Information System Analysis

1
Information System Analysis Design

• May 22, 2002

2
Contents

• System Development Process
• System Analysis Design
• Entity Relationship Diagrams
• Data Flow Diagrams

3
What is a System?

• Concept
• A set of applications that are integrated and
  sequenced to achieve a certain objective of the
  overall process

System
Motive
Result
4
System DevelopmentProcess

• Process Model
• A strategy that encompasses the process, methods,
  and tool layers and the generic phases
• Prototyping Model vs. SDLC Model (Software/System
  Development Life Cycle)

Process Model
Linear Sequential Model
Prototyping Model
Iterative Model
RAD Model
Evolutionary Model
Incremental Model
Spiral Model
Component Assembly Model
Concurrent Development Model
5
Linear Sequential Model
6
Iterative Model
RAD (Rapid Application Development)
Prototyping
7
Evolutionary Model
Incremental Model
Spiral Model
8
System Analysis Design

• Concept
• Method to communicate the contents of each
  activity that belongs to each phase of system
  development
• Motivated by the problem of software productivity
  (Software Crises)

Requirements
Analysis
Design
Design Spec.
Feedback
Programs
Coding
Feedback
Test
Feedback
9
Analysis vs. Design
analysis model
Maps into
Physical AS-IS
Logical AS-IS
design model
Logical TO-BE
Physical TO-BE
10
Structured Methods(1/2)

• Concept
• 1980?? ??? ???? ??? ????? ??? ???? ?? ?? ??????,
  ??? ?? ???? ???? Decision Table ?? ?? ???? ?????
  ??
• ??? ?????? ??? ??? ??? ??? ?? ???, ???? ?? ????,
  ?? ???? ???? Module??? ??? ??? ?? (Module? ????
  ????? ??)
• ??? ????? ???? ????? ??
• ??? ?????? ???? ????? ???? ??? ??? ??
• ???? ?????? ???? ??, ?? ???? ?? ???? ????? ????
  ????? ?? ?? ???? ???? Diagram ?? ??

11
Structured Methods(2/2)
Data Modeling
Function Modeling
Behavior Modeling
12
Data Modeling

• Definition
• A technique for organizing and documenting a
  systems data.
• A database modeling or an information modeling
  because a data model is eventually implemented as
  a database
• ????? ???? ??(entity)? ?? ???? ???? ???
  ???(abstraction)? ?
• Entity Relationship Diagrams (ERD)
• The actual model that depicts data in terms of
  the entities and relationships described by the
  data
• ??? ??? ?? ??(entity)? ?? ??? ?? ???
  (association)? ???? ??(relationship)? ???? ????
  ???? ??? ??

13
ER Diagrams

• Definition
• ??? ??? ?? ??(entity)? ?? ??? ?? ???
  (association)? ???? ??(relationship)? ???? ????
  ???? ??? ??
• Advantage
• ???? ??? ?? ??
• ???? ??? ??? ????? ???
• ???? ???? ???? ??, ???, ???? ??? ??
• ?????? ??? ??? ??

14
Abstraction of Data Model

• ??(Entity)
• ???? ???? ????? ?? ??? ?? ?
• ex) ??, ??
• ????(Entity class, Entity type)
• ??? ??? ?? ???? ??
• ex) ??, ??
• ??(Attribute)
• ??? ?? ??? ??? ???? ????? ?? ??
• ex) ??, ??, ??
• ???(Identifier)
• ???? ?? ??? ??? ?? ???? ?? ??
• ex) ??, ????
• ??(Relationship)
• ??? ?? ???

