt

Test

ApplicationApplicationdevelopmentdevelopment

ComponentComponentdevelopmentdevelopment

Operation &Maintenance

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Types of component-based developmentTypes of component-based development

Internal components as structural entities

Reusable components developed in-house

COTS (commercial off the shelf) components

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Product Line ArchitectureProduct Line Architecture

Core components building a core functionality

(Basic platform)

A set of configurable components combined building different products

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Platform-based productsPlatform-based products

Basic services

Middleware / infrastructure

Platform layer

Application layer

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Advantages of Software Product LinesAdvantages of Software Product Lines

Using existing infrastructure

Savings 30%-40% of efforts per product

Time to Market - improved

Larger variety of products

Uniform and recognizable functionality/interface

Better scalability (not obvious!)

Better maintainability (not obvious!)

Better possibility of component replacement

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Problems and research issuesProblems and research issues

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CBSE research and the SW life-cycleCBSE research and the SW life-cycle

AnalysisDesign

ImplementationTesting

Deployment

AnalysisDesign


Deployment

AnalysisDesign


Deployment

Quality Management

Project Management

ComponentsApplication

- assembly- finding - trusting - distribution- glue code

- design for customization/ variability- wrapping- specification/contracts

- development methods- frameworks

- storage- documentation

- run-time infrastructures

- configuration management

- certification- SW development process

- team structure

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SpecificationSpecificationAre more than interface method definitions

How to specify?

Interfaces, behavior (pre-/post conditions, invariants)

dependencies (required interfaces)

quality of service

How to test/verify component specifications?

How to document component specifications?

How to automatically connect components in builder tools using their specification?

How to verify the correctness of a composite system?

...

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Design for reuseDesign for reuse

Design for reuse requires additional effort

What is the best level of reuse (component granularity)?

How can the benefit of reuse be measured?

Development and documentation of component usage patterns

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RepositoriesRepositories How to store components?

How to classify and describe components?

How to find components?

fast

different aspectsinterfaces

functionality

component model

certification level

previous usage, trust

negotiable requirements

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Software development processSoftware development process

Current approach

requirements - analyses - design - implementation - test

CBSE approach must include

reuse component selection

component test

requirements reconciliation

CBSE must be supported by

modeling formalisms and tools

development tools

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Versioning and configuration managementVersioning and configuration management

Is more complex than usually (DLL hell)

especially in dynamic environments

Dependencies and composition constraints have to be resolved almost automatically

consider systems comprising thousands of components

How to do safe exchange of components e.g. upgrade, without contractual specification and proof?

All of the issues above are prerequisite for uploading and downloading of components

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SecuritySecurity

Requires trust and certification

complicated by large group of (small) vendors

‘mobile code security’ important

not user access control but code access control

current mechanisms

sandboxing: restricted functionality, restricted availability

codesigning: not necessarily suitable to establish trustprove of problem origin

difficulty of persecution

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Information sourcesInformation sources

This presentations is based on:This presentations is based on:

Ivica Crnkovic, Magnus Larsson: Building reliable component-based systems

Chapters: PART 1 The Definition and Specification of Components

Chapter 1 Basic Concepts in Component-Based Software Engineering

Chapter 2 On the Specification of Components

PART 2 SOFTWARE ARCHITECTURE AND COMPONENTS

Chapter 3 Architecting Component-based Systems

Chapter 4 Component Models and Technology

PART 3 DEVELOPING SOFTWARE COMPONENTS Chapter 6 Semantic Integrity in Component Based Development

Ivica Crnkovic: CBSE - New Challenges in Software Development

Ivica Crnkovic et al: Specification, Implementation and Deployment of Components

Page 97, April 21, 2023

http://www.idt.mdh.se/cbse-book

http://www.idt.mdh.se/cbse-book/overviews/1Part.htm



http://www.idt.mdh.se/kurser/cdt501/2011/lectures/Software-Focus-original.pdf

http://www.idt.mdh.se/kurser/cdt501/2011/lectures/p35-crnkovic.pdf

, April 21, 2023

BooksBooks Ivica Crnkovic & Magnus Larsson:

CBSE - Building reliable component--based systems Clemens Szyperski: Component Software : Beyond Object-

Oriented Programming: (1998), 2003 – second edition

Alan W. Brown: Large-Scale Component-Based Development

Betrand Meyer: Object-Oriented Software Construction, 2nd

G.T. Heineman, W. Councill: CBSE Putting the Pieces Together

J. Cheesmam, J. Daniels: UML Components

K. Wallnau: Building Systems form Commercial Components

, April 21, 2023

JournalsJournals IEEE Computer

IEEE Software

IEEE Internet Computing

IEEE Transactions on Software Engineering

IEEE Transactions on Computers

ACM Transactions on Programming Languages and Systems languages and programming systems.

ACM Transactions on Software Engineering and Methodology

ACM Transactions on Computer Systems

Software Development (www.sdmagazine.com)

… all major SW development magazines

, April 21, 2023

ConferencesConferences International Conference on Software engineering (ICSE)

International Symposium of Component-based Software Engineering (CBSE) - COmpArch

Euromicro Conference on Software Engineering and Advanced Application (SEAA) – track MOCS –Model-based development, components and services

International Workshop on Component-Oriented Programming (WCOP)

Symposium on Generative and Component-Based Software Engineering

Technology of Object-Oriented Languages and Systems (TOOLS) (www.tools-conferences.com)

International Conference on Software Reuse (ICSR)

ESEC/FSE

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