System Engineering
CIS 375
Bruce R. Maxim
UM-Dearborn
1
Computer System Elements
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Software.
Hardware.
People.
Databases.
Documentation.
Procedures (for humans, not code).
2
System Engineering
• Don't take a "software-centric" view of the
system.
• Consider all system elements before focusing
on software.
• System engineering begins with a clear
understanding of the "world view" and
progressively narrows until technical detail is
understood.
• Complex systems are actually a hierarchies
of subsystems.
3
System Engineering Hierarchy
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World view
Domain view
Element view
Detailed view
4
Project Engineering Hierarchy
• Requirements engineering
– world view
• Component engineering
– domain view
• Analysis and Design modeling
– element view (software engineers)
• Construction and Integration
– detailed view (software engineers)
5
Business Process Engineering
Hierarchy
• Information Strategy Planning
– world view
• Business Area Analysis
– domain view
• Business System Design
– element view (software engineers)
• Construction and Integration
– detailed view (software engineers)
6
Business Process Engineering
Architectures
• Data architecture
– provides framework for information needs of a
business or business function
• Applications architecture
– system elements that transform objects within the
data architecture for some business purpose
• Technology infrastructure
– provides foundation for the data and application
architectures
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Computer Systems Engineering
• Software Engineering
• Hardware Engineering
• Human Engineering
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Computer System Analysis Tasks
-1
• Transform customer defined goals and
constraints into system representation
describing:
– Function.
– Performance.
– Interfaces.
– Design constraints.
– Information structures.
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Computer System Analysis Tasks
-2
• Bound the system and select the
configuration using:
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Project schedule and costs.
Business considerations.
Technical analysis.
Manufacturing evaluations.
Human issues.
Environmental interface.
Legal considerations.
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Human Engineering
• Activity analysis
– watch the people you’re supporting
• Semantic analysis and design
– what and why they do things
• Syntactic and lexical design
– hw & sw implementation (e.g key strokes)
• User environment design
– physical facilities and HCI stuff
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Requirements Engineering - 1
• Requirements Elicitation
– find out from customer
what the product objectives are
what is to be done
how the product fits into business needs
how the product is used on a day to day basis
• Requirements Analysis
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requirements organized into subsets
relations among requirements identified
requirements reviewed for correctness
requirements prioritized based on customer needs
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Requirements Engineering - 2
• Requirements Specification
– work product produced describing:
function
performance
development constraints for system
• System Modeling
– system representation that shows relationships
among the system components
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Requirements Engineering - 3
• Requirements Validation
– examines the specification to ensure
requirement quality
– make sure work products conform to
agreed upon standards
• Requirements Management
– set of activities that help project team to
control and track requirements changes as
project proceeds
14
Traceability Tables
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Features traceability table
Source traceability table
Dependency traceability table
Subsystem traceability table
Interface traceability table
15
System Modeling
• Define processes that serve needs of the
view under consideration
• Represent process behavior and the
assumptions on which it is modeled
• Explicitly define links between constituents
and the links between constituent
components that are input to the model
• Represent all linkages (including outputs)
required to understand the view
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System Model Restraining
Factors
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Assumptions
Simplifications
Limitations
Constraints
Preferences
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System Model Template
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User interface
Input
Process and control functions
Output
Maintenance and self test
18
System Context Diagram
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Systems Modeling Process - 1
• System Context Diagram (SCD or ACD)
– top level node in system hierarchy used to
establish the boundaries for the system
being implemented
• System Flow Diagram (SFD or AFD)
– refinement of the process and control
functions from SCD
– derived by identifying the major
subsystems and lines of information flow
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Systems Modeling Process- 2
• Initial SFD is becomes the top level
node of a hierarchy of more
successively more detailed SFD's
• System Specification
– developed by writing narrative description
for each subsystem and definitions for all
data that flow between subsystems
21
System Simulation
• If simulation capability is not available
for a reactive system, project risk
increases.
• Consider using an iterative process
model that will allow the delivery and
testing of incrementally more complete
products.
22
 ACD
USER INTERFACE PROCESSING
Component
Management
Engineer
Design Component
Part Number or
Menu Selection
Validation
Result
Table1.CSV
Master PN and
3D Model Info
Part Number
Analysis (PNA) Tool
Table2.CSV
Master PN and
Cross-Ref PN
Data
Printer
Validation
Result
Error
Message
WKConnectors.
