SYSTEM ENGINEERING

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Name : SYED KEYAN ALI TAHIR (124) USMAN BIN SAAD (118) SHAHID IQBAL (160) M.RAMZAN (074) M.BILAL

SUBMITTED TO:Mehreen Akhter

What is system engineering:-

• It is an approach to design, Implement and evaluate successful development of complex system.

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Jobs for system engineers:-• System engineer• Mission operation planner• Safety engineer• Airworthiness and certification engineer• Missile defiance national team chef engineer• Signal intelligence analyst• System integration engineer• Ground test planning engineer• Space craft system engineer

Duties of software engineer:-• Engineer have to ensure must that all things are working

properly• They have to create new and latest ideas for their companies• Technical work also required in field• Coordination , leadership and organisation important aspects of

job• They are ready to cooperate with other in daily life

System Engineering•Elements of a computer-based system• Software• Hardware• People• Database• Documentation• Procedures

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SystemsA hierarchy of macro-elements

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World viewBusiness or

Product Domain

Domain of interest

Domain view

System element

Element view

Detailed view

System Modeling

• define the processes that serve the needs of the view under consideration.

• represent the behavior of the processes and the assumptions on which the behavior is based.

• explicitly define both exogenous and endogenous input to the model.• exogenous inputs link one constituent of a given view with other

constituents at the same level of other levels; endogenous input links individual components of a constituent at a particular view.

• represent all linkages (including output) that will enable the engineer to better understand the view.

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Business Process Engineering

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uses an integrated set of procedures, uses an integrated set of procedures, methods, and tools to identify how methods, and tools to identify how information systems can best meet the information systems can best meet the strategic goals of an enterprisestrategic goals of an enterprise

focuses first on the enterprise and then focuses first on the enterprise and then on the business areaon the business area

creates enterprise models, data models creates enterprise models, data models and process modelsand process models

creates a framework for better creates a framework for better information management distribution, information management distribution, and controland control

System Architectures• Three different architectures must be analyzed and

designed within the context of business objectives and goals:

• data architecture• applications architecture• technology infrastructure

• data architecture provides a framework for the information needs of a business or business function

• application architecture encompasses those elements of a system that transform objects within the data architecture for some business purpose

• technology infrastructure provides the foundation for the data and application architectures

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The BPE Hierarchy• Information strategy planning (ISP)ostrategic goals definedosuccess factors/business rules identifiedoenterprise model created

•Business area analysis (BAA)oprocesses/services modeledointerrelationships of processes and data

•Application Engineeringoa.k.a ... software engineeringomodeling applications/procedures that address (BAA) and constraints of ISP

•Construction and deliveryusing CASE and 4GTs, testing

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Information Strategy Planning• Management issueso define strategic business goals/objectiveso isolate critical success factorso conduct analysis of technology impacto perform analysis of strategic systems

• Technical issueso create a top-level data modelo cluster by business/organizational areao refine model and clustering

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Defining Objectives and Goals•Objective—general statement of direction

•Goal—defines measurable objective: “reduce manufactured cost of our product”o Subgoals:

decrease reject rate by 20% in first 6 monthsgain 10% price concessions from suppliersre-engineer 30% of components for ease of

manufacture during first year •Objectives tend to be strategic while goals tend to be tactical

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Business Area Analysis•define “naturally cohesive groupings of

business functions and data” (Martin)•perform many of the same activities as ISP, but narrow scope to individual business area

• identify existing (old) information systems / determine compatibility with new ISP modeldefine systems that are problematic defining systems that are incompatible with new information model

begin to establish re-engineering priorities

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The BAA Process

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salesacct

manufacturing

QC

eng’ring

distribution

admin.

DataModel

ProcessDecomposition

DiagramMatrices

e.g.,entity/process

matrix

Process Flow

Models

Product Engineering

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System analysis(World view)

The completeproduct

capabilities

Componentengineering

(Domain view)

Processing requirement

Analysis & DesignModeling

(Element view)

Construction&

Integration(Detailed view)

software

function

SoftwareEngineering

programcomponent

hardware

data behavior

Product Architecture Template

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user interface processing

inputprocessing

outputprocessing

maintenance and self-test

process and controlfunctions

Architecture Flow Diagram

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bar codereader

subsystem

bar codedecoding

subsystem

data baseaccess

subsystem

shuntcontrol

subsystem

reportformating

subsystem

diagnosticssubsystem

operatorinterface

subsystem

shuntcontroller

mainframecommunications

driver

operator requests CLSS queries, reports, displays

shunt control statusbar code acquisition request

bar code

pulse tach input

linespeed

bar codereader status

sensor status

raw barcode data

partnumber

reportrequests

binlocation

key

sort records

formatedreporting data

sorting reports

shunt commands

CLSS reports

BCR statusshunt status

communications status

timing/location data

operatorinterface

data acquisitioninterface diagnostic interface output interface

CLSS processing & control

sensor dataacquisitionsubsystem

System Modeling with UML•Deployment diagrams

• Each 3-D box depicts a hardware element that is part of the physical architecture of the system

