Download - Systems Analysis
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Systems Analysis
IDEF0 and IDEF1.x
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Systems Analysis
Moving from IDEF0 to IDEF1.xTechnique for describing information
structuresInformation models represent:
things - entitiesproperties of things - attributesassociations between things -
relationships
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Entities
Abstractions of real world thingseg CUSTOMER
does not relate to specifict customers ...any distinguishable person, place, thing, event or
concept about which information is kept. (Bruce 1992)
Specificcustomer
A
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AA
Attributes
Each set of data for an entity may be regarded as an ‘instance’ of that entitiy
The individual pieces of data for an instance are called attributesA
Customer
NameAddressTel No.Credithistory
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Relationships
Imagine two entities: Lecturer and Student
Lecturers teach studentsTeaching is the “relationship”
between the two abstract entities
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Types of Information Model
Entity Relationship Model: shows major entities and relationships - wide business area
Key Based Models: Third normal form model that describes major data structures (entities, keys and sample attributes) - wide business area
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Types of Information Model
Project Information Model: describes a portion of an overall data structure - specific to a development project
Fully Attributed Model: third (or higher) normal form model (entities, attributes, relationships and integrity rules) - single project
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IDEF1.x - Components
Entity
Entity Names are instances - each instance represents a customer not multiple customers
Area above line is for key attributesArea below line if for non-key attributes
Entity Name
Primary Key Area
Data Area
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Relationships
Relationships are connections or links between entities
LECTURER STUDENTteaches
One to Many
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Relationships
Non-identifying Relationship
LECTURER STUDENTteacheslecturer-no student-no
lecturer-no (FK)
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Relationships
Identifying Relationship
BOOK
BOOK-COPY
classmarkcopy-noclassmark (FK)
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Relationships
Resolving many to many linksA person may use more than one
address, an address may be used by more than one personPERSON ADDRESS
person-id address-id
ADDRESS-USAGEperson-id (FK)address-id (FK)usage-type
may use used by
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CardinalityIdentifying Relationship
P
Z
N
One to Zeroor more
One to Oneor more
One to Zeroor One
One to exactlyN
P
Z
N
Non-identifying Relationship
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Cardinality
Example - Zero or One to One or more relationship
salesperson-id
order-no
salesperson-id (FK)
P
receives credit for
SALESPERSON
ORDER
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Generating IDEF1.x
ReceivePurchaseRequest
WorksheetPack
BuyingKnowledge
Quotes
EstablishSupplier
CompletedWorksheetPack
Activity Model
QUOTESWORKSHEET-PACKAGE
Information model
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Information model
QUOTES
OPERATIONS
LAYOUTS
WORKSHEET
DRAWINGS
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GuidelinesCreate activity dia of business processFrom the info flows, create entity poolCreate entities on information modelInvestigate detail of aggregate entitiesDraw relationships between entitiesResolve many-to-many linksInsert keys and specify identifying/non-
identifying relationshipsValidate with users