Rekayasa Perangkat Lunak(Software Engineering)

M.Sukrisno Mardiyanto

Kuliah Umum

Universitas Dian NuswantoroSemarang, 16 Oktober 2008

Definisi Perangkat Lunak

Computer programs and associated documentation (plus configuration data and user training)

Software products may be developed for a particular customer or developed for a general market Generic (shrink-wrapped) - developed to be

sold to a range of different customers Bespoke (custom) - developed for a single

customer according to their specification

Definisi Rekayasa Perangkat Lunak

An engineering discipline which is concerned with all aspects of software production

Engineering discipline Discover solutions by applying theories,

methods or other mechanisms. Work within constraints

All aspects of software production Software development (technical processes) Project management Development of supporting tools, methods

and theories

Misconception

Model Pembangunan P.Lunak A simplified representation of a software

process, presented from a specific perspective

Examples of process perspectives are Workflow perspective - sequence of activities Data-flow perspective - information flow Role/action perspective - who does what

Generic process models Waterfall Iterative development Formal transformation Integration from reusable components

Waterfall ModelRequirements

definition

System andsoftware design

Implementationand unit testing

Integration andsystem testing

Operation andmaintenance

Spiral Model

Riskanalysis

Riskanalysis

Riskanalysis

Riskanalysis Proto-

type 1

Prototype 2Prototype 3

Opera-tionalprotoype

Concept ofOperation

Simulations, models, benchmarks

S/Wrequirements

Requirementvalidation

DesignV&V

Productdesign Detailed

design

CodeUnit test

IntegrationtestAcceptance

testService Develop, verifynext-level product

Evaluate alternativesidentify, resolve risks

Determine objectivesalternatives and

constraints

Plan next phase

Integrationand test plan

Developmentplan

Requirements planLife-cycle plan

REVIEW

Evolutionary Model

ValidationFinal

version

DevelopmentIntermediate

versions

SpecificationInitial

version

Outlinedescription

Concurrentactivities

Incremental Model

Valida teincrement

Develop systemincrement

Design systemarchitecture

Integrateincrement

Valida tesystem

Define outline requirements

Assign requirements to increments

System incomplete

Finalsystem

Paradigm, Methodology & Techniques

Paradigm

Methodology

Techniques

Philosophical

Practical

Metodologi Pembangunan P.Lunak

Process model (Data-flow Oriented)

Data model (Data-structure Oriented)

Object model (Object-oriented)

Pemodelan Perangkat Lunak

Data flow model showing how the data is processed at different stages.

Composition model showing how entities are composed of other entities.

Architectural model showing principal sub-systems.

Classification model showing how entities have common characteristics.

Stimulus/response model showing the system’s reaction to events.

Process Model (1)

Process models show the overall process and the processes that are supported by the system

Data flow models may be used to show the processes and the flow of information from one process to another

Process Model (2)

Get costestimates

Acceptdelivery ofequipment

Checkdelivered

items

Validatespecification

Specifyequipmentrequired

Choosesupplier

Placeequipment

order

Installequipment

Findsuppliers

Supplierdatabase

Acceptdelivered

equipment

Equipmentdatabase

Equipmentspec.

Checkedspec.

Deliverynote

Deliverynote

Ordernotification

Installationinstructions

Installationacceptance

Equipmentdetails

Checked andsigned order form

Orderdetails +

Blank orderform

Spec. +supplier +estimate

Supplier listEquipment

spec.

Data Flow Model : Procurement System

Behavioral Model

Behavioural models are used to describe the overall behaviour of a system.

Two types of behavioural model are: Data processing models that show how

data is processed as it moves through the system;

State machine models that show the systems response to events.

Data-processing models

Data flow diagrams (DFD) are used to model the system’s data processing

These show the processing steps as data flows through a system

Intrinsic part of many analysis methods

Simple and intuitive notation that customers can understand easily

Elements of a DFD

Processes Change the data. Each process has one or more

inputs and outputs Data stores

used by processes to store and retrieve data (files, DBs)

Data flows movement of data among processes and data

stores External entities

outside things which are sources or destinations of data to the system

Contoh DFD : Ordering system

Completeorder form

Orderdetails +

blankorder form

Valida teorder

Recordorder

Send tosupplier

Adjustavailablebudget

Budgetfile

Ordersfile

Completedorder form

Signedorder form

Signedorder form

Checked andsigned order

+ ordernotification

Orderamount

+ accountdetails

Signedorder form

Orderdetails

State machine models

These model the behaviour of the system in response to external and internal events.

They show the system’s responses to stimuli so are often used for modelling real-time systems.

Statecharts are an integral part of the UML and are used to represent state machine models.

Statecharts

Allow the decomposition of a model into sub-models (see following slide).

A brief description of the actions is included following the ‘do’ in each state.

Can be complemented by tables describing the states and the stimuli.

Microwave oven model

Full power

Enabled

do: operateoven

Fullpower

Halfpower

Halfpower

Fullpower

Number

Dooropen

Doorclosed

Doorclosed

Dooropen

Start

do: set power= 600

Half powerdo: set power

= 300

Set time

do: get numberexit: set time

Disabled

Operation

Cancel

Waiting

do: displaytime

Waiting

do: displaytime

do: display 'Ready'

do: display'Waiting'

Timer

Timer

State TableState Description

Waiting The oven is waiting for inputs. The display shows the current time

Half-power The oven power is set to 300 watts. The display shows “half-power”

Full-power The oven power is set to 600 watts. The display shows “full-power”

Set-timeThe cooking time is set to the user input value. The display shows the cooking time selected and is updated as the time is set.