•Activity diagrams• Represent procedural aspects of a system element

•Class diagrams• Represent system level elements in terms of the data that describe the element and the operations that manipulate the data

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Deployment Diagram

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CLSS processor

Sorting subsystem

Sensor dataacquisition subsystem

Operator display

shunt controller

Conveyor Pulse tach

Bar code reader Shunt actuator

Activity Diagram

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get conveyor speed

send shuntcontrol data

get shunt status read bar code

start conveyor line

determine bin location

valid bar code

set for reject bin

conveyor in motion

read bar code

get conveyor status

produce report entry

conveyor stopped

invalid bar code

Class Diagram

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Box

barcode forwardSpeed conveyorLocation height width depth weight contents

readBarcode() updateSpeed() readSpeed() updateLocation() readLocation() getDimensions() getWeight() checkContents()

class name

attributes note use of capital letter for multi-word attribute names

operations (parentheses at endof name indicate the list of attributes that theoperation requires)

Requirements Engineering• Inception—Establish a basic understanding of the problem

and the nature of the solution. • Elicitation—Draw out the requirements from stakeholders.• Elaboration—Create an analysis model that represents

information, functional, and behavioral aspects of the requirements.

• Negotiation—Agree on a deliverable system that is realistic for developers and customers.

• Specification—Describe the requirements formally or informally.

• Validation—Review the requirement specification for errors, ambiguities, omissions, and conflicts.

• Requirements management—Manage changing requirements.

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Inception•Ask “context-free” questions

• Who is behind the request for this work?• Who will use the solution (product/system)?• What will be the economic benefits?

• How would you characterize “good” output from the system?

• What problems does this solution address?• What environment will the product be used in?

• Are you the right person to answer these questions?• Are these question relevant?• Can anyone else provide additional information?• Should I be asking you anything else?

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Getting Requirements Right• “ The hardest single part of building a software system is deciding what to build. No part of the work so cripples the resulting system if done wrong. No other part is more difficult to rectify later.”

—Fred Brooks

• “The seeds of major software disasters are usually sown within the first three months of commencing the software project.”—Capers Jones

• “We spend a lot of time—the majority of project effort—not implementing or testing, but trying to decide what to build.”—Brian Lawrence

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Eliciting Requirements• Why is it so difficult to clearly understand what the customer wants ?• Scope

• The boundary of the system is ill-defined.• Customers/users specify unnecessary technical detail that may confuse

rather than clarify objectives.• Understanding

• Customers are not completely sure of what is needed.• Customers have a poor understanding of the capabilities and limitations of

the computing environment.• Customers don’t have a full understanding of their problem domain.• Customers have trouble communicating needs to the system engineer.• Customers omit detail that is believed to be obvious.• Customers specify requirements that conflict with other requirements.• Customers specify requirements that are ambiguous or untestable.

• Volatility• Requirements change over time.

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Collaborative Requirements Gathering

• Meetings are attended by all interested stakeholders.• Rules established for preparation and participation.• Agenda should be formal enough to cover all important

points, but informal enough to encourage the free flow of ideas.

• A facilitator controls the meeting.• A definition mechanism (blackboard, flip charts, etc.) is used.• During the meeting:

• The problem is identified.• Elements of the solution are proposed.• Different approaches are negotiated.• A preliminary set of solution requirements are obtained.• The atmosphere is collaborative and non-threatening.

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Quality Function Deployment

• Function deployment determines the “value” (to the customer) of each function required of the system.• Information deployment identifies data objects and events.• Task deployment examines the behavior of the system.• Value analysis determines the priority of requirements.

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Elicitation Work Products• Statement of need and feasibility.• Statement of scope.• List of participants in requirements elicitation.• Description of the system’s technical environment.• List of requirements and associated domain constraints.• List of usage scenarios.• Any prototypes developed to refine requirements.

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Use-Cases• A use-case scenario is a story about how someone or

something external to the software (known as an actor) interacts with the system.

• Each scenario answers the following questions:• Who is the primary actor, the secondary actor(s)?

• What are the actor’s goals?• What preconditions should exist before the story begins?• What main tasks or functions are performed by the actor?• What exceptions might be considered as the story is described?• What variations in the actor’s interaction are possible?• What system information will the actor acquire, produce, or

change? • Will the actor have to inform the system about changes in the

external environment?• What information does the actor desire from the system?• Does the actor wish to be informed about unexpected changes?

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Use-Case Diagram

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Elements of the Analysis Model

• Scenario-based elements• Use-case—How external actors interact with the system (use-case diagrams; detailed templates)• Functional—How software functions are processed in the system (flow charts; activity diagrams)

• Class-based elements• The various system objects (obtained from scenarios) including their attributes and functions (class diagram)

• Behavioral elements• How the system behaves in response to different events (state diagram)

• Flow-oriented elements• How information is transformed as if flows through the system (data flow diagram)

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Activity Diagram

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Class Diagram

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State Diagram

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Negotiating Requirements• Identify the key stakeholders

• These are the people who will be involved in the negotiation

•Determine each of the stakeholders “win conditions”• Win conditions are not always obvious

•Negotiate• Work toward a set of requirements that lead to “win-win”

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