CSV
Design Component
Part Number
PROCESS AND
CONTROL FUNCTIONS
Component
Management
Engineer
INPUT
PROCESSING
MAINTENANCE AND SELF-TEST
OUTPUT
PROCESSING
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 AFD
Operator
Interface
Design Component Part
Number or Menu Selection
Operator
Interface
subsystem
Display GUI
View/Print Validation
Results
Per form Analysis
Requested Data
Connectivity Check
MS ACCESS
Data Source
Connectivity
subsystem
Design Component Part
Number, Master Part
Number, Cross-Ref Part
Number and Model
Information
Error Code
Data Acquisition
Interface
Error
Data Request
Message and
Instructions
Application
Startup
subsystem
Design Component Part
Number, Master Part
Number, Cross-Ref Part
Number and Model
Information
Formatted
Validation
Result
Formatted
Validation
Result
MS ACCESS
Printing
subsystem
Report
Formatting
subsystem
Data Table
Management
subsystem
Error Code
Part Number
Analysis
subsystem
Error Code
Error
Code
Unformatted
Validation
Result
MS ACCESS
Run-time
Diagnostics
subsystem
PNA
Processing
and Control
Validation
Result
Error Code
Error Code
Diagnostic Interface
Output
Interfaces
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 Data Processing
10
TBL_CREATEDWKCONN
REPORT
VALIDATION DATA
WKCONNECTORS
- UNIQUE PN
- USAGE
COMPARISON RESULT
1
2
9
TABLE CRITERIA
QUERY
CONSTRUCT
SUB-TABLES
3
COMPARE DATA
8
6
TABLE1
7
TBL_CREATEDT1
QUERY RESULT
TBL_CREATEDT2
TABLE2
4
5
CRITERIA:
(1) Do not consider leading
zeroes and dashes
(2) Consider leading
zeroes and dashes
QUERY RESULT
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 Storyboard
MULTIPLE PART NUMBER VALIDATION
Main
Status
PART NUMBER ANALYSIS TOOL
Please wait…
(Version / Release Date)
Data analysis currently in progress.
Updated when
analysis is finished.
Part Number Quick Check
Analyze Part Numbers
Status
Data analysis finished.
Report has been created.
View / Print Report
Save Report
OK
(Logo / Branding)
Exit
Help
PREVIEW REPORT ON SCREEN.
Part Number Quick Check
Output To
SAVE VALIDATION
DATA
Part Number
Analyze
Select format
HTML
Microsoft Excel
MS-DOS Text
Rich Text format
Snapshot format
Close
Result
OK
Cancel
Part Number *** belongs to category X (GOOD/NEW/BAD)
Comments:
(Place Remarks here)
SINGLE PART NUMBER
VALIDATION
OK
MS ACCESS dialog
carries out File
Save Process
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 DFD/CFD Level 0 - Part Number Analysis (PNA) System
WKConnectors.XLS
Spreadsheet
Information
CSV File Creation
(WKConnectors.CSV)
Display Monitor
WKConnectors
Delimited Text
Information
Report Results
Table1.CSV
Table1 Delimited
Text Information
Table2 Delimited
Text Information
PART NUMBER
ANALYSIS (PNA) Tool
Report Results
File
Report Results
Table2.CSV
- Command
- PN data
Printer
User
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 DFD/CFD Level 1 - Part Number Analysis (PNA) Tool
WKConnectors
Delimited Text
information
Report Results
Validation Results
Table1
Delimited Text
information
Report Results
Validate Data
Process Report
Print / Save
Data
Report Results
Table2
Delimited Text
information
- Command
- PN data
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 DFD/CFD Level 2 - Validate Data
tbl_Classification
WKConnectors
Delimited Text
information
Make
tbl_createdWKConn
- Command
- PN data
Relevant WKConnector
Records
Make WKConn
Category
Reference ID
Validation
Results
tbl_createdWKConn
WKConn field
data
- Component
Remarks
- Category ID
tbl_createdT1
T1 Field data
Relevant T1
Record(s)
Table1 Delimited Text
information
Analyze/Classify Data
Criteria:
- dbs
- strCriteria
- strOrigPN
Print / Save
Data
Criteria:
- dbs
- strOrigPN
T2 Field data
Make tbl_createdT1
tbl_createdT2
Table2 Delimited Text
information
Make tbl_createdT2
Relevant T2 Record(s)
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 DFD/CFD Level 3 - Make tbl_createdT1
Table1
Delimited Text
information
Criteria:
- dbs
- strCriteria
- strOrigPN
qry_Table1UniquePN
Recreate tbl_createdT1
Table1
Query
Results
Relevant T1
Record(s)
 DFD/CFD Level 3 - Make tbl_createdT2
Criteria:
- dbs
- strOrigPN
Table2
Delimited Text
information
Recreate tbl_createdT2
qry_Table2PrelimUnique
Table2
Query
Results
Relevant
T2Record(s)
30