A Quick Review of Analysis
Dec 21, 2015
A Quick Review of Analysis
Stages of the Systems Development Life Cycle
Planning
Analysis
Design
Construction
Modeling
• A model is a representation of reality
• Systems analysts try to understand a business by drawing “pictures” or models of the business and its workings.
• Three primary types of models: (1) activity models, (2) data models, and (3) interaction models
Business Modeling In Planning and Analysis: An Overview of the MIS Approach
DataModel
Activity Models
InteractionModels
SystemsDesign
ERD
FHD, PM
PLD, ELC
Analysis Tasks with REAL Interaction Modeling
SystemsDesign
ActivityAnalysis
Interaction Analysis 1
InteractionAnalysis 2
PLD, ELC
FHD, PM
REA
Data Analysis
ERD
Types of Models• Activity models: Records the activities of
interest to the business (i.e., the things the business does or should do)
• Involves decomposition of business processes from the highest level (AMP of Resources, Conversion Processes, MSC Processes) to the lowest (elementary processes)
• Also involves the specification of process dependency events, to refine decomposition of the processes
HEART OF ORGANIZATION
Conversion
Processes
Customers
Finished Goods and Services to Customers
MSCProcesses
Supply goods and services
Receive payment
Activity Models: Template for Decomposition of Business Processes
(IPSO)Suppliers
AMP Processes
Input Resources to
the Organization
Requestinput
resources
Pay for inputresources
Adds value
RBMSSource: Hollander, Denna & Cherrington (2000), adapted
Business Processes
AMP Processes
Human ResourcesFinancial ResourcesSuppliesInventoriesProperty, Plant and Equipment
Conversion Processes
Operations
Varies widely depending upon the industry
MSCProcesses
MarketingSalesCollection and Credit
Business Process: Simple MS
Process and Events
Ship goodsTake customer order
Figure 6FHD: Partial Business Function Decomposition
Types of Models• Interaction models: Define how things the
business does (activities/events) affect things of interest to the business (data)
• Faculty at OU have combined the IE notation of an interaction model with the accounting REAL model
• Formal interaction modeling facilitates the transition from systems analysis to systems design.
REAL Model of A Business Event:The Event and Surrounding RALs
• What happened? - event
• When did it happen?- sequence
• Who was involved?-agents
• What resources were involved? – resource(s)
• Where did it occur? – loc.
Event
Internal Agent
ResourceExternalAgent
Location
Source: Hollander, Denna & Cherrington, 1996
• REAL modeling is an aid in analyzing an organization and its activities (helps develop activity models by identifying lowest level of decomposition)
• Helps decide what data to collect (helps develop data models)
• Enhances your ability to evaluate business processes
REA Template With Two Events
ResourceResource
Internal Agent
Internal Agent
ExternalAgent
ExternalAgent
LocationLocationEvent 1:
Take customer
order
Event 1: Take
customer order
Internal Agent
Internal Agent
ResourceResource
Event 2:Ship
goods
Event 2:Ship
goods
LocationLocation
External Agent
External Agent
Business Rules
• Narrative descriptions of policies, procedures, or principles in an organization
• Simple Examples: – Each purchase order must have only one vendor– Each vendor may have one or more purchase
orders
Relationships• Data modeling term that indicates an association
between tables: How the things of significance are related (A FK must match to an existing PK, or else be NULL)
• This controlled redundancy allows linking of tables (hence “relational”)
• Entity-Relationship Diagram (ERD): A data model (at the conceptual level) that shows the relationships enforcing business rules between entities (tables) in a database environment
Connectivity or Cardinality
One-to-One (PK ---> PK) - Generally indicates that your data model has two entity types that can be collapsed into one
• One-to-Many (PK ---> FK) - Most common
• Many-to-Many (FK ---> FK) - Not enforceable by RDMS; generally indicates that a modeling error has occurred - this type of relationship means that your model is missing an entity type
Cardinality of Relationships
• Mandatory - an instance of an entity in one table does require a associated record in another table (as defined by a relationship)
• Optional - an instance of an entity in one table does not require a associated record in a another table (as defined by a relationship)
Validate The REAL Model With Business Persons
• Those who understand the details and objectives of the business process and events being modeled should perform the validation.
• Validation sessions should result in either the confirmation of the model’s accuracy or modification of the model.
EventsMost events are easy to identify because the business
records data on forms or files. • Events are characterized by the fact that they
happen or have duration– For activity and REAL models, they are characterized
by at least a verb and a noun, but could have an adjective, take customer order, deliver customer order, pay supplier
– For data models (converting REAL to ERD), they are characterized by a noun, e.g., Order header, Order detail, Sales header, Sales detail, Cash receipt
Surrounding RALS
RESOURCES
• Entity types that describe tangible things.
• EQUIPMENT, INVENTORY, CASH, MACHINE, MATERIAL, PART, PRODUCT, VEHICLE, but they can also be Informational Resources, e.g., PRODUCT CATALOG
Surrounding RALs
AGENTS• Entity types that describe roles played in a
system. They usually represent people or organizations.
• APPLICANT, BORROWER, CLIENT, CREDITOR, EMPLOYEE, EMPLOYER, INSTRUCTOR, MANAGER, SALESPERSON, VENDOR
Surrounding RALs
LOCATIONS
• Entity types that describe locations
• BRANCH, BUILDING, CAMPUS, CITY, COUNTRY, COUNTY, SALES REGION, WAREHOUSE, STORE, FRANCHISEE
A REAL Interaction Model for MSC Function
Sell Goods
CustomerInventory
SalespersonDepartment
Receive Payment
CashierCash
Store
Types of Models• Data model: One type is the ERD that depicts
data (entities, attributes) and the relationships enforcing business rules between entities.
• The primary goal is to accurately portray the fundamental elements of the business information system.
• The data model is implemented as a database in a developed system (central to the IS)
ERD with Normalization