15
Component Entity

• Definition
• A class of persons, places, objects, events, or
  concepts about which we need to capture and store
  data
• Persons agency, contractor, customer,
  department, division, employee, instructor,
  student, supplier
• Places sales region, building, room, branch
  office, campus
• Objects book, machine, part, product, raw
  material, software package, tool, vehicle model,
  vehicle
• Events application, award, cancellation, class,
  flight, order, registration, renewal,
  requisition, reservation, sale, trip
• Concepts account, block of time, bond, course,
  fund, qualification, stock

Name of Entity
Name of Entity
16
Component Attribute

• Definition
• A descriptive property or characteristic of an
  entity (element, property, field)

17
Component Identifier

• Definition
• An attribute that represents the characteristics
  of an entity on behalf of all other attributes
• Primary key A candidate key that will most
  commonly be used to uniquely identify a single
  entity instance
• Candidate key A candidate to become the primary
  key of instances of an entity

18
Component Relationships

• Definition
• A natural business association that exists
  between one or more entities
• Representation of an event that links the
  entities or merely a logical affinity that exists
  between the entities
• ??? ???? ????? ???? ??

19
Component Degree

• Definition
• The number of entities that participate in a
  relationship
• ?? ??? ??? ??? ?
• ?? ??(unary) ?? ?? ?? ??
• ?? ??(binary) ??? ???? ??
• ?? ??(ternary) ??? ???? ??

20
Component Cardinality Functionality

• Definition
• ? ????? ?? ??? ?? ????? ?? ? ?? ??? ???? ?? ?? ??
• Cardinality ??? ???
• Functionality ??? ????

????
? ?
? ?
Functionality
Cardinality
21
Building an ERD

• Level 1model all data objects (entities) and
  their connections to one another
• Level 2model all entities and relationships
• Level 3model all entities, relationships, and
  the attributes that provide further depth

22
Example ERD (1/2)
????
???? ???? ?? ??? ????? ???? ??? ???? ??? ??. ???
???? ?? ??? ??? ?? ????, ????? ??? ????? ?? ???
?? ?? ?? ????? ??. ??? ???? ????? ??? ????,
??????, ???, ????? ???? ????? ????. ?? ??? ?? ??
?? ??? ??? ???? ???? ????? ??? ???? ???. ?? ?????
??? ??? ?? ?? ??? ???, ??? ??? ???? ?? ?? ??.
???? ??, ??, ?? ?? ???? ??? ?? ???? ??, ??, ?????
????. ??? ???? ?? ??? ???? ???? ??? ???? ???
???? ???. ??? ??? ?????? ???? ??? ?????? ????
???? ????? ????. 3? ? ????? ??? ???? ?????. ???
??? ??? ???? ? ?? ? ?? ? ???.
23
Example ERD (2/2)
24
Function Modeling

• Definition
• A technique for organizing and documenting a
  systems functions or processes
• Description of a systems logical process as a
  cross-functional view (linking functions with
  respect to the data flow within them)

25
Data Flow Diagram (1/2)

• Concept
• ??? ?? ??? ??? ??? ???? ??
• ????? ?? ? ????? ???? ?? (??? ?? ??)
• Edward Yourdon? ?? ??? ??? ?? ???? ???, Chris
  Gane Trish Sarson? ?? ??? ?? ??? ??
• External Entity(??) ??? ??? ?? ???? ??????, ??
  ??? ??? ?? ??? ??? ?????, ?? ?? ??? ?? ???? ??
  (Source, Sink)
• Source(???) ??? ???? ???? ????, ????? ??? ???
  ???? ?
• Sink(???) ??? ????? ???? ????, ?? ???? ?? ???
  ??? ???? ? (????, ??, ??..)

26
Data Flow Diagram (2/2)

• Property
• ???? ???? ?? ??? ??
• ????(Multidimensional)
• ???(??)? ??? ??? ?? ?? ? ??? ??
• Advantage
• ???? ?? ? ????? ?? ???
• ???? ???(???) ??? ????? ?? ???? ??
• ??? ?? ??? ???? ????? ??
• Process? ??? ??? ???? ??? ?? ??? ???? ??? ??