Enable Oven operation is enabled. Interior oven light is off. The display shows “Ready to cook”.

Disable Oven operation is disabled for safety. Interior oven light is on. The display shows “Not Ready”

Operation

Oven in operation. Interior oven light is on. The display shows the timer counts down. On completion the buzzer is sounded for 5 seconds. Oven light is on. Display shows “Cooking complete” while buzzer is sounding.

Microwave oven stimuli

Microwave oven operation

Cookdo: run

generator

Done

do: buzzer onfor 5 secs.

Waiting

Alarm

do: displayevent

do: checkstatus

Checking

Turntablefault

Emitterfault

Disabled

OK

Timeout

Time

Door open Cancel

Operation

Semantic data models

Used to describe the logical structure of data processed by the system.

An entity-relation-attribute model sets out the entities in the system, the relationships between these entities and the entity attributes

Widely used in database design. Can readily be implemented using relational databases

Library semantic modelSource

titlepublisherissuedatepages

1

Article

titleauthorspdf filefee

has-links

1

Buyer

nameaddresse-mailbilling info

places

fee-payable-to

n

1

n

published-in

deliversin

m n

1

1

1

CopyrightAgencynameaddress

Country

copyright formtax rate

1

Order

order numbertotal paymentdatetax status

in

1

Data Dictionary

Data dictionaries are lists of all of the names used in the system models. Descriptions of the entities, relationships and attributes are also included.

Advantages Support name management and avoid

duplication; Store of organisational knowledge

linking analysis, design and implementation;

Object models (1)

Object models describe the system in terms of object classes and their associations.

An object class is an abstraction over a set of objects with common attributes and the services (operations) provided by each object.

Various object models may be produced Inheritance models; Aggregation models; Interaction models.

Object models (2)

Natural ways of reflecting the real-world entities manipulated by the system

More abstract entities are more difficult to model using this approach

Object class identification is recognised as a difficult process requiring a deep understanding of the application domain

Object classes reflecting domain entities are reusable across systems

Inheritance model

Organise the domain object classes into a hierarchy.

Classes at the top of the hierarchy reflect the common features of all classes.

Object classes inherit their attributes and services from one or more super-classes. these may then be specialised as necessary.

Class hierarchy design can be a difficult process if duplication in different branches is to be avoided.

Object models and UML

The UML is a standard representation devised by the developers of widely used object-oriented analysis and design methods.

It has become an effective standard for object-oriented modelling.

Example : Library System

Super Class : - Library item - Library user

Class “Library item” : - Published item - Recorded item

Class “Library user” : - Reader - Borrower

Library class hierarchy

Catalogue numberAcquisition dateCostTypeStatusNumber of copies

Library item

Acquire ()Catalogue ()Dispose ()Issue ()Return ()

AuthorEditionPublication dateISBN

Book

YearIssue

Magazine

DirectorDate of releaseDistributor

Film

VersionPlatform

Computerprogram

TitlePublisher

Published item

TitleMedium

Recorded item

User Class hierarchy

NameAddressPhoneRegistration #

Library user

Register ()De-register ()

Affiliation

Reader

Items on loanMax. loans

Borrower

DepartmentDepartment phone

Staff

Major subjectHome address

Student

Multiple inheritance

Rather than inheriting the attributes and services from a single parent class, a system which supports multiple inheritance allows object classes to inherit from several super-classes.

This can lead to semantic conflicts where attributes/services with the same name in different super-classes have different semantics.

Multiple inheritance makes class hierarchy reorganisation more complex.

Multiple inheritance : example

# Tapes

Talking book

AuthorEditionPublication dateISBN

Book

SpeakerDurationRecording date

Voice recording

Object aggregation

An aggregation model shows how classes that are collections are composed of other classes.

Aggregation models are similar to the part-of relationship in semantic data models.

Object aggregation (example)

Videotape

Tape ids.

Lecturenotes

Text

OHP slides

Slides

Assignment

Credits

Solutions

TextDiagrams

Exercises

#ProblemsDescription

Course titleNumberYearInstructor

Study pack

Object behaviour modelling

A behavioural model shows the interactions between objects to produce some particular system behaviour that is specified as a use-case.

Sequence diagrams (or collaboration diagrams) in the UML are used to model interaction between objects.

Issues of Electronic item

:Library User

Ecat:Catalog

Lookup

Issue

Display

:Library ItemLib1:NetServer

Issue licence

Accept licence

Compress

Deliver

Unified Modeling Language (UML)

Use case Diagram Class Diagram Sequence Diagram Collaboration Diagram Interaction Diagram State chart Diagram Component Diagram Deployment Diagram

CASE Tools

IBM Rational Rose Argo UML Poseidon UML

Advance Methodologies & its future

Aspect-oriented Software development eXtreme Programming (XP) Agile Software Development method

Referensi

Ian Sommerville Roger S. Presman Ivar Jacobson