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