27
DFD Components (1/4)

• Function (Process)
• ???? ???? ??? ???? ???? ????? ?? ????, ??? ??????
  ?(Bubble)? ??? ???? ??
• ??? ???? ??? Function? ???? ? ?? ????? ???? ????
  ??
• ?????? ???? ??? ? ?? ?? Input? ????? ?
• ????? ?? ??? ??? ?? (Output)

?? ??
?? ??
28
DFD Components (2/4)

• Data Flow
• DFD? ????? ?? ?????? ??
• ???? Data Flow? ????? ??? ?????, Data Store????
  Data Flow? ????? ?
• ??? ????? ???? ?? ???? ?? (?? ???? ??? ?? ??? ???
  ???? ?? ???)
• ?? ?? Data Flow? ??? ?? ?? ??

?? ??
?? ??
????
????
???
29
DFD Components (3/4)

• Data Store
• ???? ?? ?? ??
• ???, ???, ?? ???, ???? ????? ?? ?? ???, ??? ????
  ?? ??
• ??? ???? ??? ?? (???? ??? ???? ?? ??)
• ????? ????, ??? ?? Data Store? ??? ??

?? ??
?? ??
????
????
???
30
DFD Components (4/4)

• External Entity
• ??? ??? ?? ? ?? ??
• DFD ?? ?????? ?????? ????, DFD ?? ?? ??? ??? ??
• Example ????
• ???(Inside) ??? ??, ??, ??, ??? ?
• ???(Outside) ??? ??, ???, ????, ?? ??? ?

????
???
?? ????
??
31
Modeling Guideline

• Environment Specification
• ??? ???? ????? ?? ?? ??? ?????? ??, ??? ?? ??? ??
  
• ??? ?? ? ????? ????? ? External Entity ??
• ?????? ????, ?????? ????, ?? ??????? ?????? ??
• Input/Output Specification
• ?? ???? ?????? ?? ?? ?? ??
• ????? ?? Input? Output? ??? ?? ?? ??
• ????? ??? ??? ??? ??
• Decomposition
• ?? ?? DFD ?? ? ?? ?? ??? DFD? ??
• ???? ?????(Subsystem)?? ??, ??? ?????? ??? ?
  ?(Over 7 Bubbles)? ?? ??

32
Diagram Decomposition

• Context Diagram (vs. Level 0)
• ????? ?? ???? ?? ???? ????? ???? ?? ??? ??? ???
  ??? ??
• Bottom Level Diagram (Level 2 or 3)
• DFD ?? ?? ????? ? ?? ?? ??? ???? ?? DFD? ???, ??
  ?????? ???? ?? ????

Context Diagram
Level 2
Level 1
33
Example DFD (1/5)
????
???? ???? ?? ??? ????? ???? ??? ???? ??? ??. ???
???? ?? ??? ??? ?? ????, ????? ??? ????? ?? ???
?? ?? ?? ????? ??. ??? ???? ????? ??? ????,
??????, ???, ????? ???? ????? ????. ?? ??? ?? ??
?? ??? ??? ???? ???? ????? ??? ???? ???. ?? ?????
??? ??? ?? ?? ??? ???, ??? ??? ???? ?? ?? ??.
???? ??, ??, ?? ?? ???? ??? ?? ???? ??, ??, ?????
????. ??? ???? ?? ??? ???? ???? ??? ???? ???
???? ???. ??? ??? ?????? ???? ??? ?????? ????
???? ????? ????. 3? ? ????? ??? ???? ?????. ???
??? ??? ???? ? ?? ? ?? ? ???.
34
Example DFD (2/5)

• Context Diagram

???? ??
???? ??
???? ??
??? ???
????
??
?? ??
??
ID/PWD
????
?????
??????
35
Example DFD (3/5)

• Level 1 Diagram

36
Example DFD (4/5)

• Level 2 Diagram ????

37
Example DFD (5/5)

• Level 2 Diagram ??