chapter 6 system engineering
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Chapter 6 System Engineering. System Engineering. What is a computer-based system? A set or arrangement of elements that are organized to accomplish some predefined goal by processing information Elements of a computer-based system Software Hardware People Database Documentation - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 6System Engineering
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System Engineering What is a computer-based system?
A set or arrangement of elements that are organized to accomplish some predefined goal by processing information
Elements of a computer-based system Software Hardware People Database Documentation Procedures
Systems A hierarchy of macro-elements
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The Hierarchy
World view
Business orProduct Domain
Domain of interest
Domain view
System element
Element view
Detailed view
e.g., School Administrative Information System
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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 (BPE)
Uses an integrated set of procedures, methods, Uses an integrated set of procedures, methods, and tools to identify how information systems and tools to identify how information systems can best meet the strategic goals of an can best meet the strategic goals of an enterpriseenterprise
Focuses first on the enterprise and then on the Focuses first on the enterprise and then on the business areabusiness area
Creates enterprise models, data models and Creates enterprise models, data models and process modelsprocess models
Creates a framework for better information Creates a framework for better information management distribution, and controlmanagement distribution, and control
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System Architectures
Three different architectures must be analyzed and designed within the context of business objectives and goals: data architecture applications architecture technology infrastructure
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System Architectures (cont.)
Data architecture provides a framework for the information needs of a
business or business function i.e., database schema
Application architecture encompasses those elements of a system that transform
objects within the data architecture for some business purpose
i.e., programs Technology infrastructure
provides the foundation for the data and application architectures
i.e., hardware, software,
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The BPE Hierarchy Information strategy planning (ISP)
strategic goals defined success factors/business rules identified enterprise model created
Business area analysis (BAA) processes/services modeled interrelationships of processes and data
Application Engineering a.k.a ... software engineering modeling applications/procedures that address (BAA)
and constraints of ISP Construction and delivery
using CASE and 4GTs, testing
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The BPE Hierarchy (cont.)
Information strategy planning(World view)
The enterprise
Business area
Business area analysis(Domain view)
Processing requirement
Business systemdesign
(Element view)
Construction&
Integration(Detailed view)
A business area
Informationsystem
SoftwareEngineering
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Information Strategy Planning
Management issues define strategic business goals/objectives isolate critical success factors conduct analysis of technology impact perform analysis of strategic systems
Technical issues create a top-level data model cluster by business/organizational area 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” Subgoals:
decrease reject rate by 20% in first 6 months gain 10% price concessions from suppliers re-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 model define 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
salesacct
manufacturing
QC
eng’ring
distribution
admin.
DataModel
ProcessDecomposition
DiagramMatrices
e.g.,entity/process
matrix
Process Flow
Models
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Product Engineering
Goal: To translate customer’s desire into a working product
Consist of four system components Software Hardware Data People
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Product Engineering (cont.)
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
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Product Architecture Template
user interface processing
inputprocessing
outputprocessing
maintenance and self-test
process and controlfunctions
Proposed by Hatley and Pirbhai, also known as Hatley-Pirbhai modeling
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Architecture Flow Diagram (AFD)
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
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SFD Hierarchy
A B
C
Top level AFD
AFD for B
AFD for A
AFD for C
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System Modeling with UML Deployment diagrams (Modeling hardware)
Each 3-D box depicts a hardware element that is part of the physical architecture of the system
Activity diagrams (Modeling software) Represent procedural aspects of a system element
Class diagrams (Modeling data) Represent system level elements in terms of the data that
describe the element and the operations that manipulate the data
Use-case diagrams (Modeling people) Illustrate the manner in which an actor interacts with the
system*These and other UML models will be discussed later
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Deployment Diagram
CLSS processor
Sorting subsystem
Sensor dataacquisition subsystem
Operator display
shunt controller
Conveyor Pulse tach
Bar code reader Shunt actuator
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Activity Diagram
get conveyor speed
send shunt
control 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
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Class Diagram
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)
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Use-Case Diagram
Request bar code
Request shunt control status
Request box processing report
Update product database
Run system diagnostics
CLSS operator